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  • 1
    Electronic Resource
    Electronic Resource
    Compositional variations in cast films of blends of copolymers of siloxanes and poly(methyl methacrylate) determined by energy dispersive spectroscopy and X-ray image analysis (1988)
    Stamford, Conn. [u.a.] : Wiley-Blackwell
    Polymer Engineering and Science 28 (1988), S. 1381-1391 
    Details
    ISSN: 0032-3888
    Keywords: Chemistry ; Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Notes: Films cast on gold surfaces from 3% methylene chloride solutions of syndiotactic poly(methyl methacrylate) (PMMA) (Mn = 23,000) and random copolymers of PMMA and 4-(methacryloyloxybutyl) pentamethyldisiloxane (MBPD) (Mn = 40,000) are all heterogeneous with visible phase separation occurring over most of the compositional range. Energy dispersive spectroscopy (EDS) shows that for PMMA blended with the copolymers there is an excess of silicon, ranging from 1.9 wt% to 9.7 wt%, in the surface exposed to air during casting, while the lower surface exposed to the gold is depleted in silicon. X-Ray mapping and image analysis show that for blends containing 50% or less of siloxane copolymer the upper surface is composed of large siloxane rich domains in a PMMA matrix while the lower surface is composed of much smaller and less abundant siloxane domains in a PMMA matrix. In addition, the siloxane domains of the upper surface contain small PMMA domains. For blends with a greater siloxane content, the upper surface is composed of a siloxane matrix while the lower surface remains PMMA rich.
    Additional Material: 14 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/pen.760282107
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  • 2
    Electronic Resource
    Electronic Resource
    Siloxane-poly(Methylmethacrylate) amphoteric blends (1982)
    Stamford, Conn. [u.a.] : Wiley-Blackwell
    Polymer Engineering and Science 22 (1982), S. 1123-1126 
    Details
    ISSN: 0032-3888
    Keywords: Chemistry ; Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Notes: Poly([4-(methacryloyloxy) butyl]pentamethyldisiloxane), PMBPD, has been prepared for the first time. At the weight average molecular weight of 55,900, it is a clear, viscous liquid with a glass transition temperature, Tg, of 236K. Copolymers with methylmethacrylate have also been prepared. The homo-and copolymers, all of which have methacrylate backbones with pendant siloxane groups, were blended with poly(methyl-methacrylate), PMMA. Using the existence of a single Tg as a definition of miscibility, it was found that blends of either PMMA or PMBPD with random copolymers are miscible. However, in spite of a clear appearance, the blend of the two horriopolymers were found to have two distinct Tgs.
    Additional Material: 1 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/pen.760221712
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  • 3
    Electronic Resource
    Electronic Resource
    Oxygen permeation of blends of copolymers of siloxanes and poly(methylmethacrylate) (1987)
    Stamford, Conn. [u.a.] : Wiley-Blackwell
    Polymer Engineering and Science 27 (1987), S. 1611-1619 
    Details
    ISSN: 0032-3888
    Keywords: Chemistry ; Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Notes: 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 13C 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 Tg'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.
    Additional Material: 11 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/pen.760272107
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