Borohydride-modified polyurethane foam: a new form of a widely known reducing agent in synthesis of metal nanoparticles for sensing applications

Currently a lot of synthetic routs have been proposed for preparation of various metal nanoparticles for sensing applications. A majority of them are based on the borohydride approach. We have found that some polymers (e.g. polyurethane) can be a promising support for immobilization of borohydride. The present work describes a method for preparation of polyurethane foam modified with borohydride as a new form of the widely known reducing agent and its possibilities for synthesis of metal nanoparticles. This new reagent is quite stable when stored at low temperature and is convenient for use in the synthesis of nanoparticles since it ensures precise dosing of a reductant. Metal nanoparticles could be synthesized both in solution and on polymer surface by varying reagents concentrations during the modified polyurethane foam preparation. It was illustrated that nanoparticles prepared using the borohydride-modified polymer have a narrower size distribution that probably should be ascribed to the stabilizing effect of the polymeric matrix. Optical properties of polyurethane foam-based nanocomposites with metal nanoparticles open a possibility of their using for sensing substances that affect formation of nanoparticles or their distribution between the polymer and the solution.