Effect of molecular weight to the structure of nanocellular foams: Phase separation approach. (16th March 2020)

• Record Type: Journal Article
• Authors: Yeh, Shu-Kai; Liao, Zong-En; Wang, Keng-Chuan; Ho, Yu-Ting; Kurniawan, Vania; Tseng, Po-Chih; Tseng, Tien-Wen
• Is Part Of: Polymer. Volume 191(2020)
• Publication Date: 2020-03-16
• Subjects: Nanocellular foam -- Molecular weight -- CO2 solubility; Polymers -- Periodicals; Polymerization -- Periodicals; Polymères -- Périodiques; Polymérisation -- Périodiques; 547.7
• DOI: 10.1016/j.polymer.2020.122275
• Languages: English
• ISSNs: 0032-3861

Abstract

Abstract: Nanocellular foam is one of the most exciting research areas in foam research. Creating nanocellular foams of high expansion ratio with a cell size lower than 100 nm is still a challenge. In this study, poly(methyl methacrylate) (PMMA) of three different molecular weights, namely PMMA-H, PMMA-M, and PMMA-L, were foamed using the two-step solid-state foaming method to create nanocellular foams. The results showed that the molecular weight of PMMA is one of the critical factors that affect the preparation of PMMA nanofoam. Open-cell nanocellular foams with a cell size of approximately 30–40 nm and cell density of 10 16 cells/cm 3 were successfully prepared using PMMA-H. The relative density of the foam is between 0.25 and 0.41. Qualitative phase diagrams were created based on saturating temperature, foaming temperature, and molecular weights. Phase separation theory may explain the formation of closed- or open-cell foam with spinodal decomposition contributing to nanosized open cell structure. Graphical abstract: Image 1 Highlights: The molecular weight of PMMA affect the formation of homogeneous nanocellular structure. Cell structure manipulation by controlling saturation and foaming condition. Closed-cell, open-cell wall rupture and bicontinuous structure were obtained. Qualitative phase diagrams based on Tsat, Tfoam, and Mw . Crossover of the metastable region for TIPS in the LCST system.