Synthesis of pH and temperature sensitive, core-shell nano/microgels, by one pot, soap-free emulsion polymerization

A Serrano-Medina; J M Cornejo-Bravo; A Licea-Claveríe

doi:10.1016/j.jcis.2011.12.045

Synthesis of pH and temperature sensitive, core-shell nano/microgels, by one pot, soap-free emulsion polymerization

J Colloid Interface Sci. 2012 Mar 1;369(1):82-90. doi: 10.1016/j.jcis.2011.12.045. Epub 2011 Dec 27.

Authors

A Serrano-Medina¹, J M Cornejo-Bravo, A Licea-Claveríe

Affiliation

¹ Universidad Autónoma de Baja California, Facultad de Ciencias Químicas e Ingeniería, Calzada Universidad, Tijuana, BC, Mexico.

PMID: 22226474
DOI: 10.1016/j.jcis.2011.12.045

Abstract

The synthesis and properties of thermal/pH-sensitive core-shell copolymer nano/microgels were investigated. The crosslinked core consisted of N-isopropylacrylamide (NIPAAm) while the shell was stabilized by poly(ethylene glycol) methyl ether methacrylate (PEGMA) and 2-methacryloyloxybenzoic acid (2MBA) using a "one pot" soapless emulsion polymerization method. Monodisperse particles were produced with average hydrodynamic diameters ranging from 40 to 880 nm, as determined by dynamic light scattering (DLS) in water at 25°C, depending on the synthetic recipe used. The influence of PEGMA and 2MBA content on size and temperature transition at different pH values was studied. Zeta potential measurements and acid-base titration studies demonstrated almost complete incorporation of acid comonomer (2MBA) into the nano/microgels. Two different crosslinkers, a stable and an acid labile, were compared. The crosslinker used has a major influence on the size and charge density of the nano/microgels produced. Microscopic studies confirmed the core-shell morphology of the nano/microgels.