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Preparation of Hierarchically Structured Amorphous Carbon Monoliths with Closed Spherical Mesopores via the Lower Critical Solution Temperature Phase Transition
Author(s) -
Jeon SeungYeol,
Jeon Hyeonyeol,
Park Tae Joon,
Kang Min Kwan,
Cho ByoungKi,
Hwang Seung Sang,
Hur Kahyun
Publication year - 2019
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.201900165
Subject(s) - lower critical solution temperature , materials science , differential scanning calorimetry , copolymer , chemical engineering , ethylene oxide , polymer chemistry , polymer , phase transition , glass transition , composite material , thermodynamics , physics , engineering
Some polymer mixture systems become immiscible above a specific temperature, the so‐called lower critical solution temperature (LCST). In this work, the LCST behavior of a mixture of poly(ethylene oxide)‐block‐poly(propylene oxide)‐block‐poly(ethylene oxide) triblock copolymers and phenolic resin oligomers is observed, and the corresponding phase transition is exploited to develop a facile route to hierarchically structured carbon monoliths. Whereas evaporation‐induced self‐assembly generates hexagonal channels in the monoliths, an additional phase transition at the LCST leads to an ordered arrangement of isolated pores. The fabrication method involves annealing the gel‐phased mixture with polymeric microbeads in a 3D‐structured mold at the LCST, followed by thermosetting and a carbonization process. The LCST phase transition behavior is observed experimentally by in situ small‐angle X‐ray scattering, optical transparency measurements, differential scanning calorimetry, and infrared spectroscopy. The fundamental mechanism of the LCST phase transition is further investigated by atomistic molecular dynamics simulations.