Development and optimization of uv-induced chemical foaming process

Abstract

In this study, we have investigated a UV-induced chemical foaming method to create a nanocellular polymer thin film. A small amount of photoacid generator (PAG) was mixed with poly(methyl methacrylate-co-tert-butyl acrylate) (PMMA-co-PtBA). After UV irradiation followed by heating, tert-butyl ester group in the PtBA was deprotected with the acid generated from the PAG, and isobutene gas was produced in the polymer matrix. The resulting polymer foamed with the gas had cell size and cell density ranging from 100 to 200 nm and from 1 × 10¹³ to 9 × 10¹³ cells/cm³, respectively. Several key parameters were found that would affect largely on the formation of the nanocellular structure, i.e., foaming time and temperature, UV dose, molecular weight of polymer.