Tailor-made compositional gradient copolymer by a many-shot RAFT emulsion polymerization method

2014 ◽  
Vol 5 (10) ◽  
pp. 3363-3371 ◽  
Author(s):  
Yunlong Guo ◽  
Jianhua Zhang ◽  
Peile Xie ◽  
Xiang Gao ◽  
Yingwu Luo
Keyword(s):  
Molecular Weight ◽  
Emulsion Polymerization ◽  
High Molecular Weight ◽  
Compositional Gradient ◽  
Gradient Copolymers ◽  
Gradient Copolymer ◽  
Polymerization Method

A many-shot RAFT emulsion polymerization method to synthesize gradient copolymers with high molecular weight and a tailor-made compositional gradient.

Properties of high molecular weight polycarbonate synthesized by using the solid phase polymerization method.

2000 ◽  
Vol 57 (1) ◽  
pp. 15-22 ◽  
Author(s):  
Hiroshi HACHIYA ◽  
Haruyuki YONEDA ◽  
Yuko MATSUDA ◽  
Kazuyuki YOSHIDA ◽  
Kunihiko TAKEDA
Keyword(s):  
Molecular Weight ◽  
High Molecular Weight ◽  
Solid Phase ◽  
Polymerization Method

scholarly journals Particle morphology, structure and properties of nascent ultra-high molecular weight polyethylene

2020 ◽  
Vol 7 (8) ◽  
pp. 200663
Author(s):  
Wenyang Zhang ◽  
Zhengwen Wu ◽  
Hanjun Mao ◽  
Xinwei Wang ◽  
Jianlong Li ◽  
...  
Keyword(s):  
Molecular Weight ◽  
Particle Size ◽  
High Molecular Weight ◽  
Liquid Paraffin ◽  
Particle Morphology ◽  
Particle Growth ◽  
Structure And Properties ◽  
Uhmwpe Particle ◽  
Ultra High Molecular Weight ◽  
Polymerization Method

The effects of particle morphology on the structure and swelling/dissolution and rheological properties of nascent ultra-high molecular weight polyethylene (UHMWPE) in liquid paraffin (LP) were elaborately explored in this article. Nascent UHMWPE with different particle morphologies was prepared via pre-polymerization technique and direct polymerization. The melting temperature and crystallinity of UHMWPE resins with different particle morphologies were compared, and a schematic diagram was proposed to illustrate the mechanism of UHMWPE particle growth synthesized by pre-polymerization method and direct polymerization. The polymer globules in the nascent UHMWPE prepared by using pre-polymerization technique are densely packed and a positive correlation between the particle size and the viscosity-averaged molecular weight can be observed. The split phenomenon of particles and the fluctuation in the viscosity of UHMWPE/LP system prepared by direct polymerization can be observed at a low heating rate and there is no correlation between particle size and viscosity-averaged molecular weight.

RAFT-mediated emulsion polymerization of vinyl acetate: a challenge towards producing high molecular weight poly(vinyl acetate)

2012 ◽  
Vol 290 (13) ◽  
pp. 1247-1255 ◽  
Author(s):  
Funian Zhao ◽  
Ali Reza Mahdavian ◽  
Mohammad Bagher Teimouri ◽  
Eric S. Daniels ◽  
Andrew Klein ◽  
...  
Keyword(s):  
Molecular Weight ◽  
Emulsion Polymerization ◽  
High Molecular Weight ◽  
Vinyl Acetate ◽  
High Molecular Weight Poly

scholarly journals Inverse Emulsion Polymerization for the Synthesis of High Molecular Weight Polyacrylamide and Its Application as Sand Stabilizer

2015 ◽  
Vol 2015 ◽  
pp. 1-10 ◽  
Author(s):  
Mahmoud A. Mohsin ◽  
Nuha F. Attia
Keyword(s):  
Molecular Weight ◽  
Emulsion Polymerization ◽  
High Molecular Weight ◽  
Solution Viscosity ◽  
Experimental Conditions ◽  
High Molecular Weight Polymer ◽  
Molecular Weight Polymer ◽  
Inverse Emulsion Polymerization ◽  
Inverse Emulsion ◽  
Molecular Weights

Polyacrylamides constitute a class of polymers that can entirely dissolve or swell in water to form a solution or hydrogel, respectively. Free radical polymerization of acrylamide monomer, using both solution and inverse emulsion polymerization, was applied to produce polyacrylamide with various molecular weights. This investigation was focused on the production of polymers with varying molecular weight, depending on monomer to initiator ratio. Experimental conditions were designed to produce high molecular weight polymers that can be used in stabilization of sand dunes in the arid regions. Synthesized polyacrylamide samples were characterized using Gel Permeation Chromatography and solution viscosity in order to determine the molecular weights and molecular weights distribution. The rheological behavior was also investigated in different polymer concentrations and at various temperatures using Brookfield Rheometer. Lab-scale wind tunnel was used to determine the stability of the sand before and after treatment with the polymer. Compressive stress-strain test was also used to establish the mechanical behavior of the polymer-sand composite under controlled compressive load up to failure. The results showed that the use of high molecular weight polymer gave excellent mechanical and thermal stability.

Synthesis and characterization of high molecular weight and low dispersity polystyrene homopolymers by RAFT polymerization

e-Polymers ◽  
2012 ◽  
Vol 12 (1) ◽  
Author(s):  
Cheng Jin ◽  
Chun Liu ◽  
Bo Jiang ◽  
Qin-jian in
Keyword(s):  
Molecular Weight ◽  
High Molecular Weight ◽  
Chain Transfer ◽  
Raft Polymerization ◽  
Polymerization Temperature ◽  
Polymer Molecular Weight ◽  
Mild Conditions ◽  
Reversible Addition ◽  
Polymerization Method

AbstractHigh molecular weight polystyrene homopolymers with low dispersity were synthesized by a reversible addition-fragmentation chain transfer (RAFT) polymerization method using 0.03 and 0.3 wt% of cumyl dithiobenzoate (CDB) vs. styrene (St) and the azobis(isobutyronitrile) initiator, at the polymerization temperature of 60 or 70 °C. The optimal high molecular weight polystyrene via this synthetic scheme shows Mw = 46.5×104, Mn = 33.3×104, and a dispersity of 1.40. The polystyrene chain contains a dithiobenzoate C=S moiety and thus can be used as a macro-chain-transfer agent for the polymerization of other monomers and for the synthesis of diversified block copolymers under mild conditions. The changes of the polystyrene molecular weight and dispersity were studied by the influences of the initial concentration ratio of CDB to styrene ([CDB]0/[St]0), the polymerization temperature, and the polymerization time. The PS molecular weight is inversely proportional to the [CDB]0/[St]0 ratio. Decreasing CDB from 0.3 to 0.03 wt%, a high MW PS was obtained, while the dispersity was observed to increase from 1.10 to 1.40. The PS molecular weight increases with the increase of the reaction time, while the dispersity of PS varies little from 1.12 to 1.23. The molecular weight and dispersity increase with the increase of the polymerization temperature. As the temperature arises from 60°C to 70°C, the conversion increases considerably from 25.8% to 39.9%, and the dispersity increases slightly from 1.15 to 1.17. As the temperature reaches 80°C, the conversion increases considerably to 64.7%, and the dispersity increases to 1.53. The polymer molecular weight of the polystyrene prepared by the RAFT method is suitable for the applications of engineering materials.

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