Photochromic superabsorbent polymers1

Photochromic superabsorbent polymers (PSAPs) with a hydrophilic core and a photochromic shell were prepared by inverse suspension polymerization using acrylic acid (AA) and acrylamide (AM) as monomers, potassium persulfate as the initiator, N,N'-methylene bisacrylamide (BIS) as a cross-linker, sorbitan monostearate (Span60) as the dispersant, cyclohexane as the solvent and bis(methacryloylamino)azobenzene (AC) as the photochromic surface cross-linker. The polymer was characterized by NMR, infrared spectroscopy, differential scanning calorimetry (DSC) and thermogravimetric analysis (TGA). Water absorption (Q) and the photoresponse of the PSAPs was investigated. The PSAPs prepared have excellent water absorption (2800 g g-1). When the sample is irradiated at 350 nm water expulsion from the swollen PSAPs was observed.