The pH influence of the yield and properties of photochemically synthesized poly(N-isopropylacrylamide) nanoparticles

Poly(N-isopropylacrylamide), PNIPAm, nanoparticles (10%, m/m) are prepared from monomer aqueous solutions under the irradiation of UV rays, without initiator and crosslinker addition. H+ plays an important role in the photopolymerization of PNIPAm nanoparticles: it accelerates polymerization, and determines size of the PNIPAm nanoparticles. The pH influence on the yield and properties of PNIPAm nanoparticles is investigated in detail. FTIR, DSC and swelling behaviors of the PNIPAm nanoparticles indicate that they are internally crosslinked macromolecules.