Linear and nonlinear viscoelastic properties under dynamic oscillatory shear flow were used to investigate the effects of compatibilization on polypropylene (PP)/ polystyrene (PS) blends. Two different nanoparticles (organo-modified clay and fumed silica) were used at various concentrations. To analyze nonlinear stress under large amplitude oscillatory shear (LAOS) flow, nonlinearity (I 3/1 ) was calculated from FT-rheology. To quantify the degree of dispersion of different particles at various concentrations, a new parameter, nonlinear−linear viscoelastic ratio (NLR ≡ normalized nonlinear viscoelasticity/normalized linear viscoelasticity), was used. The relationship was determined between NLR value and PS droplet size in the PP matrix. From the TEM images, clay was located mostly at the interface or partially inside the PS drops, thereby reinforcing the compatibilization effect. Therefore, clay increased the dispersion morphologies of the PP/PS blends. In contrast, fumed silica was located mostly inside the PS droplets, which means the morphologies of PP/PS blends were not improved. Linear viscoelasticities of both PP/ PS/clay and PP/PS/silica showed improvements at elevated particle concentrations. NLR values for the PP/PS/Clay blends were larger than 1 (NLR > 1), whereas NLR values for the PP/PS/silica blends were less than 1 (NLR < 1). Therefore, NLR could be classified into two categories depending on morphology. Based on these results, NLR can be used to distinguish between the effects of two different types of nanoparticles on the morphologies of PP/PS blends.

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Carboxylate-functionalized polymers of intrinsic microporosity (PIMs) are promising materials for gas separation application. However, highly carboxylate-functionalized PIMs (HCPIMs) have not been reported owing to overlooked intermediate products. Herein, we successfully prepared HCPIMs (∼92 mol % of carboxylic acid group) through a prolonged alkaline hydrolysis process (360 h). HCPIMs were found to be soluble in various organic solvents, such as tetrahydrofuran and dimethyl sulfoxide, and then free-standing HCPIM membranes could be prepared by the common solution casting method. The HCPIM membranes were found to have smaller interchain distances and higher CO2 affinity than original PIM-1 films. For example, small gas molecules, such as carbon dioxide, were effectively separated due to the enhanced diffusivity selectivity combined with the smaller cavity size. Further, strong interactions between carbon dioxide and the carboxylic acid groups increased solubility selectivity. These synergetic effects endowed the HCPIM membrane with a selectivity of 53.6 for CO2/N2 separation, the highest among reported chemically modified PIMs.