Block-copolymer containing a poly(L-lactic acid) (PLLA) segment was blended with pure poly(D-lactic acid) (PDLA) chain in chloroform solution and casted into the dried film. This method could form the stereocomplex (Sc) crystal of PLLA/PDLA within the nanometer-sized phase separation self-assembled by block-copolymer. Differential scanning calorimetry measurements of the prepared and annealed films gave the maximum achievable melting temperature of 245 °C, which was highest among those previously reported for PLA Sc-crystals. Surprisingly, all of added PDLA chains were Sc-crystallized, depending on the blend composition with block-copolymer containing PLLA.
Aqueous chemical oxidative dispersion polymerizations of pyrrole using PdCl 2 oxidant were conducted using sodium poly(styrene sulfonate)-block-poly(N-isopropyl acrylamide) as a colloidal stabilizer in order to synthesize thermo-responsive polypyrrole-palladium (PPy-Pd) nanocomposite particles in one step. PPy-Pd nanocomposite particles with number-average diameters of approximately 20 nm were successfully obtained as colloidally stable aqueous dispersions, which were stable at least for 6 months. The resulting nanocomposite particles showed themo-responsive flocculation behavior in aqueous media in the presence of additional salts, which screen surface charge of the nanocomposite particles.
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