Methacrylic Acid Esters Research Articles

Structure–property relationship in copolymers of methacrylic acid esters. I. Thermal behavior

AbstractThis article describes the synthesis and thermal characterization of copolymers of methyl methacrylate (MMA) and alkyl methacrylates. The copolymerization was carried out using different mol fractions (0.05–0.25) of alkyl methacrylates, i.e., octyl methacrylate (OMA)/decyl methacrylate (DMA)/lauryl methacrylate (LMA)/stearyl methacrylate (SMA), in the initial feed at 80°C. The copolymer composition was determined from 1H‐NMR. The thermal stability of the copolymers was investigated by thermogravimetric analysis and pyrolysis gas chromatography. A two/three‐step degradation was observed in the copolymer samples. The monomers were the major product of degradation in most of the copolymers except in SMA/MMA copolymers where the product of side‐group elimination was also observed. An attempt was also made to determine the yield of the monomers during degradation and then to evaluate the copolymer composition. © 1994 John Wiley & Sons, Inc.

Synthesis and polymerization of unsaturated derivatives of thymol

The preparation of methacrylic and p-styrenesulfonic acid esters of the antibacterial agent thymol (2-isopropyl-5-methylphenol) and their characterization by IR, 1H and 13C NMR spectroscopy is described. The monomers are radically polymerizable and give polymers in which thymol is covalently attached to the polymer backbone by ester links.

Synthesis of 4-azafluorene derivatives based on 9-(3,6-diphenylpyridazin-4-yl)-4-azafluorene

The reaction of 9-(3,6-diphenylpyridazin-4-yl)-4-azafluorene with n-butyl acrylate under conditions of the Michael reaction affords the product of the condensation at the methine group. When sterically hindered esters of methacrylic, crotonic, and cinnamic acid are utilized, the condensation does not occur, and the main reaction product under these conditions is 9-hydroxy-(3,6-diphenylpyridazin-4-yl)-4-azafluorene. The supposition concerning the existence of its conformers (rotamers) with different orientation of the diphenylpyridazinyl ring in relation to the azafluorene fragment was expressed.

Film coating of pellets with insoluble polymers obtained in situ crosslinking in the fluidized bed

Abstract A novel technique for the manufacture of water-insoluble film coatings on drug-loaded saccharose pellets is described. The method is based on the simultaneous spraying of aqueous solutions of a film-forming polymer and an appropriate crosslinking agent. Crosslinking of the polymer was achieved in situ in the film during coating of the pellets in a fluidized bed. Uniform film coatings were formed without additives. Pan coating with sequential spraying of the components yielded similar results, however, it was more time consuming. The anionic polymer, sodium alginate, was combined with different cationic crosslinking agents, such as calcium ions, aluminum ions, Cetrimide (tetradecyltrimethylammonium bromide), and Eudragit E (copolymer of dimethylaminoethylmethacrylate and neutral methacrylic acid esters) (in 0.1 N HCl) in aqueous solutions. The swelling behavior of the cast films in water depended on the crosslinking component and the film thickness. For studying the in vitro drug release through the film coatings, the pellets were drug-loaded with acetaminophen and indomethacin as model drugs. Alginate films crosslinked with calcium ions showed the most promising features for controlled drug release. The release rate of the model drug acetaminophen proved to be almost independent of the pH of the dissolution fluid (pH 7.4 phosphate buffer, 0.1 N HCl). During drug release, the coatings did not disintegrate in 0.1 N HCl, but slowly disintegrated in buffer solution. Indomethacin was released at considerably smaller rates.

Syndiotactic-Specific Polymerization of Methacrylates by Tertiary Phosphine-Triethylaluminum

Polymerization of MMA with R3P-R3′Al in toluene at low temperatures was reinvestigated and was found to give highly syndiotactic PMMA. Among the initiators examined Ph3P-Et3Al gave the PMMA with highest syndiotacticity and the polymerization at −93°C yielded PMMA with rr content of 95%. PMMAs prepared with Et3P-Et3Al and Ph3P-Et3Al contained the structural unit comprised of the phosphine components at the chain end as evidenced by 31P and 1H NMR analyses. The results clearly indicate that R3P takes an important role in the initiation process, though R3P alone does not polymerize MMA. Methacrylic acid esters of primary and secondary alcohols were also polymerized by these initiators to give highly syndiotactic polymers. Block and random copolymers of MMA with several methacrylates were also obtained. The effect of syndiotacticity on the glass transition temperature (Tg) of PMMA was examined and Tg for 100% syndiotactic PMMA with infinite molecular weight was estimated to be 141°C.

Effect of the alkyl residues on the glass transition temperature of methacrylonitrile/alkyl methacrylate copolymers

The glass transition temperature of copolymers of methacrylonitrile with methyl, ethyl and butyl esters of methacrylic acid, together with those of the corresponding homopolymers, were determined by differential scanning calorimetry. The variation of the glass transition temperature (Tg) of copolymers with the composition of the samples was analyzed for each system on the basis of treatments suggested by Barton, Johnston and Suzuki-Mathot, determining the values of the glass transition temperature of the alternating diad (Tg12). It was observed in all the cases that the alternating diad presents a flexibility higher than that expected from the combination of both kinds of monomeric units according to the Tg of the corresponding homopolymers and that the Tg12 values decrease with the length of the side chain of the methacrylate ester in the system, as the Tg values of the polymethacrylates.

Synthesis of polymerizable xylitol derivatives

Polymerizable esters of methacrylic acid, acrylic acid and crotonic acid with di-O-isopropylidenexylitol as the alcohol component have been synthesized and characterized.

Kinetics and mechanisms of water sorption in hydrophobic, ionizable copolymer gels

AbstractThe aqueous kinetic swelling properties of a class of cross‐linked hydrophobic polyamine copolymer gels based on n‐alkyl esters of methacrylic acid (nAMA) and N,N‐dimethylaminoethyl methacrylate (DMA) have been studied as a function of solution ionic composition (pH, ionic strength, and buffer content), gel composition, and temperature. Water uptake and swelling in these gels are driven by ionization of the DMA amine groups, which overcomes the hydrophobic tendency of these gels to exclude water in the unionized state. Sorption kinetics in initially glassy gel disks are generally biphasic, characterized by an initial phase of relatively slow water uptake followed by an accelerated phase during which significant volume expansion of the gel occurs. This sorption/swelling behavior strongly suggests a moving penetrant front mechanism. The initial rate of water sorption increases markedly as (1) solution pH decreases, (2) gel nAMA comonomer content decreases, (3) gel nAMA side‐chain length decreases, and (4) temperature increases. Furthermore, the initial phase of sorption in initially glassy gels is generally non‐Fickian and approaches zero‐order behavior as (1) pH increases, (2) nAMA content increases, and (3) temperature decreases. In direct contrast, sorption in initially dry, rubbery gels is monophasic, but non‐Fickian, and approaches zero‐order behavior as temperature increases. This behavior is contrary to the Fickian sorption behavior normally observed in polymers above their glass transition temperatures. Finally, sorption kinetics critically depend upon the nature of the ions in solution: Kinetics are significantly faster in the presence of weak electrolytes than that of strong electrolytes. We discuss the importance of the rate of ion transport in determining the overall sorption kinetics and how sorption kinetics can be non‐Fickian in rubbery gels. Also, we propose a mechanism for the observed enhanced kinetics in the presence of weak electrolytes.

Liquid-phase polymerization of fluorine-containing esters of acrylic and methacrylic acid in a gamma radiation field

Basic kinetic characteristics of the process of radiation liquid-phase polymerization of fluorine-containing methacrylates and their hydrocarbon analogs have been compiled. The kinetics of the polymerization of fluorine-containing methacrylates is described well by a kinetic mechanism with quadratic termination of growing macromolecules and clearly expressed gel effect. The insertion of perfluorinated substituents into the methacrylate molecule evidently leads to a decrease of the rate constant of termination of the polymer chains. The kinetics of the polymerization of fluorine-containing acrylates, like their hydrocarbon analogs, differ significantly from the polymerization of maethacrylates by the absence of a quasisteady-state regime — the rate increases sharply from the very beginning of the process because of the diffusion character of termination.

Synthesis and polymerization of unsaturated derivatives of halogenated phenols

The preparation of p-styrenesulfonic and methacrylic acid esters of the microbiocides 2, 4, 6-trichlorophenol and 4-chloro-m-cresol, and their characterization by IR, 1H and 13C NMR spectroscopy are described. The radical homopolymerization of the biocidal monomers, and their copolymerization with various vinyl monomers have been studied. The polymerization gives polymers in which the microbiocide moieties are covalently attached to the polymer backbone chain by ester links.

Controlled Theophylline Release from Microcapsules of Acrylic & Methacrylic Acid Ester Copolymer

AbstractThe goal of this work was to develop a suitable method for microencapsulation of theophylline using copolymer of acrylate and methacrylate ester (EUDRAGIT) as the coating material. The effect of protective colloids on the process of microencapsulation was evaluated. The in vitro studies revealed significant control of drug release for the developed dosage form. Individually, the polymer coated drug particles of different core: coat ratio and different proportions of protective colloids were found to influence the pharmacokinetic parameters as revealed from the in vivo bioavailability studies in gastric-emptying controlled rabbits. In vivo bioavailability data were compared using Westlake's confidence limit.

Kinetics of (CO)polymerizations at the surface of inorganic submicron particles in emulsion‐like systems

AbstractHydrophilic TiO2 particles were modified with two different titanates and thus made hydrophobic. “Emulsion” polymerizations were carried out in aqueous dispersions of these particles, stabilized with an anionic surfactant. Polymerization kinetics were determined using a densitometer. The effect of several parameters, like surface modification, surfactant and initiator concentration, and stirring speed on polymerizations were studied. Depending on reaction conditions two competitive polymerizations can take place: one in which polymer is formed at the particle surface and one in which free polymer particles are formed. The TiO2 was modified with a titanate containing a methacrylic acid ester, which was used as a comonomer. Thus a chemical bond between TiO2 particles and polymer was obtained. These polymer encapsulated inorganic particles may offer interesting perspectives in those cases, where a good coupling between particles and matrix is important, for instance in latex paints and in polymer composites.

ChemInform Abstract: Thiocyanatoarylation of Acrylic and Methacrylic Acid Esters.

AbstractThe acrylic acid esters (II) react with the arenediazonium tetrafluoroborates (I) and potassium rhodanide (III) in the presence of copper(II) acetate to give the α‐thiocyanato β‐arylacetic acid esters (IV).

Synthesis of Polymerizable Hexose Derivatives

AbstractPolymerizable esters of methacrylic and acrylic acid with di‐O‐isopropylidenehexoses as alcohol components have been synthesized.

Preparation of monomers functioning as initiators and use of their polymers for graft copolymerization

AbstractNew types of esters of methacrylic acid functioning as radical initiators, α,α′‐azobis(α‐methylbenzyl) dimethacrylate (1) and 1,1′‐azobis(1‐methylethyl) dimethacrylate (2), were synthesized by reaction of the corresponding chlorides with salts of methacrylic acid. These monomers 1 and 2 were utilized to produce copolymers containing the respective azoinitiator units. Decomposition of the initiator units in the presence of a second monomer resulted in graft copolymers. Polystyrene and poly(methyl methacrylate) were grafted onto the polymers bearing α‐azo‐α‐methylbenzyl units. Poly(styrene‐graft‐diisopropyl fumarate) was prepared by decomposition of polystyrene containing 1‐azo‐1‐methylethyl units in the presence of monomeric fumarate at 150 and 180°C. The number of the grafting sites along the main chain was estimated on the basis of the molecular weight of the polymer, the content of the initiator unit, and the decomposition rate.

The Oxidation of Methacrylic Acid Esters with H2O2 in the Presence of Chromium Catalysts. A Novel Route to Pyruvic Acid Esters

Abstract The oxidation of methacrylic acid esters to pyruvic acid esters was carried out with aqueous H2O2 in CH3CN in the presence of a catalytic amount of chromium compounds such as Cr(III)(acac)3, chromium salts, and chromic acid. The oxidation of methyl methacrylate in the presence of chromic acid and triethylamine (1:1) gave an 82% conversion with a 72% selectivity to methyl pyruvate at 40 °C for 20 h.

Metal‐free Carbanion Salts as Initiators for the Anionic Polymerization of Acrylic and Methacrylic Acid Esters

Molecular weights of up to 20 000 are attained in the polymerization of butyl acrylates with the malonates 1; the ratio of weight average molecular weight to number average molecular weight is ≤ 1.3. The likewise metal‐free salts 2 and 3 also smoothly polymerize acrylic esters in THF or toluene at room temperature. The explanation for this behavior, which differs from that of the corresponding sodium or potassium salts, could be that metal ions are necessary as activators for the typical terminating reactions of anionic polymerization. Compounds 1–3 are readily accessible and may be stored for months at 0 °C. equation image

Characteristic Ratios of Polymethacrylates

Abstract Dilute solution properties of polymethacrylates have been studied extensively over the past 30 or so years. Probably more different polymethacrylates have been prepared and characterized than any other class of polymer. A major reason for this intense interest is the ease with which various methacrylate monomers can be prepared, e.g., by esterification of methacrylic acid with the appropriate alcohol or trans-esterification of methyl methacrylate. Also, most methacrylate monomers are easily polymerized to high molecular weights by free radical methods in bulk, in dilute solution, or in emulsion. These polymerizations are generally free of chain transfer reactions which lead to branching or cross linking, so long as conversion to polymer is kept at fairly low levels. Many methacrylates also polymerize via anionic mechanisms. Thus, linear polymethacrylates with a wide variety of side groups can be readily prepared.

Study on Radical Telomerization of Esters of Methacrylic Acid Using Bromotrichloromethane and Characteristics of the Resulting Telomers VI. Difunctional Methacrylates

The radical telomerization of vinyl (VMA) and allyl (AMA) methacrylates was carried out using bromotrichloromethane (BTCM) as a telogen at 50, 70, and 90°C. The m[Cl3CBr]:n[Monomer]adducts (m=1, 2, 3; n=1, 2) were fractionated by means of silica gel column chromatography. Compared with VMA, AMA was subject to addition of BTCM and telomerized with a lower average degree of telomerization. The addition of BTCM occurred on both the vinylidene and vinyl groups, but the vinylidene group was much more susceptible to addition of BTCM in preference to the vinyl group. Furthermore, the chain of dimeric adducts was exclusively made up by a vinylidene–vinylidene coupling. The successive addition reaction of BTCM to telomeric molecules increased with temperature, time, and quantity of 2,2′-azobisiso-butyronitrile (AIBN) as an initiator. In the telomerization at 90°C, however, the addition rate of BTCM decreased in response to rapid inactivation of AIBN. The lactonization of dimeric adducts (m=1, n=2) was induced by the catalytic action of silica gel or heating. The lactone yield of the AMA adducts was higher than that of the VMA one. The VMA adduct was preferentially oligomerized by pyrolysis at 150°C.

Study on Radical Telomerization of Esters of Methacrylic Acid Using Bromotrichloromethane and Characteristics of the Resulting Telomers V. Fluorenyl Methacrylates

The radical telomerization of vinyl (VMA) and allyl (AMA) methacrylates was carried out using bromotrichloromethane (BTCM) as a telogen at 50, 70, and 90°C. The m[Cl3CBr]:n[Monomer]adducts (m=1, 2, 3; n=1, 2) were fractionated by means of silica gel column chromatography. Compared with VMA, AMA was subject to addition of BTCM and telomerized with a lower average degree of telomerization. The addition of BTCM occurred on both the vinylidene and vinyl groups, but the vinylidene group was much more susceptible to addition of BTCM in preference to the vinyl group. Furthermore, the chain of dimeric adducts was exclusively made up by a vinylidene–vinylidene coupling. The successive addition reaction of BTCM to telomeric molecules increased with temperature, time, and quantity of 2,2′-azobisiso-butyronitrile (AIBN) as an initiator. In the telomerization at 90°C, however, the addition rate of BTCM decreased in response to rapid inactivation of AIBN. The lactonization of dimeric adducts (m=1, n=2) was induced by the catalytic action of silica gel or heating. The lactone yield of the AMA adducts was higher than that of the VMA one. The VMA adduct was preferentially oligomerized by pyrolysis at 150°C.