Controlled Foaming of Polymer Films through Restricted Surface
Diffusion and the Addition of Nanosilica Particles or CO<sub>2</sub>-philic
Surfactants
Srinivas Siripurapu
Joseph M. DeSimone
Saad A. Khan
Richard J. Spontak
10.1021/ma047991b.s001
https://acs.figshare.com/articles/journal_contribution/Controlled_Foaming_of_Polymer_Films_through_Restricted_Surface_Diffusion_and_the_Addition_of_Nanosilica_Particles_or_CO_sub_2_sub_philic_Surfactants/3295249
Synergistic use of surface barriers and nanoscale additives is investigated as alternate means
by which to promote bubble nucleation in, and thus improve the porosity of, poly(methyl methacrylate)
(PMMA) thin films (<i>i</i>) constrained between impenetrable plates, (<i>ii</i>) modified with either nanosilica
particles, commercial short-chain fluorosurfactants, or designer CO<sub>2</sub>-philic block/graft copolymers, and
(<i>iii</i>) exposed to high-pressure CO<sub>2</sub>. Resultant foamed films exhibit a vast array of micro/mesocellular
morphologies in the presence of supercritical, as well as liquid, CO<sub>2</sub> and demonstrate that copolymer
micelles afford better control over bubble nucleation (with pore cell densities, <i>N</i>, approaching 10<sup>12</sup> cells/cm<sup>3</sup>) relative to hard nonporous nanoparticles, which alone increase <i>N</i> by more than 2 orders of magnitude
at low CO<sub>2</sub> pressures. Incorporation of these nanoscale additives in a surface-constrained polymer matrix
serves to enhance foaming through concurrent restriction of CO<sub>2</sub> diffusion, heterogeneous nucleation of
CO<sub>2</sub> bubbles, and/or reduced interfacial tension between PMMA and CO<sub>2</sub>.
2005-03-22 00:00:00
CO 2 diffusion
Restricted Surface Diffusion
PMMA
CO 2 bubbles
designer CO 2
CO 2
philic Surfactants Synergistic use
bubble nucleation
pore cell densities
nanoscale additives
CO 2 pressures