Microencapsulation of various reactive monomers by in situ polymerization

ROMINA OLLIER; ELISABETH PENOFF; EXEQUIEL S. RODRIGUEZ; VERA A. ALVAREZ

Ghent

Conferencia; Fourth Internation Conference on Self-Healing Materials; 2013

Ghent University

Advances in the study of composite polymeric materials for structural applicationshave suggested the possibility of an early elimination of cracks to avoid macroscopicdamage of the material. Hence, the concept of self-healing composite materials hasbeen introduced to reduce the maintenance cost and frequency, to increase the life inservice and to expand the applications of these materials. One of the most successfuland versatile approach consists on embedding an encapsulated haling agent insidethe matrix.One of the key features for the effectiveness of the healing system is themicrocapsule design. The release properties depend on the healing agent properties,wall materials, the microencapsulation method, the physico-chemical parameters ofthe process, the mean particle size and the shell thickness. In order to have asuccessful self-healing performance, it is important to synthesize microcapsules withrough surface morphology to assure a good adhesion with de polymer matrix, lowcore material permeability, appropriate diameter and core content, and adequateshell thickness.The aim of this work was to synthesize poly (urea-formaldehyde) microcapsules filledwith different reactive monomers: dicyclopentadiene and two epoxy monomers withdifferent viscosities. This parameter is important for the release properties and thehealing performance of the resulting capsules. Microcapsules were prepared by insitu polymerization in oil-in-water emulsion and the best experimental conditions wereselected to optimize the subsequent healing efficiency. Several reaction conditionswere analyzed, by changing the following parameters: the rate of agitation, theconcentration of surfactant and the viscosity of the encapsulated phase. The effect ofthe addition of nanoclay along the shell was also studied. The final step of filteringand washing the obtained capsules with different solvents was analyzed as well.