Izawa H, Kajimoto H, Morimoto M, Saimoto H, Ifuku S. Honeycomb-like porous chitosan films prepared via phase transition of poly(N-isopropylacrylamide) during water evaporation under ambient conditions.
RSC Adv 2020;
10:19730-19735. [PMID:
35520439 PMCID:
PMC9054209 DOI:
10.1039/d0ra03845h]
[Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/28/2020] [Accepted: 05/18/2020] [Indexed: 11/21/2022] Open
Abstract
Honeycomb-like porous chitosan (CS) films are attractive tools for developing functional materials for filters, catalyses, adsorbents, biomaterials, etc. A simple method for fabricating honeycomb-like porous CS films without special reagents, facilities, and techniques would make them accessible. Here we introduce an easily available method for fabricating honeycomb-like CS films without a strong acid/base, toxic reagents, or special facilities/techniques. An aqueous solution containing CS and poly(N-isopropylacrylamide) (PNIPAm) was allowed to stand at 25 °C to evaporate water. After 3 days, CS–PNIPAm composite films with homogenously phase-separated PNIPAm particles were obtained. The PNIPAm particles were removed by immersion in methanol, and the resulting films dried under reduced pressure to become honeycomb-like porous CS films. The pore size could be varied in the range of 0.5–3.0 μm by altering the CS concentration and the molecular weight of CS where the pore size was reduced under conditions with stronger interaction between CS molecules. We reveal that the key to success with this system is the decrease of lower critical solution temperature (LCST) of PNIPAm with water evaporation. In addition, we confirmed the removed PNIPAm was recyclable in this system. Furthermore, we found this method was also applicable to alginate. The proposed facile method for fabricating honeycomb-like porous polymeric films could provide various functional porous materials.
A simple method for fabricating honeycomb-like porous chitosan films without special reagents, facilities, and techniques was achieved by using poly(N-isopropylacrylamide).![]()
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