Surface modification of polymer particles

Modification for inverse combination—that is, modification of polymer particle surface with inorganic materials—might meet more closely the scope of this... 

Polymer Suiface Modifications The growing need of polymeric materials with specific properties for sophisticated applications has led to the development of new polymer surfaces, which can be created by traditional polymerization processes or by the modification of existing surfaces. Surface modification of polymers is used to improve their chemical, physical, mechanical, and tribological properties. Many techniques have been applied to produce the desired surface properties, ranging from thermal treatments, chemical and electrochemical modifications, metallization, and electrical treatments, to plasma treatments and particle beam irradiation techniques. The literature shows that SIMS is a method of choice to characterize the results of such treatments. Hereafter we introduce some examples taken from published studies. 

The surface properties of particles are very important with respect to their end use. Many particles are used for fillers and to impart properties that enhance a materials function. In order to do so, the particles need to be compatible with the environment into which they are placed. Often this is in a polymer matrix such as a film. To enhance particle compatibility of the surface of 2-5 pm silica particles and silica glass beads, surface modification of these particles was carried out. Surface modifications were accomplished by surface polymerization, surface polymer grafting, by surface dendrimerization and by developing organo-silicone particles. The surfaces obtained can have a wide variety of properties, fi om highly hydrophilic to highly hydrophobic, from anionic and cationic to nonionic, as well as being environmentally responsive. 

Imbert-Laurenceau, E., Berger, M.C., Pavon-Djavid, G., Jouan, A., and Migonney, V. 2005. Surface modification of polystyrene particles for specific antibody adsorption. Polymer 46 1277-85. 

In most practical uses of polymeric particles, their surfaces play a very important role by taking part in interfacial interactions such as recognition, adsorption, catalytic reactions, etc. When we want to use polymer particles, we first check whether the chemical and physical structures of the surfaces meet the purpose. If some of them do not satisfy the criteria, we may seek other particles or try to modify the existing particles. This chapter mainly deals with the modification of surface of existing particles. In addition to chemical modification of particle surfaces, modification of the morphology of particles is also described. 

The surface of polymer particles obtained by emulsion polymerization is occupied by emulsifier molecules, initiator fragments, and hydrophilic comonomer units. Therefore, desirable design of the surface ought to be done by choosing the emulsifier, initiator, and comonomer. Some of them are employed in aiming for postreaction at the surface to convert it into a functional one. When any change is necessary on the particle surface, modification of surface can be done by the following means ... 

Seeded polymerization using a slight amount of monomer leads to the surface modification without changing particle size. The resulting particles are a kind of core-shell particles or, more exactly, core-skin particles (Fig. 12.2.4C). Seeded polymerization of sugar-units-containing styrene derivative on polystyrene seed particle was carried out to obtain latex particles covered with sugar units (17). A necessary condition for this is that the monomer is more hydrophilic than the seed polymer. If not, the monomer permeates into the seed particle and only a small fraction remains on the... 

The surface of polymer particles is characterized by ionogenecity, hydrophilicity, softness, roughness, etc. The most prominent feature of the organic polymer particle, compared with inorganic materials, is that these characteristics can be easily modified. Various modifications were reviewed in this chapter to give a guide to those who intend to prepare functional polymer particles. 

N. Cinausero, N. Azema, M. Cochez, M. Ferriol, M. Essahli, F. Ganachaud, and J.-M. Lopez-Cuesta, Influence of the surface modification of alumina nano-particles on the thermal stability and fire reaction of PMMA composites, Polym. Adv. Technol., 2008, 19 1-9. 

---