Particle sizes and electrophoretic mobilities of poly(N-isopropylacrylamide) latex

Abstract

Average particle diameters and electrophoretic mobilites of poly(N-isopropylacrylamide) latex were measured as a function of temperature. Diameters decreased from 788 nm at 10 °C to 380 nm at 50 °C in 0.001 M KC1; the corresponding electrophoretic mobilities increased from -0.193 X 10""8 (18 °C) to -3.06 x 10*8 m2 V'1 s'1 (47 °C). The most dramatic changes with temperature occurred around 31 °C, the lower critical solution temperature of poly(TV-isopropylacrylamide) in water. The increased electrophoretic mobility with temperature reflected increasing charge density when the particle diameter decreased. Charge density increased with decreasing particle diameter because the number of charged groups per particle was constant.

Impact of volume transition on the net charge of poly-N-isopropyl acrylamide microgels

“…It is thus reasonable to assume that the charges are always attached to dangling ends [33]. Moreover, because the PNiPAM synthesis is performed at a temperature that significantly exceeds the LCST, we can expect that the charges are mainly located at the outer edge of the microgels.…”

Effect of reaction parameters on the dispersion polymerization of 1-vinyl-2-pyrrolidone

“…However, studies on dispersion polymerization of hydrophilic water-soluble monomers are rather scarce; only a few systems are described in the literature. For example, Uyama reported on the dispersion polymerization of N-vinylformamide, 1 Takahashi described that of 4-vinylpyridine, 2 Pelton dealt with the preparation of latexes from crosslinked poly(N-isopropylacrylamide), 3 and recently the dispersion polymerization of acrylamide was reported by Ray. 4 Dispersion polymerization is governed by a delicate interplay of partitioning and interactions of all the reaction mixture components, the effectiveness of steric stabilizer being a key property in the preparation of a stable latex.…”

Dispersion polymerization of acrylamide: Part II. 2,2?-Azobisisobutyronitrile initiator

“…Pelton et al described the preparation of the latexes of cross-linked poly(N-isopropyl acrylamide) (PNIPAM) without using any externally added stabilizer. [22][23] Recently, we reported on the dispersion polymerization of acrylamide (AM) in aqueous TBA media using PVME as the stabilizer and APS as the initiator at 40°C. 24,25 The process yields readily soluble finely dispersed submicronic high molecular weight polyacrylamide.…”