The effect of water solubility of the monomers on composition drift on methyl acrylate-vinyl ester combinations

It has been shown theoretically that composition drift mainly depends on reactivity ratios and water solubilities. Minimum composition drift can be obtained by lowering the monomer-to-water ratio in monomer systems where the more reactive monomer is also the more water-soluble one. Investigating the effect of water solubility on composition drift while keeping the reactivity ratios constant can elucidate the importance of the water solubility. The monomer combinations methyl acrylate-vinyl acetate (MA-VAc), methyl acrylate-vinyl 2,2-dimethylpropanoate (MA-VPV), and methyl acrylate-vinyl 2-ethylhexanoate (MA-V2EH) are ideal monomer combinations for studying the effect of water solubility on composition drift since the reactivity ratios for this series of monomer systems are approximately equal. Solution copolymerizations are performed to elucidate maximum composition drift at extremely high monomer-to-water ratios. From comparing theoretical predictions with experimental results it could be concluded that composition drift for the monomer combination MA-VAc could only be reduced since the difference in water solubility was not large enough to compensate the effects of the large difference in reactivity ratios. However, for the monomer combinations MA-VPV and MA-V2EH the difference in water solubility was large enough to make minimum composition drift possible for low monomer-to-water ratios even for monomer combinations with reactivity ratios as far apart as in the MA-vinyl ester case. © 1996 John Wiley & Sons, Inc.     

Prediction of polymer composition in batch emulsion copolymerization

Monomer partitioning in emulsion copolymerization plays a key role in determining composition drift and polymerization rates. The combination of recently developed thermodynamically based monomer partitioning relationships with mass balance equations, makes predictions of monomer partitioning in emulsion copolymerizations possible in terms of monomer mole fractions and monomer concentrations in the particle and aqueous phases. Using this approach, the effects of monomer to water ratios and polymer volumes on the monomer mole fraction within the polymer particle phase in a nonpolymerizing system at thermodynamic equilibrium can be determined. Comparison of these monomer partitioning predictions with experiments for the monomer system methyl acrylate—vinyl acetate shows good agreement. Furthermore, composition drift occurring in a polymerizing system as a function of conversion can be predicted if the assumption is made that equilibrium is maintained during reaction. Comparison of predictions with experimental results for emulsion copolymerizations of the monomer systems methyl acrylate—vinyl acetate and methyl acrylate—indene shows good agreement. © 1994 John Wiley & Sons, Inc.     

Emulsion co- and terpolymerization of styrene,methyl methacrylate,and methyl acrylate. I. Experimental determination and model prediction of composition drift and microstructure in batch reactions

In Part I of this series the reactivity ratios of the comonomer pair methyl acrylate-methyl methacrylate were determined with low-conversion bulk polymerizations. It was shown that the binary reactivity ratios of the systems styrene-methyl acrylate, styrene-methyl methacrylate, and methyl acrylate-methyl methacrylate describe composition drift in low-coversion bulk terpolymerizations with these monomers reasonably well. A computer model was developed to simulate the composition drift in emulsion co- and terpolymerizations. The composition drift in two batch emulsion copolymerization systems (styrene-methyl acrylate and methyl acrylate-methyl methacrylate) and one emulsion terpolymerization system (styrene-methyl acrylate-methyl methacrylate) was investigated both experimentally and with the model. Experimental results were compared with model calculations. The copolymer chemical composition distributions (CCD) were determined with gradient polymer elution chromatography (GPEC®). This technique was also used for the first time to obtain information about the extent of composition drift in emulsion terpolymerizations. Cumulative terpolymer compositions were determined with ³H-NMR as a function of conversion and with this information the three-dimensional CCD was obtained. The composition drift was analyzed with respect to free radical copolymerization kinetics (reactivity ratios) and monomer partitioning. It was shown that in most emulsion copolymerizations the composition drift is mainly determined by the reactivity of the monomers and to a lesser extent by monomer partitioning, except in systems where there is a large difference in water solubility. The model predictions for cumulative terpolymer composition as a function of conversion and the three-dimensional terpolymer CCD showed excellent agreement with the experiments. The GPEC® elution chromatogram of the terpolymer was found to be in accordance with the predicted CCD and the experimentally determined CCD. © 1996 John Wiley & Sons, Inc.     

AN/St悬浮共聚体系中AN在水/油两相间分配及其对共聚物组成的影响

研究了丙烯腈/苯乙烯(AN/St)悬浮共聚体系中AN在水/油两相间的分配及其对AN/St共聚物组成的影响.结果表明,AN分配于水/油两相间,使油相AN的含量低于相同单体配料比的本体聚合,导致生成的AN/St共聚物组成偏离本体共聚.为了准确预测进而控制AN/St悬浮共聚物的组成,提出了在考虑AN相分配的基础上计算AN/St悬浮共聚物组成的模型.计算结果与实验值一致,计算中用到的油相实际竞聚率与本体聚合相同,但该悬浮聚合的表观竞聚率随水/油比的变化而发生较大改变.     

Emulsion polymerization. VI. Concentration of monomers in latex particles

Nonpolymerizing latex particles surrounded by an aqueous phase saturated with monomer absorb only a finite amount of monomer, even if the monomer is a good solvent for the polymer, because the surface energy of each particle increases on swelling. At equilibrium the change in surface energy and the free energy of mixing exactly balance. Equations based on this thermodynamic principle predict with good accuracy the saturation swelling of crosslinked and uncrosslinked latex particles and the partitioning of monomer between the aqueous phase and latex particles at partial saturation. The available experimental data on swelling of latex polymers with monomers are reviewed. Earlier papers assumed that during emulsion polymerization the monomer concentration in the latex particles is independent of conversion as long as monomer droplets are present. This assumption is shown to be a justifiable approximation. The thermodynamics of the swelling of latex particles with a blend of two monomers is presented. The calculations indicate that copolymerization in emulsion should define reactivity ratios differing from those of homogeneous copolymerization by not more than 40% if the solubility of the comonomers in water is low. The reactivity ratio scheme is strictly applicable to emulsion copolymerization if the solvent properties of the two comonomers are identical.     

甲基丙烯酸甲酯水溶性对其悬浮均聚动力学的影响

通过比较在大水油比下的甲基丙烯酸甲酯 (MMA)悬浮均聚的实验数据以及本体聚合实验结果 ,发现单体的水溶性对其聚合动力学有影响 ,不能用本体聚合动力学代替其悬浮聚合动力学 .为了能更好了解单体的水溶性对其悬浮聚合动力学的影响以及影响动力学的原因 ,在MMA本体聚合动力学模型基础上 ,进一步提出 3个假设 :扣除溶于水相部分的单体量、增长和终止速率参数降低、少部分的油溶性引发剂被带到水相中 ,得到改进的悬浮聚合动力学模型 .运用该模型能很好预测水油比、聚合温度、引发剂浓度等对MMA悬浮聚合动力学的影响 ,且与实验数据能较好吻合     

Reactivity Ratios and Sequence Distribution Characterization by Quantitative 13C NMR for RAFT Synthesis of Styrene‐Acrylonitrile Copolymers

The kinetics and reactivity ratios of styrene‐acrylonitrile (SA) copolymerization have been studied extensively in bulk and in a variety of solution media using conventional free radical polymerizations (FRPs). Due to the significant difference in the two reactivity ratios for this monomer pair, at certain feed ratios the copolymers display composition drift with conversion due to monomer depletion. In this study, the kinetics of SA copolymerization using Reversible Addition‐Fragmentation Chain Transfer (RAFT) has been studied in bulk at 80 °C. The reactivity ratios for the terminal model were calculated from the comonomer sequence distributions for the RAFT process at low conversion for nine different compositions and found to be in the same range as those reported for conventional FRP of SA. The changes in the composition and sequence distribution with conversion were studied for three feed compositions. The copolymers show compositional drift with conversion, except at the azeotropic composition, and match the predictions from the reactivity ratios obtained at low conversion. From quantitative ¹³C NMR the triad distributions of these copolymers were estimated and found to match the predicted triad distributions as conversion increased. © 2017 Wiley Periodicals, Inc. J. Polym. Sci., Part A: Polym. Chem. 2017 , 55, 919–927     

Estimation of monomer reactivity ratios in free‐radical solution copolymerization of lauryl methacrylate–isobutyl methacrylate

Copolymers of isobutyl methacrylate (i‐BMA) and lauryl methacrylate (LMA) were prepared by free‐radical solution copolymerizations at 70 °C with azobisisobutyronitrile (AIBN) as an initiator. The synthesis of these copolymers was investigated over a wide composition range both at low and high conversion levels. Copolymer compositions were determined from the %C, %H, and %O contents of copolymer by elemental analysis. Monomer reactivity ratios were estimated by analyzing composition data with nonlinear least‐squares (NLLS) models based on Marquardt optimization and van Herk methods. The point estimates, 95% individual confidence intervals and 95% joint confidence intervals are obtained from differential and integral approaches. Even though no explicit integral form for penultimate unit model (PUM) is available, a numerical approach is developed for integral estimation of reactivity ratios from PUM. A simulator program was developed which upon coupling of experimental data, NLLS analysis, and D‐optimal criteria calculates the best optimized values of monomer reactivity ratios and monomer feed compositions in a sequential and iterative order for terminal and penultimate unit models. Moreover, the simulator has the capibilities to calculate all features of van Herk method, maximum compositional drift in each monomer feed composition, and data reconciliation. © 2003 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 42: 112–129, 2004     

Determination of the reactivity ratios of methyl acrylate with the vinyl acetate,vinyl 2,2-dimethyl-propanoate,and vinyl 2-ethylhexanoate

The course of composition drift in copolymerization reactions is determined by reactivity ratios of the contributing monomers. Since polymer properties are directly correlated with the resulting chemical composition distribution, reactivity ratios are of paramount importance. Furthermore, obtaining correct reactivity ratios is a prerequisite for good model predictions. For vinyl acetate (VAc), vinyl 2,2-dimethyl-propanoate also known as vinyl pivalate (VPV), and vinyl 2-ethylhexanoate (V2EH), the reactivity ratios with methyl acrylate (MA) have been determined by means of low conversion bulk polymerization. The mol fraction of MA in the resulting copolymer was determined by ¹H-NMR. Nonlinear optimization on the thus-obtained monomer feed–copolymer composition data resulted in the following sets of reactivity ratios: r_MA = 6.9 ± 1.4 and r_VAc = 0.013 ± 0.02; r_MA = 5.5 ± 1.2 and r_VPV = 0.017 ± 0.035; r_MA = 6.9 ± 2.7 and r_V2EH = 0.093 ± 0.23. As a result of the similar and overlapping reactivity data of the three methyl acrylate–vinyl ester monomer systems, for practical puposes these data can be described with one set of reactivity data. Nonlinear optimization of all monomer feed–copolymer composition data together resulted in r_MA = 6.1 ± 0.6 and r_VEst = 0.0087 ± 0.023. © 1994 John Wiley & Sons, Inc.     

Radiation-induced copolymerization of chlorotrifluoroethylene with ethyl vinyl ether

The radiation-induced copolymerization of chlorotrifluoroethylene with ethyl vinyl ether was investigated in the liquid phase at 20 and ?78°C over a wide range of monomer compositions. A copolymer was obtained in which the monomers alternate with regularity along the polymer chain over the entire range of monomer compositions investigated. Both the rate of copolymerization and the intrinsic viscosity of the resulting copolymer were found to depend strongly on the initial monomer composition, both reaching a maximum value at an equimolar concentration of the monomers. The monomer reactivity ratios were determined and correspond well with calculated values. A decrease in the irradiation temperature was accompanied by a marked decrease in the rate of copolymerization and the intrinsic viscosity of the copolymer.     

Professor Takeo Saegusa is Awarded Mark Medal

Abstract

Probability theory has been used to derive equations for the terminal model for free radical terpolymerization, showing how the polymer composition and triad fractions are related to the reactivity ratios and monomer composition. These relationships have been used to analyze the monomer-polymer composition data for the acrylonitrile-styrene-2,4,6-tri-bromophenyl acrylate system using a nonlinear least-squares method. The “best values” of the reactivity ratios which describe the polymerization have been used to calculate the triad fractions for each monomer.     

Estimation of Reactivity Ratios from Multicomponent Copolymerizations

Abstract

The composition of the copolymer formed from n monomers in addition polymerization can be expressed in terms of the monomer feed composition and n(n - 1) binary reactivity ratios, according to the familiar simple copolymer model. Reactivity ratios are determined experimentally from cor-responding feed and monomer compositions in binary co-polymerizations. This article reports methods for deriving such reactivity ratios directly from multicomponent polymerization data. Analytical solution of the multi-component copolymer equations is not feasible because of the limited number of experimental points and experimental uncertainty in the copolymer composition. Computer-assisted procedures have been developed to estimate re-activity rates by optimizing the fit of predicted and experimental copolymer compositions, given the monomer feed composition and preliminary values of the reactivity ratios. All n(n - 1) reactivity ratios are adjustable. The methods are demonstrated for styrene/methacrylonitrile/ a-methylstyrene, butadiene/styrene/2-methyl- 5-vinyl- pyridine and acrylonitrile/methyl methacrylate/& methylstyrene systems. Binary reactivity ratios predict ternary copolymer compositions generally well in these cues. Reasons are suggested why reactivity ratios from multicomponent experiments may not match the corresponding parameters from binary copolymerizations.     

Microemulsion copolymerization of styrene and acrylonitrile with n‐butanol as the cosurfactant

The microemulsion copolymerization of styrene and acrylonitrile in an n‐butanol/cetyltrimethylammonium bromide/oil/water microemulsion system was studied. The solubilization sites of the two monomers were determined with an NMR technique. The results showed that the solubilization behaviors of the two monomers were quite different. Most of the styrene was solubilized in the palisade layer of the microemulsion, whereas the acrylonitrile had an equilibrium distribution in the aqueous phase and palisade layer of the microemulsion. The reactivity ratios of styrene and acrylonitrile in the microemulsion system were different from those in other media. The effect of the monomer feed composition on the copolymerization kinetics was investigated, and the mechanism of nucleation of the latex particles was examined. The experimental results showed that the copolymerization loci were changed from the microemulsion droplets to the aqueous phase when the concentration of acrylonitrile in the monomer feed reached approximately 80%; this could be further proved by the effect of the monomer feed composition on the copolymerization kinetics. © 2004 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 43: 203–216, 2005     

Alternating copolymerization of ethylene with maleic anhydride

The copolymerization of ethylene with maleic anhydride was carried out with γ-radiation and a radical initiator, i.e., 2,2′-azobisisobutyronitrile and diisopropyl peroxydicarbonate under pressure at various reaction conditions. The homopolymerization of neither monomer was observed in this system. In the γ-ray-initiated copolymerization the G value (polymerized monomer molecules per 100 e.v.) was shown to be between 10³ and 10⁴. It was found that the dose rate exponent of the rate is approximately unity, and the rate is proportional to the amount of ethylene monomer. Apparent activation energies of 1.8 and 27.5 kcal./mole were obtained for γ-ray-initiated and AIBN-initiated copolymerization, respectively. Since the composition of copolymer is independent of monomer molar ratio and the molar ratio of ethylene to maleic anhydride in the polymer is approximately unity, the monomer reactivity ratios were obtained as r_E ? 0 and r_M ? 0 for γ-ray-initiated polymerization at 40°C. Alternating copolymerization was, therefore, concluded to occur. Infrared analysis of the copolymer is almost consistent with this. The copolymer in the solid state is amorphous. It is soluble in water, cyclohexane, and dimethylformamide and insoluble in lower alcohols, ether, and aromatic hydrocarbons. The aqueous solution of polymer gave a strong acid.     

全氟甲基乙烯基醚和其它含氟单体乳液共聚合的竞聚率测定

分别通过气相色谱法测定了全氟甲基乙烯基醚 (PMVE)与偏氟乙烯 (VDF)以及PMVE与四氟乙烯(TFE)二元乳液共聚反应中的气相单体组成和共聚物组成 ,然后用非线性回归法 (RREVM )计算得TFE PMVE及VDF PMVE乳液共聚合反应的表观竞聚率分别为γTFE =3 89和γPMVE =0 0 5以及γVDF =1 0 6和γPMVE =0 11.结合已经测定的TFE VDF二元乳液共聚的表观竞聚率 ,计算了由VDF TFE PMVE三元乳液共聚合反应合成的共聚物组成 ,后者与由1 9F NMR实测的共聚物组成吻合     

One‐step polymerization of hydrophilic ionic liquid imprinted polymer in water for selective separation and detection of levofloxacin from environmental matrices

A novel green hydrophilic levofloxacin imprinted polymer was presented via one‐step polymerization in water using ionic liquid 1,6‐hexa‐3,3′‐bis‐1‐vinylimidazolium bromine with multiple hydrophilic groups and 2‐hydroxyethyl methacrylate as a co‐functional monomer. Adsorption experiment revealed that the ionic liquid significantly improved the water compatible of imprinted polymer, and the excellent recognition of molecularly imprinted polymer for levofloxacin in water corresponds to the synergetic effect of H‐bonding and the electrostatic and π–π interactions between the levofloxacin and co‐functional monomer. Furthermore, the adsorption process of the imprinted material towards levofloxacin fitted the Langmuir model, and the maximum binding amount of levofloxacin onto the imprinted and corresponding non‐imprinted polymer were 16.45 and 6.82 mg/g at 25°C, respectively. After optimizing the parameters affecting solid phase extraction performance, an enrichment and determination system was achieved to separate and detect levofloxacin from water and sediment samples with recoveries that ranged from 83.67 to 101.33% and relative standard deviation of less than 5.59%.     

On the main locus of radical formation in emulsion polymerization initiated by oil-soluble initiators

The effect of the monomer/water ratio on the rate of polymerization per polymer particle in both seeded emulsion polymerizations and miniemulsion polymerizations was used in an attempt to elucidate the main locus of radical formation in emulsion polymerization initiated by an oil-soluble initiator (AIBN). It was found that, for the rest of conditions constant, the polymerization rate per polymer particle increased when the monomer/water ratio increased, namely when the amount of initiator dissolved in the aqueous phase per polymer particle decreased. This is an evidence against a dominant aqueous phase formation of radicals. On the other hand, these results are consistent with a mechanism in which the radicals are mainly produced in the oil-phase with significant aqueous phase termination.     

CONCURRENT INTERACTIONS BETWEEN MONOMER - EMULSIFIER AND MONOMER - POLYMER IN POLYVINYL ACETATE LATEXES

In the poly(vinyl acetate) latexes stabilized by nonyl phenol ethoxylated with 30 moles ethylene oxide, the ratio of the amount of monomer that swells the polymer particles to that of monomer remaining in aqueous phase decreases with the increase of the emulsifier concentration.

This behaviour is due to concurrent interactions between monomer - polymer and emulsifier - polymer. At the polymer particle/water interface, the monomer interacts with the adsorbed emulsifier and prevents to swelling process from occuring.     

Emulsion polymerization of acrylonitrile. Part II. Mechanism of emulsion polymerization of acrylonitrile

The mechanism of emulsion polymerization of acrylonitrile has been studied by measuring by dilatometry and electron microscopy the adsorption of monomer into polymer particles and polymerization characteristics such as rate, degree of polymerization, the growth of the particle during polymerization, and the degree of dispersion. In the emulsion polymerization of acrylonitrile, new particles are formed during polymerization at a rate which is proportional to the rate of polymerization and the ratio of unreacted monomer. The total amount of monomer adsorbed on or in the polymer particles is rather small, but the concentration on or in the polymer particles is sufficiently high and proportional to the monomer concentration in aqueous phase. The polymerization proceeds concurrently on or in the polymer particles and in aqueous phase, but the three loci may be continuous rather than discrete. A reaction scheme is introduced here which shows the coexistence of polymerizations on or in the polymer particles and in the aqueous phase.     

A Modified Local Composition-Based Model for Correlating the Vapor-Liquid and Liquid-Liquid Phase Equilibria of Aqueous Polymer-Salt Systems

In this research, a new local composition model has been proposed to study the vapor-liquid and liquid-liquid phase equilibria of polyelectrolyte solutions. The proposed model has been used in order to obtain the activity of water in polyethylene glycol (PEG) and polypropylene glycol (PPG) solutions. The interaction parameters introduced into the proposed model have been reported. The interaction parameters between the salt and water molecule have been estimated using the experimental mean ionic activity coefficients of aqueous electrolytes studied in this work. Also, the interaction parameters between the polymer and salt molecule, and the polymer and water molecule have been computed using the experimental activity of water data in aqueous polymer solutions. The results showed that the proposed model, segment-based Wilson and segment-based NRTL models have good accuracy in correlating the vapor-liquid phase equilibria of the water-polymer and water-polymer-salt systems. Also, the liquid-liquid phase behavior of the polymer-salt aqueous two-phase systems has been correlated using the proposed model. The results show that the proposed model can more accurately correlate the phase behavior of aqueous two-phase systems than the UNIQUAC and the modified Wilson models.