Cooperative and Sequential Phase Transitions in it-Poly(propylene oxide)-b-poly(ethylene oxide)-b-it-poly(propylene oxide) Triblock Copolymers

Autor:	Glenn H. Fredrickson, Youli Li, Alaina J. McGrath, Weichao Shi, Craig J. Hawker, Edward J. Kramer, Nathaniel A. Lynd
Rok vydání:	2015
Předmět:	Phase transition Materials science Polymers and Plastics Ethylene oxide Organic Chemistry Oxide law.invention Inorganic Chemistry chemistry.chemical_compound Crystallography chemistry law Tacticity Polymer chemistry Materials Chemistry Copolymer Lamellar structure Propylene oxide Crystallization
Zdroj:	Macromolecules. 48:3069-3079
ISSN:	1520-5835 0024-9297
Popis:	Sequential phase transitions were investigated in detail for a set of newly designed poly(propylene oxide)-b-poly(ethylene oxide)-b-poly(propylene oxide) (PPO–PEO–PPO) triblock copolymers, where the PPO blocks have isotactic, (R)- or (S)-, or atactic configurations. Microphase separation and thermal composition fluctuations were studied near the order–disorder transition temperature (133 ± 1 °C), and the interaction parameters χ(T) were determined. A unique feature of these materials is the cooperative and sequential nature of phase transitions, which leads to the inversion of the crystallization/melting sequence of PEO and isotactic PPO blocks. The PEO blocks crystallize quickly (ca. 50 °C) within a soft, confined lamellar template, which is followed by slow crystallization of the isotactic PPO blocks (ca. 40 °C) under hard confinement. However, in the melting process, PEO crystals melt first (ca. 60 °C) affording soft confinement which enables isotactic PPO crystals to undergo recrystallization and lame...
Databáze:	OpenAIRE
Externí odkaz:	https://explore.openaire.eu/search/publication?articleId=doi_________::9be3173f3dec97376edcd90262b9fe6e https://doi.org/10.1021/acs.macromol.5b00326 Zobrazit plný text záznamu