Synthesis Of Block Copolymers Based On PDMS Via RAFT Polymerization

Reversible addition-fragmentation chain transfer (RAFT) radical polymerization, which is a widely applied polymerzation approach, belongs to "Living"/controlled free radical processes and has developed rapidly in the past decade. By adding reversible chain transfer agents (CTAs) with high chain transfer constant in the reaction system, it provides controlled molecular weight polymers with very narrow pclydispersities. Compared with other polymerization methodologies, RAFT polymerization offers many benefits, including the applicability to a wide range of monomers, the simple and convenience reaction system, the mild reaction condition and the ability to prepare a polymer with complex architectures. Recently RAFT process receives much attention continuously as a powerful tool for the synthesis of blocks, grafts, stars, combs and other polymers of special structure.Due to its special structures, Poly(dimethylsiloxane)(PDMS) possesses many unique physics and chemistry properties, such as high and low temperature performance, hydrophobic, low surface energy, oxygen permeability, biological compatibility and physiological inert. As a "semi-inorganic" polymer, PDMS can be induced into a normal organic polymer segment to form a modified block copolymer with better properties, or an amphiphilic copolymer which is applied in the construction of supramolecular systems with different structure, morphologies and applications via self-assembly. Therefore, many related works on the synthesis of block copolymers based on PDMS have been published. However, there are rare reports on the synthesis of polyacrylonitrile (PAN)-PDMS block copolymers by RAFT polymerization.Thus, in this dissertation, based on the previous reports, the works are summarized as followed.With a CTA S-1-Dodecyl-S’-(a,a’-dimethyl-a"-acetic acid)trithiocarbonate (TTC), a series of PAN-b-PDMS-b-PAN copolymers with different molecular weight were synthesized via a RAFT process and the structures and molecular weight were characterized by IR and1H NMR. The molecular weight and the polydisperisty were also measured by GPC. Then the reaction kinetics was investigated and the results indicate the "living"/controlled characters of the polymerization reaction.PAN-b-PDMS-b-PAN copolymer films were prepared by spin-coating on glass chips. The film morphologies were performed by SEM and ordered structure were observed.Moreover, two block copolymers, PMMA-v-b-PAN-b-PDMS-b-PAN-b-PMMA and (PMMA-r-PAN)-b-PDMS-b-(PMMA-r-PAN) were prepared via "steped" and "one-pot" methods by RAFT polymerization. Their reaction kinetics was also studied.