142 Advances in Polymer Science Editorial Board: A. Abe. A.-C ...

Synthesis of Branched Polymers by Cationic Polymerization 47
3.2.2
Synthesis of the Branches by Cationic Polymerization: Poly(styrene) Branches
Poly(pentadiene-g-S) was synthesized by Peng and Dai [70] by grafting PS initiated
by adventitious moisture with various Lewis acid coinitiators onto pendant
double bonds of polypentadiene in CH 2 Cl 2 at 0 °C. After selective solvent extraction,
the products were analyzed by IR and 1 H NMR spectroscopy. The highest
grafting efficiency (73%) and close to complete S conversion were observed with
Et 2 AlCl. With BCl 3 the grafting efficiency was similar (67%), although S conversion
was only ~60%. Cross-linked polymer was not observed which was explained
by fast termination of the cation arising after grafting onto the polypentadiene
chain. The optimum temperature was ~0 °C; at lower or higher temperatures
the grafting efficiencies decreased. Although MWs were not reported, intrinsic
viscosity of the graft copolymer was found to be lower than that of
polypentadiene, which may indicate chain scission during grafting.
The synthesis of graft copolymers by “grafting from” and “grafting onto” techniques
are reported in Table 4.
Table 4. Graft copolymers obtained by “grafting from” and “grafting onto” techniques
(names of the polymers obtained by cationic polymerization are italicized)
Nature of the
backbone
Nature of the
branches
Method used a Reference
Poly(EVE-co-CEVE) Poly(oxazoline) f [58]
Poly(IB-co-CMS) Poly(oxazoline) f [60]
Triflated poly
(methyl phenyl silylene)
Poly(IBVE) f [61]
PMMA Poly(silyl vinyl ether) f [63]
PS with tert-benzylic
acetate
PS-co-poly[4-(1hydroxy-1methylethyl)styrene]
PIB f [64]
PIB f [65]
EPDM PS
Poly(a-MeS)
f [66]
Poly(CEVE) PS
Poly(butadiene)
o [67]
Poly(BMS-IB-BMS) PMMA o [69]
Poly(pentadiene) PS o [70]
a f, Grafting from; o, grafting onto