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Synthesis of a Poly(vinyl alcohol)‐Based Graft Copolymer Having Poly( ε ‐caprolactone) Side Chains by Solution Polymerization
Author(s) -
Aoi Keigo,
Aoi Hiromi,
Okada Masahiko
Publication year - 2002
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 - 10.1002/1521-3935(20020401)203:7<1018::aid-macp1018>3.0.co;2-9
Subject(s) - copolymer , polymer chemistry , polymerization , thermogravimetric analysis , vinyl alcohol , tetrahydrofuran , side chain , monomer , caprolactone , ring opening polymerization , thermal stability , materials science , chemistry , polymer , organic chemistry , solvent
Abstract Poly(vinyl alcohol)‐ graft ‐poly( ε ‐caprolactone) (PVA‐g‐PCL) was synthesized by ring‐opening polymerization of ε ‐caprolactone with poly(vinyl alcohol) in the presence of tin(II) 2‐ethylhexanoate as a catalyst in dimethyl sulfoxide. The relationship between the reaction conditions of the solution polymerization and the chemical structure of the graft copolymer was investigated. The degree of substitution ( DS ) and degree of polymerization ( DP ) of the PCL side chains were roughly controlled by varying the reaction periods and feed molar ratios of the monomer and the catalyst to the backbone. PVA‐g‐PCL with a PCL content of 97 wt.‐% ( DP = 22.8, DS = 0.54) was obtained in 56 wt.‐% yield. The graft copolymer was soluble in a number of organic solvents, including toluene, tetrahydrofuran, chloroform, and acetonitrile, which are solvents of PCL. The molecular motion of the graft copolymer from 1 H NMR measurements appears to be restricted to some extent at 27–50°C, however the 1 H NMR signal intensities measured at temperatures higher than ca. 50°C reflect the actual chemical structure of the graft copolymer as determined by elemental analysis. The graft copolymer having a short PCL side chain ( DP = 4.4, DS = 0.15) was amorphous. The melting temperature of a sample with relatively high PCL content ( DP = 22.8, DS = 0.54) was observed at 39°C. Thermogravimetric analysis revealed that the thermal stability of PVA was improved by introducing PCL side chains. The surface free energies of the air‐side of a graft copolymer film, as calculated by Owens' equation using contact angles, were comparable to that of PCL homopolymer.