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Doctoral Thesis
DOI
10.11606/T.3.2011.tde-16032012-133346
Document
Author
Full name
María Verónica Carranza Oropeza
E-mail
Institute/School/College
Knowledge Area
Date of Defense
Published
São Paulo, 2011
Supervisor
Committee
Giudici, Reinaldo (President)
Chicoma Lara, Dennis
Santos, Amilton Martins dos
Sayer, Claudia
Teixeira, Antonio Carlos Silva Costa
Title in Portuguese
Síntese e caracterização de nanopartículas núcleo-casca de poliestireno e polimetacrilato de metila obtidas por polimerização em emulsão sem emulsificante e fotoiniciada.
Keywords in Portuguese
Fotopolimerização
Nanoparticulas núcleo-casca
Poliestireno e polimetacrilato de metila
Polimerização em emulsão sem emulsificante
Síntese e caracterização
Abstract in Portuguese
O objetivo do trabalho foi sintetizar e caracterizar nanopartículas de poliestireno e polimetacrilato de metila com morfologia núcleo-casca obtidas através da polimerização em emulsão sem emulsificante em dois estágios e através da fotopolimerização. Nos experimentos avaliou-se a influência de diferentes condições operacionais baseadas em fatores cinéticos sobre os dois estágios da polimerização. As condições avaliadas para o primeiro estágio de preparação de núcleos foram: a temperatura do processo, a concentração de iniciador e de monômero, e o efeito de agentes modificadores de superfície (sal, co-monômero e reticulante). Para o segundo estágio de formação da casca as condições avaliadas foram: a concentração e o regime de alimentação de monômero. Os resultados experimentais mostraram que uma relação de co-monômero e reticulante é a melhor alternativa para preparar núcleos estáveis e de diâmetros pequenos. Assim, o revestimento uniforme dos núcleos é obtido no segundo estágio e com isso a morfologia núcleo-casca em equilíbrio é alcançada. Dois sistemas experimentais (reator convencional e reator fotoquímico) foram propostos e avaliados na sua eficiência para obter partículas com este tipo de morfologia no segundo estágio (formação do revestimento). As diversas técnicas de caracterização indicaram a formação de morfologia núcleo-casca na maioria dos casos estudados para os dois sistemas propostos. Por sua vez, as técnicas espectroscópicas (NIR e Raman) permitiram o monitoramento do processo em tempo real e a elaboração de modelos de calibração que correlacionaram o crescimento do tamanho da partícula núcleo. Da mesma forma, os fatores termodinâmicos foram estudados para predizer a morfologia final esperada nos sistemas. Os resultados, experimental e predito são comparados e discutidos em termos de aspectos chave envolvidos no controle da morfologia da partícula.
Title in English
Synthesis and characterization of core-shell nanoparticles of polystyrene and poly(methyl metacrylate) obtained by emulsifier-free emulsion polymerization and photopolymerization.
Keywords in English
Core-shell nanoparticles
Emulsifier-free emulsion polymerization
Photopolymerization
Poly(methyl metacrylate)
Polystyrene
Synthesis and characterization
Abstract in English
This work aimed at studying the synthesis and characterization of core-shell nanoparticles of polystyrene and polymethylmethacrylate obtained in a two-stage emulsifier-free emulsion polymerization and photopolymerization. The influence of different operational conditions based on kinetic factors was experimentally evaluated. In the first stage (seed preparation) the process temperature, initiator and monomer concentrations and the effect of surface-modifier agents (acids, salts, co-monomers and crosslinker) were investigated; similarly in the second stage, the concentration and feeding regime of monomer were evaluated with respect to the shell formation. Experimental results showed that both, crosslinker and co-monomer are the best alternative to achieve a stable seed with small diameter; hence, with this core, uniform coating is obtained in the second stage and core-shell morphology is reached. In order to evaluate the efficiency of the preparation of core-shell particles, two experimental systems (conventional and photochemical reactor) were studied. Different characterization techniques indicated that in most of the cases studied particles with the desired core-shell morphology were formed. The use of spectroscopic techniques NIR and Raman were tested for the real-time monitoring of the process using adequate calibration models developed to correlate the average size of the growing core particle with the spectra. In the same way, thermodynamic factors were used to predict the expected final morphology of the particles. Experimental and predicted results were compared and discussed in terms of the key aspects involved in the control of the particle morphology.
 
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Publishing Date
2012-04-10
 
WARNING: The material described below relates to works resulting from this thesis or dissertation. The contents of these works are the author's responsibility.
  • Carranza-Oropeza, M.V., CHICOMA, Dennis, and GIUDICI, R. Preparation of core-shell nano-particles in emulsifier-free emulsion polymerization and monitoring with spectroscopy Raman along the reaction. In 2010 AIChE Annual Meeting, Salt Lake City, 2010. Conference Proceedings (CR-ROM)., 2010. Abstract.
  • Carranza-Oropeza, M.V., CHICOMA, Dennis, and GIUDICI, R. Preparation of core-shell nano-particles in emulsifier-free emulsion polymerization and monitoring with spectroscopy Raman along the reaction. In 2010 AIChE Annual Meeting, Slat Lake City, 2010. Conference Proceedings (CD-ROM).New York : American Institute of Chemical Engineers, 2010. Abstract.
  • Carranza-Oropeza, M.V., CHICOMA, Dennis, e GIUDICI, R. Core-shell particles: kinetic control and thermodynamics prediction of morphology. In 11. Congresso Brasileiro de Polímeros CBPol, Campos do Jordão, 2011. 11º Congresso brasileiro de polímeros., 2011.
  • CHICOMA, Dennis, et al. Synthesis of core-shell nanoparticles of PCL-PMMA via emulsion photopolymerisation. In 11th Workshop on Polymer Reaction Engineering, Hamburg, 2013. 11th Workshop on Polymer Reaction Engineering., 2013. Abstract.
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