Self assembly of an amphiphilic diblock copolymer polysyrene b polyvinylbenzoic acid in ethanol,which is a selective solvent for the polybenzoic acid segment was studied by means of transmission electron microscopy.The diblock copolymers can self assemble into nano scale aggregates with polystyrene segment as the core and polyvinylbenzoic acid segment as the corona.The morphology of the aggregates is mainly controlled by the ratio of the two segment of the diblock copolymer.As the content of the ethanol insoluble polystyrene segment increased,the morphology can be changed from spheres to rods.The diameter of the aggregates increases slightly with concentration and decreases with the addition of CoCl 2 salt.
Reverse addition\|fragmentation chain transfer (RAFT) polymerizatin of MAn with St is reported aiming at the synthesis of a well\|defined alternating copolymer of MAn with St.The results show that the polymers possess predetermined molecular weight and molecular weight distribution as narrow as 1 2. A novel well\|defined block copolymer P(MAn\| alt \|St)\| b \|PSt has also been prepared by the copolymerization of MAn with excess amount of St in molar feed via RAFT process.
Controlled radical copolymerization including atom transfer radical polymerization(ATRP) and radical reversible addition\|fragmentation chain transfer polymerization(RAFT) of iso \|butyl vinyl ether ( i BVE) with electron\|withdrawing monomers such as maleic anhydride and N substituted maleimides,have been studied.Results show that ATRP of i BVE with electron\|withdrawing monomers does not work well,while the well\|defined copolymers are obtained via RAFT polymerization.The copolymers thus obtained possess alternating structure,predetermined molecular weight and molecular weight distribution as narrow as 1 2～1 4.
To avoid the damage to catalytic system in ATRP by the carboxyl groups in vinyl benzoic acid, a well defined poly( p vinyl benzoic acid) was synthesized via ATRP in the tertiary butyl ester form. The ATRP of t butyl p vinyl benzoate ( t BVB) was studied kinetically. The results showed that t BVB can be polymerized in a controlled way by ATRP. It was found that the polymerization rate of t BVB is much faster than that of St, meaning that the electron withdrawing ester group affects the polymerization obviously. Well defined diblock copolymers of St and t BVB were prepared by using bromo terminated PBVBs as macroinitiators via ATRP. After removal of the t butyl group by hydrolysis, well defined amphiphilic diblock copolymers of styrene and p vinyl benzoic acid (PSt b PBVA) were obtained.
