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Crystalline and disordered state of poly(dihexylsilylene) copolymers
Author(s) -
Frey Holger,
Möller Martin,
Matyjaszewski Krzysztof,
Oelfin Dieter
Publication year - 1995
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/macp.1995.021960417
Subject(s) - comonomer , side chain , copolymer , polymer chemistry , mesophase , thermochromism , monomer , crystallography , alkyl , materials science , chemistry , phase (matter) , polymer , organic chemistry
A systematic comparison of random copolymers, derived from poly(dihexylsilylene) (PDHS) by incorporation of monomeric units with shorter unbranched alkyl side chains, has been carried out based on calorimetry, variable temperature UV spectroscopy, and 29 Si MAS (magic angle spinning) solid state NMR investigations. Also, hexylmethylsilylene units and branched monomers have been copolymerized. Up to 10% comonomer with shorter linear side chains (i. e., pentyl to propyl) could be incorporated into PDHS without impeding the all‐ trans order of the crystalline phase. In this case, the UV absorption maximum of the crystalline low‐temperature phase was affected only slightly according to the length and fraction of the comonomer side chains. A less ordered crystal structure (λ max = 345–355 nm) was observed when the content of comonomers with shorter side chains was about 20%. Yet, all these materials form conformationally disordered mesophases. A clear disordering transition and corresponding thermochromism was not observed any more when 50% of propyl side chains were incorporated. The order of the crystalline and the mesophase is also strongly perturbed if only a small fraction (4%) of the side chains are branched at C 2 .