Control over the self-assembly of polymers and layered molybdenum oxide: from the micrometer scale to the molecular scale

Abstract

We report adjustment on the self-assembly between polymer of polyvinyl pyrrolidone (PVP), polyvinyl alcohol (PVA) and inorganic molybdenum oxide layers from the micrometer scale to the nanometer scale. Our method is to break the strong interactions between the organic polymers by introducing suitable bridging agents and adjust the reaction speeds of the two competitive reactions in the reaction system. We use I2 to complex with PVA and break the strong hydrogen interactions between the PVA chains, resulting in a PVA-I2/(MoxOy)∞n− complex, in which the organic and inorganic species self-assemble homogenously on the molecular scale. We also adjust the thickness of the inorganic (MoxOy)∞n− layers in the hybrid of PVP/(MoxOy)∞n− by controlling the reaction speeds of the two competitive reactions: hydrolysis of Mo7O246− into (MoxOy)∞n− and packing into thick inorganic layers on the one hand, and hybridization of (MoxOy)∞n− and PVP into layered hybrid on the other hand. Experimental results proved that when the hydrolysis is overwhelming, the inorganic molybdenum oxide chains pack into heavy layers and self-assemble with PVP polymers on the micrometer scale, and when the hybrid reaction dominates, the organic polymer and molybdenum oxide hybridize on the molecular scale. These findings open new routes to disperse organic polymer and inorganic species homogenously and fabricate novel organic/inorganic hybrid nanomaterials in situ.