Methyl Acrylate Monomer Research Articles

How the interplay of different control mechanisms affects the initiator efficiency factor in controlled radical polymerization: An investigation using organometallic Mo III-based catalysts

Compound CpMoI 2( iPr 2dad) ( iPr 2dad = iPrN CH CH N iPr), obtained by halide exchange from CpMoCl 2( iPr 2dad) and NaI, has been isolated and characterized by EPR spectroscopy, cyclic voltammetry, and X-ray crystallography. Its action as a catalyst in atom transfer radical polymerization (ATRP) and as a spin trap in organometallic radical polymerization (OMRP) of styrene and methyl acrylate (MA) monomers has been investigated and compared with that of the dichloro analogue. Compound CpMoCl 2( iPr 2dad) catalyzes the ATRP of styrene and MA with low efficiency factors f (as low as 0.37 for MA and ethyl 2-chloropropionate as initiator), while it irreversibly traps the corresponding growing radical chains under OMRP conditions. On the other hand, compound CpMoI 2( iPr 2dad) has a greater ATRP catalytic activity than the dichloro analogue and yields f = 1 for MA and ethyl 2-iodopropionate as initiator. Under OMRP conditions, it does not irreversibly trap the growing radical chains. This comparison serves to illustrate the general principle that low initiator efficiency factors, sometimes observed in ATRP, may result from the interplay of the ATRP and OMRP mechanisms, when the latter ones involves an irreversible radical trapping process.

The measurement of thermal diffusivity in poly(methyl acrylate) by photoacoustic technique

AbstractIt is suggested that when a polymer is synthesized from a monomer and an added initiator in the presence of ultrasound, the process may produce polymers with predetermined structures and physical properties. An attempt is made to measure thermal diffusivity. Poly(methyl acrylate) (PMA) is synthesized using monomer methyl acrylate and an added initiator peroxodisulfate in the presence of ultrasound of frequency 35 kHz and power 100 W/cm2 at 50°C for various known sonication periods. PMA is obtained as a colorless, semitransparent solid. The solid PMA is cut into thin wafers in a highly symmetric direction to have uniform sizes. PMA samples are synthesized for 11 different sonication periods. These PMA samples are use to study their thermal diffusivity (α) by photoacoustic (PA) technique. Thermal diffusivity is calculated by measuring the amplitude and phase of the PA signal separately. A plot of the sonication period versus thermal diffusivity obtained from amplitude measurements of PMA indicates that there is an increase in thermal diffusivity from 2 × 10−6 to 4.7 × 10−6 m2/s when sonication period is increased from 30 to 330 min in steps of 30 min. The same trend is seen in a plot between sonication period and thermal diffusivity when the thermal diffusivity is calculated by PA phase measurements. There is a small difference in the experimental values obtained by the two measurements. Dependence of thermal diffusivity of PMA on ultrasonic sonication is discussed in detail. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 3756–3760, 2006

Synthesis and photoinitiation properties of a novel quaternary ammonium tetraphenylborate salt

AbstractQuaternary ammonium salts are photobase generators. Recently, we prepared a novel quaternary ammonium tetraphenylborate salt bearing a 6‐methoxynaphthoylmethyl group. The structure of the products was confirmed by elemental analysis and 1H‐NMR. Thermogravimetry showed its good thermostability. UV spectra and fluorescence emission spectra of the samples were studied. A mass spectrometry method for the analysis of the tertiary amine and other fragments produced by photolysis was established. Photolysis was found to produce both tertiary amine and free radicals. Therefore, the products of photolysis not only could cause thermal curing of epoxide but also could initiate the free‐radical polymerization of acrylate or methyl acrylate monomer. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 100: 399–405, 2006

Gradient or statistical copolymers by batch nitroxide mediated polymerization: effect of styrene/methyl acrylate feed

Monomer reactivity ratios in controlled radical copolymerization of styrene (S) and methyl acrylate (MA) monomers at 120 °C were determined. The Fineman–Ross method was used to calculate rs and rMA. Using this method, monomer reactivity ratio values of 0.89 and 0.22 were calculated for styrene and methyl acrylate, respectively. Because of the different reactivity ratios between the two monomers, and according to the molar fractions of two monomers, S/MA statistical or gradient copolymers were synthesized by nitroxide-mediated polymerization. Indeed, for different monomer ratios, the same statistical or gradient copolymers can be obtained by batch nitroxide mediated polymerization. These copolymers have been characterized by 1H nuclear magnetic resonance and size exclusion chromatography, and evolution of the composition has been correlated with the glass transition temperature measured by differential scanning calorimetry. Integrated intensities of the three observed peaks of (–OCH3) group in the 1H NMR spectra were used to determine the MA/MA/MA, MA/MA/S and S/MA/S triad sequences in the copolymers. Specific organization at the air/polymer interface of such copolymers has also been demonstrated by comparison between classical and attenuated total reflection (ATR) Fourier transform infra-red spectra.

Preparation and Characterization of Homo‐ and Co‐Polymers of Some Vinyl Monomers via ATRP by Using Imine Macrocycle as Ligand

Imine macrocyclic ligand M1 was involved in homo‐ and co‐polymerization of some vinyl monomers via atom transfer radical polymerization technique (ATRP). Hereby, vinyl acetate, styrene and methyl acrylate monomers were homopolymerized. On the other hand, they were involved in copolymerization with MMA. M1∶CuBr∶initiator∶monomer percentages were 1∶2∶4∶400. 1HNMR confirmed the structures of the resulting polymers. The thermal behaviors of some selected polymers were studied.

Polymerisation of Acrylates Catalysed by Methylaluminoxane Activated Ditertiary Phosphine Complexes of Iron and Cobalt Dichlorides

AbstractSummary: Diphosphane complexes of iron(II) are active catalysts for the polymerisation of methyl acrylate (MA) monomers in the presence of methylaluminoxane (MAO). High molar mass atactic MA polymers ($\overline M _{\rm n}$ ∼ 200 kg/mol) were obtained under mild conditions with relatively narrow polydispersities (PDI ∼ 2). Polymerisation activity and polymer molar masses are strongly dependent on the ligand frame. The polymerisation requires the coordination of MA to a vacant coordination site at the metal centre, and processes with chain‐transfer to aluminium. Cobalt analogues proved to be less efficient catalysts, giving activities in the range of 50–250 kg/mol · h instead of 200–450 kg/mol · h for the iron complexes. MAO activated FeCl2 and CoCl2 salts also perform the polymerisation of MA with low activity.Ditertiary phosphine complex of iron(II) chloride as methyl acrylate polymerisation catalyst.imageDitertiary phosphine complex of iron(II) chloride as methyl acrylate polymerisation catalyst.

Reactivity of Carbon-Centered Radicals toward Acrylate Double Bonds: Relative Contribution of Polar vs Enthalpy Effects

The different factors controlling the reactivity of a large series of carbon-centered radicals toward the methyl acrylate monomer unit were examined in detail by using molecular orbital calculations. In agreement with the state correlation diagram, the energy barrier is governed for a large part by the enthalpy term, as supported by an increase of reactivity with increasing exothermicity of the reaction. However, important polar effects, as evidenced by molecular calculations on the transition states, were also highlighted: they dramatically enhance the reactivity of the nucleophilic radicals (aminoalkyl or dialkylketyl radicals) as well as the electrophilic radicals (malonyl radical). Their contribution to the decrease of the barrier was evaluated by using a model based on chemical descriptors. This allows a clear separation of the relative role of the polar and enthalpy effects for 22 radicals.

Hydrogen (H)-complex formation of maleic anhydride–acrylic acid (methyl acrylate) monomer system

The results of the study of complex formation through H-bond between the –CO group of maleic anhydride (MA, electron-donor monomer) and the carboxyl group of acrylic acid (AA, electron-acceptor monomer) and the charge transfer complex between the double bond of MA and vinyl acetate (VA, electron donor monomer) using ultraviolet-visible spectroscopy (Uv-vis) and nuclear magnetic spectroscopy ( 1H NMR) methods are discussed. Maleic anhydride–methyl acrylate (MAc) monomer pair as a model system is also studied. The formation of two types of complexes in the MA–AA monomer system with further determination of their K H and K C values were studied using ultraviolet-visible spectroscopy (UV-vis) and 1H NMR spectroscopy and the following well known equations of Benesi–Hildebrand, Ketelaar and Hanna–Aushbaugh, respectively. The formation of H-complex in the MA–AA system is confirmed by the analysis of electronic spectra of free monomers and their various mixtures (MA≫AA) in dioxane at 25 °C. The equilibrium constant of the MA…AA charge transfer complex (CTC) formation was determined by 1H NMR in p-dioxane and acetone at 25 °C.

EFFECT OF PROCESS VARIABLES ON THE INITIATION TEMPERATURE AND EXOTHERMIC HEAT FOR THE COPOLYMERIZATION OF ACRYLONITRILE AND METHYLACRYLATE-I

Differential scanning calorimetry (DSC) experiments were carried out on a set of laboratory-synthesized copolymers of acrylonitrile/methylacrylate precursors meant for the manufacture of hollow-fiber carbon membranes. This was done to determine the effect of the polymerization process variables on the exothermic heat and exothermic initiation temperature. Factors such as methylacrylate monomer and azo-bis-isobutyronitrile (AIBN) initiator concentrations, stirrer speed and polymerization temperature were investigated as functions of the exothermic heat and the exothermic initiation temperature. An empirical approach was adopted that employed statistical experimental designs that were used to recognize analytical and statistical methods that translate the process responses into comprehensible terms. It was established that hollow-fiber carbon membranes can be reproducibly made by exercising very strict control over the polymerization conditions when using co-monomers of acrylonitrile (AN) and methylacrylate (MA). Process variables such as stirrer speed, polymerization temperature methylacrylate and azo-bis-isobutylonitrile concentrations influence the properties of the copolymer produced and hence the properties of any carbon membranes produced from a precursor manufactured from the copolymer. The effects of the factors investigated, or the interactions of these factors on the variations observed in the initiation temperature, was rather inconclusive. This was ascribed to the unavoidable variation in the mass of the material used for the calorimetry experiments.

THE INFLUENCE OF PROCESS VARIABLES ON THE MOLECULAR MASS OF AN/MA COPOLYMERS-II

Viscometry experiments were carried out on a range of laboratory-synthesized polyacrylonitrile precursors that were to be used for the manufacture of PAN/MA hollow-fiber carbon membranes. This was done to determine the effect of the polymerization process variables on the average molecular mass of copolymers of methylacrylate and acrylonitrile. Factors such as the concentrations of methylacrylate monomer (MA) and azo-bis-isobutyronitrile initiator (AIBN), stirrer speed and polymerization temperature were investigated as functions of the molecular mass. An empirical approach that employed statistical experimental designs, used to recognize analytical and statistical methods that translate the process responses into comprehensible terms was used. It was established that hollow-fiber carbon membranes can be reproducibly prepared if the polymerization conditions are controlled. Process variables such as stirrer speed, polymerization temperature, methylacrylate and azo-bis-isobutylonitrile concentrations influence the properties of the copolymer produced and hence the properties of the carbon membranes produced from precursors made from the copolymer. The highest molecular mass PAN was obtained when the concentrations of MA and AIBN were high, while a reduced polymerization temperature favored the synthesis of high molecular mass PAN. The stirrer speed had little or no effect on the molecular mass of the synthesized PAN-based materials. The process variables interactions were statistically processed with the “F-test” method. Interaction between the initiator, AIBN and temperature had a significant effect on the average molecular mass. Monomer MA concentration was of little significance.

Starch graft poly(methyl acrylate) loose-fill foam: preparation, properties and degradation.

Starch graft poly(methyl acrylate) (S-g-PMA) was prepared by ceric ion initiation of methyl acrylate in an aqueous corn starch slurry (prime starch) which maximized the accessibility of the starch for graft polymerization. A new ceric ion reaction sequence was established as starch-initiator-methyl acrylate followed by addition of a small amount of ceric ion solution when the graft polymerization was almost complete to quench the reaction. As a result of this improved procedure, no unreacted methyl acrylate monomer remained, and thus, essentially no ungrafted poly(methyl acrylate) homopolymer was formed in the final grafted product. Quantities of the high purity S-g-PMA so prepared in pilot scale were converted to resin pellets and loose-fill foam by single screw and twin screw extrusion. The use of prime starch significantly improved the physical properties of the final loose-fill foam, in comparison to foam produced from regular dry corn starch. The S-g-PMA loose-fill foam had compressive strength and resiliency comparable to expanded polystyrene but higher bulk density. The S-g-PMA loose-fill foam also had better moisture and water resistance than other competitive starch-based materials. Studies indicated that the starch portion in S-g-PMA loose-fill foam biodegraded rapidly, whereas poly(methyl acrylate) remained relatively stable under natural environmental conditions.

Refractive index modulation in polymeric photochromic films

AbstractPhotochromic properties of methylacrylate monomers and polymers containing azobenzene groups with heterocyclic sulfonamide functionalities viz sulfisomidyne (4-amino-N-[2,6-dimethylpyrimidyn-4-yl]benzenesulfonamide) and sulfamethoxazole (4-amino-N-[5-methylisoxazol-3-yl]benzenesulfonamide) substituents were investigated. On illumination with light the azobenzene group underwent trans-cis isomerisation, which was manifested by a drop in the absorbance of the maximum absorption peak at ca. 450 nm and by decrease in refractive index.Quantum chemical calculations showed significant differences in UV-VIS spectra, dipole moments, polarizability and refractive index between both cis and trans form of the chromophoric monomers.The illumination of spin-coated polymer films during ellipsometry measurements resulted in a change in refractive index within the range of 0.014 to 0.025. The dynamics of growth and decay of refractive index changes, was described by biexponential functions approach.

Influence of End Groups on Dendrimer Rheology and Conformation

Poly(propyleneimine) (PPI) dendrimers and their end-functionalized derivatives are studied with steady and dynamic rheology to determine the influence of specific end groups. Fourth- and fifth-generation PPI dendrimers exhibit constant shear viscosities over a wide range of shear rates. Function-alizing the molecular end groups with methyl and benzyl acrylate monomers increases the glass transition temperature and leads to a significant elastic modulus and nonlinear rheological behavior at high shear rates. The zero-shear viscosity, corrected for the shift in glass transition, exhibits a unique maximum with molecular weight. The fractional free volume derived from the thermal rheological measurements is independent of the end-group derivatization and substantially larger than that for linear polymers.

Substituted propenyl end groups as reactive intermediates in radical polymerization

AbstractThe addition of propagating radicals of methyl acrylate (MA) and styrene (St) to CH2C(CO2CH3)CH2 and CH2C(C6H5)CH2 ω‐end groups of poly(methyl methacrylate) (PMMA) and polystyrene (PSt) was investigated. The end groups were as reactive as MA and St toward the poly(methyl acrylate) (PMA) and PSt radicals, respectively. The adduct radical derived from the two types of PMMA end groups and PMA radicals underwent β fragmentation exclusively to yield PMMA radicals and end groups bound to PMA chains. The addition of PSt radicals to PMMA with CH2C(CO2Me)CH2 end groups resulted in adduct radicals that underwent β fragmentation and addition to St or coupling with PSt radicals. Adduct radicals formed by the addition of PMA radicals to both types of end groups of PSt exclusively formed CC bond by coupling with PMA radicals to form branched structures or by addition to MA monomer to give a copolymer. The fate of the adduct radicals was highly dependent on the type of polymer chain and the substituent bound to the end group. Steric congestion of the adduct radical arising from the α‐methyl group of the PMMA chain was considered to be crucial for fragmentation to expel the PMMA radical. © 2003 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 41: 645–654, 2003

Surface modification of jute yarn by photografting of low‐glass transition temperature monomers

AbstractJute yarns were grafted with three types of vinyl monomers of different functionalities such as methyl acrylate (MA), ethyl acrylate (EA), and 2‐hydroxyethyl acrylate (HEA) with ultraviolet radiation. The graft copolymerization reaction between the cellulose of the jute fibers and the monomer and the chemical environment of the treated fibers were confirmed by Fourier transform infrared spectroscopy. The reduction of OH groups and increment of >CO groups in treated jute yarns were observed. DSC studies showed that the treated jute fibers were more thermally stable compared to the untreated one. The surface topography of the yarns was analyzed by an environmental scanning electron microscope. Different parameters, such as concentration of monomers and irradiation time, were optimized with the extent of mechanical properties such as tensile strength and elongation at break of the jute yarn. MA, EA, and HEA produced enhanced tensile strengths of 87, 78, and 85%, respectively. The monomers MA, EA, and HEA showed improved elongations at break of 118, 91, and 76%, respectively. The water uptake of treated and untreated jute yarns were studied. The maximum water uptake was observed of the grafted sample compared to the untreated jute yarn. The effects of additives such as urea on mechanical properties were also studied. © 2002 Wiley Periodicals, Inc. J Appl Polym Sci 87: 993–1000, 2003

Atom transfer radical polymerization of acrylates in an ionic liquid: Synthesis of block copolymers

AbstractAtom transfer radical polymerization (ATRP) of acrylates in ionic liquid, 1‐butyl‐3‐methylimidazolium hexaflurophospate, with the CuBr/CuBr2/amine catalytic system was investigated. Sequential polymerization was performed by synthesizing AB block copolymers. Polymerization of butyl acrylate (monomer that is only partly soluble in an ionic liquid forming a two‐phase system) proceeded to practically quantitative conversion. If the second monomer (methyl acrylate) is added at this stage, polymerization proceeds, and block copolymer formed is essentially free of homopolymer according to size exclusion chromatographic analysis. The number‐average molecular weight of the copolymer is slightly higher than calculated, but the molecular weight distribution is low (Mw/Mn = 1.12). If, however, methyl acrylate (monomer that is soluble in an ionic liquid) is polymerized at the first stage, then butyl acrylate in the second‐stage situation is different. Block copolymer free of homopolymer of the first block (with Mw/Mn = 1.13) may be obtained only if the conversion of methyl acrylate at the stage when second monomer is added is not higher than 70%. Matrix‐assisted laser desorption/ionization time‐of‐flight analysis confirmed that irreversible deactivation of growing macromolecules is significant for methyl acrylate polymerization at a monomer conversion above 70%, whereas it is still not significant for butyl acrylate even at practically quantitative conversion. These results show that ATRP of butyl acrylate in ionic liquid followed by addition of a second acrylate monomer allows the clean synthesis of block copolymers by one‐pot sequential polymerization even if the first stage is carried out to complete conversion of butyl acrylate. © 2002 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 40: 2799–2809, 2002

Methylacrylate polymers with photochromic side chains containing heterocyclic sulfonamide substituted azobenzene

Methylacrylate monomers containing azobenzene groups with heterocyclic sulfonamide: sulfisomidyne (4-amino- N-[2,6-dimethylpyrimidyn-4-yl]benzenesulfonamide) and sulfamethoxazole (4-amino- N-[5-methylisoxazol-3-yl]benzenesulfonamide) substituents were synthesized. The monomers were used for preparation of homopolymers and copolymers with butyl 2-methylacrylate and 2-ethylhexyl acrylate. The materials obtained showed photochromic properties manifested by trans–cis isomerization of the side chain azobenzene fragments induced by illumination with unpolarized and polarized light. The decrease of the absorbance of the E( trans) form at ≈450 nm was observed and the materials tested were in form of thin films deposited onto glass. The isomerization of the polymers carried out during ellipsometric measurements showed the reversibility of the process in repeated illumination cycles with green laser light. The change of refractive index caused by illumination was in the range ≈0.005–0.008 as determined by ellipsometry.

Effects of Filler Particle/Elastomer Distribution and Interaction on Composite Mechanical Properties

Some new characterization results are reported for composites prepared from methyl acrylate monomer and from reinforcing silica particles at various degrees of dispersion. In some cases, 3-(trimeth...

Lyotropic liquid crystalline cellulose derivatives in blends and molecular composites

Solutions of cellulose tricarbanilate (CTC) in methyl acrylate (MA) and methyl methacrylate (MMA) were prepared. The MA and MMA monomers were subsequently polymerised to produce a series of molecular composites, in which the amount of CTC and the degree of substitution (DS) of the tricarbanilate groups were varied. The CTC solutions were studied using polarised microscopy and indicated isotropic behaviour in solutions with a CTC concentration of less than 33 wt%. Solutions of 33–45 wt% CTC were found to have a nematic texture and a chiral nematic texture was detected on shearing of 45 wt% solutions. The mechanical properties and morphologies of the composites were investigated using dynamic mechanical thermal analysis (DMTA), tensile testing and scanning electron microscopy. Tensile testing measurements illustrated the reinforcing behaviour of the CTC on the composite, with the initial modulus increasing by up to 250% at 45 wt% CTC. Scanning electron microscope (SEM) micrographs for composites with <45 wt% CTC revealed a one-phase system. DMTA measurements indicated the existence of a double T g at DS of the tricarbanilate of less than 3, with a single T g for composites containing cellulose with degrees of carbanilate substitution equal to 3. The 45 wt% CTC composite showed a broad relaxation process at 350 K and another relaxation at higher temperature (490 K) corresponding to the glass transition of the CTC itself. This result, which is indicative of phase separation, is consistent with the SEM micrographs showing distinctive layered structures within the film.

Polyrotaxanes by free‐radical polymerization of acrylate and methacrylate monomers in the presence of a crown ether

AbstractPoly[(methyl acrylate)‐rotaxa‐(30‐crown‐10)] (5) and poly[(methyl methacrylate)‐rotaxa‐(30‐crown‐10)] (6) were synthesized by azobisisobutyronitrile‐initiated free‐radical bulk polymerizations of the respective monomers in the presence of 30‐crown‐10 (1; equimolar; 5 times the monomer mass). For 5, 3.8 mass % (0.81 mol % with respect to the monomer) of the crown was incorporated versus 1.7 mass % (0.39 mol % with respect to the monomer) for 6. Control reactions with 18‐crown‐6, which is to small to be threaded, showed that chain transfer to the crown ethers was detectable only for the acrylate but was relatively negligible and spectroscopically distinct. The threading yields were much higher with these systems than with polystyrene, most likely because of the greater compatibility of the crown ether with these polar monomers and polymers and the consequent ability to carry out the polymerizations homogeneously in the absence of added solvent; however, the threading process was still essentially statistical. Therefore, the polymerization of methacrylate monomers 8a–8c based on tetraarylmethane moieties connected via diethyleneoxy or triethyleneoxy spacers was examined in the presence of 1 in the belief that the supramolecular semirotaxane monomer 9 formed statistically in situ could be captured more efficiently and produce higher threading yields, presumably of side‐chain polyrotaxanes, than the simple (meth)acrylate monomers. Azobisisobutyronitrile‐initiated polymerizations either neat or in toluene produced polyrotaxanes 10 with up to about 1.6 mass % and 2 mol % threaded crown ether, presumably trapped on the pendant stoppered side chains. Although primarily statistical in nature, the latter rotaxane syntheses afforded on a molar basis 3–7 times more efficient incorporation of 1 than styrene (0.33 mol %), methyl acrylate (0.81 mol %), or methyl methacrylate (0.39 mol %) monomers for the preparation of main‐chain polypseudorotaxanes and indeed even surpassed the 60‐crown‐20/polyacrylonitrile system (1.5 mol %). This was presumed to be due to the fact that the loss of the crown ether, once it was threaded onto the monomer to form 9 and the latter was polymerized, was either retarded (by the tetraphenylmethyl stopper in 10a) or prevented completely [by tris(p‐t‐butylphenyl)phenylmethyl stoppers in 10b and 10c]. © 2001 John Wiley &amp; Sons, Inc. J Polym Sci A: Polym Chem 39: 1978–1993, 2001