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6593580 
Journal Article 
Precise Synthesis of PS-PLA Janus Star-Like Copolymer 
Fan, X; Win, KY; Hu, Z; Loh, XJ; Li, Z; , 
2019 
1 
Macromolecular Rapid Communications
ISSN: 1022-1336
EISSN: 1521-3927 
WILEY-V C H VERLAG GMBH 
WEINHEIM 
40 
5 
e1800217 
English 
30033548 
WOS:000460331900006 
In this work, an efficient strategy is designed for the precise synthesis of novel Janus star-like copolymer (polystyrene)8 -b-(poly(l-lactide))8 , (PLLA)8 -b-(PS)8 , consisting of two types of chemically distinct polymer arms, PS and PLLA, in an asymmetric structure. During the synthesis, PLLA hemisphere carrying protected hydroxyl groups at the focal point was first synthesized via a combined reactions of esterification, light-induced "Click" chemistry, and ring opening polymerization (ROP) using a specially designed dendron as initiator. After removing the protecting moiety, the terminal hydroxyl groups on the dendron segment is increased fourfold and further modified into bromopropionate-based macroinitiator through a two-step end group transformation reaction, followed by atom transfer radical polymerization (ATRP) of styrene to obtain the desired (PLLA)8 -b-(PS)8 Janus star-like copolymer. The versatility and efficiency of the designed synthetic strategy are demonstrated by the well-defined molecular characteristics and high yields of the targeted product. In addition to the controlled degradation behavior of the PLLA segments, the remaining bromide groups located at the distal end of PS arms could allow for further fabrication of diverse building blocks through consecutive ATRP of various monomers. This work signifies the first time for facile and precise synthesis of Janus star-like copolymer with unique biphasic structure and function control.