The present invention is directed generally to templates used in the creation of thin-film replicas, for example, the creation of thin films, such as carbon films, for use as specimen support in electron-beam specimen analysis. The present invention provides a vinyl polymers obtainable by atom transfer radical polymerization can be purified economically and efficiently by adsorption treatment using an acidic adsorbent and a basic adsorbent combinedly, with the result that the reactivity in hydrosilylation thereof is improved. This achieves a stress-free layer or enables stress-free growth.