title: A novel route to prepare pH- and temperature-sensitive nanogels via a semibatch process.
abstract: A novel method via a semibatch process in the absence of surfactant has been adopted to prepare pH- and temperature-sensitive nanogels. The shape, charge distribution, temperature, and pH-induced volume phase transition behavior of the latexes were investigated by scanning electronic microscopy, zeta potentials, dynamic laser light scattering, and UV/vis spectroscopy. It was found that, in the absence of surfactant, with increasing the amount of AAc from 5 to 20 mol% of N-isopropylacrylamide (NIPAM), the hydrodynamic diameters (D(H)) decrease from 230 to 60 nm. With increasing pH value from 3 to 11, the D(H) values increase slightly, which is different than the dramatic increase seen when using a conventional batch method with a range from 680 to 1700 nm. However, at pH 3, the turbidity curves of these kinds of particles increase dramatically at temperatures between 33 and 37 degrees C, while remaining constant at first and then increasing directly at pH 11. Furthermore, the distribution of carboxylic groups located not only on the interior but also on the exterior of colloidal particles as a result of adoption of the semibatch method, other than simple surface distribution of poly(NIPAM-co-AAc) latexes via the batch method.
authors.affiliation: State Key Laboratory for Modification of Chemical Fibers and Polymer Materials, Donghua University, Shanghai 200051, People's Republic of China.
authors.forename: Qingsong
authors.initials: Q
authors.lastname: Zhang
authors.forename: Liusheng
authors.initials: L
authors.lastname: Zha
authors.forename: Jinghong
authors.initials: J
authors.lastname: Ma
authors.forename: Borun
authors.initials: B
authors.lastname: Liang
mesh_terms: D000178:Acrylamides / Q000737:chemistry*; D000464:Alginates / Q000737:chemistry; D000536:Aluminum Hydroxide / Q000737:chemistry; D004338:Drug Combinations; D006863:Hydrogen-Ion Concentration; D007840:Latex; D000080385:Nanogels; D044367:Phase Transition; D011092:Polyethylene Glycols / Q000138:chemical synthesis*; D011094:Polyethyleneimine / Q000138:chemical synthesis*; D012824:Silicic Acid / Q000737:chemistry; D017693:Sodium Bicarbonate / Q000737:chemistry; D013696:Temperature
chemical_list: D000178:Acrylamides; D000464:Alginates; D004338:Drug Combinations; D007840:Latex; D000080385:Nanogels; C413692:polyethylene glycol polyethyleneimine nanogel; D012824:Silicic Acid; D011092:Polyethylene Glycols; D000536:Aluminum Hydroxide; C007829:alginate, aluminium hydroxide, magnesium trisilicate, sodium bicarbonate drug combination; D017693:Sodium Bicarbonate; D011094:Polyethyleneimine; C067295:N-isopropylacrylamide