Methacrylic Homopolymers Research Articles

Maleic and Methacrylic Homopolymers with Pendant Dibutylamine or Dibutylamine Oxide Groups as Kinetic Hydrate Inhibitors.

Kinetic hydrate inhibitors (KHIs) are applied in oil and gas fields to prevent gas hydrate formation, most often in cold subsea flow lines. The main component in industrial KHI formulations is a water-soluble polymer with many amphiphilic groups of which the hydrophilic part is most commonly the amide functional group. In the last decade, we have investigated polyamine oxides as alternatives to polyamides due to the strong hydrogen bonding of the amine oxide group. Here, we report the KHI performance of maleic and methacrylic homopolymers with dialkylamine and dialkylamine oxide pendant groups. Performance screening experiments were conducted under high pressure with a Structure II-forming natural gas mixture in steel rocking cells using the slow (1 °C/h) constant cooling test method. Polymers with dibutylamine groups gave much better KHI performance than polymers with dimethylamine or diethylamine groups. Polyamines formed from polymaleic anhydride reacted with 3-(dibutylamino)-1-propylamine (DBAPA) or 2-(dibutylamino)-ethanol (DBAE) gave good water solubility and good KHI performance, probably due to self-ionization between the dibutylamino and carboxylic acid groups. The lack of self-ionization for the methacryl homopolymers of DBAPA and DBAE explains why these polymers are not water-soluble. Oxidation of the maleic or methacryl polyamines to polyamine oxides gave water-soluble polymers with good compatibility with brines (0.5-7.0 wt % NaCl), but only the DBAPA-based polyamine oxides gave improved KHI performance compared to the polyamines. Poly(3-(dibutylamino oxide)-1-propyl methacrylamide) gave a similar performance to commercial N-vinyl pyrrolidone:N-vinyl caprolactam 1:1 copolymer and without a cloud point in deionized water up to +95 °C.

Nitroxide mediated suspension polymerization of methacrylic monomers

Suspension polymerization offers a scalable route to the synthesis of poly(methacrylic) resins with controlled molecular weight and complex macromolecular architectures, as is demonstrated herein, using 3-(((2-cyanopropan-2-yl)oxy)(cyclohexyl)amino)-2,2-dimethyl-3-phenylpropanenitrile for the first reported synthesis of methacrylic homopolymers by nitroxide mediated suspension polymerization. The limits of bulk polymerizations are overcome such that both methyl methacrylate (MMA) and n-butyl methacrylate (BMA) are successfully polymerized to high conversion with control over the molecular weight up to 100,000g/mol and with a reasonably narrow molecular weight distribution. Partitioning of the nitroxide between the aqueous and organic phases leads to inhibition of polymerization in the aqueous phase and thus prevents the formation of small polymer particles by emulsion polymerization, allowing the aqueous phase to be recycled. Block copolymers can readily be made at solids content up to 40% by sequential monomer addition, offering the potential for scalable synthesis of controlled macromolecular architectures by NMP in aqueous media.

Cinchonidinyl-Based Acrylic and Methacrylic Homopolymers: Synthesis, Characterization, and Antibacterial Activity

The monomers (5-ethenyl-1-azabicyclo [2.2.2] octan-2-yl)-quinolin-4-ylmethyl acrylate (EAOQMA) and (5-ethenyl-1-azabicyclo [2.2.2] octan-2-yl)-quinolin-4-ylmethyl methacrylate (EAOQMMA) were synthesized by reacting (5-ethenyl-1-azabicyclo octan-2-yl)-quinolin-4-ylmethanol [cinchonidine] with acryloylchloride and methacryloyl chloride, respectively, in the presence of triethylamine. The homopolymers were synthesized by the free radical polymerization in tetrahydrofuran at 70 ± 2°C in nitrogen atmosphere using 2,2′-azobisisobutyronitrile as an initiator. The monomers and homopolymers were characterized by UltraViolet (UV), Fourier transform infrared, Proton-Nuclear Magnetic Resonance (1H NMR), and Carbon-13 Nuclear Magnetic Resonance (13C NMR) spectroscopic techniques. The glass transition temperature (Tg, °C) was determined by differential scanning calorimetry. The thermal stability of the poly(EAOQMMA) was performed by thermogravimetric analysis, which showed higher thermal stability of about 706°C than that of poly(EAOQMA). The antibacterial activity of monomers and polymers has been evaluated by determining the inhibitory zone diameters against Gram-positive bacteria (Staphylococcus aureus) and Gram-negative bacteria (Pseudomonas aeruginosa), in which cinchonidine acrylate and Cinchonidine methacrylate homopolymer showed better activity than their corresponding monomers. Surface morphology of the monomers and polymers were examined by Scanning Electron Microscope (SEM) analysis.

Synthesis and characterization of diblock and statistical copolymers based on hydrolyzable siloxy silylester methacrylate monomers

Statistical and diblock copolymers of bis(trimethylsiloxy)methylsilyl methacrylate (MATM2), a hydrolyzable monomer containing a silylester and a siloxane group, and methyl methacrylate (MMA) were synthesized by the RAFT process. The controlled character of the MATM2 RAFT polymerization using 2-cyanoprop-2-yl-dithiobenzoate (CPDB) or S-(2-cyanoprop-2-yl)-S-dodecyltrithiocarbonate as chain transfer agents was assessed by linear pseudo-first-order kinetics, linear molar mass growth with monomer conversion and low molar-mass dispersity. The hydrolysis kinetics of pMATM2 homopolymers was investigated by in situ1H-NMR and compared to several methacrylic homopolymers bearing hydrolyzable tri-alkylsilylester side groups. pMATM2-block-pMMA diblock copolymers were synthesized by in situ chain extension with methyl methacrylate, using pMATM2-CPDB as a macro-CTA. p(MATM2-stat-MMA) statistical copolymers were synthesized by simultaneous polymerization of MATM2 and MMA by the RAFT process. The monomer reactivity ratios for MATM2 (r1 = 1.29) and MMA (r2 = 0.62) were obtained from the Mayo Lewis equation using the least-squares method. All the copolymers synthesized by the RAFT process had molar masses close to the targeted values and low dispersities (ĐM < 1.15). DSC analysis and contact angle measurements revealed the influence of the copolymer microstructure (statistical or diblock) on their glass transition temperature and surface energy.

A first insight into the thermal degradation mechanism of silylated methacrylic homopolymers synthesized via the RAFT process

The mechanism of thermal degradation of two series of methacrylic-based polymers was investigated. Unconventional methacrylic homopolymers bearing a tert-butyldimethylsilyl ester group were synthesized by Reversible Addition–Fragmentation chain Transfer (RAFT) and conventional free radical polymerizations using 2,2-azobis(isobutyronitrile) as initiator. 2-Cyanoprop-2-yl dithiobenzoate (CPDB) was used as chain transfer agent (CTA) in the RAFT process. The thermal stability of this polymer family was compared to the well-known thermal behavior of poly(methyl methacrylate) PMMA under nitrogen atmosphere. RAFT- and free radically-synthesized polymers were studied by non-isothermal thermogravimetric experiments (TGA). TGA data revealed two main degradation stages for all polymers. The chain transfer agent was shown to limit the production of unsaturated polymer end-groups during polymerization and consequently the thermal stability of the resulting RAFT-polymers was enhanced. Depolymerization was the main thermal degradation mechanism of silylated polymers associated with a side-group elimination for RAFT-synthesized polymers. Pyrolysis–Gas chromatography–Mass spectrometry (Py–GC/MS) experiments clearly demonstrated the formation of volatile tert-butyldimethylsilanol and bis(tert-butyldimethylsiloxane) side-products.

Synthesis and photoresponsive behavior of optically active methacrylic homopolymers containing side-chain spiropyran chromophores

Abstract Novel optically-active methacrylic homopolymers bearing in the side chain one or more chiral groups of one single configuration (based on the l -lactic acid residue) linked to the spiropyran chromophore, have been successfully synthesized and fully characterized. These intrinsically chiral polymers exhibit remarkable thermal stability, with glass transition temperatures in the range 100–130 °C and decomposition temperatures around 270 °C. The chiroptical characterization indicates the occurrence of asymmetric induction on the electronic transitions of the side-chain chromophore related to the number of l -lactic acid residues interposed between the main chain and the spiropyran chromophore. In the presence of acid, these systems can be used to modulate the protonation of polymeric azopyridine moieties upon photoisomerization of the spiropyran group. In addition to UV–Vis spectroscopy, the proton transfer process occurring between the macromolecular components can be also followed by CD spectroscopy, the system thus behaving as a chiroptical switch.

Fragmentation pathways of methacrylic homopolymers with labile trialkylsilyl ester side-groups—A mass spectrometric investigation of the RAFT process

Fragmentation pathways of methacrylic polymers containing labile silyl ester pendant groups were characterized upon collisional activation of electrosprayed oligomer adducts. Dissociation of lithiated oligomers mainly generated low mass product ions containing the α end-group and arising from backbone bond homolytic cleavages, as typically observed for poly(alkylmethacrylate)s. Combined with the sum of the end-group masses as determined from MS data, this main reaction allowed both end-groups to be validated. In contrast, loss of HCOOR (with R = triisopropylsilyl) or elimination of alkene species from alkylsilyl groups, such as reported from poly(butylmethacrylate), was not observed here, probably due to steric hindrance of the pendant moieties. Activation of ammonium oligomer adducts was found to provide highly complementary information, since they exhibited a similar behavior as compared to poly(methacrylic acid), with serial eliminations of a triisopropylsilanol neutral conducting to the determination of the polymerization degree of the dissociating precursor ion. It should be noted however that this useful pathway was not always observed to efficiently compete with dissociation of reactive ω end-groups. Based on these fragmentation rules, five poly(triisopropylsilyl methacrylate)s were identified in a sample obtained via reversible addition-fragmentation chain transfer (RAFT) polymerization using cyanoisopropyl dithiobenzoate as the chain transfer agent. Their structure could be rationalized with regards to RAFT processes: (i) dormant chains initiated by a cyanoisopropyl group and terminated by a dithiobenzoate group, as the main species; (ii) proton- and (iii) vinyl-terminated dead chains produced by disproportionation termination events; (iv) α,ω-cyanoisopropyl-terminated polymer chains arising from a combination termination between two macromolecular propagating radicals, and (v) dormant chains containing methacrylic acid monomer units within the chain.

Novel optically active methacrylic polymers containing side-chain porphyrin moieties for chiral recognition

Novel optically active methacrylic homopolymers bearing in the side chain one or more chiral groups of one single configuration ( l-lactic acid residue) linked to tetraphenylporphyrin have been successfully synthesized and fully characterized. These intrinsically chiral polymers exhibit remarkable thermal stability, with glass transition temperature in the range 250–315 °C and decomposition temperatures in the range 360–390 °C. Spectroscopic, thermal and chiroptical characterizations indicate the occurrence of dipolar interactions among the side chain moieties and the presence of chiral helix conformation at least for chain segments of the macromolecules. The macromolecular Zinc-porphyrin material resulted capable to bind optically active α,ω-diamine guests through nitrogen/zinc coordination to form complexes exhibiting exciton-coupled bisignate Circular Dichroism (CD) spectra with signs related to the absolute configuration of the guest compound. This behavior is due to the formation of diastereomeric complexes which lead to a preferred porphyrin helicity, at least for chain segments. The method turns out to be very sensitive, requiring only few micrograms of guest compound.

Photoinduced supramolecular chirality in glassy nematic linear and star shaped methacrylic azopolymers obtained by ATRP

AbstractThe induction of chirality in achiral liquid crystalline azoaromatic polymers with circularly polarized light (CPL) has been studied on well-defined macromolecular derivatives with different molecular structures, synthesized by atom transfer radical polymerization (ATRP). Two methacrylic homopolymers have been investigated: a linear and a three arms star polymer. Both the polymeric samples are featured by low polydispersity and similar average polymerization degree, so that structure-properties correlations are made possible. Irradiation with CPL of one handed rotation sense of casted films and a planar cell of these polymers in the glassy nematic phase allowed to ascertain by UV-Vis and CD spectroscopy the formation of a supramolecular chiral structure with high chirality induced into the material. The results are interpreted in terms of the structural features of the polymers.

Synthesis by ATRP and effects of molecular weight on photomechanical properties of liquid crystalline polymers containing side-chain azobenzene chromophores

The synthesis of a series of azobenzene containing liquid crystalline methacrylic homopolymers, poly(4-ω-methacryloyloxy-hexyloxy-4′-ethoxyazobenzene) [Poly( M6A)], with distinct average chain lengths and low polydispersity has been achieved by Atom Transfer Radical Polymerization (ATRP) in THF solution using allyl 2-bromoisobutyrate as initiator and Cu(I)Br as catalyst. Under the adopted conditions the living centers concentration is found to be constant throughout the polymerization process and well defined chain end-groups are obtained. All the obtained polymeric samples, having average molecular mass ( M ¯ n ) ranging from 3300 to 14000 g/mol, exhibit smectic and nematic liquid-crystalline phases on heating, with transition temperatures strongly dependent on polymerization degree, as characterized by differential scanning calorimetry and polarized optical microscopy. The photomechanical effects (i.e. the dependence of volume and density) exhibited upon trans-to- cis and cis-to- trans photoisomerization of the azobenzene mesogenic groups have been investigated by ellipsometry and related to molecular weight, with particular attention to important parameters for potential applications such as the relative variation of total volume, response time, stability and reproducibility.

Synthesis and chiroptical properties of optically active polymer liquid crystals containing azobenzene chromophores

AbstractA series of optically active methacrylic homopolymers, poly[(4‐{4′‐[(S)‐2‐methyl‐1‐butyloxycarbonyl]phenylazo}phenoxyl)x‐methylene methacrylate] (x = 0, 2, 6, or 11), were synthesized. The structures of the polymers were characterized by IR, 1H NMR, UV, differential scanning calorimetry, and gel permeation chromatography. The chiroptical properties of the polymers in films were investigated with circular dichroism (CD) measurements. The CD and UV spectra of the films suggested that CD absorptions occurred in the films of the polymers with long spacers (x = 6 or 11) but not in the films of the polymers with short spacers (x = 0 or 2). After irradiation with linearly polarized light at 442 nm, the CD values were amplified in all the polymeric films. The amplificatory values of the CD bands in the absorption region (260–360 nm) of azobenzene chromophores suggested that the spacer length had an effect on both the transfer of chirality and photoinduced chirality in the polymeric films. The largest level of photoinduced chirality was induced in the polymer containing six methylene units. © 2006 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 44: 3210–3219, 2006

Non-linear Optical Properties of Liquid Crystalline Azobenzene Polymeric Films

Non-linear optical (NLO) properties of thin films of two methacrylic homopolymers and a copolymer with cyano azobenzene chromophores in the side chain have been studied by second harmonic generation (SHG) measurements. The intensity of the harmonic signal from in-situ Corona poled polymeric films has been measured at different temperatures. The effect of 488 nm light irradiation on the azo chromophores orientation and consequently on the non-linear response of the films was investigated at several temperatures. The intensity and thermal stability of the remaining second harmonic signals obtained after the two different (thermal and photoassisted) Corona poling processes have been compared. The second order non linear coefficients have been obtained by the Maker fringes method.

Optically active polymers bearing side-chain photochromic moieties: synthesis and chiroptical properties of methacrylic homopolymers with pendanttrans-azobenzene chromophores bound throughL-leucine,L-valine andL-proline amino acid spacers

Novel optically active monomers, based on different L-amino acid residues such as trans-(S)-4-(2-methacryloylamino-3-methylbutanoylamino)azobenzene and trans-(S)-4-( N-methacryloyl-2-pyrrolidinoylamino)azobenzene, have been prepared and homopolymerizd by free radical initiation. Circular dichroism spectra of the resulting polymers, as compared with those of the corresponding low molecular weight analogues, purposely synthesized, allow one to suggest that the macromolecules assume in solution achiral or chiral conformations with a prevailing screw sense, depending on the bulkiness and rigidity of the L-amino acid residue present in the side chains. The role of intra- and/or intermolecular hydrogen bonding between side-chain amido groups along the backbone and the structural requirements of the chiral groups in determining the macromolecular arrangement in also discussed.

Optically active polymethacrylates with side-chain l-lactic acid residues connected to push–pull azobenzene chromophores

Novel optically active methacrylic homopolymers with side-chain l-lactic acid moieties interposed through ester bonds between the main chain and trans-4-azobenzene chromophores bearing in the 4′-position electron withdrawing groups, such as the cyano and nitro residues, have been synthesized and structurally characterized. Investigation by circular dichroism of the chiroptical and conformational properties of the polymers in solution indicates a much higher optical activity of these latter with respect to that of the corresponding low molecular weight model compounds, purposely prepared, due to the presence of dissymmetric conformations of one prevailing handedness. The trans to cis photoisomerization kinetics of the azoaromatic double bond has been measured in solution for polymers and models and the resulting data compared with those of previously reported similar photochromic derivatives. The influence of the nature of the electron withdrawing group in the 4′-position of the azobenzene chromophore on the chiroptical properties of the polymers is also discussed.

A Study on Langmuir Monolayers of Methacrylate Homo- and Copolymers Derivatized with Disperse Red Dyes

AbstractWe report on the organization of different disperse red dye derivatized methacrylate homo- and copolymers as Langmuir monolayers at the air-water interface. The monolayers were investigated using surface pressure and surface potential isotherms. Methacrylic homopolymers containing disperse red-1 (HPDR1) and disperse red-13 (HPDR13) and methacrylic copolymers with different mole percentages of the dye and hydroxyethyl spacer groups were synthesized and characterized. A comparison of the monolayer characteristics of HPDR1 and HPDR13 revealed the influence of the chlorine substitution in the aromatic ring of the dye. Studies with copolymers indicated a clear transition in the monolayer behavior with the change of mole percentage of the dye incorporated in the polymer. While copolymers with low dye content (up to about 5 mole%) presented an expanded monolayer, the copolymers containing higher dye content (12% and above) formed a condensed monolayer similar to that of the homopolymer. These results indicated the critical role of the dye component in the polymer chain in forming the monolayer at the air-water interface.

Structure and wettability of methacrylic polymers with fluorinated side chains

Surface properties of methacrylic homopolymers and copolymers with a random distribution of pendant perfluorinated groups R F  C nF 2n+l have been studied. These polymers are obtained by radical polymerization in solution or emulsion of fluorinated monomers (M F) CH 2  C (CH 3) CO 2 (CH 2) 2 R F with various hydrogenated comonomers (M H). Surface tensions are estimated according to the length of R F groups (n = 4, 6, 8), the fluoromonomer concentration [ M F ] in copolymers and the chemical structure of comonomers M H (MMA, BMA …), by different methods: Zisman's ( γC), geometric and harmonic mean approximation. Wettability measurements can provide useful information about the structure of polymeric surfaces. The tensiometric method used for wetting measurements reveals an abnormally large hysteresis effect between advancing and receding contact angles when the polymer surface is in contact with water. This effect is markedly decreased by the length of the R F group from n = 4 or 6 to 8 and by the concentration of fluoromonomer units in copolymers. The evolution of the surface properties of the polymer in contact with a polar liquid (water) can be explained by the reorganization and the reorientation of hydrophilic moieties of the macromolecules at the interface. At the polymer — air interface the fluorinated chain packing control the surface wettability. Hydrophilic ester groups of methacrylic units are buried in the bulk of the polymer, thus the polymer surface is different from its bulk. The evolution of surface energy cannot be explained by adsorption or absorption of water. A study by DSC has therefore been undertaken to correlate hysteresis with the potential organization of R F groups at the polymer — liquid interface and crystallinity of fluoropolymers.

Phase behaviour in molten blends of poly(vinyl choride) and methacrylic homopolymers or copolymers

Phase behaviour in molten blends of poly(vinyl choride) and methacrylic homopolymers or copolymers

Analysis of polymer surfaces by SIMS. 12. On the fragmentation of acrylic and methacrylic homopolymers and the interpretation of their positive and negative ion spectra

AbstractThe positive and negative ion spectra from homologous series of alkyl methacrylate, hydroxyalkyl methacrylate and alkyl acrylate polymers; poly (methacrylic acid) and poly(methacrylic anhydride) are reported. A systematic interpretation of the spectra can be accomplished on the basis of fragmentation pathways consistent with the known effects of other ionizing radiations. The negative ion spectra, previously little studied, are a powerful probe of structure for this class of polymer.

Ultraviolet irradiation of poly(alkyl acrylates) and poly(alkyl methacrylates)

AbstractAcrylic and methacrylic homopolymers containing different side groups were irradiated with ultraviolet light in the presence of air. The changes of molecular weight distributions of the irradiated polymers were analyzed by means of gel permeation chromatography (GPC), and the rates of chain scission and crosslinking were estimated. As the result of this study, it was found that chain scission takes place more easily in polyalkyl methacrylates than in polyalkyl acrylates.