Synthesis and Characterization of Thermoresponsive Chitosan- graft -poly( N -isopropylacrylamide) Copolymers

• Published in: Polymers Vol. 15; no. 15; p. 3154
• Main Authors: Babelyte, Migle, Peciulyte, Laura, Navikaite-Snipaitiene, Vesta, Bendoraitiene, Joana, Samaryk, Volodymyr, Rutkaite, Ramune
• Format: Journal Article
• Language: English
• Published: Switzerland MDPI AG 25.07.2023; MDPI
• Subjects: Aqueous solutions; Biocompatibility; Biopolymers; Chitosan; Composition; Copolymers; Drug delivery systems; Free radical polymerization; Graft copolymers; Molecular weight; N-isopropylacrylamide; NMR; NMR spectroscopy; Nuclear magnetic resonance; Phase separation; Phase transitions; Polyisopropyl acrylamide; Polymerization; Polymers; Potassium persulfate; Spectrum analysis; Synthesis; thermoresponsive copolymers; Tissue engineering; United States > US; Germany; chitosan; thermoresponsive copolymers; N-isopropylacrylamide
• ISSN: 2073-4360; 2073-4360
• DOI: 10.3390/polym15153154

Thermoresponsive chitosan- -poly( -isopropylacrylamide) (CS- -PNIPAAm) copolymers of different composition were synthesized by free-radical polymerization of chitosan (CS) and -isopropylacrylamide (NIPAAm) in aqueous solution using potassium persulfate (PPS) as an initiator. By changing the molar ratio of CS:NIPAAm from 1:0.25 to 1:10 graft copolymers with a CS backbone and different amounts of PNIPAM side chains were prepared. The chemical structure of the obtained CS- -PNIPAAm copolymers was confirmed by FTIR and H NMR spectroscopy. H NMR spectra were also used to calculate the content of attached PNIPAAm side chains. Moreover, the lower critical solution temperature (LCST) behavior of synthesized copolymers was assessed by cloud point, differential scanning calorimetry and particle size measurements. The aqueous solutions of copolymers containing ≥12 molar percent of PNIPAAm side chains demonstrated LCST behavior with the phase separation at around 29.0-32.7 °C. The intensity of thermoresponsiveness depended on the composition of copolymers and increased with increasing content of poly( -isopropylacrylamide) moieties. The synthesized thermoresponsive chitosan- -poly( -isopropylacrylamide) copolymers could be potentially applied in drug delivery systems or tissue engineering.