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Synthesis of new amphiphilic star polymers derived from a hyperbranched macroinitiator by the cationic ‘grafting from’ method
Author(s) -
Weberskirch Ralf,
Hettich Rainer,
Nuyken Oskar,
Schmaljohann Dirk,
Voit Brigitte
Publication year - 1999
Publication title -
macromolecular chemistry and physics
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.57
H-Index - 112
eISSN - 1521-3935
pISSN - 1022-1352
DOI - 10.1002/(sici)1521-3935(19990401)200:4<863::aid-macp863>3.0.co;2-n
Subject(s) - polymer chemistry , cationic polymerization , amphiphile , chemistry , copolymer , polymerization , monomer , benzoyl chloride , ring opening polymerization , polymer , organic chemistry
New amphiphilic star polymers possessing a hyperbranched core and hydrophilic graft arms have been prepared. The synthetic strategy involved esterification of the 4,4‐bis(4′‐hydroxyphenyl)valeric acid based hyperbranched polymer with 3‐(chloromethyl)benzoyl chloride to obtain the hyperbranched macroinitiator followed by cationic ring‐opening polymerization of 2‐methyl‐2‐oxazoline to give amphiphilic polymers. Exchange of the chloride counter ion with trifluoromethanesulfonate (KCF 3 SO 3 or AgCF 3 SO 3 ) or iodide (KI) anions leads to higher polymerization rates. Phenyl 2‐(chloromethyl)benzoate was used as a model initiator to study the effect of different coinitiators on the initiator efficiency. KI as a coinitiator yielded 56–86% initiator conversion whereas only 30–37% initiator conversion was achieved with KCF 3 SO 3 or AgCF 3 SO 3 as coinitiator after quantitative monomer consumption. Photon correlation spectroscopy (PCS) in methanol and chloroform for selected graft copolymers revealed the formation of single star molecules ranging from 22 to 50 nm in diameter.