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Degenerative Chain Transfer (degenerative + chain_transfer)

Distribution by Scientific Domains
Polymers and Materials Science100%

Selected Abstracts

Synthesis of high glass transition temperature copolymers based on poly(vinyl chloride) via single electron transfer,Degenerative chain transfer mediated living radical polymerization (SET-DTLRP) of vinyl chloride in water

JOURNAL OF POLYMER SCIENCE (IN TWO SECTIONS), Issue 24 2009
Jorge F. J. Coelho
Abstract ,,,-di(iodo) poly(isobornyl acrylate) macroiniators (,,,-di(iodo)PIA) with number average molecular weight from Mn,TriSEC = 11,456 to Mn,TriSEC = 94,361 were synthesized by single electron transfer-degenerative chain transfer mediated living radical polymerization (SET-DTLRP) of isobornyl acrylate (IA) initiated with iodoform (CHI3) and catalyzed by sodium dithionite (Na2S2O4) in water at 35 °C. The plots of number average molecular weight vs conversion and ln{[M]0/[M]} vs time are linear, indicating a controlled polymerization. ,,,-di(iodo) poly(isobornyl acrylate) have been used as a macroinitiator for the SET-DTLRP of vinyl chloride (VCM) leading to high Tg block copolymers PVC-b-PIA-b-PVC. The dynamic mechanical thermal analysis of the block copolymers suggests just one phase indicating that copolymer behaves as a single material. This technology provides the possibility of synthesizing materials based on PVC with higher Tg in aqueous medium. © 2009 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem, 2009 [source]

Synthesis of Poly(lauryl acrylate) by Single-Electron Transfer/Degenerative Chain Transfer Living Radical Polymerization Catalyzed by Na2S2O4 in Water

MACROMOLECULAR CHEMISTRY AND PHYSICS, Issue 11 2007
Jorge F. J. Coelho
Abstract Living radical polymerization of lauryl acrylate was achieved by SET/DTLRP in water catalyzed by sodium dithionite. The work describes the synthesis of a highly hydrophobic and polar monomer in aqueous medium. The plots of versus conversion and ln[M]0/[M] versus time are linear, indicating a controlled polymerization. This method leads to ,,, -diiodopoly(lauryl acrylate)s that can be further functionalized. The MWDs were determined using a combination of three detectors: RALLS, DV, and RI. The method studied in this work represents a possible route to prepare well-tailored macromolecules made of LA in environment friendly reaction medium. The syndiotactic content is 75%. [source]

Kinetic Simulations of Reversible Chain Transfer Catalyzed Polymerization (RTCP): Guidelines to Optimum Molecular Weight Control

MACROMOLECULAR THEORY AND SIMULATIONS, Issue 1 2010
Philipp Vana
Abstract Kinetic simulations of reversible chain transfer catalyzed polymerization (RTCP) were performed using the program package Predici. Mimicking the RTCP of styrene in bulk at 80,°C, the full molecular weight distributions, the polydispersities of resulting polymer and the time evolutions of monomer conversion and participating species were simulated. The influence of the kinetic coefficients governing the RTCP equilibrium , specifically, the rate coefficients of activation, ka, and deactivation, kda , on the controlled polymerization behavior was probed in detail by varying their respective simulation input values over five orders of magnitude. It was found that optimum results for molecular weight control are obtained for K,=,ka/kda in the range 1 to 10 and with ka and kda being of the order of 106 L,·,mol,1,·,s,1 or above. The influence of degenerative chain transfer on the process was found to be significant only in poorly controlled systems, but is small in well-controlled RTCP. Based on the finding that the catalyst is depleting during the polymerization due to cross-termination, guidelines for obtaining high molecular weight material via repeated addition of catalyst were developed. [source]

Processability and characterization of poly(vinyl chloride)- b -poly(n -butyl acrylate)- b -poly(vinyl chloride) prepared by living radical polymerization of vinyl chloride.

JOURNAL OF VINYL & ADDITIVE TECHNOLOGY, Issue 4 2006
Comparison with a flexible commercial resin formulation prepared with PVC, dioctyl phthalate
This work reports the synthesis and processing of a new flexible material based on PVC produced by living radical polymerization. The synthesis was carried out in a two-step process. In the first step the macroinitiator ,, ,-di(iodo)poly(butyl acrylate) [,, ,-di(iodo)PBA] was synthesized in water by single electron transfer/degenerative chain transfer mediated living radical polymerization (SET-DTLRP) catalyzed by Na2S2O4. In the second step this macroinitiator was reinitiated by SET-DTLRP of vinyl chloride (VC), thereby leading to the formation of the block copolymer poly(vinyl chloride)- b -poly(butyl acrylate)- b -poly(vinyl chloride) [PVC- b -PBA- b -PVC]. This new material was processed on a laboratory scale. The DMTA traces showed only a single glass transition temperature, thus indicating that no phase segregation was present. The copolymers were studied with regard to their processing, miscibility, and mechanical properties. The first comparison with commercial formulations made with PVC and dioctyl phthalate (DOP) is presented. J. VINYL ADDIT. TECHNOL., 12:156,165, 2006. © 2006 Society of Plastics Engineers [source]