Binary copolymerizations of 8-methacryloxy-quinoline with methyl methacrylate, methyl acrylate, styrene and acrylonitrile

8-methacryloxy-quinoline monomer (MAQ) was prepared by the reaction of 8-hydroxyquinoline with either methacryloyl chloride or methacrylic acid in the presence of triethylamine and N, N′-dicyclohexylcarbodiimide, respectively. Its structure was confirmed by IR and 1 H-NMR spectroscopy. Binary copolymerization of this new monomer with methyl acrylate (MA), acrylonitrile (AN) methyl methacrylate (MMA), styrene(ST), were performed in Dimethylformamide, using 1 mol% azobisisobutyronitrile as initiator at 65 °C. The copolymer compositions were determined from nitrogen analysis except MAQ-AN with 1 H-NMR. Copolymerization Parameters for each system were calculated by both the Finemen-Ross and Kelen-Tüdös methods. The monomer reactivity ratios for the systems MAQ-MA, MAQ-AN, MAQ-MMA and MAQ-ST were found to be r1?=?0.695?±?0.036, r2?=?0.62?±?0.235; r1?=?0.273?±?0.087, r2?=?0.259?±?0.67; r1?=?0.356?±?0.015, r2?=?1.615?±?0.052 and r1?=?0.097?±?0.003, r2?=?0.339?±?0.027 respectively. The Q and e values for MAQ monomer were found to be 1.62 and 1.40.     

Controlled synthesis of random,block-random and gradient styrene,methyl methacrylate and acrylonitrile Terpolymers via Nitroxide-mediated free radical polymerization

Different types of the styrene ? methyl methacrylate ?acrylonitrile terpolymers were synthesized according to the recently proposed concept of the living nitroxide-mediated terpolymerization. Random azeotropic and gradient terpolymers were prepared using the living TEMPO-mediated polymerization. Block random terpolymer was obtained via the living terpolymerization initiated by macro-alkoxyamine polystyrene-SG1. In all systems, terpolymerization proceeds in the living manner even in the presence of TEMPO. Upon complete polymerization at high conversions of monomers, the molecular weight of terpolymers linearly increases with the monomer conversion. The resultant terpolymers were characterized by the methods of turbidimetric titration, GPC, DSC, and TGA, and their characteristics were compared with their non-living analogs synthesized by the conventional radical polymerization. The effect of the macromolecular structure on the thermal stability of the terpolymers was studied.     

Methylene blue as a retarder of free radical polymerization: 1. Polymerization of acrylonitrile,methyl methacrylate and styrene

Methylene blue (MB), a redox dye, in monomeric form significantly retards the free radical polymerization of styrene (ST) and acrylonitrile (AN) in N,N-dimethyl formamide solvent. The effect is small in methyl methacrylate (MMA) polymerization. Partly reduced MB is found to be a stronger retarder than MB. The rate constants for the oxidation of the polymer radicals by MB at 60°C follows the order ST>AN>MMA. The results cannot be explained when only taking into consideration the reactivity and polarity parameters of the radicals and the substrate, as is done in the Q-e scheme. The low rate constant with the PMMA radical is attributed to steric effects. The current work has shown that single molecules of MB are effective chain terminators and this is in sharp contrast with the conclusion reached by Chen who postulated that only the aggregates of MB are the chain terminators in the polymerization of acrylamide in water.     

Effect of solvent on the termination step for the radical copolymerization of methyl methacrylate and styrene

The kinetics of the radical copolymerization of methyl methacrylate and styrene in benzene, chlorobenzene and benzonitrile has been investigated gravimetrically. The copolymerization termination step is analysed on the basis of the chemically controlled model, the diffusion-controlled model and the combined physical and chemical model, taking into account the corresponding reactivity ratios and the homopolymerization parameters in the three solvents used. The values obtained for the termination step parameters suggest that the termination step might be controlled by the viscosity of the reaction medium, but the sequence distribution and the stereochemical configuration of the polymer chains must also be considered.     

Radiochemical study of the radical copolymerization of styrene and methyl methacrylate

The rates of initiation for the copolymerization of styrene and methyl methacrylate at 50°, in different reaction media (bulk, acetone, dimethylformamide and dioxane) have been determined by using the isotopic labelling technique (¹⁴C - azobisisobutyronitrile). For all mixtures, except dioxane, the experimental data do not support the linear interpolation of the initiation rates, which is usually adopted in literature. In the whole range of monomer feed compositions, any modification of the reaction medium causes a relevant change of the initiation rate, so that the overall pattern is markedly modified. The strongest solvent effect is given by dioxane, which reduces the initiation rates for all monomer mixtures.The radioactive tracer method also enables the determination of the modes of termination, which occur almost exclusively by combination for monomer feed compositions up to about 70 molar % of methyl methacrylate. The $\text{P}\text{?}{}_{\mathrm{w}}\text{P}\text{?}{}_{\mathrm{n}}$ ratios obtained by g.p.c. confirm the general trend of the termination mechanisms as a function of monomer mixture and reaction medium.     

Glass transition temperatures of copolymers from methyl methacrylate,styrene, and acrylonitrile: binary copolymers

By using a new theoretical glass transition temperature (T _g)–composition equation, T _g’s of statistic binary copolymers obtained from MMA, St and AN were investigated in this article. The copolymers were prepared by bulk copolymerization using azo-bis-isobutyronitrile (AIBN) as initiator. The compositions and T _g’s were determined by NMR and DSC, respectively. The monomer reactivity ratios were obtained by nonlinear fitting with Mayo–Lewis equation. Excellent fitting results were obtained when relations of T _g’s of MMA–St, MMA–AN, and St–AN copolymers with their compositions were investigated by using a new equation which assumed additivity of bond stiff energy (Liu et al. J Phys Chem B 112:93–99, 2008). This equation contains mole fractions of triads and T _g’s of corresponding periodic copolymers. Compared with the widely used Johnston equation and Barton equation, the new equation showed its superiority. Meanwhile, T _g’s of the assumed periodic copolymers that have not been acquired were tentatively predicted which may provide useful information.     

Continuous emulsion polymerisation of styrene and methyl acrylate

An investigation of continuous emulsion polymerisation kinetics was carried out using a series of three continuous stirred tank reactors (CSTR), and styrene and methyl acrylate as types of monomer with different solubilities in water. Steady-state conversion fluctuations reported in the literature could be suppressed by holding the feed rates constant. The results obtained are only partly in agreement with the theory proposed by Gershberg & Longfield, who combined the basic assumptions of the Smith-Ewart theory with steady-state CSTR kinetics. An explanation for the deviations from this theory is therefore suggested which takes into account the tendency of relatively water-soluble monomers to form particles from the homogeneous solution and to undergo so-called interparticle termination as a result of migration of radicals between the latex particles.     

Polymerization via zwitterion. 23. Terpolymerization among 2-phenyl-1,3,2-dioxaphospholane,methyl acrylate,and carbon disulfide

Summary The present paper describes the terpolymerization involving 2-phenyl-1,3,2-dioxaphospholane, methyl acrylate, and carbon disulfide, which took place without any added initiator in benzonitrile or dimethylformamide. The structure and composition of terpolymer were determined by NMR and IR spectra, as well as by elemental analysis. A reaction scheme proceeding via zwitterion was proposed (Eq. 2–5).     

Catalytic chain transfer polymerisation of CO2-expanded methyl methacrylate

The catalytic chain transfer polymerisation of methyl methacrylate expanded with dense CO₂ is reported. Experimental values of the chain transfer constant (C_s) are presented at 50 °C and in the range of pressure from 0.1 to 6 MPa, using a cobaloxime complex as the chain transfer catalyst. The effect of small quantities of poly(methyl methacrylate) on the volumetric expansion of the monomer with CO₂ is considered. Experimental data are presented on the pressure limit for homogeneous expansion as a function of the molecular weight of the polymer. It is shown that the values of C_s in CO₂-expanded methyl methacrylate are significantly higher than that in bulk monomer. This effect is mainly attributed to the enhancement of the chain transfer rate coefficient, arising from the reduction in the viscosity of the medium, and is consistent with a diffusion-controlled rate-determining step in the chain transfer process.     

溶剂对甲基丙烯酸甲酯与苯乙烯高温聚合的影响

利用引发剂,在高温下引发甲基丙烯酸甲酯(MMA)与苯乙烯(St)聚合,研究了w(甲苯)对聚合过程及产品结构的影响。结果表明,溶剂的存在能够显著影响MMA与St的共聚合。随着w(甲苯)增加,聚合物中w(St)随之增加;w(甲苯)=5%～20%,反应转化率减小,聚合物相对分子质量增加;w(甲苯)20%,反应转化率减小趋势变慢,聚合物相对分子质量降低。     

Pyridylphosphine ligands for iron-based atom transfer radical polymerization of methyl methacrylate and styrene

Two pyridylphosphine ligands, 2-(diphenylphosphino)pyridine (DPPP) and 2-[(diphenylphosphino)methyl]pyridine (DPPMP), were investigated as complexing ligands in the iron-mediated atom transfer radical polymerization (ATRP) of methyl methacrylate (MMA) and styrene with various initiators and solvents. In studies of their ATRP behavior, the FeBr₂/DPPP catalytic system was a more efficient ATRP catalyst for the MMA polymerization than the other complexes studied in this paper. Most of these systems were well controlled with a linear increase in the number-average molecular weights (M_n) vs. conversion and relatively low molecular weight distributions (M_w/M_n = 1.15-1.3) being observed throughout the reactions, and the measured molecular weights matched the predicted values with the DPPP ligand. The polymerization rate of MMA attained a maximum at a ratio of ligand to metal of 2:1 in p-xylene at 80 °C. The polymerization was faster in polar solvents than in p-xylene. The 2-bromopropionitrile (BPN) initiated ATRP of MMA with the FeX₂/DPPP catalytic system (X = Cl, Br) was able to be controlled in p-xylene at 80 °C. The polymerization of styrene was able to be controlled using the PECl/FeCl₂/DPPP system in DMF at 110 °C.     

Free radical terpolymerization of butyl acrylate/methyl methacrylate and alpha methyl styrene at high temperature

The free radical initiated terpolymerization of butyl acrylate (BA), methyl methacrylate (MMA) and alpha methyl styrene (AMS) has been examined. Kinetic studies focused on elevated reaction temperatures (115 and 140 °C). The studies were made over the full conversion range and examined the effect of reaction temperature, feed composition and initiator level on reaction rates. The composition of terpolymer products and their molecular weights were also analyzed with respect to monomer conversion levels.     

Modelling of free radical polymerization of styrene and methyl methacrylate by a tetrafunctional initiator

A mathematical model for free radical polymerizations initiated by tetrafunctional initiators is described in detail with comparisons to experimental results. Reactions involving the fate/efficiency of functional groups are properly accounted for, while in the past, kinetic models for difunctional initiators found in the literature have ignored this. Free volume theory is used to describe the diffusion-controlled regime. Based on model predictions, multi-radical concentrations were estimated to be several orders of magnitude smaller than mono-radical concentrations. Through various case studies, the model was able to demonstrate that the concentration and chain length of various polymer structures (i.e., linear, star or coupled stars) depend upon monomer type and reaction conditions. The model was found to be useful in explaining experimentally observed differences in the behaviour of a tetrafunctional initiator with styrene compared to methyl methacrylate (MMA). In both cases, higher reaction rates could be obtained when switching from a mono- to a tetrafunctional initiator; however, the influence on molecular weight was found to vary between the two systems. Work with styrene showed similar trends as with difunctional initiators, where the tetrafunctional initiator maintained similar molecular weights compared to a monofunctional initiator. Yet, for MMA, replacing the monofunctional initiator with its tetrafunctional counterpart decreased the molecular weight.     

Synthesis and characterization of methyl methacrylate/styrene hyperbranched copolymers via living radical mechanism

Free‐radical copolymerizations of N,N‐diethylaminodithiocarbamoylmethylstyrene (inimer: DTCS) with a methyl methacrylate (MMA)/zinc chloride (ZnCl₂) complex were carried out under UV light irradiation. DTCS monomers play an important role in this copolymerization system as an inimer that is capable of initiating living radical polymerization of the vinyl group. The reactivity ratios (r₁ = 0.56 and r₂ = 0.52: DTCS [M₁]; MMA [M₂]) obtained for this copolymerization system were different from a corresponding model system (alternating copolymer) of a styrene and MMA/ZnCl₂ complex (r₁ = 0.25 and r₂ = 0.056). It was found that the hyperbranched copolymers produced exhibited a random branching structure. It was found that the Lewis acid ZnCl₂ formed the complex not only with MMA but also with the carbamate group of inimer. © 2003 Wiley Periodicals, Inc. J Appl Polym Sci 89: 2490–2495, 2003     

Sodium metabisulphite initiated aqueous polymerisation of methyl methacrylate

Sodium metabisulphite (Na₂S₂O₅) has been found to initiate the aqueous polymerisation of methyl methacrylate (MMA) at 35°C in phosphate buffer solutions of pH 6.85 and a constant ionic strength (μ) of the media in an inert atmosphere of pure nitrogen. The reaction has a well defined induction period which is a function of the concentrations of the initiator, of the monomer and also of temperature. The polymerisation is signalled by the sudden appearance of a haze at the end of the induction period in a given run, and the polymer separates out as a coarse precipitate during the progress of the polymerisation reactions. When the conversion is over 50 per cent complete, the polymerisation media looks like a thick curd if the monomer concentration is relatively high. The rate of polymerisation is found to decrease with conversion or time in a given run, and the initial rate (v_p), obtained by extrapolating the linear yield/time versus time curves to zero time, keeping the conversion below 10 percent, is found as where (I) = initiator concentration in the range, (0.26 to 3.94) × 10^?3 (mol dm^?3), and (M) = monomer concentration in the range 0.019 to 0.141 (mol dm^?3). At high initiator concentrations, the rate of polymerisation is found to decrease. In a given run, the viscosity average molecular weights (M _v) of the polymers is found to increase quickly with a conversion of up to 25 to 30 percent, and then slowly with the further increase in conversion. (M_v) however is found to decrease with the increase of the initiator concentrations at a given conversion but increases with the increase of the monomer concentrations. Hydroquinone inhibits the polymerisation reactions, whereas air is found to increase the induction period, but later enhances the polymerisation rate in the same run. It has been shown that the bisulphite addition reaction of MMA is not important under the experimental conditions, and the polymerisation occurs by the free radical mechanism. The rate constant (k₂) of the reaction, has been estimated from the analytical data as, k₂ = 14.62 × 10^?2 (dm³ mol^?1 s^?1) at 35°C.     

Effect of LiClO4 on radical polymerization of methyl methacrylate

The effect of LiClO₄ on the polymerization of methyl methacrylate (MMA) with dimethyl 2,2′-azobisisobutyrate (MAIB) was investigated at 50°C in methyl ethyl ketone. The polymerization proceeded homogeneously even at [LiClO₄] as high as 3.00 mol/L. The polymerization rate (R_p) and the molecular weight of the resulting polymer profoundly increased with increasing [LiClO₄]. R_p at 3.00 mol/L [LiClO₄] was 12 times that in the absence of LiClO₄. The rate equation depended on the presence or absence of LiClO₄: R_p = k′[MAIB]^0.5 [MMA]^1.5 in the presence of 3.00 mol/L [LiClO₄] and R_p = k[MAIB]^0.5 [MMA]^1.0 in the absence of LiClO₄. The overall activation energies of polymerization were 38.5 kJ/mol in the presence of 3.00 mol/L [LiClO₄] and 77.4 kJ/mol in the absence of LiClO₄, respectively. The tacticities of resulting poly(MMA) were insensitive to the presence of LiClO₄. In the copolymerization of MMA and styrene, Q and e values of MMA increased with increasing [LiClO₄], leading to enhanced alternating copolymerizability. © 1997 John Wiley & Sons, Inc. J Appl Polym Sci 63: 1361–1368, 1997     

Free‐radical copolymerization of [(4‐isopropyl phenyl) oxycarbonyl] methyl methacrylate with acrylonitrile and methyl methacrylate

The present investigation has been achieved in accordance with the Diels–Alder reaction (1,4 cycloaddition) to produce a new halogenated bicyclic adduct. ortho‐Bromoallylbenzoate is a new dienophile that was prepared in a pure form, and its structure was confirmed. The Diels–Alder syntheses of hexachlorocyclopentadiene and the new dienophile were studied to determine the optimum condensation reaction conditions under a temperature range of 90–160°C, reaction times of 1–8 h, and molar diene/dienophile ratios from 1:1 to 5:1 as a consequence. The optimum conditions reached were a temperature of 140°C, an initial diene/dienophile molar ratio of 3:1, and a duration time of 6 h. The maximum stoichometric yield under these optimum conditions (82.5%) was obtained. © 2003 Wiley Periodicals, Inc. J Appl Polym Sci 89: 2331–2338, 2003