Utilizing matrix-assisted laser desorption/ionization-collision induced dissociation for the generation of structural information from poly(alkyl methacrylate)s

Matrix-assisted laser desorption/ionization-collision induced dissociation (MALDI-CID) has been employed for the analysis of poly(alkyl methacrylate)s in a tandem hybrid sector-time of flight instrument. Spectra are shown for adducts of poly(ethyl methacrylate) and poly(butyl methacrylate) with sodium ions. It is proposed that the masses of the end groups may be inferred from the data for the polymers. Mechanisms are proposed for the formation of some of the series of ion peaks that are observed in the MALDI-CID spectra.     

Relative reactivity of chloroprene and methyl methacrylate toward initiator radicals

The relative rates of addition of chloroprene (CP) and methyl methacrylate (MMA) toward small model radicals structurally similar to the poly(MMA), poly(methacrylonitrile) and poly(styrene) radical was investigated following the method of Bevington and Huckerby [J Polym Sci Polym Chem 20 (1982) 2655]. Results indicate that these small radicals are significantly more selective toward CP than the corresponding polymer radicals, consistent with earlier reports that penultimate unit effects may be important in the copolymerisation of CP with MMA and styrene. As previous investigations of substituted dienes by the end-group method have given similar results for polymer radicals and small model radicals, this may constitute evidence for a penultimate unit effect that is predominantly electronic rather than steric in origin.     

Ultrasonic Modification of Polymers. II. Degradation of Polystyrene,Substituted Polystyrene,and Poly(n-vinyl Carbazole) in the Presence of Flexible Chain Polymers

Abstract

Ultrasonic (20 kHz, 70 W) solution degradations of polystyrene, substituted polystyrenes, and poly(n-vinyl carbazole) have been carried in toluene and tetrahydrofuran at 27 and -20°C in the presence of flexible chain polymers. Polystyrene formed block copolymers at 27°C with stiff-chain polymer PVCz; however, in the presence of flexible chain polymers, e.g., poly(vinyl methyl ketone) or poly(vinyl methyl ether), there were no block copolymers formed. Poly(n-vinyl carbazole) does not seem to form any block copolymers at 27°C with flexible chain polymers, e.g., poly(octadecyl methacrylate) and poly(ethyl methacrylate). Poly(p-chlorostyrene) and poly(p-methoxystyrene) also do not form block copolymers at 27°C with poly(octadecyl methacrylate) but do so with poly(hexadecyl methacrylate). It is quite possible that these may only be blends of two homopolymers. Poly(octa-decyl methacrylate) does yield a block copolymer when sonicated at -15°C with poly(p-isopropyl α-methylstyrene).     

Silica nanoparticle covered with mixed polymer brushes as Janus particles at water/oil interface

Silica nanoparticles (NSiO₂) are modified with mixed polymer brushes derived from a block copolymer precursor, poly(methyl methacrylate)-b-poly(glycidyl methacrylate)-b-poly(tert-butyl methacrylate) with short middle segment of PGMA, through one step ??grafting-onto?? approach. The block polymer precursors are prepared via reversible addition?Cfragmentation chain transfer-based polymerization of methyl methacrylate, glycidyl methacrylate, and tert-butyl methacrylate. The grafting is achieved by the reaction of epoxy group in short PGMA segment with silanol functionality of silica. After hydrolysis of poly(tert-butyl methacrylate) segment, amphiphilic NSiO₂ with ??V-shaped?? polymer brushes possessing exact 1:1 molar ratio of different arms were prepared. The functionalized particles self-assemble at oil/water interfaces to form stable large droplets with average diameter ranging from 0.15?±?0.06 to 2.6?±?0.75?mm. The amphiphilicity of the particles can be finely tuned by changing the relative lengths of poly(methyl methacrylate) and poly(methacrylic acid) segments, resulting in different assembly behavior. The method may serve as a general way to control the surface property of the particles.     

Miscibility of Halogen-containing Polymethacrylates with Various Poly(alkyl acrylate)s

The miscibility behavior of a series of halogen-containing polymethacrylates with poly(methyl acrylate), poly(ethyl acrylate), poly(n-propyl acrylate) and poly(n-butyl acrylate) was investigated by differential scanning calorimetry and for lower critical solution temperature (LCST) behavior. Poly(chloromethyl methacrylate), poly(1-chloroethyl methacrylate), poly(2-chloroethyl methacrylate), poly(2,2-dichloroethyl methacrylate), poly(2,2,2-trichloroethyl methacrylate), poly(2-fluoroethyl methacrylate) and poly(1,3-difluoroisopropyl methacrylate) are miscible with some of the poly(alkyl acrylate)s. Most of the miscible blends show LCST behavior. However, poly(3-choloropropyl methacrylate), poly(3-fluoropropyl methacrylate), poly(4-fluorobutyl methacrylate), poly(1,1,1,3,3,3-hexafluoroisopropyl methacrylate), poly(2-bromoethyl methacrylate) and poly(2-iodoethyl methacrylate) are immiscible with any of the poly(alkyl acrylate)s studied. © 1997 John Wiley & Sons, Ltd.     

Phosphorescence of thermally oxidised poly(butadiene) and model enones: temperature dependence

The temperature dependence of phosphorescence of model enone compounds in poly (methyl methacrylate) matrix and glassy methylcyclohexane/isopentane solution and of enones formed from thermal oxidation of poly (butadiene) has been studied over the temperature range 77–220°K. The single discontinuity in the plot for the model enone-glassy solvent is due to the freezing of a (solvent perturbed) barrier to rotation in the enone, and an analogous transition is also observed in the model enone poly (methyl methacrylate) samples and in thermally oxidised poly (butadiene). In the polymer matrices, a second transition corresponding to the γ-transition in poly (methyl methacrylate) and the glass transition temperature T_g in poly (butadiene) are also revealed in the Arrhenius plots. The results demonstrate that care must be taken in ascribing such discontinuities solely to polymer properties since intrinsic properties of the luminescence probe itself may exhibit similar features.     

THE COMPATIBILITY OF BLENDS OF POLY(VINYL CHLORIDE) OR CHLORINATED POLY(VINYL CHLORIDE) WITH POLY(METHYL METHACRYLATE)

IR spectral shifts of carbonyl vibrational absorption for ethyl acetate, which acts analogically as the structural unit of poly(methyl methacrylate), in cyclohexane, chloroform, chlorinated paraffins, poly(vinyl chloride) and chlorinated poly(vinyl chloride) were measured. The results suggest that there are specific interactions between the carbonyl groups and the chlorinated hydrocarbons which could be responsible for the apparent compatibility of poly(vinyl chloride)—poly(methyl methacrylate) and chlorinated poly(vinyl chloride)—poly(methyl methacrylate) blends. Additionally, the effects of the preparation mode of blend films on phase separation and observed compatibility are discussed.     

Synthesis of tritium labelled monomers and polymers

The use of P₂O₅ for promoting the tritiation of various monomers and polymers has been investigated. Methyl methacrylate and vinyl acetate may be labelled at ambient temperatures by this procedure which is also applicable to labelling polystyrene and poly(α-methylstyrene). Exchange labelling of polymer substrates is most conveniently carried out in chlorinated hydrocarbons. The rate of tritium exchange increases with solvent polarity and temperature. Monomers of high radiochemical purity may be derived from the thermal depolymerization of tritiated polystyrene, poly(α-methylstyrene) and poly(methyl methacrylate).     

Versatile ω‐end group functionalization of RAFT polymers using functional methane thiosulfonates

Five different polymers, poly[methyl methacrylate] (PMMA), poly[lauryl methacrylate] (PLMA), poly[diethylene glycol methacrylate] (PDEGMA), poly[N‐isopropylacrylamide] (PNIPA), and poly[styrene] (PS) prepared by the RAFT process and thus terminated with dithioesters were aminolyzed in the presence of S‐3‐butynyl methane thiosulfonate (MTS), which was synthesized in two steps. Analysis of the polymers by 2D NMR, UV–vis absorbance, and gel permeation chromatography revealed them to quantitatively carry acetylene end groups connected with disulfide bridges, indicating that functional MTS reagents can be employed for end group functionalization of RAFT polymers. This versatile method is of advantage compared with conjugations with functional maleimides, where isolation of terminal thiols is often required but inexpedient for poly[(meth)acrylates] because their terminal thiols may undergo backbiting and thus avoid conjugation. The acetylene‐terminated polymers were bound to an azide functionalized glass surface in a Cu(I) catalyzed cycloaddition. The modified surfaces exhibited water contact angles corresponding to the polarity of the attached polymers. In the case of the stimulus responsive polymers PNIPA and PDEGMA, the surfaces showed temperature‐dependent contact angles. The disulfide bond connecting the polymers to the surface could be selectively cleaved and resulted in all surfaces having the same contact angle, independent of the nature of the polymer prior attached to the surface. © 2009 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 47: 3118–3130, 2009     

DSC analysis of compatibility of poly(phenyl methacrylate) and some poly(xylenyl methacrylates)

Glass transition temperatures of blends of (1) poly-(phenyl methacrylate) and poly(2,3-xylenyl methacrylate), (2) poly-(phenyl methacrylate) and poly(2,6-xylenyl methacrylates and (3) poly-(2,3-xylenyl-) and poly(2,6-xylenyl methacrylate) were measured. The data obtained suggest the existance of compatibility for blends of poly(xylenyl methacrylates) mentioned and incompatibility for both poly(phenyl methacrylate)/poly(xylenyl methacrylate) systems.     

Liquid chromatography of polymer mixtures applying a combination of exclusion and full adsorption mechanisms. 5. Six-component blends of chemically similar polymers

The separation of six-component blends of chemically similar homopolymers utilising the full adsorption-desorption (FAD) process is presented. The main advantage of the FAD approach over other methods represents the successive and independent size- exclusion chromatography (SEC) characterisation of all blend components. The method is based on the full adsorption and retention of all n or n−1 components of the polymer blend from an adsorption promoting liquid (ADSORLI) in a small FAD column. Nonadsorbed macromolecules are forwarded directly into SEC for molecular characterisation. Next, appropriate displacers are successively applied to the FAD column to selectively release preadsorbed blend constituents into the on-line SEC column. Dynamic integral desorption isotherms for single constituents, as well as for polymer blends to be analysed, allow identification of optimal displacer compositions to release just one kind of macromolecule. Model polymer blends containing polystyrene (PS), poly(lauryl methacrylate), poly(butyl methacrylate), poly(ethyl methacrylate), poly(methyl methacrylate) and poly(ethylene oxide) (PEO) or, alternatively, PS, poly(2-ethylhexyl acrylate), poly(butyl acrylate), poly(ethyl acrylate), poly(methyl acrylate) and PEO of similar molar masses can be separated and characterised in one multistep run using nonporous silica FAD packing, toluene as an ADSORLI and its mixtures with a desorption promoting liquid such as ethyl acetate, tetrahydrofuran or dimetylformamide to form displacers with appropriate desorption strength. Received: 9 September 1998 Accepted in revised form: 16 November 1998     

Suspension Graft Polymerization of Methyl Methacrylate onto Selected Backbones

Methyl methacrylate was grafted onto poly(vinyl oxazoline ester) and poly(stearyl methacrylate) by a chain transfer suspension polymerization method to produce specialty polymeric products. These graft polymers should find application in powder coating, toner resin, and for encapsulating electronic components.     

白蛋白原位复合生物医用功能材料的研究(Ⅰ)──材料的合成和表面结构研究

采用大分子单体技术合成了以聚甲基丙烯酸甲酯为主链,聚氧乙烯链为侧链,末端为白蛋白诱导吸附基团的十八烷基功能聚合物聚甲基丙烯酸甲酯接枝十八烷基聚氧乙烯.采用变角X光电子能谱和表面接触角研究了该功能聚合物在空气和水界面的性质.结果表明,在聚合物-空气界面,十八烷基聚氧乙烯(SPEO)的表面含量随表面层厚度的降低而升高,并在表面发生高度富集.在聚合物-水界面,聚合物表面重组行为较弱,形成了高SPEO含量的疏水表面,该SPEO尾形结构表面预期可发挥聚氧乙烯和十八烷基的协同作用,形成白蛋白原位复合的生物医用功能材料.     

Structure of water incorporated in sulfobetaine polymer films as studied by ATR-FTIR

The structure and hydrogen bonding of water in the vicinity of a thin film of a sulfobetaine copolymer (poly[(N,N-dimethyl-N-(3-sulfopropyl)-3'-methacrylamidopropanaminium inner salt)-ran-(butyl methacrylate)], poly(SPB-r-BMA)), were analyzed with band shapes of O-H stretching of attenuated total reflection infrared (ATR-IR) spectra. The copolymer could be cast as a thin film, of approximate thickness 10 microm, on a ZnSe crystal for the ATR-IR spectroscopy. At an early stage of sorption of water into the polymer film, the O-H stretching band of the IR spectra for the water incorporated in the film was similar to that for free water. This is consistent with the tendency for another zwitterionic polymeric material, poly[(2-methacryloyloxyethylphosphorylcholine)-ran-(butyl methacrylate)] (poly(MPC-r-BMA). It is, however, contradictory to the drastic change in the O-H stretching band for water incorporated into films of polymers such as poly(2-hydroxyethyl methacrylate), poly(methyl methacrylate) and poly(butyl methacrylate). These results suggest that polymers with a zwitterionic structure do not significantly disturb the hydrogen bonding between water molecules incorporated in the thin films. The investigation into the blood-compatibility of both the poly(SPB-r-BMA) and the poly(MPC-r-BMA) films indicate a definite correlation between the blood-compatibility of the polymers and the lack of effect of the polymeric materials on the structure of the incorporated water.     

The estimation of phase modifications in polymers by the method of “molecular probes” in gas chromatography—III. Glass transition behaviour and compatibility in mixtures of poly(methyl methacrylate) with poly(vinyl chloride)

Using the method of “molecular probes” in gas chromatography, glass-transitions in mixtures of poly(methyl methacrylate) with poly(vinyl chloride) are found. The strong variation of T_g for poly (methyl methacrylate) in mixtures with more than 20% of that polymer suggests interactions although T_g for poly(vinyl chloride) remains constant. The existence of a single T_g in mixtures with less than 20% poly(methyl methacrylate), on the other hand, suggests possible compatibility in these mixtures.     

Synthesis of monodisperse submicron spherical poly(methylmethacrylate) particles and the molecular dynamics simulation

The molecular-dynamics method has been used to determine the conformational states of poly(methyl methacrylate) chains in a medium composed of water and a monomer (methyl methacrylate). Experimentally detected spherical particles resulting from polymerization have been found to take the form of droplet-type aggregates containing several chains, with the water and monomer concentrations in the aggregates differing from those in the dispersion medium. It has been shown that the methyl methacrylate concentration in an initial reaction mixture of about 20% is optimal for the formation of spherical droplet-type aggregates. It has been experimentally established that spherical poly(methyl methacrylate) particles with a narrow size distribution are formed at a methyl methacrylate concentration of ≈23%.     

Identification of a stereoblock poly(methyl methacrylate) sample with a stereocomplex

Acid hydrolysis of a stereoblock poly(methyl methacrylate) sample leads to a mixture of isotactic and syndiotactic poly(methacrylic acid) which can be separated by electrophoresis. The experiment confirms the stereochemical identity between the so-called “stereoblock” poly(methyl methacrylate) and the stereocomplex which syndiotactic and isotactic poly(methyl methacrylate) form in the ratio 2:1. A possible mechanism of replica polymerization is suggested to account for this effect.     

Linear polymers of allyl acrylate and allyl methacrylate

Allyl acrylate and allyl methacrylate were polymerized by anionic initiators to soluble linear polymers containing allyl groups in the pendant side chains. The pendant unpolymerized allyl groups of the resulting linear poly(allyl acrylates) were shown to be present by: (1) the disappearance of the acrylyl and methacrylyl double bond absorptions in the infrared spectra in the conversions of monomers to polymers; (2) postbromination of the allyl bonds in the linear polymer; (3) the disappearance of the allyl groups absorptions in the infrared spectra of the brominated linear polymers; and (4) the thermal- and radical-initiated crosslinking of the linear polymers through the allyl groups. Allyl acrylate and allyl methacrylate show great reluctance to copolymerize with styrene under anionic initiation, but copolymerize readily with methyl methacrylate and acrylonitrile. Block copolymers were prepared by reacting allyl methacrylate with preformed polystyrene and poly(methyl methacrylate) anions. The linear polymers and copolymers of allyl acrylate may be classified as “self-reactive” polymers which yield thermosetting polymers. Bromination of the linear polymers offers a convenient method of producing self-extinguishing polymers.     

Homogeneous and multiphase poly(methyl methacrylate) graft polymers via the macromonomer method

Anionic and group transfer polymerization processes were used to synthesize controlled molecular weight methacryloyloxy functionalized poly(dimethylsiloxane) and poly(methyl methacrylate) macromonomers having a narrow molecular weight distribution and high percent functionality. These macromonomers were anionically copolymerized with methyl methacrylate (MMA) to afford poly(methyl methacrylate)-graft-poly(methyl methacrylate) (PMMA-g-PMMA) and poly(methyl methacrylate)-graft-poly(dimethylsiloxane) (PMMA-g-PDMS) polymers having not only narrow molecular weight distribution graft parts but also backbone parts. The PMMA-g-PDMS system was fractionated using supercritical chlorodifluoromethane to determine its chemical composition distribution (CCD). The CCD for the PMMA-g-PDMS copolymerized in a living manner was substantially more narrow than the free radically copolymerized material. The PMMA-g-PMMA system was used to study the dilute solution properties of branched homopolymers. The appropriateness of the universal calibration gel permeation chromatography (GPC) method for branched systems exhibiting long chain branching was reaffirmed.     

Preparation of water dispersible poly(methyl methacrylate)-based vesicles for facile persistent antibacterial applications

We report a facile strategy for incorporating persistent and effective antibacterial property into a widely used polymer, poly(methyl methacrylate)(PMMA), by copolymerizing methyl methacrylate(MMA) with 2-(tert-butylamino)ethyl methacrylate(TA) in one pot via atom transfer radical polymerization(ATRP). The subsequent self-assembly of the resultant poly(methyl methacrylate)-block-poly[(2-tert-butylamino)ethyl methacrylate](PMMA20-b-PTA15) diblock copolymer affords well-defined water-dispersible vesicles, which can be facilely sprayed on the walls in hospitals for effective inhibition and killing of bacteria. 1H-NMR and gel permeation chromatography(GPC) studies confirmed the successful synthesis of welldefined copolymer. Transmission electron microscopy(TEM), atomic force microscopy(AFM) and dynamic light scattering(DLS) studies proved the formation of vesicles with narrow size distribution. DLS studies revealed the excellent stability of vesicles at various temperatures. Antibacterial tests showed effective antibacterial activities of polymer vesicles against both Gram-positive and Gram-negative bacteria. Moreover, this strategy may be extended for preparing a wide range of polymeric materials for facile antibacterial applications in many fields.