Porous polymer carbons. II. Preparation and properties of porous poly(vinylidene chloride) carbons

Authors

  • G. J. Howard,

    1. Department of Polymer and Fibre Science, University of Manchester Institute of Science and Technology, Manchester M60 1QD, England
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  • S. Knutton

    1. Department of Polymer and Fibre Science, University of Manchester Institute of Science and Technology, Manchester M60 1QD, England
    Current affiliation:
    1. The Grammar School, Mexborough, Yorkshire, England
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Abstract

Suspension–polymerized copolymers of vinylidene chloride and ethylene glycol dimethacrylate have been converted into carbons by heating to 900°C. Poly(vinylidene chloride) homopolymer may melt on a first-stage heating at ca. 200°C and consequently yields a fused 900°C carbon; restraining the first-stage heating to slightly lower temperatures permits the retention of the polymer morphology which is then retained on subsequent carbonization at 900°C. The crosslinked copolymers do not fuse at 200°C and lose the dimethacrylate component, apparently cleanly, in the temperature range of 350–450°C and give 900°C carbons which are shrunken pseudomorphs of the parent polymer; all structural features are retained, including the characteristic skin of the polymer particles. Thus, the macroporous character of the carbons is controlled by both the crosslinker and diluent contents of the original polymerization recipe. The 900°C carbons are also microporous; hysteresis in nitrogen (77°K) isotherms is attributed to activated diffusion since carbon dioxide (196°K) isotherms are reversible. The microporosity of these dual-porosity carbons depends on the content of crosslinking comonomer in the parent polymer, and possible reasons for this dependence are discussed.

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