Composites materials that combine the flexibility and mechanical robustness offered by polymers with the functionality displayed by metal oxide nanoparticles offer new insight into the development of next generation products. The outcome of which will influence the fields of catalysis, energy storage and optoelectronics, just to name a few. Herein, we investigate a novel route to incorporate metal oxide nanoparticles into a polymer membrane by an in situ growth procedure that allows one to tailor the dimensions and characteristics of the inorganic phase. Metal oxide nanoparticles are grown directly within the polymer membrane that contains an array of voids that serve as 'nano reaction vessels'. We aim to determine the mechanisms responsible for the growth of the nanoparticles within these voids, and investigate the interplay between nanopartilce growth and changes in the host polymer.