Block Copolymers With A Variety Of Architectures: Synthesis And Applications Of Modulating Nanostructures In Thermosetting Polymers

A series of block copolymers such as AB diblock copolymer, A′BA′tribolockcopolymer, B′AB′triblock copolymer, ABC triblock copolymer, A2B2miktoarmcopolymer and comb-like copolymer were synthesized via the combination of atomtransfer radical polymerization (ATRP), reversible addition-fragmentation transferpolymerization (RAFT), ring-opening polymerization (ROP) and click chemistry.These block copolymers were incorporated into thermosetting polymers to accessordered or disordered nanostructures via self-assembly or reaction-inducedmicrophase separation mechanism. Various tactics were used to modulate themicro-phase structure. The morphology and thermomechanical properties of thenanostructured thermosets were also investigated. The main results were summarizedas below:1. Block copolymers with indetical compostion and molecular weights wereincorporated into epoxy resin to acess nanostructured thermosets viareaction-induced microphase separation. The phase behaviors were quite differentin terms of the copolymer architectures and the demixing behavior of the miscibleblocks during reaction-induced microphase separation.2. It's found that the nanostructures of the epoxy thermosets can be modulated by theuse of differnet hardeners. The morphological transition was interpreted in termsof the hardener-dependent miscibilty of the ABC terpolymer blocks with epoxythermosts and the occurence of tandem reaction-induced microphase separation. 3. The M-PCL-PTFEA miktoarm copolymer was synthesized and incorporated intoepoxy resin to prepare the nanostructured epoxy thermosets. It's proved that theformation of the nanostructures follows the mechanism of self-assembly. Thestorage moduli the of nanostructured epoxy thermosets were higher than that ofpure epoxy thermoset.4. Epoxy thermosets containing ordered structures with32~41nm in diameter wereprepared with a block copolymer incorporating epoxy-reactive functionality inone block. The nanophases were created via the mechanism of self-assembly. It'sfound that the critical stress field intensity factors (K1C) as well as flexural moduliof nanostructured thermosets were higher than that of pure epoxy thermoset. Thestatic contact angle measurements indicate that the nanostructured thermosetscontaining PGMA-b-P(MA PDMS) diblock copolymer displayed a significantenhancement in surface hydrophobicity.5. Mesoporous silica were synthesized with a reactive copolymer other thancopolymers having hydrophilic block. Block copolymers used to frabricatemesoporous silica were much enriched. In addition, It's advantageous forcommerical process.6. PEO-b-PCL-b-PS triblock copolymer was synthesized and incorporated intonovolac resin to prepare the nanostructured phenolic thermosets. In terms of thedifference in miscibility of novolac and phenolic resin with the subchains of theABC triblock copolymer after and before curing reaction, it is proposed that theformation of the nanostructures follows the combined mechanisms ofself-assembly and reaction-induced microphase separation. The nanostructuredphenolic resin were subsequently pyrolysed to obtain mesoporous carbon.