Controlled (Co)Polymerization of Methacrylates Using a Novel Symmetrical Trithiocarbonate RAFT Agent Bearing Diphenylmethyl Groups

Herein, we report a novel type of symmetrical trithiocarbonate chain transfer agent (CTA) based diphenylmethyl as R groups. The utilization of this CTA in the Reversible Addition-Fragmentation chain Transfer (RAFT) process reveals an efficient control in the polymerization of methacrylic monomers and the preparation of block copolymers. The latter are obtained by the (co)polymerization of styrene or butyl acrylate using a functionalized macro-CTA polymethyl methacrylate (PMMA) previously synthesized. Data show low molecular weight dispersity values (Đ < 1.5) particularly in the polymerization of methacrylic monomers. Considering a typical RAFT mechanism, the leaving groups (R) from the fragmentation of CTA should be able to re-initiate the polymerization (formation of growth chains) allowing an efficient control of the process. Nevertheless, in the case of the polymerization of MMA in the presence of this symmetrical CTA, the polymerization process displays an atypical behavior that requires high [initiator]/[CTA] molar ratios for accessing predictable molecular weights without affecting the Đ. Some evidence suggests that this does not completely behave as a common RAFT agent as it is not completely consumed during the polymerization reaction, and it needs atypical high molar ratios [initiator]/[CTA] to be closer to the predicted molecular weight without affecting the Đ. This work demonstrates that MMA and other methacrylic monomers can be polymerized in a controlled way, and with “living” characteristics, using certain symmetrical trithiocarbonates.

Download Full-text

Synthesis and characterization of a naphthalimide–dye end-labeled copolymer by reversible addition–fragmentation chain transfer (RAFT) polymerization

Canadian Journal of Chemistry ◽

10.1139/v10-134 ◽

2011 ◽

Vol 89 (3) ◽

pp. 317-325 ◽

Cited By ~ 10

Author(s):

Binxin Li ◽

Daniel Majonis ◽

Peng Liu ◽

Mitchell A. Winnik

Keyword(s):

Chain Transfer ◽

Raft Polymerization ◽

Polymer Composition ◽

Cooh Group ◽

Agent Based ◽

Molecular Weights ◽

Reversible Addition ◽

Raft Agent ◽

End Use ◽

Naphthalimide Dye

We describe the synthesis of an end-functionalized copolymer of N-(2-hydroxypropyl)methacrylamide (HPMA) and N-hydroxysuccinimide methacrylate (NMS) by reversible addition–fragmentation chain transfer (RAFT) polymerization. To control the polymer composition, the faster reacting monomer (NMS) was added slowly to the reaction mixture beginning 30 min after initating the polymerization (ca. 16% HPMA conversion). One RAFT agent, based on azocyanopentanoic acid, introduced a –COOH group to the chain at one end. Use of a different RAFT agent containing a 4-amino-1,8-naphthalimide dye introduced a UV–vis absorbing and fluorescent group at this chain end. The polymers obtained had molecular weights of 30 000 and 20 000, respectively, and contained about 30 mol% NMS active ester groups.

Download Full-text

Polymerization of n-butyl methylacrylate using bis(β- ketoamino)nickel(II)/MAO catalytic systems

e-Polymers ◽

10.1515/epoly.2008.8.1.967 ◽

2008 ◽

Vol 8 (1) ◽

Author(s):

Xiaohui He ◽

Yiwang Chen ◽

Yongming Liu ◽

Muqing Chen ◽

Shuxian Yu ◽

...

Keyword(s):

Molecular Weight ◽

Monomer Concentration ◽

Polymerization Temperature ◽

Moderate Activity ◽

Polymerization Time ◽

Catalytic Systems ◽

Molecular Weights ◽

Molar Ratios ◽

Broad Molecular Weight Distribution ◽

C Nmr

AbstractThe polymerizations of n-butyl methylacrylate (nBMA) were carried out using bis(β-ketoamino)nickel(II) complexes (Ni[CH3C(O)CHC(NR)CH3]2: R = phenyl, 1; R = naphthyl, 2) in combination with methylaluminoxane (MAO) in toluene. The effect of parameters such as polymerization temperature, Al/Ni molar ratios, polymerization time, and monomer concentration, on catalytic polymerization activity and polymer molecular weights, were examined in detail. Both of the nickel(II) catalytic systems exhibited moderate activity, and produced P(nBMA) with high molecular weight and relatively broad molecular weight distribution (Mw/Mn=2.0~3.0. The obtained polymer has been characterized by means of FTIR, 1H NMR, 13C NMR, DSC, and WAXD technique and was confirmed to be syndio-rich stereospecific P(nBMA).

Download Full-text

Effect of silica nanoparticle loading and surface modification on the kinetics of RAFT polymerization

Journal of Polymer Engineering ◽

10.1515/polyeng.2011.601 ◽

2012 ◽

Vol 32 (1) ◽

Cited By ~ 18

Author(s):

Mehdi Salami-Kalajahi ◽

Vahid Haddadi-Asl ◽

Farid Behboodi-Sadabad ◽

Saeid Rahimi-Razin ◽

Hossein Roghani-Mamaqani

Keyword(s):

Molecular Weight ◽

Surface Modification ◽

Chain Transfer ◽

Raft Polymerization ◽

Silica Nanoparticle ◽

Maximum Level ◽

Silica Content ◽

Considerable Change ◽

Polymerization Rate ◽

Raft Agent

Abstract S-(thiobenzoyl)thioglycolic acid was used to synthesize poly(methyl methacrylate) via reversible addition-fragmentation chain transfer (RAFT) polymerization. To study the polymerization kinetics, in situ polymerization reactions were performed with different loading of nanoparticles. To investigate the effect of surface modification on the polymerization kinetics, similar reactions were performed with 3-methacryloxypropyldimethylchlorosilane-modified nanoparticles. Conversion, reaction rate, molecular weight and polydispersity index (PDI) were monitored during polymerization. According to results, pseudo-first order kinetics is achieved, but the rate constant of chain transfer reaction to the RAFT agent (Ctr) has a very small value. Adding nanoparticles causes no considerable change in the kinetic curves, while there is an optimum value for nanoparticles loading in which the polymerization rate reaches its maximum level. A similar trend is observed for molecular weight; however, increasing silica content results in an increase in PDI values. In comparison with pristine silica nanoparticles, the polymerization rate increases slowly in the case of modified particles. Also, molecular weight and PDI for free and graft chains are studied separately. The molecular weight of free chains increases with increasing nanoparticles loading up to 7 wt% and then decreases, while PDI values increase continually by adding nanoparticles. However, for graft chains, molecular weight and PDI values increase with increasing nanoparticle content.

Download Full-text

Synthesis and characterization of triphenylamine and Bbis(indolyl)methane center-functionalized polymer via reversible addition-fragmentation chain transfer polymerization

e-Polymers ◽

10.1515/epoly.2008.8.1.256 ◽

2008 ◽

Vol 8 (1) ◽

Cited By ~ 1

Author(s):

Jie Xu ◽

Wei Shang ◽

Jian Zhu ◽

Zhenping Cheng ◽

Nianchen Zhou ◽

...

Keyword(s):

Molecular Weight ◽

Chain Transfer ◽

Raft Polymerization ◽

Chloroform Solution ◽

Monomer Conversion ◽

Benzyl Ester ◽

Chain Extension ◽

Reversible Addition ◽

Raft Agent ◽

Cyclic Voltammetry Method

AbstractA novel bis-functional reversible addition-fragmentation chain transfer (RAFT) agent bearing triphenylamine (TPA) and bis(indolyl)methane (BIM) groups, {4-[bis(1-carbodithioic acid benzyl ester-indol-3-yl)methyl]phenyl}diphenylamine (BCIMPDPA), was synthesized and successfully used as the RAFT agent to mediate the polymerization of styrene (St). The polymerization results showed that reversible addition-fragmentation chain transfer (RAFT) polymerization of St could be well controlled. The kinetic plot showed it was of first order and the numberaverage molecular weight (Mn(GPC)) of the polymer measured by GPC increased linearly with monomer conversion, simultaneously, the molecular weight distribution of the polymer was also relatively narrow. In addition, the existence of the TPA and BIM groups in the middle of polymer chain was confirmed by chain extension reaction and 1H NMR spectrum. The optical properties of the functionalized polystyrene (PS) in chloroform solution were also investigated. Furthermore, the redox process of the RAFT agent and the functionalized PS were studied by cyclic voltammetry method.

Download Full-text

Investigation into the Initialization Behaviour of RAFT-Mediated Styrene–Maleic Anhydride Copolymerizations

Australian Journal of Chemistry ◽

10.1071/ch06238 ◽

2006 ◽

Vol 59 (10) ◽

pp. 742 ◽

Cited By ~ 26

Author(s):

Eric T. A. van den Dungen ◽

Jacques Rinquest ◽

Nadine O. Pretorius ◽

Jean M. McKenzie ◽

James B. McLeary ◽

...

Keyword(s):

Maleic Anhydride ◽

Raft Polymerization ◽

Polymerization Process ◽

Unit Model ◽

Reversible Addition ◽

Raft Agent ◽

Addition Rate ◽

Leaving Groups ◽

Chain Lengths ◽

Alternating Copolymerization

The living radical alternating copolymerization of styrene and maleic anhydride mediated by the reversible addition–fragmentation chain transfer (RAFT) polymerization process has been studied at short chain lengths using two different dithiobenzoate RAFT agents. The results indicate specificity of addition of the RAFT-agent leaving groups for either styrene or maleic anhydride. The addition rate of the monomers and the fact that monomers are added individually favour the penultimate unit model of polymer propagation.

Download Full-text

A Simplified Method for Formulation of Epoxy Resin Embedding Media

Microscopy Today ◽

10.1017/s1551929500058703 ◽

2006 ◽

Vol 14 (5) ◽

pp. 50-51 ◽

Cited By ~ 2

Author(s):

E. Ann Ellis

Keyword(s):

Molecular Weight ◽

Epoxy Resin ◽

Molar Ratio ◽

Molecular Weights ◽

Molar Ratios ◽

Low Viscosity ◽

Simplified Method ◽

Beam Stability ◽

Embedding Medium

In a recent paper on the revised formulation of Spurr low viscosity embedding medium with ERL 4221 the importance of maintaining an appropriate anhydride:epoxide (A:E) ratio was discussed. By understanding a few simple concepts about epoxy resin formulations and setting up a formulation table it is possible to create new resin mixtures with good sectioning properties and other desirable properties such as decreased viscosity and increased beam stability.Before starting a formulation you need to know the molecular weight of the anhydride and the WPE (weight per epoxide equivalent) of the epoxy resin component. The molecular weights and WPEs are usually printed on the bottle or can be obtained from the vendor. An A:E ratio of 0.7:1.0 -1.0:1.0 is used for most biological specimens. Increasing the A:E ratio results in a harder block; decreasing the A:E ratio results in a softer block. Table 1 shows a basic formulation spreadsheet where the molecular weights of the anhydrides and the WPEs of the epoxy resin components can be entered. The A:E ratio is entered under the anhydride for the molar ratio and the molar ratios of the epoxy components are entered under the epoxy components. The calculations are done as shown in each column and row.

Download Full-text

Dialkoxy-Substituted, C1-Symmetric Metallocenes: Synthesis and Catalytic Behavior in the Propylene Polymerization Reaction

Zeitschrift für Naturforschung B ◽

10.1515/znb-2004-0217 ◽

2004 ◽

Vol 59 (2) ◽

pp. 233-240 ◽

Cited By ~ 4

Author(s):

Martin Schlögl ◽

Bernhard Rieger

Keyword(s):

Chain Transfer ◽

Active Catalyst ◽

Propylene Polymerization ◽

Polymerization Reaction ◽

Catalytic Behavior ◽

Molecular Weights ◽

Hydrocarbon Solvents ◽

In Situ Activation ◽

Reversible Chain Transfer

The synthesis of a series of C1-symmetric metallocene complexes rac-[1-(5,6-dialkoxy-2-methyl- 1-η5-indenyl)-2-(9-η5-fluorenyl)ethane]zirconium dichlorides (alkyl: n-butyl, n-hexyl, n-octyl, n-decyl) is described. These complexes are versatile catalysts in the polymerization of propylene after in situ activation with triisobutylaluminum (TIBA) and Ph3C[B(C6F5)4] in toluene and heptane solution. All catalysts show higher solubility and improved polymerization properties in industrially used hydrocarbon solvents (e.g. heptane). However, the molecular weights and isotacticity values of the resulting polypropylene materials are decreased compared to the ethoxy-bridged analogue rac- [1-(5,6-ethylenedioxy-2-methyl-η5-indenyl)-2-(9-η5-fluorenyl)ethane]zirconium dichloride. A possible explanation is based on enhanced interaction of the active catalyst centers with Al(III) scavenger molecules even at low Al : Zr ratios, leading to reversible chain transfer.

Download Full-text

Reversible addition fragmentation chain transfer (RAFT) polymerization of styrene in fluid CO2

e-Polymers ◽

10.1515/epoly.2004.4.1.20 ◽

2004 ◽

Vol 4 (1) ◽

Cited By ~ 1

Author(s):

Toshihiko Arita ◽

Sabine Beuermann ◽

Michael Buback ◽

Philipp Vana

Keyword(s):

Chain Transfer ◽

Raft Polymerization ◽

Molecular Weights ◽

Reversible Addition ◽

Significant Difference ◽

Raft Agent ◽

Successful Control ◽

A Minor ◽

Peak Widths

Abstract Reversible addition fragmentation chain transfer (RAFT) polymerizations of styrene in fluid CO2 have been carried out at 80°C and 300 bar using cumyl dithiobenzoate as the controlling agent in the concentration range of 3.5·10-3 to 2.1·10-2 mol/L. This is the first report on RAFT polymerization in fluid CO2. The polymerization rates were retarded depending on the employed RAFT agent concentration with no significant difference between the RAFT polymerization performed in fluid CO2 and in toluene. Full chain length distributions were analyzed with respect to peak molecular weights, indicating the successful control of radical polymerization in fluid CO2. A characterization of the peak widths may suggest a minor influence of fluid CO2 on the addition reaction of macroradicals on the dithiobenzoate group.

Download Full-text

Preparation of High Molecular Weight Poly(urethane-urea)s Bearing Deactivated Diamines

Polymers ◽

10.3390/polym13121914 ◽

2021 ◽

Vol 13 (12) ◽

pp. 1914

Author(s):

Alejandra Rubio Hernández-Sampelayo ◽

Rodrigo Navarro ◽

Ángel Marcos-Fernández

Keyword(s):

Molecular Weight ◽

Experimental Work ◽

High Performance ◽

Polymerization Reaction ◽

Quantum Mechanical ◽

Synthetic Approach ◽

Molecular Weights ◽

Mechanical Methods ◽

Electronic Parameters ◽

High Molecular Weight Poly

The synthesis of poly(urethane-urea) (PUUs) bearing deactivated diamines within the backbone polymer chain is presented. Several deactivated diamines present interesting properties for several applications in the biomaterial field due to their attractive biocompatibility. Through an activation with Chloro-(trimethyl)silane (Cl-TMS) during the polymerization reaction, the reactivity of these diamines against diisocyanates was triggered, leading to PUUs with high performance. Indeed, through this activation protocol, the obtained molecular weights and mechanical features increased considerably respect to PUUs prepared following the standard conditions. In addition, to demonstrate the feasibility and versatility of this synthetic approach, diisocyanate with different reactivity were also addressed. The experimental work is supported by calculations of the electronic parameters of diisocyanate and diamines, using quantum mechanical methods.

Download Full-text

Determining chemospecificity in reactions with chain transfer agent and corresponding radical via evaluation of molecular weight dependency of apparent comonomer reactivity ratios: free-radical copolymerization of vinyl acetate and dibutyl maleate

RSC Advances ◽

10.1039/c6ra21888a ◽

2016 ◽

Vol 6 (111) ◽

pp. 109759-109768 ◽

Cited By ~ 1

Author(s):

Seyed Saeid Rahdar ◽

Mahdi Abdollahi ◽

Ebrahim Ahmadi ◽

Abbas Biglari

Keyword(s):

Molecular Weight ◽

Free Radical ◽

Chain Transfer ◽

Radical Copolymerization ◽

Reactivity Ratios ◽

Free Radical Copolymerization ◽

Molecular Weights ◽

Radical Reactivity ◽

Dibutyl Maleate ◽

Trichloromethyl Radical

Performing copolymerization with two different conditions leading to different molecular weights allows us to determine trichloromethyl radical reactivity towards comonomers.

Download Full-text