CO 2 -based polyols have a unique terminal hydroxyl group structure that makes them suitable for the production of high-performance polyurethane foams. Zn-Co double metal cyanides (DMC) are an important class of catalysts for the copolymerization reaction of CO 2 with propylene oxide (PO). In the DMC-catalyzed CO 2 /PO copolymerization to produce CO 2 -based polyols, the crucial role of chain transfer agents (CTAs) is emphasized. In this work, a high-performance composite CTA (c-CTA) was successfully developed by investigating various dicarboxylic acids and polypropylene glycol (PPG-400) as CTAs. This system combines the high reaction rate of the DMC/PPG-400 system with the high CO 2 insertion rate of the DMC/sebacic acid (SA) system, achieving 2-3 times higher activity than that of single CTA (PPG-400 or SA), reaching 0.5 kg/g. The molecular characteristics of the CO 2 -based polyols synthesized by different DMC/CTAs systems were analyzed by FTIR and 1 H NMR. The reasons for the high catalytic activity of the DMC/c-CTA system were elucidated by analyzing the hydrogen bond distribution in each DMC/CTA systems. Overall, this work provides a theoretical guidance for the development of novel CO 2 -based materials with high industrial application value.
Runan Gong,Han Cao,Hongming Zhang,Lijun Qiao,Fosong Wang,Xianhong Wang
Cationic waterborne polyurethane (CWPU) was initially developed as a specific adhesive for anionic surface but now is ubiquitous in innovative material systems such as poly(ionic liquid)s, polyelectrolytes, antibacterial coatings, and drug carriers. However, state-of-the-art CWPU faces imperative challenges like easy degradation and poor water resistance, which is caused by excessive incorporation of internal emulsifiers with tertiary amines into the backbone than necessary, since emulsification performance of cationic internal emulsifier is much less efficient compared with the anionic analogue. Here, a terminal internal emulsifier-induced efficient dispersion strategy was developed. Taking oligo(carbonate ether) diol (a CO2-polyol from telomerization of CO2 and propylene oxide) as example, stable CWPU with only 1.00 wt % internal emulsifier was prepared. An emulsifying capacity parameter was introduced to quantitatively evaluate the emulsification performance of internal emulsifier according to its steric hindrance and mobility, and the terminal internal emulsifier was proven to show the highest emulsification performance. The terminal hydrophilicity-induced dispersion strategy exhibits excellent universality for a broad range of oligomer diols, effective not only for CO2-polyols but also for widely used polyether polyols and polyester polyols, affording CWPU with excellent water resistance. Therefore, the chemistry disclosed here paves a way for a vast number of water- and oxidation-resistant CWPUs which were hardly available until now.
危险品化学品经营许可证（带存储）