Fine-tuning of thermal dissociation temperature using copolymers with hemiacetal ester moieties in the side chain: effect of comonomer on dissociation temperature

Synthesis of polymers with hemiacetal ester moieties in the side chain by radical copolymerization of 1-alkoxyethyl methacrylate with various vinyl monomers and their thermal dissociation behavior are described. Radical copolymerization of 1-alkoxyethyl methacrylates with vinyl monomers was carried out in the presence of 2,2′-azoisobutyronitrile at 60°C to afford the corresponding copolymers with hemiacetal ester moieties in the side chain. The thermal dissociation behavior of the obtained copolymers was examined by means of TG–DTA measurements to observe that the dissociation temperatures of hemiacetal ester units depended on their comonomer components. The polarity of the comonomers and the ability to form hydrogen-bonding were key forces to control their thermal dissociation behavior.     

Synthesis of copolymers of tert‐butyl vinyl ether with maleic and citraconic anhydrides

In the present study, the effects of charge‐transfer complex formation and intramolecular fragmentation (side‐chain lactonization) in radical copolymerization of tert‐butyl vinyl ether (t‐BVE) with anhydrides of maleic (MA) and citraconic (CA) acids and the structure–thermal behavior relationships of the resulting copolymers were examined using the ¹H‐NMR, FTIR, DSC, and TGA analysis methods. It was shown that copolymerization under the chosen conditions proceeded through intramolecular fragmentation with the formation of γ‐lactone units. Side‐chain fragmentation of t‐BVE–MA and t‐BVE–CA copolymers also was confirmed by TGA and DSC analysis. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 100: 2455–2463, 2006 2006     

Lewis酸存在下的自由基共聚合——Ⅰ.GeCl_4与BCl_3存在下的乙酸乙烯酯与丙烯酸交替共聚

乙酸乙烯酯(VAc)与丙烯酸(AA)在GeCl_4及BCl_3存在下通过自由基聚合可得到交替共聚物。对GeCl_4体系,聚合反应速率正比于[引发剂]~(0.5)。当VAc/AA=1:1(mol比)时有最大反应速率。CCl_4对本聚合反应无链转移作用。通过紫外光谱分析可证实VAc及AA均与GeC\(?)生成络合物;ESR分析表明,络合AA自由基较未络合AA有较强的阳离子特性,交替共聚的原因可能与络合AA自由基及活化单体络合物二者有关。     

Hydrosoluble copolymers of acrylamide‐(2‐acrylamido‐2‐methylpropanesulfonic acid). Synthesis and characterization by spectroscopy and viscometry

Hydrosoluble copolymers containing sulfonic acid groups incorporated into a macromolecule were synthesized. The group of polymers studied was obtained by free radical solution polymerization, using potassium persulfate as an initiator. The copolymerization of the monomers 2‐acrylamido‐2‐methylpropanesulfonic acid (AMPS) and acrylamide (AA) was carried out at different pH values of the reaction medium of the monomer mix. The copolymers were characterized by proton nuclear magnetic resonance spectroscopy (¹H NMR) and Fourier transform infrared spectroscopy (FTIR). The viscosity behavior of the copolymers in NaCl solution showed a dependency on the pH of the reaction medium, with higher pH leading to lower viscosities. The acidic conditions of this medium affect the initiator decomposition rate, which is a probable cause of the viscosity variation, and the extent of decomposition increases with increasing pH. © 2002 Wiley Periodicals, Inc. J Appl Polym Sci 87: 192–198, 2003     

Novel Poly(linolenic acid) Graft Copolymers: Synthesis,Characterization and Electrical Properties

A poly(linolenic acid)‐g‐poly(tert‐butyl acrylate) graft copolymer was synthesized from polymeric linolenic acid peroxide possessing peroxide groups in the main chain by free radical polymerization of tert‐butyl acrylate. Graft copolymers having structures of poly(linolenic acid)‐g‐poly(caprolactone)‐g‐poly(tert‐butyl acrylate) were synthesized from polymeric linolenic acid, possessing peroxide groups on the main chain by the combination of free radical polymerization of tert‐butyl acrylate and ring‐opening polymerization of ε‐caprolactone in one‐pot. The obtained graft copolymers were characterized by proton nuclear magnetic resonance, gel permeation chromatography, thermal gravimetric analysis, differential scanning calorimetry, and scanning electron microscopy techniques. Furthermore, Au/n‐Si diodes were fabricated with and without poly(linolenic acid)‐g‐poly(caprolactone)‐g‐poly(tert‐butyl acrylate)‐4 to form a new interfacial polymeric layer for the purpose of investigating this polymer's conformity in electronic applications. Some main electrical characteristics of these diodes were investigated using experimental current–voltage measurements in the dark and at room temperature.     

The homo and copolymerisation of 2-(dimethylamino)ethyl methacrylate in supercritical carbon dioxide

This paper describes the free radical dispersion homopolymerisation of 2-(dimethylamino) ethyl methacrylate (DMA) and copolymerisation of DMA with methyl methacrylate (MMA) in supercritical carbon dioxide (scCO₂). The polymerisations are performed in the presence of two commercially available stabilisers, poly(dimethylsiloxane) monomethacrylate macromonomer (PDMS-mma) and the carboxylic acid terminated perfluoropolyether (Krytox 157FSL). Dry, fine powdered polymer product was produced for the copolymer under optimised conditions, but only aggregated solid is formed for homo poly(DMA). The effect of reaction time, stabiliser, copolymer composition and reaction pressure on the yield, molecular weight and morphology of the copolymers has been investigated.     

Synthesis and monomer reactivity ratios of ethyl α‐acetoxyacrylate and acrylic acid copolymers

The synthesis of ethyl α‐acetoxyacrylate (EAA) and the study of its radical polymerization is described. We report the monomer reactivity ratios for copolymers of EAA and acrylic acid (AA) using three different methods: the Jaacks, the Macret and the Fineman–Ross methods. Copolymers were obtained by free radical polymerization initiated by 2,2′‐azobisisobutyronitrile in acetonitrile solutions and were analyzed by NMR and HPLC. The HPLC analysis was used to determine the molar fractions of EAA and AA in the copolymers. The reactivity ratios were estimated to be close to 1 for each monomer. Thus, copolymers of poly(acrylic acid) bearing some biodegradable units of EAA in the chain were subsequently prepared. The study of the hydrolysis of these units shows that only basic conditions were efficient to lead to hydrolyzed monomer units. Copyright © 2005 Society of Chemical Industry     

Asymmetric induction in forming poly(olefin sulphone)s

Poly(1-olefin sulphone)s have been prepared from olefins with a chiral centre at the carbon atom adjacent to the double bond. In ¹³C and ¹H NMR studies on the polymers obtained by free radical copolymerisation it has been found that the chirality of a main chain methine carbon that forms part of the backbone depends upon the chirality of the carbon initially present within the same hydrocarbon residue. The introduction of bulky groups into the chiral group of the monomeric olefin increased the ratio of diastereoisomers formed within the residue. In the most favoured case 69% of the backbone chiral centres were fixed with reference to the side chain structures. By employing a simple theory based upon an enumeration of steric interactions and upon the γ-gauche effect on carbon chemical shifts, it was deduced that the main chain chiral centre preferred to adopt the opposite stereochemistry to that of the side chain when that carries an ethyl group, a methyl group and a hydrogen atom. A bias was also found at the backbone when the monomer chiral centre contained polar acid or ester groups.     

Radical Ring Opening and Vinyl Copolymerization of 2,3,4,5,6-pentafluorostyrene with 5,6-Benzo-2-methylene-1,3-dioxepane: Synthesis and Structural Characterization Using 1D and 2D NMR Techniques

Radical ring opening polymerisation behaviour of 5,6-Benzo-2-methylene-1,3-dioxepane (BMDO) during its copolymerisation with 2,3,4,5,6-pentafluorostyrene (PFS) is reported using t-butyl peroxide (TBPO) conventional radical initiator. The reactivity behaviour of PFS for its copolymerisation is compared with that of the corresponding non-fluorinated monomer styrene. The presence of five fluorine atoms affected the course of polymerisation and led to the synthesis of well defined copolymers as compared to the formation of only homo poly styrene. Structural characterisation of the copolymers was done using 1D and 2D NMR spectroscopic techniques. The microstructural characterisation showed the formation of gradient copolymers with increased reaction time and/or increased amount of BMDO in the feed. The reactivity ratios for the copolymerisation of BMDO and PFS were determined using Kelen-Tüdos method and was found to be r _BMDO = 0.35 and r _PFS = 9.9. Thermal stabilities of copolymers are also compared with that of the homopolymers.     

Radical copolymerization studies of an amphiphilic macromonomer derived from Triton X-100. Reactivity ratios determination by in situ quantitative H NMR monitoring

This article deals with the estimation of the reactivity of a novel methacrylic macromonomer with amphiphilic character derived from Triton X-100 (MT) in radical copolymerisation reaction with acrylic acid (AA). Two approaches to estimate the reactivity ratio of the macromonomer are described. The first involves the use of the Jaacks equation valid for systems with a large excess of one of the comonomers and leads to r_AA=0.31. The second method uses a low molecular weight model monomer (MTm) that reproduces the chemical structure of the macromonomer. A non-linear fitting of the experimental data of the system MTm-AA to an integrated form of the copolymerisation equation which describes the terminal model postulated by Mayo and Lewis, gave reactivity ratio values of r_MTm=2.5 and r_AA=0.30. The results obtained from the two estimations suggest that methacrylic double bond reactivity is not affected by poly(oxyethylene oxide) chain length. In situ quantitative ¹H NMR analysis was used to monitor monomer consumption and therefore to follow the course of the copolymerisation reaction in both approaches.     

One‐pot synthesis of {Mo6I8}4+‐doped polystyrene microspheres via a free radical dispersion copolymerisation reaction

Molybdenum octahedral clusters, when incorporated into an appropriate polymer matrix, are considered as promising agents for a range of biological applications. This work describes the one‐pot synthesis, morphology and cellular toxicity of nano‐sized polystyrene beads doped with luminescent cluster complexes [{Mo₆X₈}(NO₃)₆]^2? (X = Cl, Br or I). Specifically, the particles were obtained by free radical dispersion copolymerisation of styrene and methacrylic acid or 4‐vinylpyridine in the presence of the cluster complexes. The effects of the cluster loading in the reaction mixture on both the content of the final material and number‐average molar mass of the copolymers were evaluated. © 2017 Society of Chemical Industry     

Synthesis and characterization of new hydrogels on the basis of water‐soluble maleic anhydride copolymers with γ‐aminopropyltriethoxysilane

This work describes the synthesis and macromolecular reactions of maleic anhydride (MA)–acrylic acid (AA) binary reactive copolymers with γ‐aminopropyltriethoxysilane (APTS) as a polyfunctional crosslinker. Copolymers with a given composition of MA–AA (47.17–52.83 wt %) were synthesized by radical binary copolymerization with benzoyl peroxide as an initiator in p‐dioxane at 70°C in nitrogen atmosphere and initial monomer ratio of 1 : 1. It is shown that the network structure is formed in MA–AA/APTS in water by intermolecular reaction between the anhydride unit and the amine group, as well as between the etoxysilyl fragment and free carboxyl groups of the acrylic acid and maleic anhydride unit. Swelling parameters such as beginning time of hydrogel formation, initial rate of swelling, swelling rate constant, equilibrium swelling, and equilibrium water content were determined for copolymer/APTS/water systems with various copolymer/crosslinker ratios. Formation of a hyperbranched network structure through the fragmentation of side‐chain reactive groups in the studied systems was confirmed by FTIR, TGA, and DSC methods. © 2003 Wiley Periodicals, Inc. J Appl Polym Sci 90: 4009–4015, 2003     

醚型聚羧酸系减水剂的合成及性能研究

烯丙基聚氧乙烯醚、顺酐、丙烯酸、丙烯酰胺为共聚单体,过硫酸铵为引发剂,通过自由基溶液聚合制得四元醚型聚羧酸减水剂。实验表明,最佳工艺条件为n（APEG）：n（MA）：n（AM）：nn（AA）=1：2：1：1．5,引发剂用量为4％．该减水剂在折固掺量为0．14％,水灰比为0129时,水泥的净浆流动度达到336mm,1h后为308mm。放置数月后减水剂稳定性不变。对不同厂家的四种水泥进行了净浆流动度试验,水泥适应性不佳但可调整掺量得到合适流动度。通过FTIR分析,表明MA、AM、AA均接入主链中,APEG接在AM上形成侧链。并依此得出了自制减水剂的分子式。     

Free‐radical polymerization of urea,acrylic acid,and glycerol in aqueous solutions

The main objective of the present study is to produce copolymers of urea, acrylic acid, and glycerol through aqueous solution free‐radical polymerizations and analyze the structural, thermal, rheological, and release properties of the obtained materials. To do this, aqueous solution copolymerizations were performed in different reaction conditions and the obtained copolymers were characterized by Fourier transform infrared spectroscopy, differential scanning calorimetry, rheological analyses, thermogravimetry, gel permeation chromatography, and rates of urea release in distilled water. The obtained results indicate that all constituents of the reacting mixture (potassium persulfate, glycerol, urea, and acrylic acid) affect the characteristics of the produced copolymers. In particular, it is shown that urea can be incorporated into the final copolymer through the proposed reaction scheme, that glycerol promotes crosslinking of polymer chains and that the obtained copolymer materials can be used in agricultural applications. POLYM. ENG. SCI., 55:1219–1229, 2015. © 2015 Society of Plastics Engineers     

Polymeric Photoinitiators Containing Side-chain Ketoaromatic Moieties for Fast Ultraviolet Initiated Polymerisation of Acrylic Monomers

The synthesis of polymeric photoinitiators having side-chain cyclohexylphenylketone as well as benzophenone moieties at different distances from the backbone is described. Study of the activity of the former systems, in the ultraviolet initiated polymerisation of acrylic monomers, indicates that a remarkable increase in the polymerisation rate is observed when the cyclohexylphenylketone chromophore is attached to the main chain through an ethereal linkage rather than an ester group. In the case of the latter systems, considerable improvement is observed in the photoinitiating activity with respect to the corresponding low molecular weight model compounds in the polymerisation of acrylic monomers. Moreover, in general the copolymers of benzophenone-containing monomers show higher activity than the corresponding homopolymers. These results are discussed in terms of photoexcitation energy migration along the polymer chain, as well as of intramolecular hydrogen abstraction from both main and side chains. This last occurrence seems to be the main activation process, as suggested by a strict correlation between activity and hydrogen-donating properties of the co-units in the copolymers, Photophysical evidence supporting this point is also reported. Finally, the synthesis of polymeric photoinitiators, containing both benzophenone and tertiary amine groups in the same macromolecule, has been accomplished via copolymerisation of 4-acryloxybenzophenone with 4-(N,N-dimethylamino)styrene. Preliminary data concerning photoinitiating activity of these last copolymers indicate that conformational mobility affects the formation capability of exciplexes and then the activity itself.     

Amphiphilic maleic acid copolymers as corrosion inhibitors for aluminum pigment

Aluminum pigments react in aqueous alkaline media (e.g., water-borne paints) by the evolution of hydrogen. Maleic acid copolymers, which were synthesized by copolymerization of maleic acid anhydride, styrene, and acrylic esters (ethyl-, n-butyl-, n-hexyl-, n-dodecyl-, and n-octadecyl acrylate) inhibit this corrosion reaction. With the increasing chain length of the ester alcohol of the acrylate monomer, the evolved hydrogen volume decreases (i.e., the corrosion inhibiting effect increases). There seems to be a potential correlation between the number of carbon atoms of the ester alcohol of the copolymers and the evolved hydrogen volumes. With the addition of 0.5 wt % of the copolymers with n-butyl, n-hexyl, n-dodecyl-, and n-octadecyl acrylate no hydrogen evolution was observed at pH 8 within 21 days (complete corrosion inhibition). Conductivity measurements of aqueous copolymer solutions indicate that with an increasing chain length of the ester alcohol, the copolymers possibly associate by hydrophobic bonding. © 1998 John Wiley & Sons, Inc. J Appl Polym Sci 69: 2169–2174, 1998     

Synthesis of degradable copolymer networks containing hemiacetal components and well‐defined backbones

A novel copolymer network was prepared using divinyl ether bis[4‐(vinyloxy)butyl] (4‐methyl‐1,3‐phenylene) biscarbamate (BECT) as crosslinking agent. First, the backbone chains were synthesized by the copolymerization of acrylic acid (AA) and methyl methacrylate (MMA) using reversible addition‐fragmentation chain‐transfer technique. The molecular weight of poly(AA‐co‐MMA) was well‐controlled, and the polydispersity was low. Carboxyl group on the poly(AA‐co‐MMA) chains then reacted with BECT in the presence of pyridinium p‐toluenesulfonate, generating a copolymer network with hemiacetal component in the crosslinking segment. After being treated in strong acid, this copolymer network was able to be degraded owing to the hemiacetal structure, but the backbone chains remained intact. The copolymer network was stable in basic or neutral environment. © 2011 Wiley Periodicals, Inc. J Appl Polym Sci, 2011     

Synthesis and properties of new water‐soluble copolymers based on methyl acrylic acid sucrose ester and methyl acrylic acid

The new series of copolymers were obtained based on free radical solution copolymerization by mixing self‐made methyl acrylic acid sucrose ester (MASE) and methyl acrylic acid (MAA) with different ratios. Copolymerization behavior and properties of the new copolymers was investigated with the reaction time, temperature, monomer ratios and characterized by Fourier transform infrared spectra (FT‐IR), carbon nuclear magnetic resonance (¹³C NMR), and intrinsic viscosity. The results indicated that sucrose was successfully grafted onto poly (methyl acrylic acid). Further, it was demonstrated that low temperature benefited the esterification of MASE. Importantly, the copolymers were founded to have good compatibility with polymethyl methacrylate (PMMA), polytetrafluoroethylene (PTFE), and polyethylene (PE). © 2016 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2016 , 133, 43627.     

The free-radically prepared copolymers of acrylonitrile with furfuryl alcohol and similar furan derivatives

The preparation of copolymers of acrylonitrile with furfuryl alcohol, furfuryl acetate, bis-2,5-hydroxymethyl furan and bis-2,5-acetoxymethyl furan by a free radical reaction is described. Proton and ¹³C-n.m.r. spectroscopy has been used to characterise the residues that form from the furan monomers by the addition reaction. The residues produced by a 5,4-addition to the furfuryl alcohol ring or by 2,3-addition to the 2,5-dihydroxyfuran ring are susceptible to acid and undergo a rearrangement which removes the olefinic structure. The copolymers are decomposed to a hard, glassy carbonaceous material by heating in nitrogen in a process that has been examined by thermogravimetric analysis and elemental analysis. The copolymers prepared from furan monomers that contain a methylol group decompose more readily at a lower temperature than those which lack the group or than those in which the alcohol has been acetylated.     

Thermal crosslinking behavior of poly (aryl ether ketone) copolymers containing naphthalene moieties

A series of poly[(ether ether ketone)‐co‐(ether naphthalene ether ketone)] (P(EEK‐co‐ENEK)) copolymers were heated under a variety of conditions. The thermal crosslinking behavior was monitored by differential scanning calorimetry (DSC), electron spin resonance (ESR) and wide‐angle X‐ray diffraction (WAXD). The results indicate that under a non‐oxidative environment such as nitrogen P(EEK‐co‐ENEK) is more stable, while under oxidative conditions a crosslinking reaction takes place that causes a reduction in the crystallizability of the copolymers, and an increase in the concentration of free radicals on the copolymer. ESR results suggest that the crosslinking reaction proceeds via free radicals. Subsequently two kinds of free radicals were characterized: one is an RO^? type free radical and the other is a naphthalene ring free radical. Copyright © 2004 Society of Chemical Industry