There is currently a great interest in nanoparticles that can react to an external stimulus by performing a given task. Often these nanoparticles are composed of more than one material in order to enhance the responsiveness to the trigger and the action performed by independent but coupled mechanisms. An example, is the composite of metal nanoparticles with environmentally sensitive polymers such as p(N-isopropylacrylamide) (PNIPAM). These nanocomposites have applications in medicine and biotechnology where they can for instance change size or release a trapped content upon exposure to light. Often multiple steps are needed to form these nanocomposites and it is therefore desirable to develop synthesis methods that can combine several steps. For instance, silver nanoparticles of controlled size and shape need to be created in the presence of a capping agent (such as polyvinylpyrrolidone (PVP) that slows the progress of the particle growth. This capping polymer then has to be replaced with a polymer of interest presenting a thiol functionality for conjugation. We have developed a novel synthesis method that uses PNIPAM as nucleation and capping agent in the synthesis of silver nanoparticles and so creates a light and temperature responsive polymer-metal nanocomposite. We demonstrate that PNIPAM of a defined length, but not the monomer can be used as a capping agent to achieve size-controlled silver nanoparticles. The polymer also acts as a nucleation site thereby providing an additional handle to control size polydispersity of the particles. The product obtains has a narrow distribution of the particles. Additionally, the composite is temperature sensitive without further modification at the, for PNIPAM typical, LCST of 32°C. Finally, the composite is shown to be optically sensitive at wavelengths between 360 and 420 nm. All of these processes are reversible, and the system can be cycled several times.