Biomedical subjects
Publications and source records attributed to Xinyuan Zhu.
A new type of materials, the backbone-thermoresponsive hyperbranched polyether, was successfully synthesized by proton-transfer polymerization of 1,4-butanediol diglycidyl ether and various triols, and the lower critical solution temperature (LCST) values can be readily adjusted from 19.0 to 40.3 degrees C by changing the hydrophilic/hydrophobic balance of BDE and triols.
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The conformational change of isotactic poly(propylene) (iPP) during the thermal degradation process has been carefully studied by in situ Fourier transform infrared (FT-IR) spectroscopy. This new method of studying thermal degradation of iPP not only shows the conventional kinetic parameter information of thermal degradation such as the degradation activation energy DeltaE and the degradation factor n, which are in accord with the results of traditional thermogravimetry experiments, but also indicates that many significant molecular structure changes occur during the thermal degradation process that come from some characteristic absorption band changes of in situ FT-IR. A multivariate approach, principal components analysis (PCA), is applied to the analysis of infrared (IR) data, and the results further confirm the multi-step processes of the thermal degradation of iPP. Above all, this is a new application to polymer thermal degradation by in situ FT-IR that connects the intermediate conformational change with final results during thermal degradation.
A new class of crystalline inclusion complexes of a multiarm hyperbranched polyether combined with various cyclodextrins (CDs) was successfully prepared. Using self-condensing ring-opening polymerization, a kind of multiarm polyether with a hyperbranched poly(3-ethyl-3-oxetanemethanol) core and multiple linear poly(ethylene glycol) (PEG) arms was obtained. It has been found that this kind of hyperbranched polyether can be dissolved in water. Adding alpha-CDs to the multiarm hyperbranched polyether solution, molecular recognition results in the formation of crystalline inclusion complexes based on the noncovalent interactions between the linear PEG arms of the polyether particles and the alpha-CDs. These multiarm polyether inclusion complexes have been well characterized. Interestingly, quite different from inclusion complexes of CDs and linear polymeric guests, the complexes of the multiarm hyperbranched polyether with alpha-CDs show a novel lamellar morphology. The experimental results validate that the resultant lamellar crystals have a juxtaposed structure. In addition, the formation mechanism of these inclusion complexes of a multiarm polyether with alpha-CDs has also been well described. Besides the role of displacement of associated water molecules and the presence of hydrogen bonding between CDs in channel structure CD inclusion complexes, the noncovalent intermolecular forces between CDs and polymers also play an important role in the formation of complex architectures.
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