Optimized buffered polymerizations to produce N-vinylcaprolactam-based microgels |
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Authors: | Ainara Imaz Jacqueline Forcada |
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Institution: | aInstitute for Polymer Materials (POLYMAT) and Grupo de Ingeniería Química, Departamento de Química Aplicada, Facultad de Ciencias Químicas, Universidad del País Vasco/Euskal Herriko Unibertsitatea, Apdo. 1072, San Sebastián-Donostia 20080, Spain |
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Abstract: | Temperature-sensitive N-vinylcaprolactam (VCL)-based microgel particles were synthesized by emulsion polymerization in a batch reactor. To avoid the hydrolysis of VCL, optimized buffered reactions were carried out by using VCL as main monomer, N,N′-methylenebisacrylamide (BA) as cross-linker and a sugar-based comonomer (3-O-methacryloyl-1,2:5,6-di-O-isopropylidene-α-d-glucofuranose, 3-MDG). The amounts of initiator, cross-linker, surfactant, comonomer, and reaction temperature were the reaction variables. The effects of these variables on the kinetic features of the different polymerizations were analyzed. The colloidal characterization of the microgel particles consists of the analysis of the evolution of the average hydrodynamic diameters as a function of the temperature of the medium. The results showed that in all cases BA reacted faster than VCL. All final microgel particles showed swelling-de-swelling behavior by changing the temperature of the medium in which they are dispersed. Initially formed microgel particles were not temperature-sensitive being necessary up to about 30% of VCL conversion for the onset of the swelling-de-swelling behavior. The final colloidal characteristics of these new microgels can be tuned by modulating the reaction variables. |
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Keywords: | Microgels Stimuli-sensitive polymers Kinetics N-vinylcaprolactam |
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