Premium
Synthesis of statistical PET/PEN random block copolymers and their crystallizability in the bulk and at the surface
Author(s) -
Shinotsuka Kei,
Assender Hazel E.,
Claridge Timothy D. W.
Publication year - 2018
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.46515
Subject(s) - crystallization , copolymer , materials science , lamellar structure , annealing (glass) , glass transition , polymer chemistry , melting point , morphology (biology) , chemical engineering , enthalpy , crystallography , composite material , thermodynamics , polymer , chemistry , biology , engineering , genetics , physics
A series of PET/PEN copolyesters were synthesized by molten transesterification. The degree of randomness and the sequence length of the copolymers were determined by 1 H NMR spectroscopy, and the changes in the bulk glass transition temperature ( T gB ), bulk crystallization temperature ( T cB ), and bulk melting temperature ( T mB ) were observed by DSC. A clear relationship was obtained between the observed enthalpy of melting (Δ H m ) and degree of randomness ( B ), and T mB was suppressed for the midcompositions. As with their homopolymer counterparts, there was significant depression in crystallization temperature at the surface ( T cS ) of the random/block copolymers compared with the bulk, and so surface‐localized crystallization could be induced in spin‐coated thick films (thickness ranging from ca. 400 to 700 nm) by annealing at a temperature in which the surface region is mobile, but the bulk is not. The formation of these clear surface crystals allows the morphology to be directly imaged by AFM, and we observed that the crystallizability and the lamellar morphology of the surface crystals deviated from those of the original homopolymers, depending on the mixing ratio of PET/PEN and degree of randomness. © 2018 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2018 , 135 , 46515.