Novel siloxane block copolymers

[摘要] The research presented in this dissertation was concerned with the living radicalpolymerization (LRP) of an amphiphilic, water-soluble, bi-substituted andbiologically compatible acrylamide derivative, namely n-acryloylmorpholine (NAM).The primary objective of this research was the synthesis of novel blockcopolymers containing poly(dimethylsiloxane) (PDMS) and various chain lengthsof poly(acryloylmorpholine) (polyNAM) using a LRP technique, namely reversibleadditionfragmentation chain transfer (RAFT) polymerization. This is the first reporton the synthesis of these block copolymers using RAFT polymerization. Thesenovel siloxane block copolymers were synthesized using a monohydroxyterminatedPDMS material which had to first be modified into a thiocarbonylthiocontainingmoiety in order for it to be used as macromolecular chain transfer agent(macroCTA) in the RAFT copolymerization with NAM.Suitable reaction conditions for the synthesis of these novel block copolymers hadto, firstly, be determined, and secondly, optimized. In order to determine suitablereaction conditions, a series of homopolymerizations with NAM were firstperformed in order to compare which chain transfer agent (CTA), solvent,temperature etc. could possibly be best suited for the block copolymerizations ofPDMS-b-polyNAM. Reported in this work is the first account of thehomopolymerization of NAM and 2-(dodecylsulfanyl)thiocarbonylsulfanyl-2-methylpropionic acid (DMP) as CTA using RAFT polymerization.The resulting novel siloxane block copolymers are amphiphilic in nature and theexistence of these structures was confirmed by size exclusionchromatography/multiangle light scattering (SEC/MALS), proton nuclear magneticresonance (1H-NMR) spectroscopy, gel elution chromatography (GEC) andtransmission electron microscopy (TEM). Interesting phase behaviour wasobserved in the latter technique.

[发布机构] Stellenbosch University