Emulsion Polymerization Of Butyl Methacrylate Research Articles

Polymerisable surfactants for polymethacrylates using catalytic chain transfer polymerisation (CCTP) combined with sulfur free-RAFT in emulsion polymerisation

Statistical copolymers of methacrylic acid and methyl methacrylate were synthesised via free radical catalytic chain transfer polymerisation (CCTP) in emulsion to form a hydrophilic emulsifier/surfactant. The vinyl-terminated oligomers were in turn utilised as chain transfer agents, with no further purification, for the formation of diblock copolymers with butyl and methyl methacrylate which constitutes the emulsifier via sulfur-free reversible addition–fragmentation chain transfer polymerisation (SF-RAFT). In turn these polymers were solubilized with various concentrations of ammonium hydroxide and utilised in the surfactant-free emulsion polymerization of butyl methacrylate using persulfate initiators, which also stabilized the polymer particles with observed no coagulation, with solid contents as high as 40%.

Antimicrobial films obtained from latex particles functionalized with quaternized block copolymers

New amphiphilic block copolymers with antimicrobial properties were obtained by atom transfer radical polymerization (ATRP) and copper catalyzed cycloaddition following two approaches, a simultaneous strategy or a two-step synthesis, which were proven to be very effective methods. These copolymers were subsequently quaternized using two alkyl chains, methyl and butyl, to amplify their antimicrobial properties and to investigate the effect of alkyl length. Antimicrobial experiments in solution were performed with three types of bacteria, two gram-positive and one gram-negative, and a fungus. Those copolymers quaternized with methyl iodide showed better selectivities on gram-positive bacteria, Staphylococcus aureus and Staphylococcus epidermidis, against red blood cells, demonstrating the importance of the quaternizing agent chosen. Once the solution studies were performed, we prepared poly(butyl methacrylate) latex particles functionalized with the antimicrobial copolymers by emulsion polymerization of butyl methacrylate using such copolymers as surfactants. The characterization by various techniques served to test their effectiveness as surfactants. Finally, films were prepared from these emulsions, and their antimicrobial activity was studied against the gram-positive bacteria. The results indicate that the antimicrobial efficiency of the films depends not only on the copolymer activity but also on other factors such as the surface segregation of the antimicrobial agent to the interface.

Semicontinuous Emulsion Polymerization of Butyl Methacrylate and 1, 3-Butadiene in the Presence of Cyclodextrins and Cytocompatibility of Dicarboxylic Acid Telechelic Oligo(butyl Methacrylate)s Derived from Ozonolysis of the Latexes

Semicontinuous Emulsion Polymerization of Butyl Methacrylate and 1, 3-Butadiene in the Presence of Cyclodextrins and Cytocompatibility of Dicarboxylic Acid Telechelic Oligo(butyl Methacrylate)s Derived from Ozonolysis of the Latexes

Glycoparticles and bioactive films prepared by emulsion polymerization using a well-defined block glycopolymer stabilizer

A well-defined amphiphilic diblock glycopolymer of poly(2-{[(D-glucosamin-2-N-yl)carbonyl]oxy}ethyl methacrylate)-b-poly(butyl methacrylate) (PHEMAGl-b-PBMA) was synthesized via atom transfer radical polymerization (ATRP). Due to its capability to form micelles in aqueous solution, the obtained block glycopolymer was used as polymeric surfactant in the emulsion polymerization of butyl methacrylate in order to prepare glycosylated polymer particles. Core–shell particles consisting of a soft core of poly(butyl methacrylate) covered with glycopolymer bearing glucose moieties were obtained. Then these latex particles were employed to prepare polymer films with active surface. The surface bioactivity of this polymer coating was examined using the specific lectin Concanavalin A, Canavalia ensiformis. The specific and successful binding to the Concanavalin A was demonstrated by both fluorescence microscopy and spectroscopy being more intense with increasing concentration of block glycopolymer surfactant. The good accessibility of the glucose moieties at the surface of the coating makes this method a powerful tool to achieve potential materials for biomedical applications involving molecular recognition processes.

Stability of nanoparticles during semibatch emulsion polymerization of butyl methacrylate, in the presence of methacrylic acid via RSM

AbstractThe size and stability of latex particles in the semibatch emulsion polymerization of butyl methacrylate (BMA), in the presence of 0–10% methacrylic acid (MAA), were investigated. Response surface methodology (RSM), as a design of experiment, was used to obtain a more systematic understanding of the role of emulsifier and MAA in the stability of the particles. The amount of coagulum can be greatly reduced by increasing the concentration of sodium lauryl sulfate (SLS) in the monomer emulsion feed (MEF) and initial reactor charge (IRC). On the other hand, increasing the concentration of SLS in the IRC can result in a decrease of the particles size. According to the experimental data, the yield of reaction can be improved with incorporation of MAA into the emulsion polymers. The size and morphology of particles were obtained by scanning electron microscopy (SEM). FTIR and titration were used to determine the percentage of MAA in the copolymer. © 2007 Wiley Periodicals, Inc. J Appl Polym Sci 2007

Role of anionic and nonionic surfactants on the control of particle size and latex colloidal stability in the seeded emulsion polymerization of butyl methacrylate

AbstractThe evolution of the main colloidal parameters in the seeded starved‐feed semi‐continuous emulsion polymerization of butyl methacrylate (BMA) was investigated, with the main purpose of assessing the effectiveness of the semi‐empirical relationship S = K · SS · ΔA/AS as a tool to define the surfactant/monomer feed ratio (∝ K) best suited to achieve a target particle size. In particular, the effect of the type and amount of surfactant [i.e., anionic, sodium dodecyl sulfate (SDS), or nonionic, Brij 58P] added during the semi‐continuous stage was considered. Coagulum formation was never observed under the adopted experimental conditions. To detect the occurrence of secondary nucleation or particle aggregation, or both, the particle size and number of particles, the surface tension and the particle surface coverage ratio were correlated. The best results were obtained with SDS and 0.8 ≤ K ≤ 3. In fact, under the selected experimental conditions, only with SDS did the number of particles remain nearly constant throughout the polymerization at the value defined by the seed latex; the particle size distribution was highly monodisperse, and the final particle diameter closely matched the calculated one (∼ 120 nm). The above semi‐empirical relationship based on the adjustable parameter K was validated by running test polymerizations aimed at lattices with well‐defined particle size. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 102: 3083–3094, 2006

Preparation of organic–inorganic nanocomposites with core‐shell structure by inorganic powders

AbstractOrganic–inorganic nanocomposites with core‐shell structure were prepared in two steps. In the first step, the latex particles in the semibatch emulsion polymerization of butyl methacrylate (BMA), in the presence of methacrylic acid (MAA), were prepared. Small amounts of acrylic acid incorporated into the latex to have better interaction between the surface of particles and inorganic phase. MAA also increased the latex stability and decreased the amount of coagulum. In the second step, the core‐shell structures were prepared by coating the latex particles with three types of inorganic powders. Pectin coated precipitated calcium carbonate, alumina, and silica. The examinations show that pectin‐coated calcium carbonate has the best response than other types of calcium carbonate. Alumina was the second type of inorganic powder that was used for coating the core particles. Silicagel and fumed silica (Aerosil) were used for coating by silica. Scanning electron microscopy and transmission electron microscopy showed the particle morphology and the core‐shell structure, respectively. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci, 2006

Adsorption of block copolymers at latex surface and their utilization in emulsion polymerization

Amphiphilic block copolymers have been investigated for their utilization in emulsion polymerization of butyl methacrylate. Special attention has been paid to the adsorption mechanism of the block copolymers from systematic measurements of equilibrium adsorption isotherms. A series of well-defined water-soluble amphiphilic block copolymers, composed of poly(butyl methacrylate) and poly(sodium methacrylate) blocks, were synthesized by anionic polymerization of butyl methacrylate and tert-butyl methacrylate followed by the thermal deprotection of the tert-butyl ester groups and final hydrolysis. The number density of emulsion polymer particles N P varied as [copolymer] α, α lying between 0.44 and 0.73 according to the hydrophilic content of the copolymers. In contrast with SDS taken as a reference emulsifier, the adsorption of the copolymers was very strong and this provided quite an efficient stabilization of the polymer particles during emulsion polymerization, even at low concentrations (<10 −4 mol L −1) and low coverages (<10% of the interfacial area).

Modified emulsifier-free emulsion polymerization of butyl methacrylate with ionic or/and nonionic comonomers

A modified emulsifier-free emulsion polymerization of butyl methacrylate (BMA) with ionic or/and nonionic comonomers was successfully used to prepare nanosized poly(butyl methacrylate) (PBMA) latices with high polymer contents. After seeding particles were generated in an initial emulsion system, consisting of a portion of BMA, water, ionic comonomer [sodium styrenesulfonate (NaSS)] or nonionic comonomer [2-hydroxyethyl methacrylate (HEMA)] and potassium persulfate, most of the BMA monomer or the mixture of BMA and HEMA was added dropwise to the polymerizing emulsion over a period of 6–12 h. Stable latices with high PBMA contents up to 27% were obtained. It was found that the latex particle sizes (2Rh) were largely reduced (34 nm) by the continuous addition of monomer(s) compared to those (107 nm) obtained by the batch polymerization method. The effect of comonomer concentration on the particle size, the number of PBMA particles/mL of latex (Nd), and the molar mass (Mw) of copolymer during the polymerization were discussed. The surface compositions of latex particles were analyzed by X-ray photoelectron spectroscopy, indicating that the surface of latex particles was significantly enriched in NaSS or/and HEMA. © 2004 Wiley Periodicals, Inc. J Appl Polym Sci 92: 3080–3087, 2004

In‐Situ Kinetic Pursuit of Emulsion Crosslinking Copolymerizations of Monomethacrylate and Dimethacrylate by Means of ReactIR®

The usefulness of tthe ReactIR® reaction analysis system as a powerful tool to in situ monitor the kinetics of the emulsion polymerization of vinyl monomers was verified by comparison with the conventional gravimetric method and by checking the rate dependencies on the initiator and surfactant concentrations in the emulsion polymerization of butyl methacrylate (BMA). The system was then applied to the kinetic monitoring of emulsion crosslinking copolymerizations of monomethacrylate and dimethacrylate, including methyl methacrylate/ethylene dimethacrylate and BMA/1,6- hexanediol dimethacrylate systems of different hydrophilicitics.

Soapless emulsion polymerization of butyl methacrylate through microwave heating

AbstractSoapless emulsion polymerization of n‐butyl methacrylate (BMA) was carried out through microwave heating with potassium persulfate (KPS) as an initiator at 73 ± 2°C. The influence of the monomer amount, the initiator amount, and the addition of ethanol on the monomer conversion, the particle size, and its distribution were studied. The results indicate that microwave polymerization had a much higher rate and produced smaller particles with a slightly broader size distribution compared with normal polymerization. © 2001 John Wiley &amp; Sons, Inc. J Appl Polym Sci 80: 2455–2459, 2001

Effects of alkali soluble resin on the emulsion polymerization of butyl methacrylate

In this work, alkali soluble resin (ASR) was evaluated as a surfactant in the emulsion polymerization of butyl methacrylate (BMA). Kinetic analysis indicated that the ASR surfactant retarded the reaction rate and reduced the average number of radicals per latex particle. Since the particle nucleation period proceeds until the disappearance of droplets, Interval II does not exist in this system. Experimental results show that the particle number depends on the 0.31 and 0.51 powers of the ASR and KPS concentration, respectively. The particle size distribution of the latex becomes broad with the increase of the ASR concentration in the emulsion polymerization. This phenomenon explains why the period of the particle nucleation is proportional to the ASR concentration used in the reaction.

Structural effects of a novel polymeric emulsifier – SSIPM modified tetracarboxylic acid terminated polyester on the emulsion polymerization of butyl methacrylate

A novel polymeric emulsifier, SMTAPE, was prepared by end-capping sulfopolyester polyol with TMA in this study. This polymeric emulsifier is applied for BMA emulsion polymerization. Also investigated herein is how SMTAPE’s chemical structures, e.g. SSIPM contents and molecular weights, influence the behavior of emulsion polymerization and subsequent PBMA lattices. Experimental results indicate that SMTAPE emulsifiers with a shorter average hydrophobic length stabilize the PBMA latex by the depletion mechanism. Although possessing good mechanical stability, using those emulsifiers has a higher coagulum during the synthesis stage. However, the SMTAPE emulsifiers with a longer average hydrophobic length anchor strongly on the PBMA latex particles and stabilize them by an electrostatic force with a negligible amount of steric stabilization. Although possessing better synthesis stability, using these emulsifiers has a poor mechanical stability. In addition, according to these experimental results, formation of the subsequent PBMA latex is attributed to a coagulation process of particle precursors, micellar particles as well as existing PBMA latex particles.

Emulsion polymerization of butyl methacrylate initiated by 2,2′‐azoisobutyronitrile, 3. On the applicability of the modified Smith‐Ewart model

AbstractThe applicability of the modified Smith‐Ewart model to the butyl methacrylate emulsion polymerization in interval II, initiated by both 2,2′‐azoisobutyronitrile (AIBN) and ammonium persulfate at 60°C, was tested. The equilibrium monomer concentration in the latex particles in interval II was found to be constant and independent of the emulsifier concentration and the initiator type used. The rate of initiation increases with increasing emulsifier concentration for the polymerizations initiated with a water‐soluble initiator. In the systems with the oil‐soluble initiator, the rate of initiation is independent of the emulsifier concentration. The rate of polymerization increase with increasing emulsifier concentration for both initiator systems. In the system with the oil‐soluble initiator lower values of the polymerization rate and higher values of the viscosity‐average molecular masses of the polymer were observed. The number of particles, the radical concentration within polymer particles and the calculated rate of polymerization increase, while the mean particle radius decreases with increasing concentration of the emulsifier for both systems. The average‐number of radicals per particle and the ratio of the rate constants for propagation and termination was found to be independent of the emulsifier concentration and the initiator type. A good agreement was observed between the estimated and observed particle radii for both initiator systems. The Smith‐Ewart model was found to be applicable for the emulsion polymerization of butyl methacrylate initiated by both ammonium persulfate and AIBN.

Emulsion polymerization of butyl methacrylate initiated by 2,2′‐azoisobutyronitrile, 1. Kinetics and mechanism

AbstractThe effect of 2,2′‐azoisobutyronitrile (AIBN) on the kinetics and mechanism of emulsion polymerization of butyl methacrylate was studied in the presence of anionic emulsifier disodium dodecylphenoxybenzene disulfonate (Dowfax® 2A1) at 60°C. The ratio between the proportion of the polymerization in monomer droplets and that of the polymerization in the aqueous phase was determined for the overall initial rate of butyl methacrylate polymerization in the region of the increasing polymerization rate (interval I). Using the model of polymerization in discrete particles, the portion of the polymerization in monomer droplets with a diameter of 100 nm in the overall polymerization rate is 24,4%; the portion of the polymerization in the water phase is only 0,022% for a concentration of Dowfax® 2A1 of 5 · 10−2 mol · dm−3, and 60,4% and 0,054% for a Dowfax® 2A1 concentration of 1 · 10−2 mol · dm−3. The exponent of the emulsifier concentration in the equation for the polymerization rate is 0,56 for interval I and 0,36 for interval II; the exponent for the concentration of AIBN over the conversion range between 0 and 30% is 0,34. For the proposed reaction mechanism it is assumed that 2‐cyanoisopropyl radicals, generated from AIBN in the water phase, are responsible for the initiation of polymerization in micelles swollen by monomer and in polymer/monomer particles. Polymer/monomer particles are formed also by co‐precipitation of oligomer radicals, which in turn are formed by polymerization of monomer molecules present in the water phase. Polymerization within monomer droplets has no significant influence on the course of emulsion polymerization.

Emulsion polymerization of butyl methacrylate initiated with 2,2′‐azoisobutyronitrile, 2 Mechanism of the termination reaction

Emulsion polymerization of butyl methacrylate initiated with 2,2′‐azoisobutyronitrile, 2 Mechanism of the termination reaction

A study of the kinetics of the emulsion polymerization of butyl methacrylate

The kinetics of the emulsion polymerization of butyl methacrylate at 50 °C have been studied dilatometrically. Thermal initiation, γ-radiolysis initiation and initiation by K2S2O8 were employed, the last over a wide concentration range. Rates were obtained for the steady state, for the approach to steady state and (for γ-radiolysis initiation) for the decay from steady state on removal from the radiolysis source. These data yield unambiguous and accurate values for the rate coefficients for free-radical propagation, exit (desorption), entry (as a function of initiator concentration) and bimolecular termination. It is found that aqueous-phase kinetics are characterized by re-entry of desorbed free radicals into the particles and by a capture efficiency of primary free radicals that is significantly less than 100%. Exit is found to be a transfer-diffusion-dominated process. The system has a comparatively high average number of free radicals per latex particle (e.g. ca. 0.7 for [S2O2–8]= 10–3 mol dm–3). The methodology presented here should be applicable to other emulsion-polymerization systems.