The Roles Played by DMF in the Structure Formation of Epoxy-Based Porous Monolith
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STRUCTURE AND PROPERTIES
The Roles Played by DMF in the Structure Formation of Epoxy-Based Porous Monolith Yace Mia, Sa Liua, Yongfeng Zhanga, Junmin Suna, and Weiqing Zhoub,c,d,* a
Inner Mongolia University of Technology, Hohhot, 010051 China National Key Laboratory of Biochemical Engineering, Institute of Process Engineering, Chinese Academy of Sciences, Beijing, 100190 China cUniversity of Chinese Academy of Sciences, Beijing, 100049 China dInstitute for Stem Cell and Regeneration, Chinese Academy of Sciences, Beijing, 100049 China *e-mail: [email protected]
b
Received April 13, 2020; revised May 11, 2020; accepted May 29, 2020
Abstract—Epoxy-based porous monoliths are prepared by chemically induced phase separation. The roles played by N,N-dimethylformamide (DMF) in both curing and phase separation kinetics are studied in detail. It is found that the addition of DMF not only changes the speed of phase separation, but the way. Meanwhile, the occurrence of secondary phase separation is partly inhibited, which is in favor of the formation of skeletal network structure. In addition, the schematic pseudo phase diagrams were deduced, which are of great significance to understand the roles played by DMF for the targeted control of materials structure. The results show that by the addition of DMF, the phase diagram moves to the lower right, which means more porogen is needed to obtain skeletal network structure. The spinodal line moves toward the binodal line and the internal space of spinodal line is enlarged. Therefore, it becomes more available to obtain skeletal network structure. DOI: 10.1134/S1560090420050097
good solvent was used, a small amount could make a big difference and changing the amount of good solvent was an effective approach to regulate the polymer structure. It was generally known that the good solvent improved the solubility of generated polymer in porogen and inhibited the development of phase separation [13–15], but the details were not clear. In our previous work [16], we have studied the influence of certain factors on the final polymer structure in chemically induced phase separation. It was interesting to find that it became more available to obtain skeletal network structure without globules by the addition of good solvent. In this study, N,N-dimethylformamide (DMF) was chosen as good solvent and the roles played by DMF in both curing and phase separation kinetics were studied in detail. In addition, the schematic pseudo phase diagrams of DGEBA/DDCM/P (the reactive blends with diglycidyl ether of bisphenol A (DGEBA) and 4,4'-diaminodicylohexylmethane (DDCM) as monomers, and polyethylene glycol 200 (PEG 200) as porogen) and DGEBA/DDCM/P-D (the reactive blends with DGEBA and DDCM as monomers, and PEG 200 with DMF as porogen) were obtained, which were of great significance to understand the roles played by DMF for the targeted control of materials structure.
INTRODUCTION Chemically induced phase separation was first proposed as a physical modification method of polymer materials in 1980s,
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