title: Preparation and characterization of pH- and temperature-responsive nanocomposite double network hydrogels.
abstract: A methodology is described for the preparation of pH- and temperature-responsive double network (DN) hydrogels with poly(N-isopropylacrylamide) (PNIPAM) as a tightly crosslinked 1st network, polyacrylic acid (PAA) as a loosely crosslinked 2nd network and graphene oxide (GO) as an additive. GO sheets were first prepared via an oxidation reaction and then dispersed in NIPAM aqueous solution via silanization. Free-radical polymerization of NIPAM was carried out at 20 °C in a water bath, and then subjected to UV light, leading to the formation of pH- and temperature-responsive PNIPAM/AA/GO DN hydrogels. The effects of GO sheets and AA contents on various physical properties were investigated. Results show that PNIPAM/AA/GO hydrogels undergo a large volumetric change in response to temperature. It also exhibits significantly fast swelling/deswelling compared with conventional PNIPAM hydrogel. Moreover, the PNIPAM/AA/GO hydrogels have a much better mechanical property than the conventional PNIPAM hydrogels.
authors.affiliation: Center of Special Materials and Technology, Fudan University, Shanghai 200433, China.
authors.forename: Zhiqiang
authors.initials: Z
authors.lastname: Li
authors.forename: Jianfeng
authors.initials: J
authors.lastname: Shen
authors.forename: Hongwei
authors.initials: H
authors.lastname: Ma
authors.forename: Xin
authors.initials: X
authors.lastname: Lu
authors.forename: Min
authors.initials: M
authors.lastname: Shi
authors.forename: Na
authors.initials: N
authors.lastname: Li
authors.forename: Mingxin
authors.initials: M
authors.lastname: Ye
mesh_terms: D000179:Acrylates / Q000737:chemistry; D000180:Acrylic Resins / Q000138:chemical synthesis / Q000737:chemistry; D002152:Calorimetry, Differential Scanning; D019245:Compressive Strength; D005612:Freeze Drying; D006108:Graphite / Q000737:chemistry; D020100:Hydrogels / Q000138:chemical synthesis* / Q000737:chemistry*; D006863:Hydrogen-Ion Concentration; D008422:Materials Testing; D053761:Nanocomposites / Q000737:chemistry* / Q000648:ultrastructure; D017550:Spectroscopy, Fourier Transform Infrared; D013314:Stress, Mechanical; D013696:Temperature; D014961:X-Ray Diffraction
chemical_list: D000179:Acrylates; D000180:Acrylic Resins; D020100:Hydrogels; C052970:poly-N-isopropylacrylamide; D006108:Graphite; C036658:acrylic acid