Synthesis of novel chitaline–silica aerogels with spontaneous Au and Ag nanoparticles formation in aerogels matrix

A composite of a silica aerogel and a copolymer of chitosan and polyaniline (chitaline) with Au or Ag nanoparticles was prepared by a surfactant-free sol–gel process. By grafting polyaniline on the chitosan backbones, the copolymer chitaline was synthesized, which is soluble in aqueous solution. It can be combined with silica gels to form aerogel composites, the specific surface areas of chitaline/silica aerogels are over 650 m2/g, with densities low to 0.09 g/cm3. Upon protonic doping, the chitaline/silica aerogels conductivity rises from less than 10−8 to 10−4 S/cm. This kind of chitaline possesses primary amines in the backbone structure that can bind metal ions, and the reduction potential of chitaline was tested lower to 0.735 V, which can easily reduce high potential ions such as Au(III) and Ag(I) to form nanostructured metal particles. And the reduced nanoparticles were observed homogenously dispersed in the aerogels.

Figure optionsDownload as PowerPoint slideHighlights
► Aerogel composites of silica and chitosan–polyaniline copolymer were synthesized.
► Copolymer can bind and reduce high potential metallic ions to form nano particles.
► Spontaneously formed metal nanoparticles are homogenously dispersed in porous aerogels.
► In situ particle formation/growth mechanism of nanoparticles was discussed.