Controlled Free Radical Polymerization in Dispersed Media

Controlled free-radical polymerizations are ways of producing polymers of well-defined microstructure. In particular, narrow MWDs and various types of block copolymers can be produced by these techniques without the purity requirements typical of ionic polymerization. Recently, this technique has been implemented in polymerization in dispersed systems. It seems that the rationale behind these works is to take advantage of the compartmentalization of emulsion polymerization to minimize bimolecular termination. In this project, we will attempt to use controlled free radical polymerization to modify in-situ the particle morphology.

Miniemulsion Polymerization

Miniemulsion and miniemulsion polymerization are attracting an increased attention in the last few years. Indeed, the versatility of the technique and its potential for the synthesis of new high value added products fascinate both the academic and industrial community. Exploitation of the possibilities of the miniemulsion polymerization technique for synthesizing novel smart materials will be focused on the research program, with special emphasis on the engineering aspects of novel processes.

Nanostructured polymer/polymer hybrid particles

The synthesis of hybrid polymer/polymer particles focus on the potential synergy between the characteristics of the base polymers. Consequently, epoxy/acrylic hybrids may combine the hydrolysis stability, oxygen and UV resistance of acrylics with heat resistance and adhesive properties of epoxys. Current state-of-the-art relies primarily on blends, where often the microdomain dimension is larger than the size of the dispersed particles. Moreover, products have a limited solids content. Fine tuning of microdomains sizes and increase of solids content may impart beneficial properties to the products. Future research will address the synthesis of several types of nanostructured polymer/polymer hybrid particles, combining acrylics and epoxy resins, silicones, urethanes. Special attention will be dedicated to understand the influence of operational variables on the particle morphology in order to control the product quality. Correlating particle morphology to end-use property is also envisaged in this investigation.

Nanostructured composite polymer/clay particles

The morphology of composite polymer/clay particles is characterized by both the particle size distribution of the dispersed particles and the internal distribution of the nanostructures composed by the inorganic material. The inorganic material has a thickness of approximately 1 nm and a length of ca. 200 – 300 nm. The synthesis of composite materials with controlled particle sizes in the range of 200 and 300 nm may open a vast field of new applications, due to the enhanced properties of the nanostructured material. In this project the exfoliation of the clay will be carried out through a preferential polymerization within the interstices of the clay employing cationic surfactants. The effect of the nanostructure on the MFFT, mechanical resistance, permeability, thermal stability, aging stability and gloss will be studied.

Conducting Polymers

Great expectation is evolving around intrinsic conducting polymers due to the increasing application of these materials in microelectronics. Among the different conducting polymers, polypyrol is the most used in face of the easiness to synthesize the material and its stability. Nevertheless, difficulties on polymer processing jeopardize further development of novel materials. Most commercial applications demand products that are capable of forming conducting transparent films. The greatest aim of this project is the synthesis of latexes based on polypyrol presenting a good balance between conducting properties and film formation characteristics for application on batteries. The synthesis process will be composed by two stages. First, a standard latex will be prepared, and then the pyrol will be polymerized in the presence of previously formed polymer particles, aiming at the deposition of polypyrol on the surface of the particles. The effect of the base polymer and the content of polypyrol on the aging characteristics, conducting performance and film formation will be studied. Establishment of appropriate process condition for the synthesis of aqueous conduction-polymer dispersion will be addressed.

Functionalized Latexes

New types of polymer particles with surface functional groups able to form chemical bonding with proteins have been developed. Covalent bonding prevents the protein desorption (common in physically adsorbed proteins) and maintains the native conformation of the protein. A technology for the preparation of surface-functionalyzed monodisperse latexes has been developed. Surface functionalities include aldehyde, amino, carboxylic acid, hydroxyl, chloromethyl, and acetal. Research is in progress to use these particles to determine prostate specific antigen (a marker for tumors in prostate) and ferritin (a marker of hepatic pathologies). Future research will also include the application of functionalized latexes for photonic crystals.

Microgels for controlled drug release

The dual behavior of a given materials (collapsed of swollen depending on the environmental conditions) is the base for the controlled release of substances in general. A microgel particle is a crosslinked latex particle, which swells when dispersed in a good solvent and collapses when the dispersed in a bad solvent. The main objective of this project is the synthesis and characterization of biocompatible, biodegradable, temperature and pH sensible microgels that can be used for controlled release of biomolecules and pharmacologically active substances.