Simple method for preparation of thermally expandable microspheres of PMMA encapsulating NaHCO3 via thermally induced phase separation

Abstract

ABSTRACTThermally expandable microspheres (TEMs) employing poly(methyl methacrylate) (PMMA) as shell and sodium bicarbonate (NaHCO3) as core were prepared by a simple method of thermally induced phase separation (TIPS). The addition of NaHCO3 improved the foaming properties of TEMs. The effects of preparation parameters on the morphology, amount of encapsulated NaHCO3, and foaming properties of TEMs were studied; the parameters investigated included the quench rate, the molecular weight (Mw) and amount of PMMA, and the amount of NaHCO3. The results show that when 0.5 g of PMMA 50k, 3 g of NaHCO3, and 50 g of ethanol were used, with quenching temperature at 0 °C, the TEMs were fully spherical and the maximum expansion volume of TEMs was about 3.8 times the original volume. The expansion volume of TEMs increased with increasing amount of encapsulated NaHCO3, and the foaming onset temperature and temperature of complete bursting of TEMs were related to the Mw of PMMA. © 2018 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2018, 135, 46179.