丙烯酸甲酯和丙烯酸全氟烷基乙酯嵌段共聚物的合成和表面性能

用原子转移自由基聚合法合成了丙烯酸甲酯和丙烯酸全氟烷基乙酯的两嵌段共聚物,研究了嵌段共聚物的表面性能。结果表明,嵌段共聚物具有低表面能特性。且X射线光电子光谱法证明氟烷基链有强烈的趋于表面的特性。     

Effect of cardinyl acrylate on thermal behavior of methyl methacrylate copolymers

Cardinyl acrylate (CA), prepared by the reaction of acryloyl chloride and cardinol, was copolymerized with methyl methacrylate (MMA) in bulk at 80°C using 2% benzoyl peroxide as an initiator. The copolymer composition was determined by ¹H-NMR spectroscopy. Three copolymer samples containing 0.0048–0.0838 mol fraction of cardinyl acrylate were obtained. A significant improvement in the thermal stability of MMA was observed by incorporating 0.0048–0.0838 mol fraction of CA in the backbone. The activation energy for decomposition in the temperature range 350–480°C for copolymers was higher than PMMA. © 1992 John Wiley & Sons, Inc.     

Production,cellular structure and thermal conductivity of microcellular (methyl methacrylate)–(butyl acrylate)–(methyl methacrylate) triblock copolymers

Microcellular foaming of a (methyl methacrylate)–(butyl acrylate)–(methyl methacrylate) triblock copolymer was carried out by means of supercritical CO₂ in a single‐step process. The experiments were performed at 40 °C using a pressure of 300 bar (30 MPa) during 24 h. The depressurization times were modified from 2 to 30 min, leading to cell sizes from 10 to 100 µm, and relative densities from 0.11 to 0.17. It was found that the key parameter to control cell size and density was depressurization time: longer depressurization times generated larger cell sizes and lower densities. The thermal conductivity of these materials was measured using the transient plane source technique, and it was found that this decreased as the density was reduced. Various models for the prediction of thermal conductivity by conduction were tested. It was found that all the models underestimated the experimental results due to a significant contribution of radiation heat flow for these materials. Copyright © 2010 Society of Chemical Industry     

Pyrolysis/gas chromatography/mass spectrometry of glycidyl methacrylate—alkyl acrylate copolymers

Thermal degradation pattern of copolymers of glycidyl methacrylate with alkyl acrylates have been studied by pyrolysis/gas chromatography/mass spectrometry method. Various degradation products have been identified and based on the products obtained, the mechanisms of polymer degradation have been elucidated.     

Crosslinking of carboxyl functional (meth)acrylate copolymers with bisketeneimine

Summary The bisketeneimine Ph₂C=C=N-C₆H₄-N=C=CPh₂ 1 has been used as a crosslinker for carboxyl functional (meth)acrylate copolymers of various molar masses, in which the COOH group is attached to the backbone through spacers of various length. The crosslinking reaction, carried out at various temperatures, was monitored by infrared spectroscopy and by dynamic mechanical analysis. From a modelreaction with nonanoic acid kinetic parameters were calculated. The products poly(meth)acrylate-polyimide networks were characterised by NMR and FTIR spectroscopy. The thermal stability (TGA measurement) was comparable to that of a corresponding polyurethane.     

Microstructure analysis of methyl acrylate/methyl methacrylate copolymers by two‐dimensional NMR spectroscopy

Methyl acrylate (A)/methyl methacrylate (B) copolymers of different compositions were synthesized in bulk at 50°C and the compositions were determined from ¹H NMR spectra. Reactivity ratios were optimized using the least square methodology. Compositional and configurational assignments were done using two‐dimensional (2D) Heteronuclear Single Quantum Correlation (HSQC) and Total Correlation Spectroscopy (TOCSY) experiments. Methylene proton and carbon resonances were assigned for compositional and configurational sensitivity at tetrad level. Carbon resonances of methine group of methyl acrylate were assigned for compositional sensitivity up to triad level with the help of 2D HSQC spectra. α‐Methyl group of methyl methacrylate was assigned up to triad level of compositional and configurational placements for carbon and proton resonances by 2D HSQC spectroscopy. © 2005 Wiley Periodicals, Inc. J Appl Polym Sci 99: 1437–1445, 2006     

Effect of copolymer composition on the miscibility of blends of styrene-acrylonitrile copolymers with poly (methyl methacrylate)

The phase behaviour for blends of various polymethacrylates with styrene-acrylonitrile (SAN) copolymers has been examined as a function of the acrylonitrile content of the copolymer. Poly(methyl methacrylate), poly(ethyl methacrylate) and poly(n-propyl methacrylate) were found to be miscible with SANs over a limited window of acrylonitrile contents while no SANs appear to be miscible with poly(isopropyl methacrylate) or poly(n-butyl methacrylate). These conclusions were reached on the basis of lower critical solution temperature (LCST) and glass transition temperature behaviour. All miscible blends exhibited phase separation on heating, LCST behaviour, at temperatures which varied greatly with copolymer composition. An optimum acrylonitrile (AN) level ranging from about 10 to 14% by weight resulted in the highest temperatures for phase separation which has important implications for selection of SANs to produce homogeneous mixtures by melt processing. The basis for miscibility in these systems is evidently repulsion between styrene and acrylonitrile units in the copolymer as explained by recent models. The excess volumes for all blends are zero within experimental accuracy which suggests that the interactions for miscibility are relatively weak even for the optimum AN level. This interaction becomes smaller the larger or more bulky is the alkyl side group of the polymethacrylate.     

Fluorinated poly(meth)acrylate: Synthesis and properties

Due to good reactivity of fluorinated (meth)acrylates with other monomers or polymer segments, fluorinated poly(meth)acrylates possess more economical and convenient synthesis routes than other fluoropolymers. This feature article initially summarizes different types of fluorinated (meth)acrylates, which can be divided into fluorinated alkyl (meth)acrylates and fluorinated aryl (meth)acrylates. Subsequently, various approaches for synthesizing fluorinated poly(meth)acrylates including random, block, graft or star copolymers are described. Conventional free radical polymerization can be used in synthesizing random copolymers, while controlled/“living” radical polymerization can provide well-defined copolymers with accurate control over molecular weight and special structures as expected. In particular, introduction of fluorinated components into as-prepared copolymers offers an alternative route to synthesize fluorinated poly(meth)acrylates which are difficult to be obtained directly via polymerization. The incorporation of fluorine can confer unique and highly desirable properties to poly(meth)acrylates such as low surface energy, thermal stability, chemical and weather resistance, low refractive index, and self-organization characteristics. Such properties are described in great details based on many recent articles.     

Synthesis and properties of amphiphilic copolymers of butyl acrylate and methyl methacrylate with uniform polyoxyethylene grafts

Amphiphilic copolymers of butyl acrylate (BA) and methyl methacrylate (MMA) with uniform polyoxyethylene (PEO) grafts were synthesized by the copolymerization of BA and MMA with a methacrylate‐terminated PEO macromer in benzene with azobisisobutyronitrile as an initiator. The effects of various copolymerization conditions on the grafting efficiency and molecular weight of the copolymers, as well as the effect of the copolymerization time on the conversions of the macromer and the monomers, were reported. The copolymers, with uniform PEO grafts, were purified by successive extractions with water and ether/acetone (3/7) to remove unreacted macromer and ungrafted copolymers of MMA and BA, respectively. The purified graft copolymers were characterized with IR, ¹H‐NMR, membrane osmometry, gel permeation chromatography, and differential scanning calorimetry. The highest grafting efficiency was about 90%, and molecular weight of the copolymers varied around 10⁵. The average grafting number of the copolymer was about 10. A study of the crystalline properties, emulsifying properties, phase‐transfer catalytic ability, and mechanical properties of the graft copolymers showed that the emulsifying volume decreased with the increasing molecular weight of the PEO grafts but increased with the PEO content. The conversion of potassium phenolate in the Williamson solid–liquid reaction obviously increased with an increasing PEO content of the graft copolymers. The crystallinity of the graft copolymers increased with the PEO content of the graft copolymers or the molecular weight of the macromer used. The copolymers, prepared under certain conditions, behaved as thermoplastic elastomers. © 2003 Wiley Periodicals, Inc. J Appl Polym Sci 89: 2982–2988, 2003     

Pyrolysis of random and block copolymers of ethyl acrylate and methyl methacrylate

Pyrolysis gas chromatography can distinguish random from block copolymers of ethylacrylate and methyl methacrylate. The pyrograms depend on the pyrolytic temperature, the ratio of copolymerized monomers, the degree of conversion, and the method of polymerization. Larger amounts of ethyl methacrylate and methyl acrylate are formed on pyrolysis of random copolymers than of block copolymers. The presence of mixed dimers indicates random copolymerization. The sum of the percent recovery of ethyl alcohol and ethyl acrylate is fairly constant over a range of compositions and monomer sequence. Random copolymers produce less ethyl alcohol than ethyl acrylate on pyrolysis, while homopolymers and block copolymers produce more ethyl alcohol and less ethyl acrylate. In a set of random copolymers with different EA/MMA ratios, there is an increasing per cent recovery of EA monomer with decreasing EA in the copolymer, while ethyl alcohol shows the opposite behavior. The characteristic degradation patterns are thought to be governed by the availability of the tertiary hydrogen for abstraction by the alkoxy oxygen of a neighboring acrylate unit, the availability depending on the sequence distribution of acrylate/methacrylate molecules.     

Preparation and properties of alkoxysilane/butyl acrylate/methyl methacrylate copolymer latices

The incorporation of alkoxysilanes into latex systems is of major interest in the field of colloidal science. Two kinds of vinyl‐containing alkoxysilanes, methacyloxypropyltrimethoxyl silane and vinyltriethoxysilane, were copolymerized with butyl acrylate and methyl methacrylate by seeded emulsion polymerization, and copolymer latices were obtained. The morphologies of the latex particles were characterized with transmission electron microscopy. Dynamic light scattering showed that the particle size increased and the particle size distributions of all the copolymer latex particles were alike with increasing amounts of organosilane. The effects of the organosilane content on the morphology of the particles, the rheology, and the swelling properties were also investigated. © 2008 Wiley Periodicals, Inc. J Appl Polym Sci, 2009     

Correlation between molecular structure and copolymer composition and the Mark-Houwink constants of methyl methacrylate/N-phenylmaleimide copolymers

The determination of Mark-Houwink constants using gel permeation chromatography data, based on a universal calibration and Ubbelohde capillary viscosimetry, for methyl methacrylate (MMA)/N-phenylmaleimide (NPI) copolymers of different molar mass or molar mass distribution has been examined. Mark-Houwink constants of bimodal molar mass distributions could not be obtained. They give, under the prerequisite of similar chemical composition, considerable deviations from the usual relation between intrinsic viscosity and molar mass. The Mark-Houwink constants determined for MMA/NPI copolymers with monomodal molar mass distributions containing 20–30 mol-% NPI at 35°C in tetrahydrofuran were K = 1.34 · 10^–4 and α = 0.73. Comparison with poly(methyl methacrylate) (PMMA) under the same measurement conditions shows constants of the Mark-Houwink relation with K = 1.43 · 10^–4 and α = 0.71, similar to those for monomodal MMA/NPI copolymers with 20–30 mol-% NPI. Higher contents of NPI in monomodal MMA/NPI copolymers or poly(N-phenylmaleimide) (PNPI) give no clear linear proportionality of the intrinsic viscosity to molar mass.     

Different composition poly(methyl methacrylate-co-butyl methacrylate) copolymers through seeded semi-batch emulsion polymerization

In the present work the synthesis and the chemical and thermal characterization of poly(methyl methacrylate-co-butyl methacrylate) copolymer, in three different macromolecular compositions, are reported. The aim of the present work was the identification of a standard method to obtain copolymers with controlled macromolecular composition, molecular weights and particle size distribution, together with the identification of the effect of the macromolecular composition on the material properties. A monomer-starved seeded semi-batch emulsion reaction was carried out and optimized, monitoring the kinetic of the copolymerization through the evaluation of residual monomer amounts. Then, an evaluation of the macromolecular composition was performed by Fourier transform infrared spectroscopy analysis. Molecular weight, molecular weight distribution, latex characteristics and thermal behaviour were also investigated.     

Microstructure analysis of methyl acrylate/methyl methacrylate copolymers by two‐dimensional NMR spectroscopy. II

In the present article, a comprehensive two‐dimensional heteronuclear multi bond correlation (HMBC) spectral analysis of methyl acrylate (A)/methyl methacrylate (B) copolymers is reported. The methylene carbon and methine carbon resonances assigned from the 2D HSQC spectroscopy were established by analyzing the two and three bond order couplings with α‐methyl protons, methylene protons, and methine protons. Quaternary carbon resonances of the B unit were assigned by investigating the two bond order couplings with α‐methyl protons and methylene protons. Assignments of carbonyl carbon resonances based on the analysis of three bond couplings with α‐methyl protons and methylene protons are reported. The analyses present comprehensive assignments of the carbonyl carbon resonances showing the critical contribution of 2D HMBC spectroscopy in the indirect analysis of carbon resonances. © 2005 Wiley Periodicals, Inc. J Appl Polym Sci, 2006     

Mechanical properties and water vapor permeation of vinyltriethoxysilane/methyl methacrylate copolymers

Methyl methacrylate (MMA) was copolymerized with vinyltriethoxysilane (VTES) using ⁶⁰Co-γ-radiation at varying volume fractions of the liquid monomers in the feed. Thin copolymer films were prepared by casting tetrahydrofuran solutions of the copolymers on a mercury surface. The effect of the mole fraction of VTES in the copolymer on the glass transition temperatures, mechanical properties and water vapor permeabilities were investigated. Glass transition temperatures and mechanical properties decreased with increasing VTES content in the copolymer. However, the water vapor permeabilities were found to increase with the VTES content. The increased water vapor permeation was attributed to increased water solubility in the copolymers due to the presence of Si-O-bonds.     

Pyrolysis of poly(methyl methacrylate co ethyl acrylate)

An investigation of the behavior of poly(methyl methacrylate co ethyl acrylate) with a commercially available filament-type pyrolysis unit and gas chromatogaph was conducted. It has been hypothesized that the quantity of ethyl acrylate monomer produced under the conditions of the experiment is dependent upon the number of ethyl acrylate–methyl methacrylate bonds contained in the copolymer. These observations were made possible by a standardized samples-handling technique in which a uniformsize disk was pyrolyzed at a maximum pyrolysis temperature of 600°C. This enabled reproducible pyrolysis gas chromatograms to be obtained and permitted pyrolysis products of copolymers containing different ratios of ethyl acrylate and methyl methacrylate to be compared. An examination of sequence distribution data, obtained with the aid of a sequence distribution program for copolymers, showed sufficient agreement with the pyrolysis data to support the hypothesis. It has been demonstrated that pyrolysis gas chromatography may be applied to experimentally determine the sequence distribution of copolymers.     

Effect of chemical structure and crosslinking density on the thermo-mechanical properties and toughness of (meth)acrylate shape memory polymer networks

The objective of this work is to characterize and understand structure-mechanical property relationships in (meth)acrylate networks. The networks are synthesized from mono-functional (meth)acrylates with systematically varying sidegroup structure and multi-functional crosslinkers with varying mole fraction and functionality. Fundamental trends are established between the network chemical structure, crosslink density, glass transition temperature, rubbery modulus, failure strain, and toughness. The glass transition temperature of the networks ranged from −29 to 112 °C, and the rubbery modulus (E_r) ranged from 2.8 to 129.5 MPa. At low crosslink density (E_r < 10 MPa) network chemistry has a profound effect on network toughness. At high crosslink densities (E_r > 10 MPa), network chemistry has little influence on material toughness. The characteristic ratio of the mono-functional (meth)acrylates' components is unable to predict trends in network toughness as a function of chemical structure, as has been demonstrated in thermoplastics. The cohesive energy density is a better tool for relative prediction of network mechanical properties. Due to superior mechanical properties, networks with phenyl sidegroups are further investigated to understand the effect of phenyl sidegroup structure on toughness.     

Synthesis and characterization of butyl acrylate/methyl methacrylate/glycidyl methacrylate latexes

The butyl acrylate (BA)/methyl methacrylate (MMA), and glycidyl methacrylate (GMA) composite copolymer latex was synthesized by seeded emulsion polymerization technique taking poly(methyl methacrylate) (PMMA) latex as the seed. Four series of experiments were carried out by varying the ratio of BA : MMA (w/w) (i.e. 3.1 : 1, 2.3 : 1, 1.8 : 1, and 1.5 : 1) and in each series GMA content was varied from 1 to 5% (w/w). The structural properties of the copolymer were analyzed by FTIR, ¹H‐, and ¹³C‐NMR. Morphological characterization was carried out using transmission electron microscopy (TEM). In all the experiments, monomer conversion was ～99% and final copolymer composition was similar to that of feed composition. The incorporation of GMA into the copolymer chain was confirmed by ¹³C‐NMR. The glass transition temperature (T_g) of the copolymer latex obtained from the differential scanning calorimetry (DSC) curve was comparable to the values calculated theoretically. With increase in GMA content, particles having core‐shell morphology were obtained, and there was a decrease in the particle size as we go from 2–5% (w/w) of GMA. The adhesive strength of the latexes was found to be dependent on the monomer composition. With increase in BA : MMA ratio, the tackiness of the film increased while with its decrease the hardness of the film increased. © 2009 Wiley Periodicals, Inc. J Appl Polym Sci, 2010     

Effect of branched alkyl groups on physical properties in poly(ethylene-co-branched alkyl methacrylate)s

Summary Poly(ethylene-co-5.4 mol% n-alkyl/branched alkyl methacrylate)s (PEM) were prepared by a dehydrogenchloride reaction of poly(ethylene-co-5.4 mol% alkyl methacrylic chloride) with the corresponding alkyl alcohol to investigate effect of branching structure and length of alkyl ester on a few physical properties of PEM [glass transition temperature (T_g), degree of crystallinity in polyethylene region (X_c) and dielectric molecular motion], where the alkyl groups used here are n-propyl, n-butyl, n-hexyl, n-decyl, 2-ethylhexyl, 3,5,5-trimethylhexyl and 2-(1,3,3-trimethylbutyl)-5,7,7-trimethyloctyl. In the n-alkyl methacrylate copolymers, T_g and X_c were almost unchanged with the presence of alkyl ester, but T_g increased and X_c decreased in the highly branched alkyl methacrylate copolymers even at the low methacrylate content of 5.4 mol%.     

Physical properties of poly(cyclohexyl methacrylate)-b-poly(iso-butyl acrylate)-b-poly(cyclohexyl methacrylate) triblock copolymers synthesized by controlled radical polymerization

The microphase segregation of different poly(cyclohexyl methacrylate)-b-poly(iso-butyl acrylate)-b-poly(cyclohexyl methacrylate), PCH-b-PiBA-b-PCH, triblock copolymers obtained by atom transfer radical polymerization has been evaluated by dynamic mechanical thermal analysis through location of the two relaxations ascribed to cooperative motions of each block. Additionally, other secondary relaxations have been found, whose characteristics are also dependent on molecular weight of outer and rigid segments. The length of these hard blocks influences significantly the stiffness and microhardness found in these triblock copolymers. These two mechanical parameters increase as molecular weight of poly(cyclohexyl methacrylate) does. The morphological aspects have been examined by small angle X-ray scattering and atomic force microscopy.