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4708195 
Journal Article 
Facile synthesis and characterization of star-shaped polystyrene: self-condensing atom transfer radical copolymerization of N-[4-(alpha-bromoisobutyryloxy)phenyl]maleimide and styrene 
Cao, Yun; Hong, Yan; Zhai, G; Zhang, D; Song, Yan; Yu, Q; Ren, Q; Jiang, B 
2008 
1 
Polymer International
ISSN: 0959-8103 
57 
10 
1090-1100 
WOS:000260361700002 
BACKGROUND: Generation of stars around in situ formed cores provides a facile approach to star-shaped polymers. Therefore the self-condensing atom transfer radical copolymerization (SCATRCP) of N-[4-(alpha-bromoisobutyryloxy)phenyl]maleimide (BiBPM) and a large excess of styrene (St) was investigated.



RESULTS: BiBPM and St formed a charge transfer complex (CTC), which underwent the SCATRCP, leading to the branched core initiating the atom transfer radical polymerization of St, finally giving star-shaped polystyrene (PS). Kinetic and structural study showed that a higher dosage of BiBPM resulted in an enhanced polymerization rate, a higher degree of branching and a larger number of short PS arms. Differential scanning calorimetry suggested that the glass transition temperature of the star-shaped PS decreased with molecular weight. Melt rheometry showed that even a slightly branched architecture of the PS led to a significantly lower viscosity; both the melt flow index and the activation energy increased with the degree of branching.



CONCLUSION: Due to the preferential consumption of BiBPM and formation of a CTC, even a very low dosage of BiBPM could lead to star-shaped PS, which, in comparison with linear analogues, could possess much better melt fluidity. (C) 2008 Society of Chemical Industry 
N-[4-(alpha-bromoisobutyryloxy)phenyl]maleimide; star-shaped polymer; polystyrene; self-condensing atom transfer radical copolymerization