Abstract
This study deals with the unique morphology and properties of methylene diphenyl diisocyanate (MDI)-modified bacterial cellulose/poly(N-isopropylacrylamide) (BC/PNIPAAm) composite hydrogel prepared by in situ polymerization method. The influence of the molar ratio of MDI/glucose unit of BC on the properties of the resulting hydrogel was investigated. Scanning electron microscopic analysis revealed that after the MDI modification the BC/PNIPAAm hydrogel could preserve the unique layered (known as anisotropic) structure. The mechanical property evaluated by stress–strain test was significantly enhanced when compared to that of neat PNIPAAm hydrogel, due to the presence of the BC matrix as well as the MDI modification. Based on the deswelling behaviors, the BC/PNIPAAm hydrogel exhibited improved and controlled responsive rate when compared with neat PNIPAAm hydrogel. Furthermore, the anisotropic thermo-sensitive property was proved by temperature-responsive test with the fact that the composite hydrogel could only deswell and swell in the axial perpendicular to the layers. Along with desired recyclability, the present composite hydrogel may have an application as artificial muscles.
Highlights
Anisotropic swelling and deswelling of hydrogels are essential for their utilization in biomedical elds
methylene diphenyl diisocyanate (MDI)-modi ed Bacterial cellulose (BC)/PNIPAAm composite hydrogels were studied by Fourier transform infrared spectroscopic analysis (FT-IR) spectra (Fig. S1†)
We developed a novel MDI-modi ed BC/PNIPAAm composite hydrogel by in situ polymerization and elucidated the 12612 | RSC Adv., 2018, 8, 12608–12613
Summary
Anisotropic swelling and deswelling of hydrogels are essential for their utilization in biomedical elds. The anisotropic thermo-sensitive property was proved by temperature-responsive test with the fact that the composite hydrogel could only deswell and swell in the axial perpendicular to the layers. By the combination of MDI-modi ed BC and PNIPAAm, the composite hydrogel is aimed to have uniaxial deswelling–swelling (socalled anisotropic thermo-sensitivity), enhanced mechanical strength as well as fast response rate to temperature change.
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