Browsing by Author "Qiao Wang"

Now showing 1 - 2 of 2

Effect of tacticity and molecular weight on the rheological properties of poly(N -isopropylacrylamide) gels in benzyl alcohol
(Society of Rheology, 2017) Chandra Sekhar Biswas; Yuhang Wu; Qiao Wang; Lei Du; Kheyanath Mitra; Biswajit Ray; Zhi-Chao Yan; Bing Du; Florian J. Stadler
Two series of different isotactic poly(N-isopropylacrylamide) of number average molar masses (Mn) ∼ 100 000, 200 000 and narrow molar mass distribution are prepared by reversible addition fragmentation chain transfer polymerization. Their thermoreversible, physical gels are prepared in benzyl alcohol and rheologically characterized to assess the effect of tacticity and molar masses on the rheological properties. In general, higher tacticity, higher molar mass, and higher concentration lead to stiffer gels and a sol-gel transition at a higher temperature. The results are interpreted based on partial phase separation leading to stiff but labile spongelike structures. The tacticity influences the strength of the phase separation tendency. Concentration and molar mass determine how far reaching and how connected these domains are. © 2017 The Society of Rheology.
Synthesis and characterization of novel amphiphilic biocompatible block-copolymers of poly(N-isopropylacrylamide)-b-poly(L-phenylalanine methyl ester) by RAFT polymerization
(Elsevier Ltd, 2020) Chandra Sekhar Biswas; Arpan Biswas; Massimillano Galluzzi; Mehdihasan I. Shekh; Qiao Wang; Biswajit Ray; Pralay Maiti; Florian J. Stadler
The synthesis of amphiphilic block-copolymers of poly(N-isopropylacrylamide) (PNIPAM) and poly(N-acryloyl-L-phenylalanine methyl ester) (PNALPA) by RAFT polymerization is reported. The polymers were characterized by proton NMR (1H NMR), gel permeation chromatography (GPC), powder X-ray diffraction (XRD), differential scanning calorimetry (DSC), and thermogravimetric analysis (TGA) to understand their structure-property relationships. All synthesized polymers show pH triggered release at acidic (pH 5) and biological pH (pH 7.4). Critical micellar concentration also varied systematically depending on the amphiphilic nature of the polymers. Biocompatibilities of the polymers are also determined to check their suitability for biomedical applications. © 2020 Elsevier Ltd