Enhanced solubility of siloxy-modified polyhedral oligomeric silsesquioxanes in supercritical carbon dioxide

Highly Crystalline Poly(l-lactic acid) Porous Films Prepared with CO2-philic, Hybrid, Liquid Cell Nucleators

“…The inefficiency of scCO 2 to foam PLLA can be attributed to the highly ordered crystalline structure and thus stiffness of PLLA, preventing the efficient dissolution and diffusion of CO 2 in the polymer matrix and, thus, plasticization and pore growth in the matrix. 24,26 In order to both increase the affinity of PLLA matrix to CO 2 and create nucleation sites in the matrix, two different CO 2soluble, liquid additives, IPOSS 41 and MPOSS, 42 were added to the polymer matrix at 10 wt %, which was the highest additive concentration yielding polymer films without phase segregation. We observed that concentrations higher than this value led to phase segregation and caused problem in film integrity.…”

“…The other one is methacrylisooctyl POSS (MPOSS) (Figure 1c), which has recently been reported as CO 2 -philic. 42 It has a molecular structure similar to that of IPOSS, except one of the isooctyl branches is replaced with a methacryl group. 2.2.…”

Controlling the foam morphology of supercritical CO2‐processed poly(methyl methacrylate) with CO2‐philic hybrid nanoparticles

“…Polyhedral oligomeric silsesquioxanes (POSS) nanoparticles are environmentally friendly materials, which have a silica cage structure with functional groups attached to the Si atoms of the cage. These nanoparticles can be modified with different functional groups to have the desired properties, 40 which can be very advantageous in scCO 2 foaming process, if they are functionalized with CO 2 ‐philic groups 41–44 . The effects of highly CO 2 ‐philic POSS as cell nucleators on the scCO 2 foaming performance of the polymer were studied for the first time by Novendra et al 45 In this study, highly crystalline poly( l ‐lactic acid) (P L LA) was used as the matrix material.…”

“…These nanoparticles can be modified with different functional groups to have the desired properties, 40 which can be very advantageous in scCO 2 foaming process, if they are functionalized with CO 2 -philic groups. [41][42][43][44] The effects of highly CO 2 -philic POSS as cell nucleators on the scCO 2 foaming performance of the polymer were studied for the first time by Novendra et al 45 In this study, highly crystalline poly(Llactic acid) (P L LA) was used as the matrix material. P L LA is known to require high processing temperature close to its melting temperature and pressure around or above 20 MPa to be foamed with scCO 2 .…”

“…In this study, octatrimethylsiloxy POSS nanoparticles which was found to have the highest solubility among all the studied CO 2 ‐philic POSS types 43 were used for enhancing the foaming performance and foam morphology of PMMA in terms of pore density and pore diameter. A complete range of process parameters such as temperature, pressure, time, and venting rate on foam morphology were investigated using two‐factorial design method.…”