ABSTRACT
The presence of emulsifier during emulsion poly mer i za tion helps the particles to retain colloidal stability. It forms the micelles in the beginning of the poly mer i za tion, which subsequently become the loci of poly mer i za tion due to the entry of the radicals in them [1,2]. The amount of the surfactant can also be varied to achieve different rates of poly mer i za tion or different sizes of the particles, so the presence of surfactant is important in more than one way to tune the properties of the poly mer particles. Therefore, the majority of the emulsion poly mer i za tion reactions are carried out in the presence of the surfactants. However, there are also some cases where the poly mer i za tion is achieved in the absence of any surfactant. Such a poly mer i za tion process is then termed surfactant-free poly mer i za tion [1,3]. This kind of poly meri za tion is carried out when the poly mer particles are required for specific applications (like calibration of particle characterization methods or use of the particles as standards) that cannot tolerate the presence of even minor amounts of impurities on the surface of the particles or in the aqueous phase due to the desorption of the surfactant. Surfactant-free poly mer i za tion is also required when the surface charges are needed to be accurately known. Apart from that, this mode of poly mer i za tion is required when the particles are subjected to subsequent surface functionalization processes that are not compatible with the presence of the emulsifier molecules on the surface. One example is the poisoning of the copper catalyst by reaction with emulsifier
CONTENTS
10.1 Introduction ................................................................................................ 307 10.2 Particle Nucleation .....................................................................................308 10.3 Functional Particles by Surfactant-Free Polymerization ......................309 Acknowledgments .............................................................................................. 324 References ............................................................................................................. 325
when carrying out particle surface functionalization by atom transfer radical poly mer i za tion (ATRP) [4,5].
