title: Synthesis of micrometer-size poly(N-isopropylacrylamide) microgel particles with homogeneous crosslinker density and diameter control.
abstract: Poly(N-isopropylacrylamide) microgel particles are synthesized using a semi-batch surfactant-free emulsion polymerization method. Particle diameter can be precisely adjusted by controlling the initial conditions, the electrolyte concentration, and the monomer feeding rate and duration. Larger particles are obtained in the presence of small amounts of co-monomer with cationic amino groups that compete against the negative charges arising from the initiator. Monodisperse particles with uniform cross-linker density, homogeneous optical properties, and pronounced thermoresponsivity are readily produced with a wide variety of diameters ranging from several hundred nanometers to a few micrometers. The charge stabilization mechanisms that control particle growth are discussed.
authors.affiliation: Department of Physics and Astronomy, University of Pennsylvania, Philadelphia, PA 19104, USA. timstill@seas.upenn.edu
authors.forename: Tim
authors.initials: T
authors.lastname: Still
authors.forename: Ke
authors.initials: K
authors.lastname: Chen
authors.forename: Ahmed M
authors.initials: AM
authors.lastname: Alsayed
authors.forename: Kevin B
authors.initials: KB
authors.lastname: Aptowicz
authors.forename: A G
authors.initials: AG
authors.lastname: Yodh
mesh_terms: D000180:Acrylic Resins / Q000737:chemistry*; D015374:Biosensing Techniques; D003102:Colloids / Q000737:chemistry*; D003432:Cross-Linking Reagents / Q000737:chemistry; D003460:Crystallization; D020100:Hydrogels / Q000737:chemistry; D008027:Light; D016011:Normal Distribution; D010316:Particle Size; D011108:Polymers / Q000737:chemistry; D012542:Scattering, Radiation; D013696:Temperature; D013997:Time Factors
chemical_list: D000180:Acrylic Resins; D003102:Colloids; D003432:Cross-Linking Reagents; D020100:Hydrogels; D011108:Polymers; C052970:poly-N-isopropylacrylamide