title: Effect of monomer dosing rate in the preparation of mesoporous polystyrene nanoparticles by semicontinuous heterophase polymerization.
abstract: The semicontinuous heterophase polymerization of styrene in the presence of cross-linking and porogen agents was carried out. Latexes with close to 20% solid content, which contained mesoporous nanoparticles with 28 nm in average diameters, up to 0.5 cm3/g in porosity and 6-8 nm in pore diameters were obtained. By varying the monomer dosing rate over the micellar solution, an unexpected direct dependence of instantaneous conversion on the monomer dosing rate was found. This was ascribed to the higher average number of radicals per particle attained in the polymerization at the higher dosing rate, which in turn would arise from the higher gel percentage in the polymer. It is believed that the cross-linked chains prevent encounters between radicals, delaying the bimolecular termination reactions and allowing the existence of more than one radical inside the particles, which in turn increases the propagation rate.
authors.affiliation: Departamento de Procesos de Polimerización, Centro de Investigación en Química Aplicada, Blvd. Enrique Reyna No. 140, C. P. 25294 Saltillo, Coahuila, Mexico.
authors.forename: Dalia Y
authors.initials: DY
authors.lastname: Sosa
authors.affiliation: Departamento de Procesos de Polimerización, Centro de Investigación en Química Aplicada, Blvd. Enrique Reyna No. 140, C. P. 25294 Saltillo, Coahuila, Mexico.
authors.forename: Lourdes
authors.initials: L
authors.lastname: Guillén
authors.affiliation: Departamento de Procesos de Polimerización, Centro de Investigación en Química Aplicada, Blvd. Enrique Reyna No. 140, C. P. 25294 Saltillo, Coahuila, Mexico.
authors.forename: Hened
authors.initials: H
authors.lastname: Saade
authors.affiliation: Departamentos de Química e Ingeniería Química, Centro Universitario de Ciencias Exactas e Ingenierías, Universidad de Guadalajara, Blvd. M. García-Barragán No. 1451, C. P. 44430 Guadalajara, Jalisco, Mexico.
authors.forename: Eduardo
authors.initials: E
authors.lastname: Mendizábal
authors.affiliation: Departamentos de Química e Ingeniería Química, Centro Universitario de Ciencias Exactas e Ingenierías, Universidad de Guadalajara, Blvd. M. García-Barragán No. 1451, C. P. 44430 Guadalajara, Jalisco, Mexico.
authors.forename: Jorge E
authors.initials: JE
authors.lastname: Puig
authors.affiliation: Departamento de Procesos de Polimerización, Centro de Investigación en Química Aplicada, Blvd. Enrique Reyna No. 140, C. P. 25294 Saltillo, Coahuila, Mexico. guillermo.lopez@ciqa.edu.mx.
authors.forename: Raúl G
authors.initials: RG
authors.lastname: López
mesh_terms: D007700:Kinetics; D017348:Microscopy, Electron, Scanning Transmission; D053758:Nanoparticles / Q000737:chemistry*; D010316:Particle Size; D058105:Polymerization; D011137:Polystyrenes / Q000737:chemistry*; D016062:Porosity; D013500:Surface Tension
chemical_list: D011137:Polystyrenes