Nanoporous PMMA foams with templated pore size obtained by localized in situ synthesis of nanoparticles and CO2 foaming

Abstract

a b s t r a c tPolymer foams with controlled and templated pore size have been obtained for the first time by CO 2 gas dissolution foaming from poly(methyl methacrylate) (PMMA) films. This kind of materials, with a variable porous structure, mimic some high-performance natural materials and could present significant interest in many applications. However, up to now their controlled fabrication has not been successfully achieved. Herein, we present a method to achieve a fine control in the production of such materials. Thermal in situ synthesis of ZnO nanoparticles from Zn(OAc) 2 was proposed to obtain PMMA nanocomposites, in which the ZnO nanoparticles induce heterogeneous nucleation that leads to formation of pores with size below the micron, upon CO 2 foaming. Starting from templated solid PMMA samples with well-differentiated regions, presenting or not ZnO nanoparticles, it was possible to obtain PMMA-based foams with well-defined areas of different pore sizes.

Nanocellular Polymers with a Gradient Cellular Structure Based on Poly(methyl methacrylate)/Thermoplastic Polyurethane Blends Produced by Gas Dissolution Foaming

“…[11] There are several strategies to produce cellular polymers with graded morphologies. One approach is the use of nucleating agents gradually distributed, such as in the work of Pinto et al [12] With a localized synthesis of the nanoparticles in the solid material, they reached a templated porous structure after foaming. In the work of Yu and coworkers, [13] polymers were foamed in a nanoporous substrate that enhanced nucleation near the substrate, reaching a graded cellular structure.…”

Low-density PMMA/MAM nanocellular polymers using low MAM contents: Production and characterization

“…The first approach is the use of nanoparticles as nucleating agents to favor nucleation [22,23]. Costeux et al [24] take advantage of heterogeneous nucleation for the production of low relative density (0.15) nanocellular PMMA (cell size of 100 nm).…”

Understanding the role of MAM molecular weight in the production of PMMA/MAM nanocellular polymers

“…When adding an appropriate second phase to a pure polymer, the interfaces between the matrix and the second phase act as preferable nucleation sites, that is, the Gibbs energy barrier, which should be overcome to form a nucleus, is lower when this second phase is added [24]. To produce nanocellular polymers with this approach, nanoparticles [25][26][27] or block copolymer micelles [10,[28][29][30] can be used as the second phase. In particular, block copolymer spherical micelles with CO 2 -philic domains gather all the qualities required to act as ideal nucleants: the nucleation is favourable in the micelles, they present uniform size and surface properties, they are easily dispersible, and the number of micelles formed is usually large [31].…”