Mikro struktura polihipe polimerov dosežena s sinerezo, hiperzamreženjem in graftiranjem

doktorska disertacija

Amadeja Koler (Avtor), Peter Krajnc (Mentor)

Povzetek

V doktorski disertaciji smo pripravili polimere stirenskega tipa z več nivojsko poroznostjo. Dobro definirano porozno strukturo smo dosegli s kombiniranjem različnih tehnik za uvedbo poroznosti v polimere. S polimerizacijo kontinuirne faze emulzije z visokim deležem notranje faze smo ustvarili makro porozne polimere s povezovalno odprto celično poliHIPE strukturo. Mikro poroznost smo dosegli s Friedel-Craftsovo reakcijo hiperzamreženja in s sineretsko fazno separacijo z uporabo mešanice topil. Več nivojska porazdelitev velikosti por je izjemno pomembna pri uporabi polimernih materialov v pretočnih sistemih, kjer makro pore omogočajo konvektivni prenos snovi in zmanjšujejo povratne tlake, medtem ko manjše mezo in mikro pore vplivajo na povečanje specifične površine.%Visoko porozne poli(stiren-ko-divinilbenzen) polimere smo pripravili s polimerizacijo kontinuirne faze emulzije z visokim deležem notranje faze. Monolite smo sintetizirali s prosto radikalsko in RAFT (reverzna adicijsko-fragmentacijska polimerizacija s prenosom verige) polimerizacijo. V obeh primerih polimerizacij so imeli polimeri tipično poliHIPE strukturo. Polimere smo nato hiperzamrežili z radikalskim iniciatorjem di-tert-butil-peroksidom in tako pridobili mikro in mezo pore, ter posledično vplivali na dvig BET specifične površine (3-4-kratno povišanje). Prav tako je na mikro strukturo poliHIPE materialov vplivala vrsta polimerizacije. Z RAFT polimerizacijo smo dobili 4-5-krat višje specifične površine ne hiperzamreženih poliHIPE materialov kot pri uporabi proste radikalske polimerizacije, kar kaže na porast formiranja mikro por pri RAFT zamreženju.%Poli(stiren-ko-4-vinilbenzil klorid-ko-divinilbenzen) poliHIPE materiale s tipično poliHIPE odprto celično strukturo smo sintetizirali pri različnih stopnjah začetnega zamreženja (2, 5 in 10%). Z dodatkom stirena v monomerno mešanico smo dosegli redčenje funkcionalnih skupin in tako študirali vpliv redčenja na potek Friedel-Craftsove reakcije hiperzamreženja. S hiperzamreženjem smo v makro porozne poliHIPE materiale uvedli mikro pore in dosegli visoke BET specifične površine (do 731 m2/g). Pri dodatku 57-63 mol % STY je bilo redčenje funkcionalnih skupin preveliko, da bi bilo hiperzamreženje še učinkovito, specifične površine so drastično padle, kar kaže na pomanjkanje mikro por. %Graftirali smo glicidil metakrilat s površine makro poroznih poli(4-vinilbenzil klorid-ko-divinilbenzen) monolitov pripravljenih z radikalsko polimerizacijo kontinuirne faze emulzije. Z namenom povišanja specifične površine smo visoko porozne poliHIPE materiale hiperzamrežili s Friedel-Craftovo reakcijo in jih nadalje funkcionalizirali z razvejanim tris(2-aminoetil)aminom. Proste amino skupine razvejanega amina smo uporabili za imobilizacijo RAFT reagenta, ki je bil primeren za graftiranje glicidil metakrilata s površine. Z graftiranjem s površine poliHIPE materialov z vezanim RAFT reagentom smo dobili visoko gostoto glicidil metakrilatnih molekul na površini. Graftiranje smo izvedli le na hiperzamreženih materialih, saj so ti dosegli večje konverzije pri reakciji z aminom in RAFT reagentom, zaradi večje dostopnosti reaktivnih mest. Učinkovitost reakcije graftiranja smo potrdili z gravimetrijo, elektronsko vrstično spektroskopijo in infrardečo spekroskopijo. Dinamična mehanska analiza je pokazala, da smo z RAFT polimerizacijo izboljšali mehanske lastnosti poli(4-vinilbenzil klorid-ko-divinilbenzen) poliHIPE materialom.%V drugem delu doktorske disertacije smo uporabili sineretsko fazno separacijo pri sintezi poli(4-vinilbenzil klorid-ko-divinilbenzen) zrn s suspenzijsko polimerizacijo. Monomerno fazo smo razredčili s toluenom ali z mešanico topil toluen/heksan. Mikro pore so se formirale zaradi mikrosineretske fazne separacije ob prisotnosti toluena, ki je dobro topilo za stirenske tipe polimerov. Zrna smo hiperzamrežili in s tem uvedli v material nove mikro pore, ki so posledica nastanka novih metilenskih povezav. S tem smo dosegli visoke

Ključne besede

poliHIPE materiali;hiperzamreženje;sinereza;RAFT graftiranje s površine poliHIPE materialov;RAFT polimerizacija;disertacije;

Podatki

Jezik:	Slovenski jezik
Leto izida:	2020
Tipologija:	2.08 - Doktorska disertacija
Organizacija:	UM FKKT - Fakulteta za kemijo in kemijsko tehnologijo
Založnik:	[A. Koler]
UDK:	66.095.26(043.3)
COBISS:	40183811
Št. ogledov:	2058
Št. prenosov:	168
Ocena:	0 (0 glasov)
Metapodatki:

Ostali podatki

Sekundarni jezik:	Angleški jezik
Sekundarni naslov:	Creating micro structure in polyHIPEs through syneresis, hypercrosslinking and grafting
Sekundarni povzetek:	Within the doctoral dissertation, styrene-based polymers with multilevel porosity were prepared. A well-defined porous structure was achieved by combining different techniques to introduce porosity into the polymers. By polymerizing the continuous phase of a high internal phase emulsion, macroporous polymers with an open cell interconnected polyHIPE structure were formed. Micropores were obtained using a Friedel-Crafts hypercrosslinking reaction, and by syneretic phase separation using a mixture of solvents. Multilevel pore size distribution is advantageous when using polymeric materials in flow systems where macropores allow convective mass transfer and reduce back pressures, while smaller meso- and micropores increase the specific surface area.%Highly porous poly (styrene-co-divinylbenzene) polymers were prepared by polymerizing the continuous phase of a high internal phase emulsion. Monoliths were synthesized by free radical and RAFT (reversible addition-fragmentation chain transfer) polymerization. In both polymerization types, the polymers had a typical polyHIPE structure. The polymers were then hypercrosslinked with the radical initiator di-tert-butyl peroxide to obtain micro- and mesopores, and consequently to raise the BET specific surface area (3 to 4 fold increase). The microstructure of the polyHIPE materials was also affected by the type of polymerization. Compared to the polymers prepared using free radical polymerization, the specific surface areas of non-hypercrosslinked polyHIPE materials prepared with RAFT polymerization were 4-5 times higher, which indicates increased formation of micropores in the case of RAFT crosslinking mechanism. %Furthermore, poly (styrene-co-4-vinylbenzyl chloride-co-divinylbenzene) polyHIPE materials with a typical open cellular polyHIPE structure were prepared at different initial crosslinking degrees (2, 5 and 10%). The addition of styrene to the monomer mixture dilutes the functional groups and enables the study of the effect of dilution on the Friedel-Crafts hyperlinking reaction. The hypercrosslinking reaction introduces micropores into the macroporous polyHIPE materials which results in high BET specific surfaces (up to 731 m2/g). At 57-63 mol% of STY the dilution of the functional groups is too intense to enable effective hypercrosslinking which results in a drastic drop in specific surface areas and a lack of micropores, compared to samples with higher concentrations of functional groups.%In continuation, glycidyl methacrylate was grafted from the surface of macroporous poly (4-vinylbenzyl chloride-co-divinylbenzene) monoliths which were prepared by the radical polymerization of the continuous phase of the high internal phase emulsion. In order to increase the specific surface area the highly porous (80% porosity) polyHIPE materials were hypercrosslinked by Friedel-Craft reaction and further functionalized with branched tris (2-aminoethyl) amine. The free amino groups of the branched amine were used to immobilize a suitable RAFT agent for glycidyl methacrylate grafting from the surface. High surface density of the glycidyl methacrylate molecules on the surface was obtained by surface grafting of the polyHIPE materials with bound RAFT reagent. Grafting was performed only on the hypercrosslinked materials, as these achieved higher conversions in the reaction with the amine and RAFT reagent, due to the greater accessibility of the reactive sites. The efficiency of the grafting reaction was confirmed by gravimetry, scanning electron microscopy and infrared spectroscopy. The RAFT polymerization also improved the mechanical properties of the poly (4-vinylbenzyl chloride-co-divinylbenzene) polyHIPE materials.%In the second part of the doctoral work, syneretic phase separation was used as the tool for porosity induction in the synthesis of poly (4-vinylbenzyl chloride-co-divinylbenzene) beads using suspension polymerization. The monomer phase was diluted with toluene or with a
Sekundarne ključne besede:	polyHIPE materials;hypercrosslinking;syneresis;RAFT grafting from the surface of polyHIPE materials;RAFT polymerization;Polimeri;Disertacije;
Vrsta dela (COBISS):	Doktorsko delo/naloga
Komentar na gradivo:	Univ. v Mariboru, Fak. za kemijo in kemijsko tehnologijo
Strani:	XIV, 133 f.
ID:	12012017