Kinetics Of Methyl Methacrylate Polymerization Research Articles

Kinetics of Methyl Methacrylate Polymerization in the Presence of Initiating Systems “Peroxide + Zirconocene Dichloride” When the Methyl Methacrylate Adhesive is Cured

Kinetics of Methyl Methacrylate Polymerization in the Presence of Initiating Systems “Peroxide + Zirconocene Dichloride” When the Methyl Methacrylate Adhesive is Cured

Bulk polymerization kinetics of methyl methacrylate at broad temperature range investigated by differential scanning calorimetry

AbstractBulk polymerization directly provides glassy polymers from liquid monomers and has been used for many engineering applications. Recently, it has drawn attention for potential use as a resin for fiber‐reinforced plastics and additive manufacturing. For such applications, detailed and precise information of the reaction kinetics, including non‐ideal conditions, is required. Here, we investigate the reaction kinetics of isothermal bulk polymerization using differential scanning calorimetry (DSC) at a broad temperature ranged from 40°C to 90°C. 2,2'‐Azobis(isobutyronitrile) (AIBN) or 2,2'‐Azobis(4‐methoxy‐2,4‐dimethylvaleronitrile) (V‐70) is used as an initiator. We analyze the data focusing on the onset of sudden reaction acceleration known as Trommsdorff effect. Because of the reaction kinetics and the nature of Trommsdorff effect, a higher temperature does not always lead to a shorter time for the completion of the reaction. We discuss the reaction kinetics in conjunction with the molecular weight distributions.

Catalytic effectiveness of azobisisobutyronitrile/[SiMes)Ru(PPH3)(Ind)Cl2 initiating system in the polymerization of methyl methacrylate and other vinylic monomers

The catalytic system of azo-bis-isobutyronitrile (AIBN) combined with (SiMes)Ru(PPH3)(Ind)Cl2 [M20] was investigated for the controlled radical polymerization of methyl methacrylate (MMA) in solution. Various factors that may influence the catalytic polymerization process, such as the aging time of the initiating system, AIBN/M20 ratio, concentration of monomer, polymerization time, temperature, and the nature of solvent were examined. The results showed that the yield, molecular weight, and molecular distribution are practically unaffected by these parameters; however, the syndiotactic stereo-structure tendency that characterizes the produced poly(methyl methacrylate) (PMMA) varied with temperature. The optimum conditions for PMMA synthesis were determined to produce an essentially syndiotactic material with uniformly high molecular weights. It was also revealed that the kinetics of MMA polymerization is of first order with respect to the concentration of monomer. A comparison was also made for some vinylic polymers synthesized either with the AIBN alone or with the AIBN/M20initiating system under the same conditions.

New near UV photoinitiators containing benzophenone part for photoinitiating polymerization of methyl methacrylate

Abstract In this study, a variety of new trans -diphenylethylene derivatives containing phenylketone segment was synthesized, which were used as hydrogen abstracting type photoinitiators to compose two-component photoinitiating systems for free radical photopolymerization of methyl methacrylate under near UV light irradiation. The corresponding photosensitizers free of phenylketone group were synthesized to compose three-component photoinitiating systems. The large molar extinction coefficients of the target molecules in near UV light region (350–400 nm) were observed. Near UV photoinitiating polymerization kinetics of methyl methacrylate by the target molecules was studied by photo-differential scanning calorimetry. The results suggested that the two-component photoinitiating systems produced more efficient photoinitiating polymerization of methyl methacrylate than the three-component ones. The photoinitiating mechanism of the studied photoinitiators was studied by the electron spin resonance as well as the cyclic voltammograms. The thermal stabilities of the studied photoinitators were further evaluated.

Conjugated dyes carrying N, N-dialkylamino and ketone groups: One-component visible light Norrish type II photoinitiators

This work presents new conjugated dyes carrying N, N-dialkylamino and ketone groups for using as one-component Norrish type II visible light photoinitiators. The novel dyes without ketone group were also synthesized to compose two-component visible light photoinitiators for comparisons. The target dyes show the remarkable absorption in visible light region. Photo-differential scanning calorimetry was employed to study visible light photoinitiating polymerization kinetics of methyl methacrylate by new one-component photoinitiators and two-component photoinitiators respectively. The results suggest that the one-component photoinitiators showed much more efficient photoinitiating polymerization of methyl methacrylate than the two-component photoinitiating systems under visible light irradiation. The molecular weight of visible light photopolymer produced by the new photoinitiators was determined. The visible light photoinitiating mechanism of the one-component photoinitiators was studied by absorption and emission spectra, electron spin resonance spectra and cyclic voltammograms analysis.

Toward the development of a mathematical model for the bulk in situ radical polymerization of methyl methacrylate in the presence of nano‐additives

The effect of nano‐additives on the radical polymerization kinetics of methyl methacrylate is investigated through a simulation model. The mathematical model developed is based on the elementary chemical reactions that take place and the detailed mass balance equations. To account for the effect of diffusion‐controlled phenomena on the initiation, propagation, and termination reaction, appropriate theoretical equations based on sound principles such as the free volume theory were developed. The model predictions were found to be in satisfactory agreement with literature data for both monomer conversion as a function of time, and final product average molecular masses and molecular mass distribution of the produced polymer. It is believed that this work could be used to further investigate radical polymerization in the presence of nano‐additives.

Organosilicon surfactants: Effects of structure on the kinetics of heterophase polymerization of methyl methacrylate and behavior in Langmuir films on the surface of water

The kinetics of methyl methacrylate polymerization in the presence of α,ω-functional polydimethylsiloxanes is investigated. The formation of polymer suspensions with a narrow particle-size distribution is explained by the ability of the surfactants to form strong adsorption layers in the interfacial layers of polymer–monomer particles. This assumption is confirmed by data obtained via the Langmuir method with the use of model systems: thin films of the mentioned organosilicon compounds.

Thermal decomposition of diethyl ketone triperoxide in methyl methacrylate: Theoretical and experimental study of the initial solvation state and its influence on the polymerization process

ABSTRACTThe decomposition rate constant (kd) of diethyl ketone triperoxide (DEKTP, 3,3,6,6,9,9‐hexaethyl‐1,2,4,5,7,8‐hexaoxacyclononane) in methyl methacrylate (MMA) was determined by the kinetic study of its thermal decomposition at temperatures from 110 to 140°C. The calculated kd for DEKTP in MMA was 2.4 times lower (at 130°C) compared with that previously determined and reported in styrene (St). Density functional theory (DFT) calculations demonstrated that the decomposition of DEKTP molecule in MMA required higher interaction energy than in St, thus explaining its lower kd value. Bulk polymerization kinetics of MMA using DEKTP as the initiator revealed the presence of an induction period, in contrast with St polymerization, providing clear evidence of the solvation state influence at early polymerization stages. This work provides mechanistic insights into the interactions among the multi‐functional cyclic peroxide DEKTP and vinyl monomers; St and MMA, and their influence on the polymerization kinetics. © 2015 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2016, 133, 42905.

Investigating the effect of pristine and modified silica nanoparticles on the kinetics of methyl methacrylate polymerization

To study the effect of silica nanoparticles on the kinetics of methyl methacrylate free radical polymerization, a number of batch polymerizations were performed using pristine and methacrylate-modified silica nanoparticles at 75 °C. In addition, effect of temperature was investigated on the kinetics of polymerization with 1 wt% loading of pristine nanoparticles. Monomer conversion, reaction rate, molecular weight and polydispersity index (PDI) of each polymerization were monitored during polymerization. According to results, no considerable change was obtained on the polymerization kinetics by introduction of any type of nanoparticles, while there is an optimum loading value in which the polymerization rate reaches its maximum level. A similar trend is observed for molecular weight of free chains; however, increasing silica content results in increased PDI values. Also, polymerizations rate is slower for batches containing modified nanoparticles. For chains which are grafted on the surface of modified nanoparticles, molecular weight and PDI values increase by increasing nanoparticle content.

Modeling the Solvent Effect on the Tacticity in the Free Radical Polymerization of Methyl Methacrylate

The control of stereochemistry in the free radical polymerization of methyl methacrylate (MMA) is important because the physical properties of PMMA are often significantly affected by the main-chain tacticity. In this study, the role of the solvent on the tacticity of MMA polymerization has been investigated by considering the propagation rate constants for the syndiotactic and isotactic free radical polymerization of MMA in vacuum, in methanol (CH3OH), and in 1,1,1,3,3,3-hexafluoro-2-(trifluoromethyl)propan-2-ol ((CF3)3COH). All geometry optimizations have been carried out with the B3LYP/6-31+G(d) methodology. The kinetics of the propagating dimer have been evaluated with the B3LYP/6-31+G(d), B3LYP/6-311+G(3df,2p), MPWB1K/6-311+G(3df,2p), and B2PLYP/6-31+G(d) methodologies. The role of the solvent has been investigated by using explicit solvent molecules and also by introducing a polarizable continuum model (IEF-PCM) with a dielectric constant specific to the solvent. Experimentally, the free radical polymerization of MMA in (CF3)3COH is found to be highly syndiotactic (rr = 75% at 20 °C): the stereoeffects of fluoroalcohols are claimed to be due to the hydrogen-bonding interaction of the alcohols with the monomers and growing species. This modeling study has revealed the fact that the solvents CH3OH and (CF3)3COH, which are H-bonded with the carbonyl oxygens located on the same side of the backbone hinder the formation of the isotactic PMMA to some extent. Methanol is less effective in reducing the isotacticity because of its small size and also because of the relatively loose hydrogen bonds (∼1.9 Å) with the carbonyl oxygens. The methodologies used in this study reproduce the solvent effect on the free radical polymerization kinetics of MMA in a satisfactory way.

The effect of Co(II)‐mediated catalytic chain transfer on the emulsion polymerization kinetics of methyl methacrylate

AbstractThe effect the catalytic chain transfer agent, bis[(difluoroboryl) dimethylglyoximato] cobalt(II) (COBF), on the course of the ab initio emulsion polymerization of methyl methacrylate, and the product properties in terms of the molecular weight distribution were investigated. The emulsion polymerization kinetics have been studied with varying surfactant, initiator, and COBF concentrations. The experimentally determined average number of radicals per particle strongly depends on the concentration of COBF and proves to be in good agreement with the results of model calculations. The apparent chain transfer constant, determined up to high conversion, is in excellent agreement with the predicted value based on a mathematical model based on COBF partitioning and the Mayo equation. The results of this work enhance the fundamental understanding of the influence a catalytic chain transfer agent has on the course of the emulsion polymerization and the control of the molecular weight distribution. © 2009 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 47: 5078–5089, 2009

Kinetics of the complex-radical polymerization of methyl methacrylate in the presence of initiating metallocene systems

The kinetics of methyl methacrylate polymerization in the presence of benzoyl peroxide + metallocene (ferrocene, titanocene dichloride, and zirconocene dichloride) initiating systems is considered, and the effects of the nature and amount of metallocene in the system are reported. The polymerization is assumed to be a complex-radical process. The structure of the complex-radical sites of chain propagation and a scheme of their formation are deduced from quantum-chemical calculations.

Free radical polymerization in ionic liquids—Influence of the IL-concentration and temperature

The influence of the ionic liquid (IL) 1-ethyl-3-methylimidazoliumethylsulfate ([EMIM]EtSO 4) on the polymerization kinetics of methyl methacrylate was investigated. ILs are liquids with relatively high polarities and viscosities. These two characteristic properties are strongly correlated with the rate coefficients of propagation k p and termination k t of polymerizations carried out in ILs. The rate constant of termination k t decreases when the concentration of ionic liquid, and thus the viscosity is increased, whereas the propagation rate coefficient k p increases with increasing IL content. The viscosity of ILs can be varied by either working with mixtures of ILs with conventional organic solvents – here the IL [EMIM]EtSO 4 was mixed with dimethyl formamide (DMF) – or by variation of the temperature. The studies were carried out to determine the influence of the viscosity on the propagation and the termination reaction as well as the molecular weight distribution.

Ionic Liquids ‐ New Solvents in the Free Radical Polymerization

Summary: The analysis of the influence of ionic liquids (ILs) in polymer synthesis as an alternative for common organic solvents is still an active field of research.1 Using ILs as solvents for free radical polymerizations implies a significant increase in polymerization rates and molecular weights which can be observed. In this work we examined the copolymerization behaviour of styrene (S) and methyl methacrylate (MMA), glycidyl methacrylate (GMA) and 2-hydroxypropyl methacrylate (HPMA) with acrylonitrile (AN) in 1-etyhl-3-methylimidazolium ethylsulfate ([EMIM]EtSO4). ILs are liquids with comparable high polarities and viscosities. These two characteristic properties are strongly correlated with the rate coefficients of propagation kp and termination kt.2-4 The rate constant of termination kt decreases when the IL concentration and therefore the viscosity of the reaction mixture is increased, whereas the propagation rate coefficient kp increases with increasing IL content. The viscosity of the IL can be varied by either working with mixtures of IL with conventional organic solvents – here the IL [EMIM]EtSO4 was mixed with DMF – or by variation of the temperature. The influence of the viscosity of the IL ([EMIM]EtSO4) on polymerization kinetics of methyl methacrylate (MMA) and styrene/acrylonitrile (S/AN) was investigated.

Kinetics of methyl methacrylate and n‐butyl acrylate copolymerization mediated by 2‐cyanoprop‐2‐yl dithiobenzoate as a RAFT agent

AbstractThe RAFT (co)polymerization kinetics of methyl methacrylate (MMA) and n‐butyl acrylate (BA) mediated by 2‐cyanoprop‐2‐yl dithiobenzoate was studied with various RAFT concentrations and monomer compositions. The homopolymerization of MMA gave the highest rate. Increasing the BA fraction fBA dramatically decreased the copolymerization rate. The rate reached the lowest point at fMMA ∼ 0.2. This observation is in sharp contrast to the conventional RAFT‐free copolymerization, where BA homopolymerization gave the highest rate and the copolymerization rate decreased monotonously with increasing fMMA. This peculiar phenomenon can be explained by the RAFT retardation effect. The RAFT copolymerization rate can be described by 〈Rp〉/〈Rp〉0 = (1 + 2(〈kc〉/〈kt〉)〈K〉)[RAFT]0)−0.5, where 〈Rp〉0 is the RAFT‐free copolymerization rate and 〈K〉 is the apparent addition–fragmentation equilibrium coefficient. A theoretical expression of 〈K〉 based on a terminal model of addition and fragmentation reactions was derived and successfully applied to predict the RAFT copolymerization kinetics with the rate parameters obtained from the homopolymerization systems. © 2007 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 45: 3098–3111, 2007

Comparison of the kinetics of conventional and microwave methyl methacrylate polymerization

AbstractA comparative investigation of the conventional and microwaves kinetics of methyl methacrylate (MMA) polymerization was performed. A method for determining the increase of the reaction rate in the microwave field (β) was presented. It was found that at all of the investigated temperatures and powers the polymerization rates increased in the presence of microwave energy by up to 8.9 times compared with conventional polymerization. Isothermal kinetics of the conventional MMA polymerization was investigated and its parameters were determined using isoconversion method. It was found that the calculated kinetics parameters changes complexly with degree of MMA conversion (α) and are in the mutual linear functional relationship, which is so called “compensation effect.” The complex changes of the kinetics parameters with α are explained with the postulated model for the mechanism of the MMA polymerization. The kinetics of the MMA polymerization under the microwave field (MWF) with different input power was investigated and its parameters were determined on the basis of the conversion‐temperature curves and Arrhenius equation. The values of the kinetics parameters for MMA polymerization in the MWF are dependent on α and are from 1.2 to 12 times lower than that for conventional MMA polymerization. A new method for the determination of activation energy (Ea) of the investigated process in the MWF was described. Decreased Ea value of the polymerization process in the MWF compared with the conventional polymerization is explained with the formation of the nonequilibrium energetic distribution of the reactants due to the rapid transfer of energy in the reaction system. © 2007 Wiley Periodicals, Inc. J Appl Polym Sci 104: 1775–1782, 2007

Polymerization kinetics of methylmethacrylate by oxidation: Reduction system using cerium(IV)/lactic acid in aqueous medium

AbstractThe kinetics of polymerization of methylmethacrylate initiated by cerium(IV)–lactic acid redox system was studied in an aqueous medium in the temperature range of 25–50°C. The rate of polymerization (Rp) and the rate of cerium(IV) disappearance have been measured. The effects of some water‐miscible organic solvents, cationic, anionic, nonionic surfactants, and complexing agents on the rate of polymerization were investigated. The temperature dependence of the rate was studied, and the activation parameters were computed using the Arrhenius and Eyring plots. The effects of inorganic and organic solvents on polymerization were also investigated. All of them depressed both the initial rate and limiting conversion. A mechanism consistent with the experimental data, involving cerium(IV)–lactic acid complex formation, which generates free radicals, is suggested. The chain termination step of the polymerization reaction is by mutual interaction of the growing macromolecules. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 103: 3498–3505, 2007

Kinetics and Mechanism of Potassium Persulphate/L-Serine Initiated Polymerization of Methylmethacrylate

The polymerization kinetics of methyl methacrylate with K2S2O8/L-serine redox system has been investigated volumetrically at 35±0.1 °C under nitrogen atmosphere acidic aqueous medium in DMF/H2O mixture (50% v/v). The rates of polymerization were measured varying concentrations of the monomer, initiator, L-serine as well as temperature; and it was found to increase with increasing of both temperature and concentrations of monomer, initiator, and L-serine. The overall energy of activation (E a ) has been calculated to be 29.48 kJ/mol from the Arrhenius plot in temperature range 25–50 °C. The molecular weight of the polymer was determined by gel permeation chromatography (GPC). Based on kinetic studies and depending on the results obtained, a suitable reaction mechanism has been suggested and the rates of polymerization found to obey the following equation: V p ∝[methyl methacrylate]1.09[L-serine]1.03[K2S2O8]0.96.

A kinetic investigation of the in situ polymerization of methyl methacrylate under supercritical fluid CO2 conditions using high‐pressure DSC

AbstractThe polymerization kinetics of methyl methacrylate (MMA) under supercritical fluid CO2 was studied by using high‐pressure DSC. The results indicate that CO2 can significantly reduce the cage effect and improve the chain propagation reactions, with the observed solvent‐like effects being enhanced by increased CO2 pressures. The polymerization of MMA under isothermal conditions and 56 atm of CO2 was characterized by a first‐order kinetic rate expression over the conversion range 20–80%. The apparent activation energy for the reaction was found to be 51.6 kJ/mol, which is less than the value reported under ambient conditions (68.2 kJ/mol). The polymerization kinetics were also evaluated under nonisothermal conditions. © 2004 Wiley Periodicals, Inc. J Appl Polym Sci 93: 1236–1239, 2004

Tl(III) initiated polymerization of methyl methacrylate in micellar phase

AbstractThe polymerization kinetics of methyl methacrylate (MMA) was studied, using Tl(III)‐cyclohexanone (CH) redox system as initiator, in the presence of emulsifier [i.e., sodium dodecyl sulfate (SDS), cetyltrimethylammonium bromide (CTAB), and thallium triacetate (TX‐100)] over a temperature range of 25–45°C. The effect of various concentrations of MMA, Tl(III), cyclohexanone, H+, and varying ionic strengths on the rate of polymerization, rate of Tl(III) consumption (−RTl), and the percentage of monomer conversion were examined in the presence of 0.015M SDS. The kinetic results of polymerization in the absence and presence of 0.015M SDS were compared in terms of overall activation energy (Ea) for the process. The viscosity‐average molecular weight (MV) of the polymers, obtained in the presence of varying concentrations of anionic surfactant (SDS), was also determined. © 2004 Wiley Periodicals, Inc. J Appl Polym Sci 92: 2480–2485, 2004