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Controllable preparation of poly(butyl acrylate) by suspension polymerization in a coaxial capillary microreactor / Zhendong Liu in Industrial & engineering chemistry research, Vol. 50 N° 21 (Novembre 2011) 

Public ISBD [article]  in Industrial & engineering chemistry research > Vol. 50 N° 21 (Novembre 2011) . - pp. 11853–11862 Titre : Controllable preparation of poly(butyl acrylate) by suspension polymerization in a coaxial capillary microreactor Type de document : texte imprimé Auteurs : Zhendong Liu, Auteur ; Yangcheng Lu, Auteur ; Bodong Yang, Auteur Année de publication : 2011 Article en page(s) : pp. 11853–11862 Note générale : Chimie industrielle Langues : Anglais (eng) Mots-clés : Microreactor Résumé : In this work, a new controllable and continuous free radical polymerization process was developed and characterized in a coaxial capillary microreactor. In this process, the monomer solution was first dispersed into monodispersed droplets followed by thermal-initiated polymerization in the following capillary immersed in an oil bath. Poly(butyl acrylate) prepared in this microreactor possessed a much higher average molecular weight (Mn) and far lower polydispersity index (PDI) than that produced in a typical stirred vessel. The microreactor method possesses two unique advantages which allow for the optimization of the free radical polymerization process. First, the use of highly monodispersed droplets as polymerization units ensures that the polymerization process occurs uniformly in each individual droplet. Second, the small droplet size, on the order of several hundred micrometers, greatly enhances heat transfer efficiency with no heat accumulation within the droplets during polymerization. A simplified numerical simulation was used to show the superiority of the microreactor in effectively removing polymerization heat due to the miniaturization of the droplets to submillimeter scale. Simulation results also demonstrated that, in contrast to polymerization processes occurring in macroreactors, the polymerization conducted in the microreactor proceeded in a nearly isothermal condition. Experimental results in the microreactor showed that the molecular weight distribution was mainly determined by the size of the droplet, while the molecular weight of the polymer could be adjusted by changing the reaction temperature and 2,2-azobis(isobutyronitrile) concentration. This type of microreactor can potentially be applied to research involving the mechanisms of highly exothermic free radical polymerization processes and can also be used as an efficient tool for their controllable preparation. DEWEY : 660 ISSN : 0888-5885 En ligne : http://pubs.acs.org/doi/abs/10.1021/ie201497b [article] Controllable preparation of poly(butyl acrylate) by suspension polymerization in a coaxial capillary microreactor [texte imprimé] / Zhendong Liu, Auteur ; Yangcheng Lu, Auteur ; Bodong Yang, Auteur . - 2011 . - pp. 11853–11862. Chimie industrielle Langues : Anglais (eng) in Industrial & engineering chemistry research > Vol. 50 N° 21 (Novembre 2011) . - pp. 11853–11862 Mots-clés : Microreactor Résumé : In this work, a new controllable and continuous free radical polymerization process was developed and characterized in a coaxial capillary microreactor. In this process, the monomer solution was first dispersed into monodispersed droplets followed by thermal-initiated polymerization in the following capillary immersed in an oil bath. Poly(butyl acrylate) prepared in this microreactor possessed a much higher average molecular weight (Mn) and far lower polydispersity index (PDI) than that produced in a typical stirred vessel. The microreactor method possesses two unique advantages which allow for the optimization of the free radical polymerization process. First, the use of highly monodispersed droplets as polymerization units ensures that the polymerization process occurs uniformly in each individual droplet. Second, the small droplet size, on the order of several hundred micrometers, greatly enhances heat transfer efficiency with no heat accumulation within the droplets during polymerization. A simplified numerical simulation was used to show the superiority of the microreactor in effectively removing polymerization heat due to the miniaturization of the droplets to submillimeter scale. Simulation results also demonstrated that, in contrast to polymerization processes occurring in macroreactors, the polymerization conducted in the microreactor proceeded in a nearly isothermal condition. Experimental results in the microreactor showed that the molecular weight distribution was mainly determined by the size of the droplet, while the molecular weight of the polymer could be adjusted by changing the reaction temperature and 2,2-azobis(isobutyronitrile) concentration. This type of microreactor can potentially be applied to research involving the mechanisms of highly exothermic free radical polymerization processes and can also be used as an efficient tool for their controllable preparation. DEWEY : 660 ISSN : 0888-5885 En ligne : http://pubs.acs.org/doi/abs/10.1021/ie201497b

Controllable preparation of polyacrylamide hydrogel microspheres in a coaxial microfluidic device / Bodong Yang in Industrial & engineering chemistry research, Vol. 51 N° 26 (Juillet 2012) 

Public ISBD [article]  in Industrial & engineering chemistry research > Vol. 51 N° 26 (Juillet 2012) . - pp. 9016-9022 Titre : Controllable preparation of polyacrylamide hydrogel microspheres in a coaxial microfluidic device Type de document : texte imprimé Auteurs : Bodong Yang, Auteur ; Yangcheng Lu, Auteur ; Guangsheng Luo, Auteur Année de publication : 2012 Article en page(s) : pp. 9016-9022 Note générale : Industrial chemistry Langues : Anglais (eng) Mots-clés : Fluid  mechanics  Microfluidics  Microsphere  Preparation Résumé : A thermal-initiated polymerization procedure is described for the controlled preparation of monodispersed polyacrylamide (PAM) hydrogel microspheres. A coaxial microfluidic device was designed to disperse uniform drops (∼500 μm) of acrylamide monomer aqueous solution into n-octane. Using a delay loop immersed into a heat bath, the polymerization is initiated and carried out in separate droplets. Combining the improvement of heat transfer in the microfluidic device and the sufficient addition of n-octane, the controllable preparation can still be achieved at 95 °C, much higher than 20-60 °C as reported prevalently. Herein, the PAM microspheres can be prepared within 2 min or less, with the CV of diameter less than 4%. Furthermore, based on this controllable reaction platform, PAM microspheres were prepared at various reaction temperatures (higher than 90 °C) and monomer solution compositions to investigate the fundamental rules of controlling on their skeleton structure and absorbent capacity in deionized water. DEWEY : 0888-5885 En ligne : http://cat.inist.fr/?aModele=afficheN&cpsidt=26107459 [article] Controllable preparation of polyacrylamide hydrogel microspheres in a coaxial microfluidic device [texte imprimé] / Bodong Yang, Auteur ; Yangcheng Lu, Auteur ; Guangsheng Luo, Auteur . - 2012 . - pp. 9016-9022. Industrial chemistry Langues : Anglais (eng) in Industrial & engineering chemistry research > Vol. 51 N° 26 (Juillet 2012) . - pp. 9016-9022 Mots-clés : Fluid  mechanics  Microfluidics  Microsphere  Preparation Résumé : A thermal-initiated polymerization procedure is described for the controlled preparation of monodispersed polyacrylamide (PAM) hydrogel microspheres. A coaxial microfluidic device was designed to disperse uniform drops (∼500 μm) of acrylamide monomer aqueous solution into n-octane. Using a delay loop immersed into a heat bath, the polymerization is initiated and carried out in separate droplets. Combining the improvement of heat transfer in the microfluidic device and the sufficient addition of n-octane, the controllable preparation can still be achieved at 95 °C, much higher than 20-60 °C as reported prevalently. Herein, the PAM microspheres can be prepared within 2 min or less, with the CV of diameter less than 4%. Furthermore, based on this controllable reaction platform, PAM microspheres were prepared at various reaction temperatures (higher than 90 °C) and monomer solution compositions to investigate the fundamental rules of controlling on their skeleton structure and absorbent capacity in deionized water. DEWEY : 0888-5885 En ligne : http://cat.inist.fr/?aModele=afficheN&cpsidt=26107459