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Liu S.,University of Chinese Academy of Sciences | Qin Y.,Key Laboratory of Polymer Ecomaterials | Guo H.,Key Laboratory of Polymer Ecomaterials | Wang X.,Key Laboratory of Polymer Ecomaterials | Wang F.,Key Laboratory of Polymer Ecomaterials
Science China Chemistry | Year: 2016

Synthesis of polyols from carbon dioxide (CO2) is attractive from the viewpoint of sustainable development of polyurethane industry; it is also interesting to adjust the structure of the CO2-polyols for versatile requirement of polyurethane. However, when renewable malonic acid was used as a starter, the copolymerization reaction of CO2 and propylene oxide (PO) was uncontrollable, since it proceeded slowly (13 h) and produced 40.4 wt% of byproduct propylene carbonate (PC) with a low productivity of 0.34 kg/g. A careful analysis disclosed that the acid value of the copolymerization medium was the key factor for controlling the copolymerization reaction. Therefore, a preactivation approach was developed to dramatically reduce the acid value to ~0.6 mg(KOH)/g by homopolymerization of PO into oligo-ether-diol under the initiation of malonic acid, which ensured the controllable copolymerization, where the copolymerization time could be shortened by 77% from 13 to 3 h, the PC content was reduced by 76% from 40.4 wt% to 9.4 wt%, and the productivity increased by 61% from 0.34 to 0.55 kg/g. Moreover, by means of preactivation approach, the molecular weight as well as the carbonate unit content in the CO2-diol was also controllable. © 2016 Science China Press and Springer-Verlag Berlin Heidelberg Source


Song Z.,Jilin University | Shi B.,Key Laboratory of Polymer Ecomaterials | Ding J.,Key Laboratory of Polymer Ecomaterials | Zhuang X.,Key Laboratory of Polymer Ecomaterials | And 3 more authors.
Science China Chemistry | Year: 2015

Complications arising from tendon injury include tendon sheath infection and peritendinous adhesion, in which tendon adhesion often leads to serious motor dysfunction. In this work, the electrospun membranes of poly(L-lactide) (PLA) and poly(ε-caprolactone) (PCL) with different degradation kinetics were used to investigate their efficacy for anti-adhesion toward Achilles tendon repair. Compared with the PCL membrane, the PLA sample showed a faster rate of degradation in 42 d, and all the degradation media (i.e., phosphate-buffered saline) maintained at a constant pH of around 7.4. Meanwhile, the superior biocompatibility of both the PLA and PCL membranes were proved by the in vitro cellular adhesion tests and in vivo histopathological assays. Simultaneously, the PLA membrane was more effective than the PCL sample in decreasing adhesion and promoting functional recovery. Furthermore, the experiment result was further confirmed by hematoxylin-eosin and Masson’s trichrome staining, and type I collagen immunohistochemical analysis. All results revealed that the model treated with the electrospun PLA membrane was obviously better with regard to both anti-adhesion and tendon repair than that in the PCL membrane group. Considering the results of degradation and adhesion prevention efficacy, the electrospun polyester membranes, especially the PLA one, would be applied with fascinating potential in clinical prevention of postoperative tendon adhesion. © 2015 Science China Press and Springer-Verlag Berlin Heidelberg Source

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