Polyvinyl alcohol latices, particle size

The adsorption of fully and partially hydrolyzed (88%) polyvinyl alcohol (PVA) on 190-1lOOnm monodisperse polystyrene latex particles was investigated. The effect of molecular weight was investigated for 190 nm-size particles using the serum replacement adsorption and desorption methods. The adsorption density at the adsorption-isotherm plateau followed the relationships for the fully hydrolyzed... 

Polymerisation of vinyl toluene in quaternary microemulsions containing cetyltrimethylammonium bromide as the cationic surfactant was studied using laser Raman spectroscopy and dilatometry. The influences of water soluble (potassium peroxodisulphate, ammonium peroxodisulphate) and oil-soluble (azobisisobutyronitrile, benzoyl peroxide) initiators, monomer, surfactant, cosurfactants (n-alcohol and bifunctional alcohols) and temperature on the rates of polymerisation, energy of activation, particle diameter, number of polymer particles, molecular weight of polyvinyl toluene and number of polymer chains per latex particle were investigated. The dependencies of the kinetic and latex size parameters on the initiators and co-surfactants are discussed in terms of the efficiency of the initiators in initiating the polymerisation and on the interfacial partitioning behaviour of various co-surfactants. 19 refs. 

The homogeneous dispersion of cellulose nanoparticles in a polymer matrix in order to obtain nanomaterials is due to their size, which allows penetration in hydrosoluble or at least hydrodispersible structures (as latex-form polymers) as well as dispersion of polysaccharide nanocrystals in nonaqueous media especially using surfactants and chemical grafting. Thus, one of the processing techniques of polymer nanocomposites reinforced with polysaccharide nanocrystals was carried out using hydrosoluble or hydrodispersible polymers. In this respect, the literature has reported preparation of polysaccharide particles with reinforced starch (Svagan et al. 2009), silk fibroin (Noishiki et al. 2002), poly(oxyethylene) (POE) (Samir et al. 2006), polyvinyl alcohol (PVA) (Zimmermann et al. 2005), hydroxypropyl cellulose (HPC) (Zimmermann et al. 2005), carboxymethyl cellulose (CMC) (Choi and Simonsen 2006), or soy protein isolate (SPI) (Zheng et al. 2009). 

In the common procedure extremely large oil-water interfacial area is generated and the particle nuclei grow in size with the progress of the polymerization. Thus, effective stabilizers such as ionic and non-ionic surfactants and protective colloids e.g. hydroxyethyl cellulose and polyvinyl alcohol), which can be physically adsorbed or chemically incorporated onto the particle surface, are often required to prevent the interactive latex particles from coagulation. Under the circumstances, satisfactory colloidal stability can be achieved via the electrostatic stabilization mechanism [268], the steric stabilization mechanism [269] or both. 

These polymerizations normally utilize the formation of an emulsion from a mixture of water, monomer, and surfactant. The most common type of emulsion polymerization is an oil-in-water (0/W) emulsion, in which droplets of monomer (the oil) are emulsified (with surfactants) in a continuous phase of water. Water-soluble polymers, such as certain polyvinyl alcohols can also be used to act as emulsifiers/stabilizers for the monomer droplets. The polymerization takes place within the monomer latex particles, which are composed of individual polymer chains and are typically 100 nm in size. These latex particles form... 

---