One-step synthesis of hollow spherical polyethylene by dispersion polymerization

Effect of N-Aryl Para-Benzhydryl Substituent on the Thermal Stability of α-Diimine Nickel Catalyst

The thermal stability of α-diimine nickel catalysts has always been the focus of research. The introduction of large groups in the backbone or N-aryl ortho-position is a relatively mature solution. However, the question of whether the N-aryl bond rotation is a factor affecting the thermal stability of nickel catalysts is still open. In this work, the effects of N-aryl para-benzhydryl substitutes on catalyst thermal stability are investigated, and the results of ethylene polymerization and the factors affecting thermal stability (steric effect, electronic effect, five-membered coordination ring stability, N-aryl bond rotation, etc.) are systematically analyzed. It is believed that the introduction of large steric hindrance groups at the N-aryl para-position hinders the rotation of the N-aryl bond. This obstacle effect is beneficial to improving catalyst thermal stability, and the obstacle capacity is weakened with the increase of ortho-substituent size.

Precipitation Polymerization: A Powerful Tool for Preparation of Uniform Polymer Particles

Precipitation polymerization (PP) is a powerful tool to prepare various types of uniform polymer particles owing to its outstanding advantages of easy operation and the absence of any surfactant. Several PP approaches have been developed up to now, including traditional thermo-induced precipitation polymerization (TRPP), distillation precipitation polymerization (DPP), reflux precipitation polymerization (RPP), photoinduced precipitation polymerization (PPP), solvothermal precipitation polymerization (SPP), controlled/‘‘living’’ radical precipitation polymerization (CRPP) and self-stabilized precipitation polymerization (2SPP). In this review, a general introduction to the categories, mechanisms, and applications of precipitation polymerization and the recent developments are presented, proving that PP has great potential to become one of the most attractive polymerization techniques in materials science and bio-medical areas.

Combining hydrogen bonding interactions with steric and electronic modifications for thermally robust α-diimine palladium catalysts toward ethylene (co)polymerization

Thermally robust α-diimine palladium catalysts are highly active for ethylene (co)polymerization at high temperatures by steric and electronic modifications in combination with hydrogen bonding interactions.