Spontaneous zwitterionic copolymerisation: An undervalued and efficacious technique for the synthesis of functional degradable oligomers and polymers

The spontaneous zwitterionic copolymerisation (SZWIP) of compatible nucleophilic and electrophilic monomers is a relatively unknown and unexplored method for the synthesis of (predominantly alternating) degradable co- and terpolymers. A wide range of monomers allows for the synthesis of different polymer classes with various functionalities, including poly(aminoester)s, poly(ester amide)s and poly(phosphoester)s. In this review, we discuss this undervalued copolymerisation method and its potential for the facile preparation of functional polymeric systems. In this context, the polymers synthesised to date by SZWIP as well as recent insights into this polymerisation technique are highlighted. Post-polymerisation modifications and applications of polymers obtained by SZWIP are also discussed.     

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.     

Electro-copolymerisation of indene and styrene

Electroinitiated cationic copolymerisation of indene and styrene was investigated by constant potential electrolysis. Effects of copolymerisation potential and temperature on the copolymer composition and the reactivity ratios are discussed. The reactivity ratios of the monomers were calculated according to the integrated Lewis-Mayo equation.     

Effects of applied potential on electroinitiated copolymerisation of α-methylstyrene and β-bromostyrene

Electroinitiated cationic copolymerisation of α-methylstyrene and β-bromostryene has been studied at various applied potentials. The relationship between copolymerisation potential and resulting copolymer composition was investigated. The advantages of employing constant potential electrolysis over constant current electrolysis are discussed in terms of the reactivity ratios. The reactivity ratios of the monomers are calculated according to the integrated Lewis-Mayo equation.     

Free radical initiation mechanisms in copolymerisation studied by the nitroxide trapping technique

The initiation mechanism for the radical copolymerisation of vinyl acetate, a typical electron donor monomer, and acrylonitrile, a typical electron acceptor monomer, initiated by t-butoxy radicals, has been investigated by the nitroxide radical trapping technique: 1,1,3,3-tetramethyl-1,3-dihydroisoindol-2-yloxyl (T) was the radical trapping agent. Two adducts (diastereomers) containing both vinyl acetate and acryionitrile monomers were isolated. From a kinetic analysis of these and other products over a wide range of conditions, a mechanism involving separate monomer addition, which may be regarded as normal kinetic control of monomer addition, is shown to be most consistent with the observed results.     

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     

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.     

Synthesis and characterisation of N-toluyl methacrylatoethyl carbamates,homopolymers and copolymers with methyl methacrylate

The paper describes the synthesis of N-2/4-toluyl methacrylatoethyl carbamates using 2/4-toluyl isocyanate and 2-hydroxyethyl methacrylate. Homopolymerisation and copolymerisation of these novel monomers with methyl methacrylate was carried out using benzoyl peroxide as an initiator and tetrahydrofuran as solvent. Photopolymerisation of N-4-toluyl methacrylatoethyl carbamate could be carried out without the use of photosensitiser. Structural characterisation of copolymers was done using ¹H-NMR. Thermal stability of copolymers was evaluated in a nitrogen atmosphere by dynamic thermogravimetry.     

Structure and properties of ionic hydrogels

Ionic gels were prepared by cross-linking copolymerisation of monofunctional ionic monomers together with a small amount of a bifunctional cross-linker. Gels with a lower degree of ionisation were obtained by starting from a mixture of ionic and nonionic monomers. The complex modulus of the gels has been measured over a wide frequency scale as a function of cross-link density, concentration, and degree of ionisation. The results obtained were interpreted by employing the theory of rubber elasticity to determine the fraction of elastically effective network chains, p, and the influence of concentration and ionisation thereon. At concentrations below 10 wt.-%, no continuous network is formed. Beyond this point, p increases with concentration and seems to approach unity at more than 60 %. The concentration of the crosslinker has only little influence on p. When lowering the degree of ionisation by copolymerisation with a nonionic monomer, p decreases considerably, presumably because such copolymer chains adopt a less expanded conformation than the totally ionic chains. Thus, the formation of elastically ineffective rings is more likely to occur.     

Fettpolymere – Herstellverfahren und Eigenschaften

The radical polymerization of esters of acrylic, methacrylic or crotonic acid with fatty alcohols proved to be an efficient method for production of polymers with hydrophobic moieties. By co-polymerisation with hydrophilic co-monomers - such as maleic anhydride - copolymers with a broad spectrum of properties can be designed. As an example the copolymerisation of fatty crotonates with maleic anhydride was studied in detail. The reaction was carried out as bulk polymerisation in a semi-batch process. By this method the compatibility problems of the two monomers, which have very different hydrophilicities could be overcome. The product acts as a very effective fat liquoring agent in leather treatment: the maleic moieties cause an outstanding fixing of the agent on the leather and the fatty crotonate moieties create a very smooth leather. Terpolymers of fatty acrylates, hydrophilic monomers and terpenes could also be synthesized in a similar way. These terpolymers proved to be useful as dispersing agents for pigments in paints and varnishes.     

Controlled polyethylene chain growth on magnesium catalyzed by lanthanidocene: A living transfer polymerization for the synthesis of higher dialkyl-magnesium

The rare-earth metallocene chloride complexes (C₅Me₅)₂LnCl₂Li(OEt₂)₂ (Ln = Nd, Sm or Y) combined with an excess of dialkyl-magnesium compounds (butyl-ethyl-magnesium) afford active species for the polymerization of ethylene in alkanes or aromatic solvents at atmospheric pressure. A dynamic equilibrium between dormant species and a low concentration of catalytically active species is suggested to explain the living character of the polymerization process observed at temperatures up to 80 °C. A fluxional behavior of the polynuclear structure of the dormant species accounts for the fast and reversible exchange/transfer reaction of alkyl chains between lanthanide and magnesium metallic centers. The resulting mixture contains mainly di(polyethylenyl)magnesium compounds and can be directly used either for block copolymerisation with polar monomers or for any classical Grignard-like reaction for the synthesis of functionalized polyethylenes.     

Hybrid organic-inorganic materials using zirconium based NBBs and vinyl trimethoxysilane: Effect of pre-hydrolysis of silane

Various Nano Building Blocks (NBBs) such as polyhedral silsesquioxanes (POSS), functionalized metal oxide particles and transition metal oxoclusters have been already developed and used to improve thermal and mechanical properties of organic polymers. The NBBs ideal for the preparation of hybrid materials and nanocomposites are monodispersed, well-defined objects capped with polymerisable functions suitable for copolymerisation with organic monomers.In this study zirconium oxoclusters (ZrNBB) were obtained as a crystalline precipitate by reaction between zirconium propoxide and vinylacetic acid. They were post-functionalised by copolymerisation with vinyl trimethoxysilane in different molar ratios. The hybrid samples were prepared both with the organosilane pre-hydrolysis step and without adding water. Hybrid materials were obtained through the radical polymerization process by adding benzoyl peroxide (BPO). Silane pre-hydrolysis prevents bulk samples from being obtained.The polymerization process was studied using differential scanning calorimetry (DSC), and the shear storage modulus (G′) and loss modulus (G″) of hybrid polymers were investigated by dynamic mechanical spectroscopy (DMS). Multinuclear liquid- and solid-state NMR analyses and Fourier transform infrared (FTIR) spectroscopy were used to characterize the reagents and hybrid materials, and to study the influence of the synthesis conditions on condensation and polymerization.     

Hydroxyl-bearing poly(α-hydroxy acid)-type aliphatic degradable polyesters prepared by ring opening (co)polymerization of dilactones based on glycolic, gluconic and l-lactic acids

The synthesis of HO-protected poly(glycolic acid-co-gluconic acid) and poly(l-lactic acid-co-glycolic acid-co-gluconic acid) by copolymerisation of l-lactide and 3-(1,2-3,4-tetraoxobutyl-diisopropylidene)-1,4-dioxane-2,5-dione (DIPAGYL) is reported. The resulting polymers were characterized by size exclusion chromatography, FT Infrared, nuclear magnetic resonance, differential scanning calorimetry and X-ray diffractometry. The composition of reaction media and the reactivity ratios of the two cyclic monomers were determined at low conversion and indicated random distributions of lactyl and gluconoglycolyl constitutive units. X-ray diffraction data showed semi-crystalline morphology, as observed for poly (lactide) stereocopolymers containing more than 90% of l-enantiomer. Deprotection of the isopropylidene-protected side chain OH was possible under acidic conditions and yielded copolymers with various degrees of hydroxylation. Deprotection of the 5-6 OH groups was fast and complete whereas that of 3-4 ones was partial and occurred at the expenses of partial degradation of the aliphatic polyester chains. T_g increased with the number of hydroxyl functions, a feature attributed to the formation of hydrogen bonds. Comparison is made with features reported previously for analogs derived from dl-lactide.     

Das Copolymerisationsverhalten von Diallylmaleinat gegenüber Akzeptor-Donor-Monomeren

The copolymerisation behaviour of diallylmaleate (DAM) with methyl methacrylate (MMA), N-phenylmaleimide (NPI), and styrene (S) in radical polymerisation was studied under the aspect of interaction of monomers with high and low electron density vinyl groups. The system DAM/S showed some indications for interaction. Generally, the strong control of degradative chain transfer could be recognised in polymerisation. A huge increase of the molecular mass is observed at low parts of DAM in the monomer composition.     

苯并三唑类紫外线吸收剂的现状及发展趋势

综述了不同种类的紫外线吸收剂,着重介绍了苯并三唑类紫外线吸收剂。苯并三唑类紫外线吸收剂由于性能优异而广泛应用于各种高分子合成材料和制品中。但由于其相对分子质量较小,在高分子材料加工过程中,容易通过向表面迁移、表面挥发而引起损失,所以其耐光性比较差。在苯并三唑类紫外线吸收剂分子中引入可聚合的基团使它可以和不同的单体聚合成高分子化合物。从共价键到聚合物链的转变使其在介质中更稳定,更不易迁移和挥发。含有可聚合基团的紫外线吸收剂相比普通的紫外线吸收剂显示出了相当优良的耐光稳定性。     

Inhomogeneity of gel and microsyneresis in porous styrene-divinylbenzene copolymers

The porosity of styrene-divinylbenzene copolymers prepared by suspension copolymerisation of the monomers carried out in the presence of inert diluent changes due to solvent pretreatment is investigated. The changes seem to reflect the inhomogeneity of copolymer gel. Various portions of it are transferred from the rubber-like into the glassy state at different stages of either swelling solvent exchange or the drying process. A microsyneresis, i.e. a local collapse of loosely crosslinked gel portions not followed by a shrinkage of the whole system, leads to the porosity changes.     

Increased enzyme activity in immobilised cell composites with a highly hydrophilic polymer matrix

Streptomyces phaeochromogenes cells were immobilised by radiation polymerisation of hydrophilic monomers; highest levels of glucose isomerase activity were found in immobilised cell composites with highly hydrophilic polymer matrices. The enzyme activity in the composites from the copolymerisation of hydroxyethyl acrylate (or methacrylate) and N-vinyl-2-pyrrolidone monomer increased markedly with increase in the content of the N-vinyl-2-pyrrolidone monomer, owing to the higher water absorption by the polymer matrix, and was close to that of the non-immobilised cells. The enzyme activity was affected by monomer concentration, the hydrophilicity, and chemical structure of the polymer matrix. The Michaelis constant of the composites from hydrophilic monomers was close to that of the intact cells.     

Synthesis of some symmetrically substituted stilbene‐triazine derivatives containing tetramethylenepiperidine fragments and their application to make self‐whitening polyacrylonitrile

This study reports the synthesis of nine new fluorescent stilbene‐triazine whitening agents containing a tetramethylpiperidine fragment. These products were isolated and characterised by spectroscopic techniques, i.e. infrared, ultraviolet, and fluorescent spectra, and confirmed by proton nuclear magnetic resonance spectroscopy. The photostability of the new compounds and two optical brighteners containing an unsaturated group without a stabiliser fragment was studied. It was found that the compounds containing tetramethylpiperidine have better photostability. The possibility of the copolymerisation of the unsaturated compounds with acrylonitrile was investigated, and self‐whitening polymers with an intense blue fluorescence were obtained. It was established that 85–86% of the fluorophores are chemically bound to the polymer chain.     

Synthesis and Electroluminescence of Side-chain Liquid Crystalline Polyacrylates and Polyoxiranes Containing Bistolane Side Groups

The synthesis and characterization of side-chain liquid crystalline (LC) polyacrylates and polyoxiranes containing bistolane side-groups are presented. The phase behavior of the prepared monomers and polymers was characterized by differential scanning calorimetry and optical polarizing microscopy. All of the obtained monomers and polymers reveal an enantiotropic nematic phase. The birefringences of the LC monomers are in the range from 0.35–0.6 depending on the measuring wavelength. The photoluminescence (PL) and electroluminescence (EL) properties of the obtained monomers and polymers are also reported.     

Copolymerisation of Vinyl Stearate with Other Fatty Vinyl Monomers

Homopolymerisation of vinyl stearate and its copolymerisation with five other fatty vinyl monomers have been carried out in benzene using benzoyl peroxide as the initiator. The comonomers included stearyl acrylate, stearyl methacrylate, allyl stearate, stearyl vinyl ether and divinyl sebacate. Stearyl acrylate and stearyl methacrylate furnished copolymers with inherent viscosities much higher than that of the vinyl stearate homopolymer while allyl stearate and stearyl vinyl ether gave copolymers with inherent viscosities much lower than that of the vinyl stearate homopolymer.