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Oxygen permeation of blends of copolymers of siloxanes and poly(methylmethacrylate)
Author(s) -
Blahovici T. F.,
Brown G. R.
Publication year - 1987
Publication title -
polymer engineering and science
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.503
H-Index - 111
eISSN - 1548-2634
pISSN - 0032-3888
DOI - 10.1002/pen.760272107
Subject(s) - copolymer , materials science , siloxane , polymer chemistry , oxygen permeability , polymer , permeation , differential scanning calorimetry , polymerization , chemical engineering , oxygen , composite material , organic chemistry , chemistry , membrane , biochemistry , physics , engineering , thermodynamics
A series of low molecular weight (≈40000) copolymers of methylmethacrylate (MMA) and 4‐(methacryloyloxy)butylpentamethyldisiloxane (MBPD) have been synthesized by free radical polymerization in dimethylformamide solution. The microstructure, as derived from 13 C NMR spectra, indicates that the copolymers are about 80% syndiotactic with an overall random distribution of mers. At room temperature, copolymers rich in MMA are clear, rigid glasses but become liquid at high MBPD content. Blends of these copolymers with PMMA are all heterogeneous with visible phase separation over most of the composition range. Differential scanning calorimetry studies show the presence of two T g 's when the relative concentration of PMMA to copolymer is high. Blends of two co‐polymers of similar siloxane content produce clear films with no indication of phase separation. The permeability to oxygen at 25°C increases from 0.20 for pure PMMA to 3.0 (fmol/m·s·Pa.) for a copolymer of MMA/MBPD of the mole ratio of 3:1. Evaluation of the permeation behaviors of the blends suggests that blends rich in siloxane exist as a layered structure with the PMMA rich component dominating the observed permeability.