Synthesis of Polymeric (Nano)Capsules Based on Dopamine and Derivatives Using Emulsion Templating

摘要

A soft-templating method has been developed for the synthesis of hollow polymer (nano)capsules comprising dopamine and derivatives. The method involves the use of an aqueous emulsion comprising toluene or cyclohexane droplets as templates. Dopamine (and derivatives) polymerization is conducted at room temperature in the aqueous phase and/or at the droplet surfaces, thus forming hollow polymer (nano)capsules. Dialysis was demonstrated to be an effective technique for removal of surfactant, hexadecane and unreacted monomer without destroying the capsule structure and introducing other materials. This method demonstrates that emulsion droplets can serve as templates with advantages of high stability, small size and straight-forward elimination. By using this method, the shell thickness can be readily tuned by adjusting the initial amount of monomer. Nanocapsules of diameters as low as ~50 nm can be readily prepared using this novel approach. When using Shirasu porous glass (SPG) membrane emulsification to produce emulsion templates, the capsule size can be tuned easily by applying different pore size membranes. Attempts were made to functionalize the capsules - silver nanoparticles were explored for encapsulation within the capsules via miniemulsion templating. A simple method was employed to produce monodisperse fine silver nanoparticles of approximate diameters 10 nm. However, encapsulation proved to be extremely challenging. It is believed that the difficulties were caused by side reactions between components of the silver nanoparticle synthesis step and the polymerization step. Overall, the work presented represents a creative one-step method providing a new approach to the synthesis of hollow polymer (nano)capsules comprising dopamine and derivatives, which has the potential to dramatically expand their commercial applications.