scholarly journals Polymerization in soft nanoconfinement of lamellar and reverse hexagonal mesophases

Soft Matter ◽  
2019 ◽  
Vol 15 (41) ◽  
pp. 8238-8250 ◽  
Author(s):  
Sahar Qavi ◽  
Alireza Bandegi ◽  
Millicent Firestone ◽  
Reza Foudazi
Keyword(s):  
Monomer Concentration ◽  
Polymerization Rate ◽  
Bulk State ◽  
Segregation Effect

The polymerization rate decreases in the nanoconfined structure compared to the bulk state due to the segregation effect, which increases the local monomer concentration and enhances the termination reaction.

Living free radical polymerization of styrene with 2-cyanoprop-2-yl dithionaphthalate as RAFT agent

e-Polymers ◽  
2003 ◽  
Vol 3 (1) ◽  
Author(s):  
Zhu Jian ◽  
Zhu Xiulin ◽  
Zhou Di ◽  
Chen Jianying
Keyword(s):  
Molecular Weight ◽  
Reaction Temperature ◽  
Raft Polymerization ◽  
Monomer Concentration ◽  
Gel Permeation Chromatography ◽  
Monomer Conversion ◽  
Bulk Polymerization ◽  
Polymerization Rate ◽  
Chain Extension ◽  
Raft Agent

Abstract The reversible addition-fragmentation chain transfer (RAFT) bulk polymerization of styrene was studied using 2-cyanoprop-2-yl dithionaphthalate (CPDN) as RAFT agent in the presence or absence of 2,2’-azoisobutyronitrile (AIBN). The results of both thermally and AIBN-initiated styrene (St) polymerizations show that St can be polymerized in a controlled way using CPDN as RAFT agent; i.e., the polymerization rate is first order with respect to monomer concentration, and molecular weight increases linearly with monomer conversion. The molecular weights obtained from gel permeation chromatography are close to the theoretical values and molecular weight distributions are relatively narrow (Mw/Mn < 1.2). It is confirmed by chain extension reaction that the polymer prepared via RAFT polymerization can be used as a macroRAFT agent. The effects of reaction temperature and mole ratios [St]0/[CPDN]0/[AIBN]0 on the polymerization were investigated. The results indicate that the reaction temperature has a positive effect on the polymerization rate, but little effect on molecular weight and molecular weight distribution, and the optimum mole ratios were found to be [CPDN]0/[AIBN]0 > 4/3 and [St]0/[CPDN]0 < 800.

scholarly journals Tuning the physical properties of malleable and recyclable polyimine thermosets: the effect of solvent and monomer concentration

RSC Advances ◽  
2017 ◽  
Vol 7 (76) ◽  
pp. 48303-48307 ◽  
Author(s):  
Chengpu Zhu ◽  
Cally Xi ◽  
William Doro ◽  
Tianyi Wang ◽  
Xin Zhang ◽  
...  
Keyword(s):  
Physical Properties ◽  
Monomer Concentration ◽  
Polymerization Rate ◽  
Effect Of Solvent

We report the effect of solvent choice and polymerization rate on the physical properties of polyimine based malleable thermosets.

Radiation polymerization of 2-hydroxyethyl methacrylate-vinyl pyrrolidone-water system

1988 ◽  
Vol 53 (6) ◽  
pp. 1242-1246
Author(s):  
Minoru Kumakura ◽  
Isao Kaetsu
Keyword(s):  
Glass Transition ◽  
Low Temperatures ◽  
Water System ◽  
Monomer Concentration ◽  
Temperature Curve ◽  
Irradiation Temperature ◽  
Polymerization Rate ◽  
Vinyl Pyrrolidone ◽  
Hydroxyethyl Methacrylate ◽  
Radiation Polymerization

Radiation polymerization of 2-hydroxyethyl methacrylate-vinyl pyrrolidone-water system at low temperature was studied. The polymerization rate-irradiation temperature curve had a maximum peak at near glass transition temperaure, and it was shifted to the site of high temperature with increasing monomer concentration. The polymerization rate in vinyl pyrrolidone at low temperatures was accelerated by the addition of water. The polymers obtained by radiation polymerization of 2-hydroxyethyl methacrylate-vinyl pyrrolidone-water system at low temperatures were a high hydrophilicity and had porous structure.

Nitroxide-Mediated Radical Polymerization in Nanoreactors: Can Dilution or Increased Nitroxide Concentration Provide Benefits Similar to Compartmentalization?

2010 ◽  
Vol 63 (8) ◽  
pp. 1195 ◽  
Author(s):  
Per B. Zetterlund
Keyword(s):  
Radical Polymerization ◽  
Polymerization Rate ◽  
Confined Space ◽  
Segregation Effect ◽  
Polymerization System ◽  
Space Effect ◽  
Modelling And Simulations ◽  
The Cost

Compartmentalization of a nitroxide-mediated radical polymerization system can lead to improved levels of both control and livingness, but at the cost of a reduced polymerization rate. Improved control is a result of the confined space effect on deactivation, whereas improved livingness stems from the segregation effect on bimolecular termination. Modelling and simulations have been carried out for the systems styrene/2,2,6,6-tetramethylpiperidine-N-oxyl (TEMPO) and styrene/2,2,5-trimethyl-4-phenyl-3-azahexane-3-oxy (TIPNO) using the respective nitroxide-based polystyrene macroinitaitors (alkoxyamines) at 125°C to elucidate whether similar benefits can be obtained in the corresponding bulk polymerizations by merely diluting the systems or by addition of extra free nitroxide. The results have shown that neither approach leads to simultaneous improvement in control and livingness relative to the corresponding bulk systems, thus accentuating the merits of compartmentalization in nanoreactors.

Polymerization of styrene using 1,1,2,2-tetraphenyl-1,2- ethanediol as initiator in the presence of 2,2,6,6-tetramethyl- 1-piperidinyloxy

e-Polymers ◽  
2004 ◽  
Vol 4 (1) ◽  
Author(s):  
Gang Wang ◽  
Xiulin Zhu ◽  
Dijun Hu ◽  
Zhengping Cheng ◽  
Jian Zhu
Keyword(s):  
Molecular Weight ◽  
Monomer Concentration ◽  
Bulk Polymerization ◽  
Polymerization Rate ◽  
First Order ◽  
Molecular Weights ◽  
Molecular Weight Distributions ◽  
Weight Distributions ◽  
End Groups

Abstract The bulk polymerization of styrene using 1,1,2,2-tetraphenyl-1,2-ethanediol as initiator in the presence of 2,2,6,6-tetramethyl-1-piperidinyloxy (TEMPO) was investigated. The results show that polymerization proceeded in a controlled/ ’living’ way, i.e., polymerization rate is first order with respect to monomer concentration. Molecular weights increase linearly with conversion and molecular weight distributions are relatively low (Mw/Mn = 1.10 - 1.35). Well-defined polystyrenes with α-hydrogen and TEMPO end groups were obtained.

scholarly journals Self-Initiated Butyl Acrylate Polymerizations in Bulk and in Solution Monitored By In-Line Techniques

Polymers ◽  
2021 ◽  
Vol 13 (12) ◽  
pp. 2021
Author(s):  
Jonas Mätzig ◽  
Marco Drache ◽  
Sabine Beuermann
Keyword(s):  
High Temperature ◽  
Linear Regression ◽  
Monomer Concentration ◽  
Nir Spectroscopy ◽  
Polymerization Rate ◽  
Additional Parameter ◽  
Initial Monomer Concentration ◽  
Rate Of Polymerization ◽  
Initial Monomer ◽  
Kinetics Of

High-temperature acrylate polymerizations are technically relevant, but yet not fully understood. In particular the mechanism and the kinetics of the thermal self-initiation is a topic of current research. To obtain more detailed information the conversion dependence of the polymerization rate, rbr, is determined via in-line DSC and FT-NIR spectroscopy for reactions in bulk and in solution at temperatures ranging from 80 to 160 °C. Solution polymerizations revealed that dioxane is associated with the highest rbr, while aromatic solvents result in the lowest values of rbr. Interestingly, rbr for polymerizations in solution with dioxane depends on the actual monomer concentration at a given time in the system, but is not depending on the initial monomer concentration. The overall rate of polymerization in bulk and in solution is well represented by an equation with three or four parameters, respectively, being estimated by multiple linear regression and the temperature as additional parameter.

Binding of Thrombin to Fibrin

1979 ◽  
Author(s):  
L. Róka ◽  
F. G. Rademacher
Keyword(s):  
Antithrombin Iii ◽  
Monomer Concentration ◽  
Active State ◽  
Clot Formation ◽  
Constant Amount ◽  
Bovine Thrombin

After clot formation using bovine thrombin and bovine fibrinogen, one can detect no longer the total amount of thrombin. The amount missing in the supernatant is trapped in the clot and can be removed in active state after lysing the clot. The capacity for trapping thrombin by a constant amount of fibrin depends on the structure of the fibrinpolymer. This can be shown by producing different kinds of clots by variation of pH or monomer concentration during polymerisation or using Arvinmonomer insted of Thrombinmonomer. The trapped thrombin shows no clotting activity but some activity with chromogenic substrats remains. to neutralize trapped thrombin about 5 times more antithrombin III is necessary than for the same amount of free thrombin. The trapped thrombin diffuses out of the clot indicating the reversibility of the binding of thrombin to fribin.

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