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Indexed by:期刊论文

Date of Publication:2016-10-07

Journal:POLYMER CHEMISTRY

Included Journals:SCIE、EI、Scopus

Volume:7

Issue:37

Page Number:5840-5848

ISSN No.:1759-9954

Abstract:An efficient method for the synthesis of well-defined cyclic polystyrenes using anionic polymerization, silicon chloride linking chemistry, and metathesis ring closure has been developed. The macrocycle precursor, alpha,omega-bis(4-pentenyl)polystyrene, was formed by 4-pentenyllithium-initiated polymerization of styrene, coupling of alpha-pentenylpoly(styryl)lithium (PLi) with dimethyldichlorosilane to form alpha,omega-bis(4pentenyl)polystyrene (M-n = 4600 g mol(-1)) and reaction of excess PLi with ethylene oxide to facilitate purification. Cyclization of the purified alpha,omega-bis(4-pentenyl)polystyrene was performed in dichloromethane under mild conditions using a Grubbs catalyst, bis(tricyclohexylphosphine)benzylidine ruthenium(IV) chloride, as a metathesis ring-closure agent. In contrast to prior work, no fractionation is required to obtain the pure product. Both the divinyl precursor and resulting macrocycle were characterized by SEC, MALDI-TOF mass spectrometry (MS) and NMR. The macrocycle was unambiguously distinguished from its precursor using the fragmentation patterns from tandem mass spectrometry (MS2) experiments. The results show that the macrocyclic precursor, alpha,omega-bis(4-pentenyl)polystyrene, was of high purity and that the cyclization was highly efficient.