Full transcript
0:01um I personally studied a lot of block
0:03of polymer so I I know lot about
0:07Professor work but then yeah anyways uh
0:10and then uh after um his postoral
0:13training he uh Dr Lee M to um Shanghai
0:17Tech in uh
0:182015 uh and he developed his own uh
0:21research career um and then uh very
0:24recently in 2024 he joined the
0:26University of alite um the school of
0:28physics chemistry and Earth sence so
0:31yeah please me welcoming U
0:34Dr thank you uh first i' would like to
0:37thank Professor Sean for inviting me
0:39over to have a seminar here and uh this
0:42is the second time I'm here at UTS and
0:46uh I would like to show some of the re
0:48research that we did over the past uh
0:50eight eight years uh mainly back in sh
0:54Tech I think it's easier for me to stand
0:57over here and uh the topic I would like
0:59to uh talk about today is Reinventing
1:02Forest composite materials and uh the
1:05specific strategy is uh botom up
1:07fabrication of moth polymer hybrid
1:10materials so a little bit about my uh
1:13background uh although
1:16uh so uh I I uh studied my PhD degree at
1:22uh University of Pittsburgh in the
1:23United States where I studied the design
1:26of new moths mainly and then uh after I
1:29graduated in 2013 I went to UC Berkeley
1:33where I studied uh polymer physics
1:36that's these are two completely
1:37different fields of area and uh it was
1:40kind of coincidental because when I
1:43graduated from PhD I was looking for an
1:45industrial job and I got one but then uh
1:48right before my defense uh the the
1:51company said we cannot give you the
1:53offer because it was the oral offer not
1:55a written on paper offer so I applied
1:58for several postto right way and I ended
2:01up in UC Berkley uh in the topic that I
2:03don't know very much but it was kind of
2:06a blessing because by combining these
2:08two areas uh I was able to develop my
2:12independent career at Shanghai Tech
2:14University studying in 2015 and I I
2:17actually had a pretty successful career
2:19back in Shang Tech where I had a group
2:22of around 10 graduate students and then
2:25but uh after the pandemic um my family
2:28and I decided to move abroad to
2:30Australia so I kind of give up the
2:33permanent position there and I uh took a
2:36took me a while to find a position in
2:38Australia but uh right now I I ended up
2:41being University of La and Professor sha
2:43also gave me some very good advice last
2:45year on how to start my restart my
2:48science
2:50Journey so uh uh since my work mainly
2:53focuses on moth and its composite
2:56materials I just give you a brief
2:58introduction of what is a moth uh in
3:00case you're not familiar with this type
3:02of material moth is uh called the
3:05metalorganic Frameworks and it's a type
3:07of material made up of metal ions and
3:10multi- dented organic lians and when
3:13they connect they tend to connect into a
3:153D periodic structure uh which often
3:19holds a substantial amount of cacity
3:22after removing solvent molecule and they
3:25typically show very nice single Crystal
3:27structures which is really nice for
3:29chemist because we can study the
3:31structure precisely and know exactly the
3:34poor size and poor chemistry of
3:37it but because of its single
3:40crystallinity it also comes as a curse
3:42because we know crystals are always
3:44brittle if the crystals are sponge and
3:46soft like then they will lose their
3:49periodicity right so they are hard to
3:52process and hard to shape as
3:54well and if we think about moth
3:58applications uh even for the simplest
4:00application like gas storage and we can
4:03put M particles into a gas tank to
4:06enhance the gas storage capacity we
4:09cannot directly apply powdery material
4:11into the tank because the powder can go
4:13everywhere and clock clock the pipeline
4:16and if we use this kind of Po material
4:18for catalysis large single crystals are
4:21not ideal because it will impose a
4:23diffusion limitation or if it's a nanoc
4:26crystals then it will be difficult to
4:28recycle and it will have tons of defects
4:31and there will be a issue of size
4:33control if we want to use mouths as a
4:36separation membranes we need to apply it
4:39onto a robust substrate such as alumina
4:43and this is very costly as well so
4:46really it's using moth by itself is
4:49quite
4:50difficult and uh there are different
4:52people studying moth chemistry as a
4:55chemist uh we tend to focus on the
4:58beautiful structures of MTH and that's
5:00where why I got into this area in the
5:03first place but we don't really care
5:04about what's next for Ms and how does it
5:07go to Industrial applications as an
5:10engineer uh Engineers probably don't
5:12care too much about the details of the
5:14structure but they uh focus on scaling
5:17up the math production and also how to
5:19reduce its cost and make it more
5:21environmentally friendly and there's a
5:24gap in between these two field which uh
5:27supposedly should be filled by material
5:29scientist
5:32and my solution towards that is that I
5:34want to combine my expertise in moth
5:37chemistry and polymer physics and
5:40combine these two material into composit
5:43and but this concept is not new uh
5:46people have been combining materials for
5:49uh several decades for moth and polymer
5:51the blending studed when the mo was
5:54first invented so the idea is to utilize
5:58the hard and hard uh hardness of the
6:01moth to preserve the procity whereas the
6:03softness of the polymer to make the
6:06material more
6:08processible so um my research at
6:11Shanghai Tech University focuses on two
6:13types of composite moth and polymer
6:16composite as well as moth composite with
6:18itself and uh today's talk we'll just be
6:22focusing on this area of
6:24research so if you think about combining
6:27moth and polymer into a composite
6:29materials or we study the composite
6:31material at different length scale in a
6:33microscopic scale we look at the shape
6:36and geometry of the and the form factor
6:39of the composite material and uh in the
6:42misos scopic scale we can use em
6:44techniques to study the interior a
6:47detailed structure of it but that's not
6:49enough if you further zoom in and the
6:52information that's missing is the
6:56structure of polymer around the moth
6:58particle and that's the most difficult
7:00to uh study and characterize if you
7:03consider a dense composite material such
7:06as mixed Matrix membrane it's the same
7:08thing people usually break the membrane
7:10into half and study the cross-section of
7:13the membrane but uh what's the
7:15information is missing is still the
7:17polymer around the mouth whether uh what
7:19is The Binding uh what is the
7:21interaction at the interface that's the
7:23critical part that's uh closely related
7:26to the performance of the final
7:28composite materials
7:30so for example if we consider the
7:33polymer around the MTH particle there
7:35are three case scenarios the first case
7:37is that the polymer is a uniform layer
7:40that coat The Moth particle uh without
7:43defects then the gas molecules has to go
7:47through the polymer to access the
7:48interior of the moth right then the
7:50polymer can serve as a barrier to
7:52protect the moth mechanically and
7:54chemically but if there's a little bit
7:57defects the C covering is not
8:00uh complete then the polymer cannot
8:02serve as a protective layer for the moth
8:05particle if we put this Mo particles
8:08collectively into uh a big composite
8:12then without polymers these Mo particles
8:14have very little interaction with each
8:16other so the composite is very fragile
8:19if we have too much polymer then the
8:21polymers filled into the gaps of the
8:24moth particle then the diffusion of gas
8:26molecule will become an issue so we just
8:28need the right amount of polymer that's
8:31coding all the mouth particles without
8:33uh clogging the inter particle gaps so
8:36that's the ideal case scenario if we
8:39look at the dense compos such as a mixed
8:41Matrix membrane even though polymers are
8:43all around the MTH particle but at the
8:45MTH polymer interface that can be
8:48defects right because of the drawing of
8:51the polymer that creates the this
8:52pulling uh Force the polymer can peel
8:55off from the M surface which creates a
8:58nanoscale gap hard to characterize but
9:01the gas molecules when it diffuses it
9:03will go around the moth particle and
9:06thereby The Moth particle cannot exhibit
9:08any enhanced s activity to the overall
9:11polymer so my Approach uh as a chemist
9:15and material scientist is we want to uh
9:17take the concept from nanoscience where
9:20people are proud of using a strategy
9:22called bottom up fabrication uh where
9:25they use atoms and building to clusters
9:27into the final Nano structure and I I
9:31want to apply the same concept to
9:33composite materials and I want to build
9:35a m at polymer cor shell particle first
9:39uh at this stage I want to carefully
9:41contr chol the interfacial interaction
9:43by Design and then once we have this
9:45Nano building blocks we can use that to
9:48self assemble into a secondary structure
9:51uh whether it's sheets uh chains
9:55or other kind of super structures or we
9:59can use blend this composite particle
10:03with more polymers and utilize the power
10:06of polymer physics to drive uh into more
10:09sophisticated
10:10structures this is like a different
10:12stages of protein
10:17folding so the the first part is the
10:19most crucial right we want to have a
10:21know interface to start with so that we
10:23can know exactly that what uh what the
10:26interface is so my research uh
10:30centering around this Mor polymer coell
10:32particle we want to study first how to
10:35apply different polymers to the MTH
10:37surface second how to control different
10:40interactions at the MTH polymer
10:42interfaces then we can once we have this
10:45library of materials we can study how
10:48this surface polymer can uh impart MTH
10:50with new functions such as uh
10:52controllable surface energy improved
10:55chemical stability improved
10:56dispersibility in different matrices as
10:59well well as how to use this uniform
11:01polymer layer to control the gas
11:04diffusion across the polymer uh
11:06surface so when when I just started this
11:09project uh in 2015 there were very
11:11little examples very few examples
11:14showing that polymers can be cated onto
11:17the M surface uh into a uniform layer
11:20for example uh this work published in
11:232014 utilized a coupling reaction to
11:27cross link a microporus conjugated
11:30polymer to the m particle surface and
11:33this work uh published in Advanced
11:36Materials in 2013 actually uses a layer
11:40by layer self assembly method to apply
11:42positiv and negatively charged polymer
11:45onto surface in multiple layers and
11:47eventually after digesting The Moth you
11:49can see a very uniform layer of polymer
11:51on the moth Sur but that's the only two
11:54examples uh at in
11:562015 so when we started we want to first
12:00start with this category of polymer
12:02addition polymers because we can use
12:05controled radical polymerization to
12:07control the polymer growth on the MTH
12:08surface but when you think about growing
12:11polymers on Ms it's not like other
12:14nanomaterials if you talk about gold
12:16nanop particles it's only one element
12:19and you can use tho Gold Bond to create
12:22this coent linkage between polymer and
12:24the gold nanop particles if we talk
12:26about oxides you can utilize the o
12:29groups and connect to siline and then
12:31you can append the polymer to the
12:32surface for proteins you can use Amino
12:35groups or thy groups or other coent
12:37linkages but moth is not one material
12:40it's a collection of tens of thousands
12:42of materials and you want to find a
12:44method that is suitable for all moths
12:47you cannot rely on coent linkage so
12:50that's why we uh came up with an idea
12:52that uses a random copolymer that's
12:55designed to bind to the MTH surface
12:58through hydrogen B uh cross linking so
13:01this random copolymer contains at least
13:03two functional groups one is uh a
13:07carboxilic acid group which can create
13:10hydrogen uh Bond Network to interact
13:13with the m surface as well as to other
13:15polymer strings another functional
13:17groups is an atrp initiating Group which
13:20allows us to grow polymers further from
13:22this random polymer so when we mix the
13:25moth with this random polymer the random
13:27polymer can be physically to the MTH
13:29surface within couple of seconds and
13:32that brings uh the ATP initiating group
13:35to the MTH surface then we can add this
13:38particle into a mixture of MERS and
13:42cross linkers and initiate the atrp
13:44polymerization now we can grow a very
13:46uniform layer of Crosslink polymer on
13:49the MTH surface so this is the example
13:51of we growing poly styring onto five
13:55different M surfaces all all of which do
13:58not have a coal
13:59linkage groups on the surface so we can
14:02grow it into a very uniform polyer layer
14:05with the thickness highly controllable
14:07by the polation process and uh uh this
14:11we call it precise Mo and polymer
14:13composite because we have the exact
14:15thickness measurable under
14:18TM and because of the initiating uh
14:21process starts from the mo surface it
14:23will not create a linkage between Mo
14:26particles so that we can use this uh
14:30coell particles to do self assembly
14:32because these are very monodispersed
14:34particles we can change the Monas to
14:37control the surface energy of the moth
14:39particle from very hydrophilic by using
14:42the O abundant polymers to hydrophobic
14:46by using the poly coding or to
14:49very super hydrophobic by using a
14:52peroral functional groups we can
14:55linearly tune the surface function of
14:57the moth we can also use the Crosslink
15:00polystyrene layer that that has a
15:02thickness of only 7 NM to improve Some
15:06Mo stability uh for example this deonia
15:09Mo called
15:10u66 uh is very sensitive to Hy sulfuric
15:15acid and it degrades within 10 minutes
15:17and the room temperature in the one mol
15:20sulfuric acid solution but when we coat
15:23this moth with a 7 NM polystyrene then
15:26the stability drastically improved it
15:28can with stand
15:29Hydro sulfuric acid at 50° for over 24
15:34hours and this uh this graph shows the
15:37CO2 absorption of the uio 66 moth after
15:42uh sulfuric acid treatment and there's
15:44not much change of the CO2 uptake
15:46capacity after
15:49that so once we have this uh great
15:53method to apply polymer to nearly all
15:56kinds of moths we uh immediately thought
15:59another application is uh when in 2015 a
16:02new type of material emerged in Material
16:05Science Community called por liquids uh
16:08this is a very unique material because
16:09we consider traditional liquids a non
16:12porous because of the close packing of
16:14uh liquid molecules but if we can
16:18disperse a porous particle into a bulky
16:20liquid where the bulky liquid is larger
16:23than the core of the porous particle
16:25then the porosity of the porous particle
16:29can be retained inside a liquid which
16:31makes a liquid porous so that material
16:33is called porous liquids and why why is
16:36it you uh interesting for po liquids if
16:39we think about an industrial wet
16:42scrubbing process where we REM remove
16:44CO2 and other acid gases and typically a
16:48liquid zbin is used because liquid zbin
16:50can be pumped uh into the absorber and
16:53spray into droplets once it contacts
16:56with the uh gas and removes CO2 it
16:59condenses and then can be pumped back
17:01into another container for regeneration
17:03so this process is very con convenient
17:06in
17:07industry but what they use is typically
17:10highly corrosive uh organic uh aiming
17:14Solutions uh for acid gas removal and
17:17also the organic aiming uh liquid uh has
17:21a high heat of absorption for uh
17:24regeneration so if we can
17:27disperse uh Z such as MTH particles into
17:30a liquid successfully then we can create
17:33a porous liquid that ex exhibits the
17:36same aborption behavior as moths since
17:39we have tens of thousands of moths we
17:41can uh expand the possibility of liquid
17:44zbin indefinitely so we chose a poly uh
17:49dimethyl Cy oxin which is called silicon
17:52oil or called pdms as a solvent and this
17:55is a solvent has a lot of benefit as uh
17:58as solvent for porous liquids because it
18:01has a low melting point has a low vapor
18:03pressure and it has very good chemical
18:06Thermo stability it's non-corrosive and
18:09also low
18:10cost and when we use moths uh the moth
18:14surfaces are typically hydrophilic and
18:16it doesn't like to disperse into pdms
18:19but we have developed this uh polymer
18:22coding strategy that that can allow us
18:24to coat a layer of pdms containing
18:26polymer to the mouth surface so that now
18:29Mo particles can be well dispersed into
18:32pdms liquid then it becomes a fre free
18:35flowing liquid now we select this moth
18:37called Ur 66 where we can change the
18:40functionality of the moth by replacing
18:43the simply replacing the organic
18:47Lig so uh here is the mo at polymer
18:51coell particle where we have coded a
18:53layer of a thin layer of pdms on the MTH
18:56surface and then we can
19:00squee uh once this uh particle is mixed
19:03with pdms we can squeeze this liquid
19:06through a very thin syringe so you can
19:10see that it behaves like a liquid and um
19:13Mo particles can absorb CO2 uh within
19:16this long ISO and you can see the porous
19:20liquids can uh exhibit very similar CO2
19:23uptake isotherms as uh the moth itself
19:28and the PDM Ms can only absorb CO2 a
19:31very a little bit uh according to the
19:33Henry's law so we have now successfully
19:35inut pdms liquid with the unique gas
19:39absorption properties of a mo
19:45particle so the next
19:53step a little bit uh insensitive yeah
19:57but now we have created micr PES in
19:59liquids the next stage is how can we
20:01create larger PES such as misop 2 to 50
20:05NM right these PES are so large that you
20:07cannot find a solvent that can uh uh
20:10that's larger than this this pore size
20:13so the strategy that we use is to coat
20:15The Moth surface first with a dense poly
20:20tibo mulate layer which serves as a
20:22barrier layer that can block the solvent
20:25then we can code this polymer uh surface
20:28with another polymer containing pdms for
20:31better dispersion of the mo particles
20:33then we use this composite particles and
20:35disperse into pdms we can retain a large
20:39por even uh bigger than 2 NM into the
20:42Miso porus
20:44region so in this example we show that
20:47we can successfully create uh a porous
20:50liquid contains a Poe as large as 3.4
20:53nanometer within a liquid and this is
20:56the water uptake isotherm shows that the
20:59porous liquid shows very similar water
21:01uptake Behavior as a bare moth
21:05itself so the next step is that we want
21:08to create micro pores macro pores are
21:10defined as pores larger than 50 NM right
21:13but how can we create such a big pore in
21:16a liquid and uh we use uh the product of
21:20from the other part of my research is to
21:23uh design Hol morphs we created a holor
21:26that contains a cavity as large as 400
21:28nanm but with a crystalling single
21:31crystalling shell that's only has a PO
21:33size of4 nanom so that the the liquid
21:37cannot diffuse through this microl and
21:40occupy the micropor inside when we
21:42functionalize this holor and disperse it
21:45into pdms we can retain this micropulse
21:48in the liquid very well so this is a
21:50cryo SCM cross-section image where we m
21:54the m a freezed a porous liquid and then
21:58cut a cross-section using iron knife and
22:01now we can see very clearly that these
22:03microl are retained within the liquid
22:05and we use this microporosity in a
22:08liquid to absorb water reversibly and we
22:12can use the water uptake as a a mean to
22:16switch the thermal conductivity of the
22:19liquid when the water is filled within
22:21the microporosity of the porous liquid
22:24then the thermal conductivity of the
22:26liquid goes up when we Evacuate the
22:29material and remove the water the
22:31thermal conductivity of the material
22:33goes down so essentially it becomes a
22:35thermal
22:37switch so now we have addressed this
22:39problem how to uh put addition polymers
22:42onto Mo surfaces another challenge is
22:44how to apply condensation polymers onto
22:47M Mo surfaces this part has never been
22:50done by any anyone else it's very
22:52difficult because of a condensation
22:54polymer the polymerization process is
22:57not easily controlled
22:59but if we can do that it would be great
23:02because a lot of condensation polymers
23:03are used in membrane science for gas
23:06separation and liquid separation but to
23:08create a strong interface between the
23:10mouth and the polymer Matrix we need to
23:12grow the same condensation polymer on
23:15the mo surface so uh when you consider a
23:19traditional mix mix mixed Matrix
23:21membrane the polymer interact with the
23:23MTH surface through side weak
23:25interactions if we can grow up a brush
23:28of condensation polymer that has the
23:31same composition as a matrix polymer
23:33then we can essentially increase its
23:34interaction
23:36substantially so this is like a tree
23:38growing Roots into the soil then after
23:41that it's hard to extract the tree uh
23:43from the ground and uh the way we do it
23:47uh the first successful example that we
23:49did was by using a Amino functionalized
23:52mouth called U6 aiming and then we can
23:56first Prime the surface with a D and
23:58hydride molecule and then we can uh
24:01start the polymerization in the solution
24:04with the presence of the moth then the
24:06polymer can grow onto the moth as well
24:08as growing on in the solution then we
24:10can centrifuge The Moth particle
24:12separate out this functionalized moth so
24:15you can see under the TM there's a a
24:17uniform layer of poly image growing on
24:20each moth particle surface and we can as
24:23a chemist I'm uh also uh care about
24:27whether this polymer actually connect to
24:29the mou surface so I I kind of verified
24:33this brush structure using massp by
24:36digesting the moth and even though the
24:40polymer layer on the moth surface is
24:41very thin the stickiness between this
24:44particle is uh it's pretty high so you
24:47can see when we draw dry this particle
24:49directly it forms a three standing film
24:52that contains 88% of moth and only 12%
24:57polymer if we slice this mixed Matrix
25:00membrane using uh a Diamond Knife and
25:03the ultr Micron a traditional mix Matrix
25:06membrane you will see a lot of
25:07interfacial tearing under sheer force
25:10but in a a polymer brush modified
25:13membrane the interfacial tearing
25:16phenomena almost disappeared that means
25:18there's a stronger interaction was
25:20established between the mouth particle
25:22and the polymer Matrix and you can also
25:24see that when we studied the uh glass
25:27transition temp temperature of the mixed
25:29Matrix membranes the polymer brush
25:32modified membranes showed a significant
25:34increase of glass transition temperature
25:37of the polyic Matrix because of this
25:40strong interaction at the interface that
25:41limited the polymer chain Mobility uh in
25:44The Matrix but the traditional mixed
25:46Matrix membrane only showed a slight
25:48increase a 4 degree increase of glass
25:50transition temperature of the polymer
25:52Matrix when you compare the mechanical
25:55uh stability the ductility of the mixed
25:57Matrix m you can see at 5% Mo loading
26:01there's almost a 500% increase of
26:03membrane ductility of the brush modified
26:07uh Mo membrane compared to the
26:09traditional mixed Matrix membrane and
26:12the most important part is the gas
26:14separation uh performance uh in for
26:18membran gas separation we care about two
26:21Matrix one is uh the gas permeability in
26:24this case is CO2 permeability another is
26:27this CO2 nitrogen or CO2 methan
26:31selectivity and when we add moth into
26:34the polymer Matrix we expect and
26:36simultaneous increase of both the
26:38permeability and selectivity but in a
26:41traditional mixed Matrix membrane you
26:43often see a decrease of uh selectivity
26:47although the permeability increases this
26:48is because of the defect generation at
26:51the interface but when we functionalize
26:53the mouth surface with a polymer brush
26:55then we can see a simultaneous increase
26:57of both permeability and the CO2
27:00nitrogen and CO2 methan selectivity so
27:03this is uh an ideal membran that doesn't
27:06have interfacial
27:08defects so another question arises is uh
27:12the previous example we've shown that we
27:14can functionalize an amino moth with uh
27:18polyamid but what about moths without
27:20Amino functional groups for example zium
27:23moth that using these lians uh and
27:25chromium moth using this Lian and Z8
27:29this Mo doesn't have any calent linkage
27:31groups for us to append the polymer so
27:34we need to find a way that can address
27:37the common feature shared by most moth
27:40which in this case is
27:42pro and can we utilize Pro instead of a
27:46calent anchoring point to connect
27:49polymers to the moth so then we
27:52immediately thought of mechanical
27:54linkage right for example in a metal
27:56chain there is no chemical bond between
27:59chains but it's very strong and in this
28:01who can Loop sticky tape there's also no
28:05chemical interaction it's just little
28:07nylon Hooks and nylon Loops that they
28:10can bind very strongly to each other in
28:12molecular uh crystals there's a recent
28:16example called uh interwoven coughs
28:20which use mechanical linkage to link
28:22this um polymers into a crystal so what
28:26if we do not connect polymers to the
28:29moth but rather connect polymer to
28:31another polymer that's inter woven
28:34entangled within the mo framework so we
28:37first introduced a moth called M 101
28:40chromian with a monomer reactive monomer
28:44I and once we polymerize this reactive
28:47Mona it becomes a polymer that's
28:50threading through the moth Crystal and
28:53because the polymer is going entangled
28:55with the MTH Crystal it cannot come out
28:57but it presents functional groups then
29:00we can further functionalize it with an
29:02uh poly aiming molecule then this moth
29:06particle is now functionalized with
29:08amino group then we can use a poly ID
29:11oig terminated with an anhyd group to
29:14connect to these Amino groups in uh
29:17inside the polymer inside the moth so
29:20after this the first three stages of
29:22functionalization the last stage
29:24actually uh connect the polymer to the
29:27mouth surface which we can see directly
29:29under the
29:30ten and although the nitrogen absorption
29:33ESO showed that a decrease of paracity
29:36after we introduce additional polymers
29:38to the mo the CO2 update capacity
29:40actually increased because of the
29:42smaller P size and stronger IND
29:44direction of the functionalized moth
29:46with CO2 and when we make a mixed Matrix
29:50membrane of using that moth uh uh with
29:54poly imid and we can see that this extra
29:57surface functionalization of the poly
29:59image can also lead to a a Increase of
30:03CO2 permeability without s much
30:05sacrifice of CO2 nitrogen and CO2
30:08mething
30:09selectivity whereas without any
30:12functionalization when the moth is made
30:14into a mixed Matrix membrane the
30:16selectivity of the membrane just
30:17decrease uh
30:19dramatically but this method is also has
30:22some its own limitations because it
30:24changes mocity therefore it's not
30:27suitable for Ultra microporus moths
30:30where these moths do not have much
30:31procity to be utilized and it only works
30:35for poly image in this case and uh at
30:38the same time uh our groups was working
30:40on another collaborative project with
30:42Professor Jerry Ator from the University
30:44of Missouri they developed uh this very
30:48unique metal uh metal organic nanoc
30:52capsules in this case is a copper um
30:55octahedral metal organic capsule
30:58that exposes 24 open Metal sites and we
31:02take their material and blend it with
31:05poly image and other condensation
31:07polymers and heat it up and these open
31:09Metal sites can bind strongly with this
31:11oxygen and nitrogen groups on the
31:14condensation polymer and essentially
31:16Crosslink them into a nonsoluble
31:18membrane and for example when these uh
31:23Nano capsules are mixed with a range of
31:25polymers and heated up to around 200°
31:27these membranes are no longer soluble in
31:30uh in a good organic solvent due to
31:33cross linking and we thought we can we
31:36utilize this met organic nanocapsule as
31:38a mean to functionalize Mo surfaces with
31:41poly imid and other condensation
31:43polymers so we first mix moth with this
31:47uh organic metal organic nanocapsule and
31:51in solution of because they have opposed
31:55charge on the surface that the capsules
31:57can can be absorbed to the moth surface
31:59rapidly through electrostatic
32:01interaction then we embed this surface
32:03functionalized moth particle into a
32:05polymer Matrix and then heat it up so
32:08that these nanocapsules can bind to the
32:11surface polymers uh through coordination
32:14linkage then we wash away the Matrix
32:16polymer and what we left is a m surface
32:20uniformly functionalized with a layer of
32:23poly or other condensation polymers and
32:27by studying the charge we did find that
32:30Mo most moths contains a positive charge
32:32on the surface whereas this nanocapsule
32:34contains negative charge that explains
32:36the electrostatic interaction between
32:39the two and because this surface polymer
32:43functionalization process does not
32:44involve any small molecules so after
32:47functionalization the procity of the
32:49moth uh doesn't change at all that's a
32:52great sign and uh we can show that this
32:56method works on a range of M with a
32:58range of different polymers not only
33:00poly imid but polyone a polymer of micro
33:04uh intrinsic micro one as those as well
33:08as
33:12polycarbonate so um so we now we have a
33:16range of method to functionalize Mo
33:18surfaces with poly imid and another
33:20thing we want to apply to as catalysis
33:23can this surface polymerization method
33:25to be used uh for the imobil I Iz ation
33:28of homogeneous catalyst the idea we had
33:30is that the one of the fundamental
33:32dilemma for the physical encapsulation
33:35of homogeneous catalyst in a moth
33:38crystal is that larger crystals cannot
33:41get into the moth where small cry
33:45smaller Catalyst can get into the mouth
33:47but it can also reach out right uh so if
33:50we want to encapsulate this small uh
33:53Catalyst in the mouth without leeching
33:55we can apply a layer of polymer on the
33:57surface that can prevent its leing but
34:00to do that is not easy if we look at how
34:04people grow polymers on M surfaces it
34:06usually takes 24 hours or longer right
34:10if you uh put the encapsulated
34:13homogeneous cist in a polymerization
34:15solution and wait for 24 hours the
34:17catalist will reach out already we need
34:19to find a way to grow polymer fast
34:21enough before it Lees out the the
34:25challenge here is actually the mon
34:28concentration uh for this polymerization
34:30is very low because the higher mon
34:33concentration will lead to
34:34polymerization in solution rather than
34:36on the MTH surface so this is a a quite
34:40a unique strategy that we developed and
34:42that we first mixed moth particle with
34:46uh a solution containing DMF and DCM a
34:49two good solvents for monus
34:53um here we use monus of a poly imid poly
34:56aing and and hydride at this stage the
35:00mon concentration is quite low so
35:02polymerization occur at a very slow rate
35:05and then we suddenly add a non solvent
35:08called a petrum ether into this mixed
35:11solvent so petrum ether is missable with
35:15DCM but not missable with DMF so the DMF
35:18droplets will nucleate on the surface of
35:21each Mo particles because the monus
35:24likes to dissolve in DMF the Mona will
35:26also uh
35:28gets concentrated on each Mo particle
35:30surfaces So within seconds the
35:32concentration of monus on the moth
35:34surface increased exponentially and then
35:37the polymerization occurred only on M
35:39surface so uh this is the result after
35:4330 seconds of polymerization the poly
35:45imid is successfully grown onto every
35:48single MTH particle surfaces and we can
35:51confirm it using ir and we can also
35:54confirm that the prosity of the moth
35:56doesn't change after surface
35:58functionalization process then we use
36:01this mesoporus moth encapsulate it uh
36:05with uh encapsulate the phosphonic acid
36:08homogeneous catalyst and then uh we coat
36:12the surface with a uh thin layer of poly
36:15to prevent it from leeching and you can
36:17see that in 10 cycles of cletic
36:20degradation of phenol using hydrogen
36:23peroxide with the surface polymer coding
36:26the catalyst doesn't suffer a decrease
36:28of uh reactivity whereas without the
36:31polymer coding the ktic reactivity goes
36:35down with each cycle because of the
36:37leion as you can see that the uh amount
36:40of PTA observed in the solvent increases
36:43after each
36:45cycle and since this layer of polymer is
36:48so thin it also doesn't affect the
36:50diffusion kinetics of the ktic process
36:53which uh uh in here it shows that the
36:56surface the
36:58homo uh the encapsulated catet shows the
37:01almost the exact same cletic uh kinetics
37:04as the homogeneous cat list
37:07itself so uh I have showed you guys that
37:10uh various ways to construct this
37:12building unit but I haven't really
37:14showed much work in this area and this
37:16area and I will give an example that we
37:19use the building block of Mo at polymer
37:22coell particles to construct more
37:24complicated me membrane morphologies
37:28so if you consider a conventional mixed
37:30Matrix membrane for gas separation it's
37:32a mo particle dispersed in a polymer
37:35matrics although uh the moth particle
37:37can increase the diffusion kinetics of
37:40gas through the membrane but the gas
37:43will have
37:44to uh diffuse through this bottlenecks
37:47right the polymer is really what's
37:49slowing down the Gas diffusion the one
37:51way to address the problem is to
37:53increase the M loading in the polymer
37:54Matrix to have connected Pathways of Mo
37:57particles that's called percolation but
38:00the consequence of that is the membrane
38:03become so brittle that's difficult to
38:05handle so what if we can use two polymer
38:09um Matrix and blend them together and
38:12allow them to face separate into
38:14different morphologies for example if
38:16one polymer is a minor component then it
38:19will separate into this jopet domains
38:21like Sea Island uh structure and uh or
38:26we can uh when we
38:27uh put moth particles in into two
38:30polymer Matrix then the moth particle
38:33will selectively go to the preferred
38:34polymer matrics and are gathered into
38:37one domain so ideally we want to create
38:39something that has a co-continuous
38:42morphology where M particles can be
38:44connected and condensed into one face
38:46and connect through one end of the
38:48membrane to the other can we do that so
38:53we started with mixing these two poly
38:55image called ODP a and and 6fda d and we
39:00also made some random copolymers that
39:02has a mixture of these two uh uh mmers
39:06so that the properties of this random
39:08copolymer is in between these two
39:11polymers when we mix this random
39:13copolymers with 6 FDA DM you can see a
39:17different degree of face separation if
39:20the amount of 6 FDA in the random
39:22copolymer increases then the degree of
39:25its separation uh decreases
39:28so we can control the degree of face
39:30separation of a polymer Bland if we put
39:33Mo particles into this polymer blend
39:35then we can actually push Mo particles
39:38into one domain in this case it's a very
39:40unique uh morphology that Mo particles
39:43are gathered at the interface of two
39:46polymers and using this method we can
39:49basically achieve a wide range of uh
39:51moth structures for example here moth uh
39:54goes into a Sea Island domain of the of
39:57one polymer and in this case we put two
39:59moth particles where one moth particle
40:02reside in one polymer domain and the
40:04other moth particle reside in another
40:06polymer
40:07domain and this is what we are after we
40:09want to create a continuous
40:11co-continuous pathway where the mo
40:13particles can be connected throughout
40:15the membrane and another polymer phase
40:17is also connected so that it can provide
40:19mechanical stability and in this
40:22particular membrane The Moth loading is
40:24only 19% but the moth can be connected
40:27into a percolation pathway and if we
40:30compare the uh moth packing density uh
40:34within the this domain this is nearly
40:3750% of the mo packing
40:40density so mechanically this Co
40:43continuous morphology showed a much uh
40:46higher ductility uh compared to a
40:49conventional mixed Matrix membr at the
40:50same loading and we when we look at the
40:53CO2 nitrogen CO2 methan separation uh
40:57performance of this mixed Matrix
40:59membrane you can see that this
41:0119% uh face separated mixed Matrix
41:04membrane outperformed even this 29%
41:08conventional membrane uh both by
41:11permeability and
41:15selectivity and when we analyze further
41:17whether this contribution is due to the
41:20increased solubility or increased
41:22diffusivity we find that actually it's
41:24due to the increased diffusivity of the
41:27gas molecules within this percolated
41:29network of mixed Matrix
41:32membrane so this kind of membran is not
41:35only good for designing a a gas
41:38transport Highway for gas separation but
41:41the preference of the mo for a certain
41:43polymer domain also gives us some
41:46information can we so the question
41:48arises can we use this face separation
41:51process and uh the auto partitioning of
41:54the mo particle within one polymer
41:56domain to tell which polymer domain moth
41:59prefers because there's one issue in
42:01mixed Matrix mem Community is whether
42:04the moth uh has a compatible interface
42:07with a polymer right so if we can mix
42:09two polymer with the mo and then try it
42:12make into a face separated membrane if
42:15the moth prefers one polymer over
42:16another we know this polymer has a
42:19better interface with the moth then
42:21another
42:23polymer so we selected six poly imates
42:26and then we combine these six poly image
42:29uh each two uh poly image into pH
42:32separated membranes as an example I
42:35showed maid polymer and 6 FDA 6 fap when
42:40we mix these two they face separate and
42:42the darker domain is the floring
42:45containing polymer
42:47here if we put Ms into it the moth
42:50prefers
42:52majur and it is revealed in the Eds
42:55mapping results
42:58so I just skipped a lot of results here
43:01but we actually Blended two two polymers
43:04for 15 Pairs and then we eventually
43:07figured out that is compatibility
43:10ranking of six poly imids so the Majid
43:13is the uh has the best interface with
43:17the particular MTH we selected among six
43:21uh poly image and 6 FD BF has the worst
43:24interface and
43:28then we selected these three polymers
43:30one with the worst interface with the
43:32moth another with the best interface
43:34with the moth and another with the
43:35intermediate interfacial compatibility
43:37with the MTH and then makes them into
43:39mixed Matrix memory and you can see
43:42that's the the uh Matrix matroid with a
43:46good interface with a moth showed a
43:48simultaneous increase of uh CO2 mething
43:51selectivity as well as permeability
43:53whereas this PO polymer that has worst
43:57interface with the moth it shows a
43:59decrease of uh CO2 mething selectivity
44:02so uh this method tells us that we can
44:05use this method as a guideline to
44:07rapidly screen which polymer has a good
44:09interface with a MTH or not so to this
44:12end I would like to conclude our work in
44:15the polymer Mo uh composite field that
44:18we utilize this uh polymer M at polymer
44:22uh building block and oh and construct
44:27more complicated uh structures for
44:29example face separate mixed M membranes
44:32and we can increase the uh complexity in
44:36polymer moth Composite Materials as well
44:38as a number of components we can have a
44:41a very good interfacial control within
44:43this um um uh porous Composite Materials
44:48uh with both short range and long range
44:51ordering so uh at the end I would like
44:53to thank
44:54the the students that who did this work
44:57they are all students from Shanghai Tech
45:00University in particular these six
45:02students that I circled out and uh uh
45:06during the time at Shanghai Tech my
45:08research was founded by nsfc as well as
45:11uh two industrial Partners such sve and
45:14shell uh thank you for listening and I
45:16would like happy to answer any of the
45:20questions thank you very much for any
45:25question thank you so much very very
45:29interesting box I have two small
45:31questions uh the first one uh is about
45:34the de coing of the polymers outside the
45:37MS so I I saw the very SE polymer how do
45:43the near outside the polymer which one
45:46the the one from our group or the one
45:48that I showed earlier that's from the
45:50earlier one oh that one was done by
45:54Professor Frank Caruso from University
45:55of Melbourne and also Steve granik from
45:58uiu and what they did is he use the
46:01electrostatic interaction of of a
46:04negatively charge polymer which is uh a
46:07negatively charged polystyrene to absorb
46:09to the m surface first and then takes
46:11the mo particle out and put it into a
46:14polymer solution that contains positive
46:15charge so then the positive charge
46:17polymer will absorb to the mo surface
46:20again then they do it back and forth so
46:23then after each layer uh coding the
46:26polymer thickness will increase by
46:28around one.5 to 1 nm so it's a
46:32traditional like coing of first you can
46:35do dip coding uh as well if you deposit
46:38Mo particle onto a substrate first
46:42yes the second question is about the
46:45nonsolvent induced process is the
46:48nonsolvent induced process is happens
46:50sing right it's very quick so how do you
46:53control the uniform coing during this
46:57the right that's a a very good question
46:59that uh the process happens very uh
47:02quick but if you think about when non
47:05solvent is introduced DMF will get
47:07pushed out from the liquid and where
47:09does it prefers to go it prefers to go
47:11to a surface that has high surface
47:13energy which is M surface and it doesn't
47:16like homogeneous nucleation because
47:18homogeneous nucleation has higher energy
47:20penalty so as long as you give uh give
47:23the solution enough M surface area by
47:26using a small Mo particle then the the
47:29liquid droplet will always coat
47:31uniformly onto each Mo particle so all
47:34the exposed Mo surface will be coded by
47:36a layer of polymer and defect free so
47:39it's a kind kind of very smart uh
47:42strategy
47:45yes very good top I just wondering
47:48what's the cuse when you use this cor to
47:51D Sy I saw you absor
47:55so I'm still not sure how you absorb CO2
47:58yeah okay I just explain how you use
48:01this P liquid absorb CO2 and what's the
48:04drin FSE you use to dis OPP yeah so uh
48:08for the CO2 isotherms we collected for
48:10porous liquids these are un conventional
48:14like uh absorption analyzer basically
48:17gas is introduced in vacuum and it gets
48:19absorbed by the liquid and it forms an
48:22equilibrium then for disor it will just
48:24increase the vacuum uh uh
48:28right so because the interaction it's
48:30still the mo CO2 interaction it's a weak
48:32physic interaction instead of a c
48:35Direction like yeah because the you know
48:37theen Oran use for just
48:41use just buttion need heat but case you
48:47need just like
48:49a but uh for moth the diffusion is
48:52faster but for liquid in a conventional
48:54setup the liquid thickness is quite uh
48:57quite thick right it's millimeter thick
48:58so the diffusion is slightly slower but
49:01we we have a little trick is that we put
49:03a stab bar inside to stir the liquid
49:06during the aborption so that the
49:08equilibrium can be reached earlier yeah
49:10okay yeah thank you thank
49:13you any other question from the
49:18audience uh thank you for the great
49:21presentation so my question is about
49:24your could is lium research
49:27group T and lium is the one of the looks
49:31like your area of the so T so I want to
49:36have a medium related
49:38questions so uio 66 and the JF you have
49:43a experiened JF also you have a JF 60 JF
49:49some of the modification right so it
49:52looks like uh based on our group so we
49:55have a lum AB abortion with the m
49:58material u66 and JF so they have a very
50:02strong absorption Al some people mention
50:06about mechanism of the lithium like a
50:08hydrate rium and dehydrate in the G and
50:12then goes to the their M molecule of the
50:16inside so do you have any idea why the
50:21lithium especially very strong
50:24absorption or some
50:27seel selectivity for the leum with the
50:30you more for some Chief and U 66 I think
50:36this kind of uh hypothesis are I'm quite
50:40skeptical about because having lium
50:43going into the mouth uh and needs to
50:47dehydrate first I think the energy
50:50barrier is quite High and the B
50:52interaction between the moth and lithium
50:54is not as strong as the interaction
50:56between the hydren layer and lithium but
51:00I think the the small Port of the MTH
51:02does play an critical role in uh
51:05enhancing its interaction with the
51:07lithium ion so I think maybe some uh
51:11moth defects contains carboxilic acid
51:14groups uh that's exposed to interact
51:17with lithium so that can be a
51:19contribution to uh like more lithium
51:23absorption involves okay so if we can
51:26increase the caroy grow and we can have
51:29a more absorption of Le right I think so
51:32that's a like likelihood all
51:37right yeah maybe maybe you can
51:39deliberately increase the defect
51:43there right
51:45okay uh thank you very much for such a
51:48wonderful talk um I just want to get
51:51some your expert opinion probably not
51:54really Rel to what you are doing right
51:56now now um do you know any kind of Mo
52:00that have very high stivity towards
52:04CO2 uh but not very high stivity towards
52:07water if you have like these two
52:09together that's a central old question I
52:11don't believe there is because water has
52:14a higher polarity than CO2 and it's
52:18smaller than CO2 so size selectivity is
52:20impossible the uh the kinetic diameter
52:23of water is only 2.6 amstrong or CO2 is
52:263.3 amp so using size exclusion to block
52:31water is uh it's not possible and uh and
52:35water has a higher polarity and it
52:37always interact with uh like polar
52:39groups within the moth but uh one
52:42possibility is hydrophobic moth which it
52:45doesn't like to bind with water but it
52:47can still have a dipole interaction with
52:50CO2 so that this is the only possibility
52:54that I can think of but hydrophobic Ms
52:58in general do not have a strong CO2
53:00interaction at low pressure so do you
53:02any mo that can quickly absorb CO2 under
53:07mild conditions like let's see like
53:09around 50° and then you can release it
53:11oh okay and put abortion will be lower
53:15temperature but you have to I guess
53:16increase the temperature little bit to
53:18get it released yeah so we can't get
53:21that kind of I mean forget about water
53:23right now just talk
53:25about uh
53:27do we have a good Mo for CO2
53:30abortion under M conditions for which
53:34application depends on the partial
53:35pressure of CO2 if it's direct
53:39just high
53:41pressure uh like flu gas something like
53:4510 to 15% CO2 I think right right now
53:47there are some uh uh I think the one
53:51example is C 12 uh from University of
53:55Calgary and they have a zinc imidazolate
53:58based moth that's uh almost as a process
54:01of commercialization and you can
54:03interact with CO2 at uh 10 to 20% very
54:07strongly and uh another example is cost
54:107 from uh the King Abdullah University
54:13of Science and Technology and they that
54:16moth has a very strong interaction with
54:18CO2 even at 400 PPM and the uptate
54:21capacity is around 2 milles per gram and
54:24there are other examples that's not as
54:28good but there plenty if you do do not
54:30talk about water then there plenty of
54:32water yeah yeah I mean like I think
54:33about it maybe just like you know remove
54:36water and somehow and then we can just
54:38pick up the CO2 because uh uh okay maybe
54:42we can have a separate discussion sure
54:46okay I have couple of questions so you
54:49studed about the U um the brush and then
54:53um using the at or condensation mization
54:55and you studied about the length of the
54:57brush and their dispersity in the
54:59polymer right so we we showed a
55:03massack data that shows the molecular
55:05weight centered around I think
55:084,000 around 4,000 do so if you consider
55:13a repeating unit of poly image is 400 to
55:17500 uh D then there will be like eight
55:20to nine repeating unit of uh the poly
55:23imit so it's not very long it's a short
55:26[Music]
55:28uh and then does that having think the
55:31brush does it improve the interfacial
55:33diffusion yes we show the uh bulk
55:36mechanical property as well microscopic
55:39mechanical properties of the membrane
55:41but both increased and also the uh from
55:44the increase of glass transition
55:46temperature of the polymer matrix it's
55:47also an indirect characterization
55:50telling you that there's a much stronger
55:52interaction at the interface and then
55:54you think that that's the same case for
55:56the ion conduction across this um you
55:59know organic interface ion we haven't
56:03studied yeah haven't say yeah so if it's
56:06iron then you have to use a different
56:08type of poly needs to be a Charged
56:12polymer instead of a
56:16poage last one question seems like your
56:20last chapter um you used some um polymer
56:25and the uh seems like that the backbone
56:28chain is a bit stiff because there are
56:30lots of like um aromatic rings so um do
56:34you think that polymer crystallizes and
56:37also no because these polys are all
56:40glassy and because of the stickness and
56:43it bends at a certain angle it's never
56:45going to pack efficiently into crystals
56:48so all pretty much all poly uh used in
56:51gastion are glossy
56:54po any
56:58question Let's uh thank again uh Dr Lee
57:01for his very great