Numerical calculations reveal that the target and spiral growth patterns in spherulites can be generated from the time-dependent Ginzburg-Landau equations (model $C$) by coupling a conserved compositional order parameter and a nonconserved crystal ordering parameter. Of particular interest is that the periodic concentric rings (target) or the spirals at the spherulitic core remain stationary in both the crystal (orientational) ordering field and the concentration field. Another intriguing observation is that the growth of target and spiral spherulites occurs in a stepwise fashion in synchronism with the rhythmic energy dissipation during crystallization.

We report novel nanoporous polyimides formed from jungle‐gym‐type rigid polyimide gels by supercritical CO₂ drying. By virtue of supercritical CO₂ drying to avoid the collapse of nanostructure, porosity above 90 vol.‐% was achieved. We found a rich variety of nanoporous structures in the range of 50–800 nm such as crisp fragments, minute network, and highly‐connected beads. These characteristic structures were formed by the competitive progress of liquid‐liquid phase separation and crystallization induced due to the two chemical reactions of end‐crosslinking and thermal imidization during gelation. magnified image

(−)-β-Pinene, a major constituent of pine tree oil, was cationically polymerized to generate a high-molecular-weight polymer and then subsequently hydrogenated via metal catalysts to give a high-performance, bio-based cycloolefin polymer with an alicyclic backbone. To obtain the high-molecular-weight polymer, the controlled/living cationic polymerization of (−)-β-pinene was investigated by an initiating system, consisting of a protonic acid, a Lewis acid, and an added base, along with an incremental monomer addition technique. Among the various systems, the RCl/EtAlCl₂/Et₂O system gave a high-molecular-weight poly(β-pinene) (M_w > 100 000). The catalytic hydrogenation of the obtained high-molecular-weight poly(β-pinene) was examined using various metal catalysts, among which Pd/Al₂O₃ enabled the quantitative hydrogenation (>99.9%) of the unsaturated CC group in the repeating unit under mild reaction conditions (1.0 MPa pressure of H₂). These reactions could be performed even at relatively large scales to produce several hundred grams of the polymer, which can be then processed through injection-molding. The synthesized bio-based cycloolefin polymers demonstrated promising potential properties as high performance optical plastics with good processability, low density, high optical transparency, low birefringence, non-hygroscopicity, high mechanical strength, and excellent thermal properties.