Synthèse d'hybrides polymère-polymère par la polymérisation en miniémulsion et la caractérisation des latex hybrides

The objectives of work presented in this thesis are to understand droplet and particle formulation processes in order to make useful polymer-polymer hybrids in aqueous dispersions and use our fundamental understanding of these processes to: 1. Improve monomer conversion as much as possible. 2. Understand impact of these processes on hybrid film properties. Specific case studies of interest under commercially feasible conditions (i.e. solids content of 50wt %) were done based on two systems namely alkyd-acrylic and polyurethane-acrylic. Miniemulsification, miniemulsion polymerisation and characterisation of hybrid latex, chemical incorporation of alkyd and polyurethane to acrylic monomers were studied in detail. We have been able to successfully synthesise and characterise hybrid latex of about 100nm in particle diameter and high solids content (50wt %) to be used in coating and adhesive applicationsLes objectifs du travail présenté ici sont de comprendre les procédés de formulation des gouttelettes et des particules afin de faire des hybrides polymère-polymère de qualité en dispersions aqueuses et d’utiliser notre compréhension fondamentale de ces procédés pour : 1. Augmenter le taux de conversion de(s) monomère(s) autant que possible. 2. Comprendre l’impact de ces procédés sur les propriétés des films hybrides. Des cas particuliers ont été étudiés dans des conditions commercialement viables (taux de solide de 50% en masse) basés sur deux systèmes appelés alkyde-acryliques et polyuréthane-acrylique. La préparation des miniémulsions, la polymérisation en miniémulsion et la caractérisation des latex hybrides, l’incorporation chimique d’alkyde et de polyuréthane dans les monomères acryliques ont été étudiés en détails. Nous sommes parvenus à synthétiser et caractériser des latex hybrides avec de haut taux de solides (50% en masse) composés de particules de 100nm de diamètre utilisables dans des applications de revêtement et d’adhésif

Influence of composition on the morphology of polyurethane/acrylic latex particles and adhesive films

International audiencePolyurethane (PU)/acrylic hybrid particles with different PU contents were synthesized by miniemulsion polymerization and subsequently dried to give solid adhesive films. The morphologies of the particles and the morphologies and mechanical properties of the resulting films were investigated by Transmission electron microscopy combined with selective staining of the PU and by uniaxial tension tests. Morphological investigations showed a clear change in the particle morphology as the PU weight fraction increased. While at 5 wt% and 25 wt%, PU (with respect to total organic content) the particles were relatively homogeneous and mechanical properties of the films could be readily interpreted with molecular arguments, at 50 wt% PU a core-shell structure was observed. This heterogeneous structure of the 50 wt% PU particles persisted in the films, resulting in a percolating network of the harder PU phase. The low deformability and strain at failure of the 50% PU films suggest that, unlike the adhesives with lower PU content, the relatively weak interfaces between the original latex particles dominate the mechanical properties. (C) 2014 Elsevier Ltd. All rights reserved

Acrylic-Alkyd Hybrids: Secondary Nucleation, Particle Morphology, and Limiting Conversions

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