Cyclic carbonates,novel expandable monomers on polymerization

A variety of cyclic carbonates was shown to undergo volume expansion on polymerization. The degree of volume expansion, which was measured by the density gradient tube method, was ranging from 1.1% to 7.7%. The volume expansion was examined by assuming a change in molecular interaction such as dipole moment between monomer and polymer states.     

Click chemistry with ynamides

A series of diversely 1-substituted 4-amino 1,2,3-triazoles were synthesized by [3+2] cycloaddition between azides and ynamides. This copper catalyzed process represents the first examples of a ‘click reaction’ employing ynamides and should expand the scope of the ynamide chemistry both synthetically and industrially. Various azides (even highly functionalized) were allowed to react with N-benzyl, N-tosyl ynamide to give the corresponding triazole adducts in high yield and with very high levels of regioselectivity.     

Click chemistry to functionalise peptidomimetics

Sharpless modified Huisgen’s [2+3] cycloaddition of azide and acetylenic derivatives was employed as an efficient and simple method to conjugate azabicycloalkane amino acids, mimics of a homoSer-Pro dipeptide, with biologically relevant partners.     

Click reactions in chitosan chemistry

The review provides the first generalized and systematized information on the use of click reactions in chitosan chemistry for the preparation of novel polymers with attractive physicochemical and biological properties. The reactions of copper-catalyzed azide—alkyne cycloaddition and the click reactions of chitosan derivatives occurring in the absence of salts or metal complexes are discussed in detail. The data on the pre-click modification of chito-san (i.e., the introduction of azide function, alkyne fragment, highly dipolarophilic moieties, and thiol group into the polymer) are reviewed. Special attention is given to the application of new chitosan derivatives obtained by click modification.     

Click chemistry with fullerene derivatives

C₆₀ derivatives bearing either terminal alkyne or azide functional groups have been prepared and used as building blocks under the copper-mediated Huisgen 1,3-dipolar cycloaddition conditions leading to 1,2,3-triazole derivatives.     

Electroinitiated polymerization of arylvinyl monomers

The electroinitiated polymerizations of styrene, 2-vinylnaphthalene, and 9-vinylanthracene were compared in sulfolane and acetone solvents in the presence of ZnCl₂. The relative orders of polymerization rates and polymerization efficiencies, in both solvents, were 9-vinylanthracene > 2-vinylnaphthalene > styrene, with faster rates and higher efficiencies occurring in sulfolane. Data obtained from viscosity and gel permeation chromatography (GPC) studies indicate that the molecular weights of the polymers produced in these systems are extremely low, <5000. Chemical composition and infrared (IR) spectral data suggest that abnormal transfer reactions (possibly from solvent) may be occurring in the electroinitiated 9-vinylanthracene polymerizations. The polymerization mechanism appears to be cationic in these monomer–solvent systems with ZnCl₂.     

Enzymatic polymerization of vinyl monomers

The possibility of using horse radish peroxidase as a catalyst for polymerization of monomers (vinylformamide and sodium vinylsulfonate) in the presence of hydrogen peroxide and 2,4-pentanedione in aqueous medium at room temperature was studied.     

Emulsion polymerization of hydrophobia monomers

Emulsion polymerization is the most important industrial polymerization process for manufacturing water based polymers. The heterogeneous nature of the process requires the diffusion of monomers from the emulsified droplets, through the aqueous medium, into the polymer particles where the polymerization takes place. Adequate solubility of the monomer is necessary for the diffusion process to occur effectively. Consequently, very hydrophobic monomers cannot be readily incorporated by emulsion polymerization. The use of a catalytic level of cyclodextrin allows the use of very hydrophobic monomers in emulsion polymerization.^[1] The mechanism of the process is believed to involve a catalytic cycle in which cyclodextrin acts as a “Phase Transport Catalyst”, continuously complexing and solubilizing the hydrophobic monomers and releasing them to the polymer particles. The kinetics and thermodynamics are favorable for the reaction to proceed.     

Heterocyclic monomers via reissert chemistry

An AA bisphenolic monomer ( 13 ), an AB activated fluoro‐phenolic monomer ( 14 ), and an AB₂ alcohol‐diester monomer precursor ( 17 ), all based on the isoquinoline nucleus, were prepared using Reissert compound chemistry. Additionally, model reactions established the efficiency of condensation of isoquinoline Reissert compounds with dihaloalkanes, providing evidence of the potential of this reaction to produce high molecular weight polymers, which was subsequently realized. © 2011 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem, 2011     

Radiation-induced graft polymerization of metal-containing monomers

Graft polymerization of acrylates and acrylamide complexes of Mn(II), Cr(III), Fe(III), Co(II), Ni(II), and Cu(II) from alcohol solutions onto a polyethylene powder preirradiated in air up to total doses of 10–300 kJ/kg was studied. Graft copolymers with a metal content of as high as 1.7 mass% were obtained. The addition of a σ- or a coordinate-bound metal atom to the monomer molecule (acrylic acid, acrylamide) was shown to decelerate the process of thermal homopolymerization by 4 to 8 times, significantly reduce the reaction order in respect with monomer concentration in solution, and in most cases produce no effect on the polymer chain termination mechanism. The grafting of metal-containing monomers was found not to alter the structure of the monomer unit, valent state, and coordination of the metal atom, either. The graft polymerization of the monomers from solution is distinguished by a weak effect of the radical reaction inhibitors. The effective activation energies for the grafting of the metal-containing monomers lie within 42–60 kJ/mol.     

Two-phase frontal polymerization of metal-containing monomers

A mathematical model of two-phase frontal polymerization in a moving conversion layer is proposed. Using fractional differential-integral calculus, an analytical solution for temperatures in the vicinity of the phase boundary (melting-polymerization) and the dependence of temperature at the front on the rate of the motion of the phase transition boundary are obtained. A formula for the front advancement rate that agrees with the experimental results is found, and a method for estimating the effective activation energy of frontal polymerization is proposed.     

Trimethylsilylmethyllithium: A novel initiator for the anionic polymerization of cyclosiloxanes and vinyl monomers

Trimethylsilylmethyllithium has been successfully used for the ring opening polymerization of cyclosiloxanes, in toluene or in the bulk, with the [211] cryptand or DMSO as promoters. Initiation reaction has been followed by ¹H, ¹³C, ²⁹Si and ⁷Li NMR in the case of D3 and D4 polymerizations. Suitable conditions have been found in which monomodal distributions of molecular weights of polysiloxanes are observed even in the case of D4 and 1,3,5,7-tetramethyl-1,3,5,7-tetravinylcyclotetrasiloxane homopolymerizations and copolymerizations. This organolithium compound can also initiate the anionic polymerization of vinyl monomers such as butadiene, styrene and MMA.     

Click chemistry for high-density biofunctionalization of mesoporous silica

The applicability of click chemistry for high-density functionalization of mesoporous silica is demonstrated. The mild conditions of the copper(I)-catalyzed Huisgen reaction allow for a surface functionalization with intact biomolecules. The high covalent enzyme functionalization density under simultaneous retention of enzyme activity and the absence of leaching demonstrate the promising potential of this approach.     

Spacer effect of novel bifunctional organophosphorus monomers in metal-imprinted polymers prepared by surface template polymerization

The interfacial activity and the molecular structure of functional monomers are critical factors that determine the success of synthesizing metal-imprinted polymers by surface template polymerization. From this point of view, first we prepared three distinct novel bifunctional organophosphorus monomers that are interspaced, in each case, by an alkyl spacer having a specific length. Each monomer carries two phosphonic acid groups and two aromatic groups in its molecular structures. Further, by using the synthesized bifunctional monomers, we prepared highly selective Zn(II)-imprinted polymers by the surface template polymerization initiated from a water-in-oil emulsion. To evaluate the template effect, we conducted diagnostic adsorption studies on Zn(II)-imprinted and unimprinted polymers with zinc ions. A high interfacial activity was found to be required for the functional monomers to create the predominant template effect. It became clear that Zn(II)-imprinted polymers having bifuctional monomers with 12-length alkyl chains (1,12-dodecanediol-O, O′-diphenyl phosphonic acid: DDDPA) yielded the best results. Moreover, analysis results of adsorption behavior supported a high-performance of the Zn(II)-imprinted polymers with DDDPA. © 1998 John Wiley & Sons, Inc. J Polym Sci A: Polym Chem 36: 2727–2734, 1998     

Synthesis and polymerization of heteroaromatic vinyl monomers

Methods of preparing new monomers, 2-vinyl and 2-isopropenyloxazoles and 2-isopropenyl-1,3,4-oxadiazoles are described. New methods were developed to synthesize monomers containing an isoxazole or a thiazole ring. Radical homopolymerization and copolymerization with styrene of these monomers were carried out by using AIBN as an initiator. Monomer reactivity ratios r₁, r₂ and Alfrey-Price Q–e values were determined by the Fineman-Ross and the Mayo-Lewis methods. The localization energy of the β-carbon was calculated by a HITAC-5020 computer, and the monomer reactivity is discussed in terms of L_β.     

Anionic polymerization of vinyl monomers with xanthates

The polymerization of vinyl monomers with various xanthates (potassium tert-butylxanthate, potassium benzylxanthate, zinc n-butylxanthate, etc.) were carried out at 0°C in dimethylformamide. N-Phenylmaleimide, acrylonitrile, methyl vinyl ketone, and methyl methacrylate were found to undergo polymerization with potassium tert-butylxanthate; however, styrene, methyl acrylate, and acrylamide were not polymerized with this xanthate. In the anionic polymerization of methyl vinyl ketone with potassium tert-butylxanthate, the rate of the polymerization was found to be proportional to the catalyst concentration and to the square of the monomer concentration. The activation energy of methyl vinyl ketone polymerization was 2.9 kcal/mole. In the polymerization, the order of monomer reactivity was as follows: N-phenylmaleimide > methyl vinyl ketone > acrylonitrile > methyl methacrylate. The initiation ability of xanthates increased with increasing basicity of the alkoxide group and with decreasing electronegativity of the metal ion in the series, lithium, sodium, and potassium tert-butylxanthate. The relative effects of the aprotic polar solvents on the reactivity of potassium tert-butylxanthate was also determined as follows: diethylene glycol dimethyl ether > dimethylsulfoxide > hexamethylphosphoramide > dimethylformamide > tetrahydrofuran (for methyl vinyl ketone); dimethyl sulfoxide > hexamethylphosphoramide > dimethylformamide ? diethylene glycol dimethyl ether (for acrylonitrile).     

Photoinitiated cationic polymerization of epoxy alcohol monomers

A series of epoxy alcohols were prepared by simple, straightforward methods. These compounds were very reactive monomers that polymerized rapidly on UV irradiation in the presence of cationic photoinitiators. The kinetics of the cationic photopolymerization of these monomers were studied with diaryliodonium salt photoinitiators and real‐time IR spectroscopy. The rate of epoxide ring‐opening polymerization was enhanced markedly by the presence of the hydroxy group. Using model compounds, the monomers were shown to polymerize via an activated monomer mechanism. Simple epoxy alcohols polymerized to give polymers with a hyperbranched structure. The novel monomers also were observed to accelerate the rate of the photopolymerization of mono‐ and multifunctional epoxides. © 2000 John Wiley & Sons, Inc. J Polym Sci A: Polym Chem 38: 389–401, 2000