Amphiphilic Heteroarm Star Polymers Synthesized By RAFT Aqueous Dispersion Polymerization

Star polymers with a number of arms connected to a central point or core have uniqueproperties and have been intensively studied for applications inbiomaterials,catalysis,encapsulation, molecular recognition, coating andemulsion.While CCSs can be synthesized by all the three main strategies: core-first,arm-firsand grafting.The arm-first approach has gained more attention, because itallows facile synthesis to CCSs with a very large number ofarmswhich can beseparately tailored.Although the self-assembly of heteroarmstar polymers hasbeenextensively studied,most of the starpolymers studied only have a limited number ofarms connected toa small compound core. On the other hand, the self-assemblyofheteroarm CCSs has been much less explored,especially forthose synthesizeddirectly using the arm-first strategy.This is mainly because the general lackof efcientmethods for CCS synthesis by RAFT, the potentially varied reactivity of diferent armpolymers, andthe difering solubility of diferent arm polymers in a commonsolvent.In this thesis, we have synthesizeda new type of amphiphilic heteroarm CCS byRAFT co-cross-linkingof hydrophilicpoly(N, N’-dimethylacryla-mide)(PDMA) andhydrophobicpoly(2-methoxyethyl acrylate)(PMEA) ina1:1water/ethanolsolution.furthermore, we systematically studied their self-assemble behavior and their use asemulsifiers. The main contents are listed as follows:1. We have successfully synthesized a new type of amphiphilicheteroarm CCS byRAFTco-cross-linkingofhydrophilicpoly(N,N’-dimethylacrylamide)(PDMA)andhydrophobicpoly(2-methoxyethyl acrylate)(PMEA) in a1:1water/ethanolsolutionusing1,6-hexanediol diacrylate(HDDA) as the corsslinker.In order toreducethespace steric hindrance,butyl acrylate (BA)was used as a spacingmonomer.The finalarm conversionreached70%.2. On the basis of the study we made before, we synthesized star polymers in the samereactionconditions but without the spacing monomerbutyl acrylate(BA).Interestingly we found that the CCSs arebettershaped and with higherarm conversion. A series of homoarm and heteroarm CCSpolymers with adjustablepolarity was easily prepared by controling the feeding ratio.We systematicallystudied their self-assemble behaviorin water.3. With the series of CCS polymers of tunable polarity in hand, we next investigatedtheir use as emulsiers. Wefound that the polarity of the CCSpolymers cansignicantly afect their emulsifying behaviour.