No abstract

No abstract

No abstract

Summary The effect of temperature and type of solvent on the microdomain orientation during solvent‐annealing of block copolymer ultrathin films on silicon substrates was investigated using asymmetric polystyrene‐block‐poly(2‐vinylpyridine) (PS‐b‐P2VP) diblock copolymer. When the solvent‐annealing was performed with THF at 20°C, the ultrathin film exhibited a mixed orientation of cylinders parallel and perpendicular to the substrate while at 25°C only parallel cylinders were observed by AFM. The solvent annealing with acetone gave a dot pattern at 20°C and a line pattern at 25°C. On the other hand, in the case of solvent‐annealing with toluene perpendicular cylinders were observed at 25°C while at 20°C the morphology was not clear. The orientation and morphology of microdomains as well as the kinetics in PS‐b‐P2VP ultrathin films on solvent‐annealing is significantly affected by temperature and type of solvent. By controlling temperature and selecting the solvent, perpendicular cylinders can be formed predominantly on the substrates.

Natural rubber latex (NRL) is a natural polymer with versatile properties.However, uncured NRL has low strength and limited practical use. Therefore, we utilized low-dose gamma irradiation to induce cross-linking in blended NRL/poly(styrene-block-isoprene-block-styrene) (SIS). Blends were prepared in various ratios, and the 70 NRL /30 SIS blend gave optimal mechanical properties. The 70 NRL /30 SIS blend was then irradiated from 4 to 16 kGy. An exposure of 12 kGy led to the highest tensile strength (4.49 MPa), Young's modulus (0.41 MPa), gel content (45%), and cross-link density (12.18 Â 10 À5 molÁcm À3 ).The results of study show irradiation has improved the crystallinity of the polymer blend, which has been determined by the formation of a new NRL crystal peak at 31.2 and the decrease of the crystallization temperature from 58 to 19 C due to strain-induced crystallization. Moreover, the radiation has trans-