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Miniemulsion System (miniemulsion + system)
Selected AbstractsSynthesis of PMMA- b -PBA block copolymer in homogeneous and miniemulsion systems by DPE controlled radical polymerizationJOURNAL OF POLYMER SCIENCE (IN TWO SECTIONS), Issue 17 2009Ying-Da Luo Abstract In this research, poly(methyl methacrylate)- b -poly(butyl acrylate) (PMMA- b -PBA) block copolymers were prepared by 1,1-diphenylethene (DPE) controlled radical polymerization in homogeneous and miniemulsion systems. First, monomer methyl methacrylate (MMA), initiator 2,2,-azobisisobutyronitrile (AIBN) and a control agent DPE were bulk polymerized to form the DPE-containing PMMA macroinitiator. Then the DPE-containing PMMA was heated in the presence of a second monomer BA, the block copolymer was synthesized successfully. The effects of solvent and polymerization methods (homogeneous polymerization or miniemulsion polymerization) on the reaction rate, controlled living character, molecular weight (Mn) and molecular weight distribution (PDI) of polymers throughout the polymerization were studied and discussed. The results showed that, increasing the amounts of solvent reduced the reaction rate and viscosity of the polymerization system. It allowed more activation,deactivation cycles to occur at a given conversion thus better controlled living character and narrower molecular weight distribution of polymers were demonstrated throughout the polymerization. Furthermore, the polymerization carried out in miniemulsion system exhibited higher reaction rate and better controlled living character than those in homogeneous system. It was attributed to the compartmentalization of growing radicals and the enhanced deactivation reaction of DPE controlled radical polymerization in miniemulsified droplets. © 2009 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 47: 4435,4445, 2009 [source] Synthesis of hollow crosslinked miktoarm polymer using miniemulsion as templatesJOURNAL OF POLYMER SCIENCE (IN TWO SECTIONS), Issue 6 2009De'an Xiong Abstract Hollow crosslinked polymers (HCPs) were synthesized using arm first method via atom transfer radical polymerization. The polymerization process was performed in miniemulsion system, in which the macroinitiator, PEG-Br, was in the water phase, whereas the vinyl-monomer, 4-vinylpyridine (4VP), and the crosslinker, DVB, were in the butanone phase. TEM images and light scattering characterization showed that the resultant polymer contained a hollow space, and the volume of the hollow space could be adjusted by changing the ratio of water to butanone. Also, hollow crosslinked Miktoarm polymers (HCMPs) were synthesized through this method when two different macroinitiators, PEG-Br and PNIPAM-Br, were used to coinitiate the polymerization of the vinyl-monomer, 4VP and DVB. The 1H NMR spectra showed that the hollow polymers contained both PEG arms and PNIPAM arms. The hollow morphologies of the resultant Miktoarm polymers were the same as the HCPs. © 2009 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 47: 1651,1660, 2009 [source] Kinetics of Miniemulsion Polymerization of Styrene in the Presence of OrganoclaysMACROMOLECULAR MATERIALS & ENGINEERING, Issue 6 2008Zhaohui Tong Abstract The impacts of nanoclays on the miniemulsion polymerization kinetics of styrene were studied. It was found that both RP and the fractional conversion decreased upon increasing the organoclay content in the miniemulsion system. In the presence of nanoclay the molecular weight of polystyrene nanoclay composite is lower and the particle size polydispersity of the final composite latex is greater than that of pure styrene miniemulsion polymerization. The effect of the nanoclays is mainly caused by the destabilization of the miniemulsion by the organoclay particles. The increase in the monomer viscosity and the decrease in the diffusion rate of the monomer and the living polymer inside the monomer droplet also accounts for the reduction in the polymerization rate. [source] Polymerisable Miniemulsions Using Rotor-Stator HomogenisersMACROMOLECULAR REACTION ENGINEERING, Issue 4 2008Ula El-Jaby Abstract The use of a rotor-stator mixer as a homogenisation device to make miniemulsion droplets with industrially pertinent solid contents was investigated. Methyl methacrylate/butyl acrylate (50:50 w/w ratio) miniemulsions with droplet diameters from 2 µm to 300 nm and polydispersity indices from 1.2 to 3.6 were used. Miniemulsions with three different mean droplet diameters (300, 400, 600 nm) were polymerised and the evolution of particle size was observed. When 300 nm droplets were polymerised they yielded particles of similar diameter to the original droplets, whereas particle coalescence of the growing particles with a loss of control over the particle size distribution was observed for the 400 and 600 nm droplets. The influence of costabiliser, agitation speed, solid content, colloidal protectors and surface coverage on the evolution of the droplet size and size distribution as well as on the evolution of the average particle size and its distribution were examined. It was observed that changing the above parameters had no impact on the evolution of the particle size, suggesting we have a very robust miniemulsion system. [source] Synthesis of PMMA- b -PBA block copolymer in homogeneous and miniemulsion systems by DPE controlled radical polymerizationJOURNAL OF POLYMER SCIENCE (IN TWO SECTIONS), Issue 17 2009Ying-Da Luo Abstract In this research, poly(methyl methacrylate)- b -poly(butyl acrylate) (PMMA- b -PBA) block copolymers were prepared by 1,1-diphenylethene (DPE) controlled radical polymerization in homogeneous and miniemulsion systems. First, monomer methyl methacrylate (MMA), initiator 2,2,-azobisisobutyronitrile (AIBN) and a control agent DPE were bulk polymerized to form the DPE-containing PMMA macroinitiator. Then the DPE-containing PMMA was heated in the presence of a second monomer BA, the block copolymer was synthesized successfully. The effects of solvent and polymerization methods (homogeneous polymerization or miniemulsion polymerization) on the reaction rate, controlled living character, molecular weight (Mn) and molecular weight distribution (PDI) of polymers throughout the polymerization were studied and discussed. The results showed that, increasing the amounts of solvent reduced the reaction rate and viscosity of the polymerization system. It allowed more activation,deactivation cycles to occur at a given conversion thus better controlled living character and narrower molecular weight distribution of polymers were demonstrated throughout the polymerization. Furthermore, the polymerization carried out in miniemulsion system exhibited higher reaction rate and better controlled living character than those in homogeneous system. It was attributed to the compartmentalization of growing radicals and the enhanced deactivation reaction of DPE controlled radical polymerization in miniemulsified droplets. © 2009 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 47: 4435,4445, 2009 [source] Preparation of gradient copolymers via ATRP using a simultaneous reverse and normal initiation process.JOURNAL OF POLYMER SCIENCE (IN TWO SECTIONS), Issue 16 2005Abstract Spontaneous gradient copolymers were prepared in both bulk and miniemulsion systems via Atom Transfer Radical Polymerization (ATRP) utilizing a Simultaneous Reverse and Normal Initiation (SR & NI) process. Both instantaneous and cumulative compositions were used to characterize the gradient copolymers. The gradient copolymers were obtained with an array of gradient compositions ranging from a subtle to strong variation in monomer distribution along the polymer backbones, depending on the ratio of comonomers initially added to the copolymerization system. The compositions of the gradient copolymer produced in miniemulsion systems were similar to those generated in bulk. © 2005 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 43: 3616,3622, 2005 [source] Controlled, radical reversible addition,fragmentation chain-transfer polymerization in high-surfactant-concentration ionic miniemulsionsJOURNAL OF POLYMER SCIENCE (IN TWO SECTIONS), Issue 4 2004J. B. McLeary Abstract Living free-radical polymerization of methacrylate and styrenic monomers with ionic surfactants was carried out with reversible addition,fragmentation chain transfer in miniemulsion with different surfactant types and concentrations. The previously reported problem of phase separation was found to be insignificant at higher surfactant concentrations, and control of the molar mass and polydispersity index was superior to that of published miniemulsion systems. Cationic and anionic surfactants were used to examine the validity of the argument that ionic surfactants interfere with transfer agents. Ionic surfactants were suitable for miniemulsion polymerization under certain conditions. The colloidal stability of the miniemulsions was consistent with the predictions of a specific model. The living character of the polymer that comprised the latex material was shown by its transformation into block copolymers. © 2004 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 42: 960,974, 2004 [source] | ||||||||||