writer：Jiming Yang, Yongjiu Liang, Stephan Salzinger, Ning Zhang, Dewen Dong, Bernhard Rieger
keywords：fracture; group transfer polymerization; microspheres;
source：期刊
specific source：J. Polym. Sci.,Part A: Polym. Chem.
Issue time：2014年
We demonstrate a facile, yet efficient method for the
functionalization of crosslinked polystyrene (PS) microspheres
with biocompatible poly(vinylphosphonate)s via the combination
of a UV grafting polymerization and a surface-initiated group
transfer polymerization. Self-initiated photografting and photopolymerization
of ethylene glycol dimethacrylate results in direct
photografting of poly(ethylene glycol dimethacrylate) on the PS
microspheres with dangling methacrylate functionalities, which
are used to immobilize ytterbocene complexes to form the
surface-bound rare-earth metal catalyst system. The surfaceinitiated
GTP of dialkyl vinylphosphonates from the initiator system
leads to the functionalization of PS microspheres with poly(-
vinylphosphonate) brushes. Polymerization kinetic investigation
indicates that surface-initiated GTP leads to a constant and
remarkably rapid weight gain of the microsphere (a microsphere
weight increase of 600% within 3 min), owing to the highly living
and efficient character of GTP. The surface-initiated GTP occurring
inside the microsphere causes an accumulation of the tension
between the polymer chains in the microsphere, which
eventually induces fracture of the microsphere for longer polymerization
time.