Preparação de microesferas poliestirenicas aminadas atraves de copolimerização entre estireno e aminoestireno para utilização em testes imunologicos

AUTOR(ES)
DATA DE PUBLICAÇÃO

1998

RESUMO

The synthesis of the functionalized PS particles containing amino-groups on their surfaces, was the subject of study in the present work. It consisted of two different steps of the research: development of a method for polymerization of styrene, resulting in homogeneous particle size distribution; application of the developed method to prepare PS particles containing amino-groups on their surfaces, by styrene and aminostyrene monomers copolymerization reaction. The techniques which have been tested for these purposes were the emulsion and dispersion polymerization. It was verified that the particles obtained through the dispersion polymerization presented the best results in terms of mean particle diameter and particle size distribution. Polimerization tests were carried out in order to study the influence of reagents concentration on the particle size. The results show that in the emulsion polymerization process, particle size decreases with increasing initiator concentration, while in the dispersion polymerization process, this effect was the oposite. In both cases the increase of the monomer concentration resulted in increased particle size and it was also verified that the emulsifier (in the emulsion process) and the dispersant (in dispersion process) have an important role in controlling the particle dimensions. In both cases, by the reduction of their concentrations, the particles presented an increase in their mean diameter. In the second phase of this work, the dispersion polymerization reaction was applied to obtain functionalized particles with amino-groups on their surfaces, through the styrene copolymerization with aminostyrene. The results demonstrated that the styrene monomer is preferentially inserted in the copolymer, presenting a low conversion rate for the aminostyrene, even at higher aminostyrene/styrene ratios in the feed. To overcome the above situation, it was decided to carry out the protection of the amino groups of the aminostyrene monomer by reaction with t-butyl carbamate (BOC group), obtaining the BOC-aminostyrene monomer. By using the BOC-aminostyrene monomer with styrene in copolymerization reactions, the reactivity ratios were determined for both monomers and it was also verified that the reactivity of the BOC-aminostyrene (rBOCAMS=T0,96) is higher than the reactivity of the styrene(rSTY= 0,47).These results demonstrated that these monomers get the formation of statistic copolymers with a tendence to give alternated sequences. The obtainment of the amino groups on the surfaces of the polymer particles was carried out by chemical treatments, using a solution of HCI in isopropanol in order to remove the BOC groups of the polymer structure, obtaining the NH3+groups. By the neutralization reaction, using NaOH solution, the NH2group were obtained on the particles surfaces. These chemical treatments demonstrated to be very efficient when applied to particles with low BOCAMST concentration in the copolymer composition. However, these treatments have to be improved for the application to particles with high BOCAMST concentrations in the copolymer composition, because it was verified very strong effect on the particles shape, resulting in their destruction

ASSUNTO(S)

latex polimerização poliestirenos particulas polimeros na medicina

ACESSO AO ARTIGO

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