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The significant influence of graphene oxide (GO) on the unidirectional foaming of poly(lactic acid) (PLA) using supercritical CO 2 as blowing agent was investigated in this study for the first time. Highly oriented and elongated cell structures were obtained from the PLA/GO nanocomposites foams. The thermal, rheological, and CO 2 absorption properties of the PLA/ GO nanocomposites were studied to investigate the effect of GO on PLA unidirectional foaming. It was found that the incorporation of GO improved the storage modulus, loss modulus, and complex viscosity of the PLA/GO nanocomposites significantly. The addition of GO improved the CO 2 absorption ability of the nanocomposites, which caused high expansion ratio and increased average cell size during foaming process. The high expansion force by enhanced CO 2 absorption, high matrix viscosity of PLA/GO nanocomposites, and restriction of the mold in three directions together caused the formation of the highly elongated cell structure during foaming.

Both poly(lactic acid) (PLA) and poly(ethylene glycol) (PEG) are biodegradable polymers, blending PLA with PEG is expected to toughen PLA matrix while maintaining its biodegradability. In this study, PLA/PEG blends in different ratios were prepared through triple-screw extruder, and the foaming behavior was investigated using supercritical carbon dioxide as physical blowing agent. The mechanical, thermal, rheological properties, and crystallization behavior were also studied. By the incorporation of PEG, the impact strength of the PLA/PEG blends improved by 98% with the specimens fractured in a ductile mode. The crystallization process of the blends was accelerated, and the crystallinity was significantly increased to 45.1%. The viscoelasticity of the PLA/PEG matrix was weakened, and the cells tended to break at the cell wall during cell expansion; thus, a highly interconnected structure with a maximum porosity of 82.3% was obtained. Moreover, the PLA/PEG blends exhibited higher cell densities and smaller cell size, compared to their neat counterparts.

Mesoporous silica nanoparticles have been widely adopted in energy, biology and medicine due to their well-ordered and stable structures. Nevertheless, few attempts have been made to study these materials as a sensing tool. Herein, we report a "smart" sensor for the dual-detection of the pH value and temperature, which was implemented with environmentally responsive polyelectrolyte/mesoporous silica electrodes. Using SBA-15 silica as the framework, we functionalized the internal mesopores with DMAMEA monomer via surface-initiated RAFT polymerization ("grafting-from" method). By controlling the degree of polymerization, the pore size and the specific surface area can be precisely controlled. When the degree of polymerization was optimized to 75, the hybrid material showed significant sensitivity in response to the pH value in the range of 4-10 and optimally responded to the temperature at 39°C, setting a pH value of 10.The ionic conductivities of the template Fe(CN) 6 4−/3− and Ru(NH 3 ) 6 2+/3+ ions were switchable in different conditions. These results suggest that the polyelectrolyte/mesoporous silica hybrid materials could have potential for application in dual-functional sensors in environmental detection.

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Anode aluminum oxide (AAO) porous materials have been widely used in ionic translocation for many biological and chemical studies.

Ultrahigh molecular weight polyethylene (UHMWPE) is usually difficult to be melt processed due to severe intermolecular entanglement in its melt. In this work, we reported the development of a poly(amido amine) (PAMAM) dendrimer (G1) and its derivatives with different terminal groups which showed promising feasibility for aiding UHMWPE melt processing. The rheological, crystalline, and mechanical properties of the blends were investigated comprehensively. The addition of the dendritic modifiers to the UHMWPE matrix resulted in a significant decrease in melt viscosity, thus an obvious enhancement of the processability. The dynamic analysis of the mechanical properties and rotation‐rheological test indicated a disentanglement effect of the UHMWPE melt molecules was generated by the PAMAM dendrimer (G1) and its derivatives. Furthermore, the PAMAM dendrimer (G1), as an internal lubricant, was uniformly distributed in the UHMWPE matrix. The heteronucleation effect of the PAMAM dendrimer (G1) with its derivatives led to a higher degree of crystallinity, smaller crystallites in the matrix and enhanced tensile strength in the UHMWPE blends. POLYM. ENG. SCI., 57:153–160, 2017. © 2016 Society of Plastics Engineers