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Effect of the length of branches on the critical surface tension of poly( n ‐alkyl methacrylates) and copolymers of stearyl methacrylate with methacrylonitrile
Author(s) -
Kamagata Kazuo,
Toyama Mitsuo
Publication year - 1974
Publication title -
journal of applied polymer science
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.575
H-Index - 166
eISSN - 1097-4628
pISSN - 0021-8995
DOI - 10.1002/app.1974.070180115
Subject(s) - methacrylonitrile , methacrylate , copolymer , alkyl , polymer chemistry , materials science , methyl methacrylate , polymer , acrylonitrile , chemistry , composite material , organic chemistry
Critical surface tension values γ c were measured for poly( n ‐alkyl methacrylates) and copolymers of stearyl methacrylate with methacrylonitrile. Surface tension values γ L of n ‐alkyl methacrylate increase with increasing side chain length: γ L = 23.2 dynes/cm for methyl methacrylate to 33.2 dynes/cm for stearyl methacrylate, but γ c values of poly( n ‐alkyl methacrylate) decrease with increasing side chain length: γ c = 36.3 dynes/cm for poly(methyl methacrylate) to 20.8 dynes/cm for poly(stearyl methacrylate). The decrease in γ c is attributed to a tighter packing of the alkyl chain with a greater concentration of the pendent CH 3 group at the air/solid interface. Values of γ c of copolymers hardly depended on the methacrylonitrile content in copolymers and did not satisfy the equation γ c = N 1 γ c 1 + N 2 γ c 2 proposed by Lee. The difference in γ c values for casting, annealing, and quenching films of poly(stearyl methacrylate) and the surface structure of copolymers were discussed using electron microscopy and measurement of melting point, heat of melting, and γ c .