Radical Polymerization Of Monomers Research Articles

Radicals and Polymers.

This article describes some selected results of my 30 years as an industrial researcher. During this time, I had the chance to work on many very different projects. About two thirds of them were dealing with the fascinating interaction of radicals and polymers. Of the more than 350 million tons of industrial polymers produced worldwide every year, about 50% are made by the radical polymerization of monomers that are often stabilized against undesired premature polymerization by addition of polymerization inhibitors. Stabilizers are necessary to protect the majority of polymeric materials during their service life from radical degradation processes triggered by oxygen, heat or light. Modification of the polymeric architecture can be easily achieved via radical polymer analogous reactions. One of the most important developments in polymer science in the last 25 years is controlled radical polymerization. Recently, radical bearing redox-active polymers emerged as promising in energy storage applications, for example, in organic radical batteries. Our contributions to the fields mentioned above are described with examples of: a) novel benzofuranone stabilizers for polymers; b) the serendipidous discovery of novel dyestuffs; c) eco-friendly polymerization inhibitors; d) novel nitroxides and alkoxyamines for the first industrial realization of controlled radical polymerization; e) novel and safe radical initiators; f) nitroxide radicals bearing polymers for electrochemical applications.

Additive-free photosynthesis of acrylamide hydrogels initiated with CdS and TiO2 as light visible nano-photocatalysts

Hydrogels are three-dimensional polymer networks which can be synthesized by different techniques, such as free-radical addition reaction which is the most well-known technique in functional vinyl monomer polymerization. Photopolymerization, as an attractive technique, has been used in radical polymerization of monomers and has revitalized interest in the idea that it congregates a wide range of economic and ecological expectations. Due to the spatial–temporal control and a mild curing process of polymerization, photoinitiator semiconductor nano-particles offer great advantages, such as effective and quantitative reaction. Cadmium sulfide nanowire, titanium dioxide (TiO2) nanotube, and TiO2 nanowire were used as visible photocatalysts for photopolymerization of acrylamide hydrogel without using any additive under the sunlight and purple LED irradiations. The effects of different synthetic parameters, including initiator type and concentration and type of light sources, were investigated to achieve hydrogels with maximum swelling capacity. The results showed that the swelling of hydrogel reached 80 g water/g hydrogel when the TiO2 nanowire was used as the photoinitiator. The synthesized semiconductors and hydrogels were characterized by X-ray diffractometry, adsorption isotherm, infrared spectroscopy, thermogravimetric analysis, and transmission electron microscopy. According to the results, the new initiators led to semiconductor-based hydrogels, achieved with high swelling property through a high-speed high-efficient photopolymerization reaction in a safe manner.

In situ immobilization on the silica gel surface and adsorption capacity of polymer-based azobenzene on toxic metal ions

In situ immobilization of poly[(4-methacryloyloxy-(4′-carboxy)azobenzene] on silica gel surface has been performed by radical polymerization of monomer. The fact of polymer immobilization is confirmed by IR spectroscopy. TG and DSC-MS analysis showed that the mass of the immobilized polymer was 10.61%. The SEM-microphotograph-synthesized composite analysis showed that the immobilized polymer on the silica gel surface is placed in the form of fibers. It has been found that the synthesized composite exhibits the sorption ability in terms of microquantities of Cu(II), Cd(II), Pb(II), Mn(II) and Fe(III) ions in a neutral aqueous medium. The quantitative sorption of microquantities of Pb(II) and Fe(III) ions has been recorded. It has been found that immobilization of the silica gel surface leads to an increase in its sorption capacitance for Fe(III), Cu(II) and Pb(II) ions by half.

Development of new multifunctional terpolymer sorbent for proteomics applications.

Determination of the availability of phases for specific separations is an important task achieved by a separation chemist. This becomes vital when the complex samples like biofluids are dealt with in proteome science. The work presented here involves the synthesis and application of terpolymeric sorbent with different functionalizations adopted for the selective enrichment of biomolecules of interest from biological fluids. Synthesis of terpolymer was carried out by the radical polymerization of monomers: methyl acrylate, acrylic acid and vinyl acetate with diethylene glycol dimethacrylate as cross-linking agent, benzoyl peroxide as initiator and chloroform as a porogenic solvent. Characterization was done through Fourier transform infrared spectroscopy, scanning electron microscopy and nitrogen adsorption porosimetry. The polymer was further modified to immobilized metal ion affinity chromatographic material, with immobilized Fe(3+)/La(3+) ions that allowed phosphopeptide enrichment from tryptic digests of standard proteins as well as milk, egg yolk and human serum. Sensitivity of enrichment down to 50 fmol was achieved in the presence of complex protein background as bovine serum albumin. Hydrophobicity was introduced through octadecyl amine, which provides comparable results to ZipTip C18/C4 for desalting of complex mixtures of all caseins. Analysis of the enriched content was performed by Matrix Assisted Laser Desorption Ionization Mass Spectrometry (MALDI-MS).

Synthesis, characterization, thermal and optical properties of styrene derivatives having pendant p-substituted benzylic ether groups

The derivatives of styrene monomer, 4-chlorophenyl-4-vinylbenzyl ether (M1), 4-methoxyphenyl-4-vinylbenzyl ether (M2), 4-ethylphenyl-4-vinylbenzyl ether (M3) and 1-naphtylphenyl-4-vinylbenzyl ether (M4) were synthesized. The normal free radical polymerization of monomers in 1,4-dioxane were performed by using 2,2′-azobisisobutyronitrile as an initiator at 65 °C. The monomers and their homopolymers were characterized by FT-IR, NMR and elemental analyses measurements. The thermal stability of polymers was investigated by thermogravimetric and differential scanning calorimetric analysis. Thermal degradation activation energies of the polymers were calculated by the Ozawa and Kissinger methods. In addition, photo-stability tests of the polymers under near-UV irradiation were performed.

Synthesis and Characterization of Silica–Polymer Nanocomposites Functionalized with Piperazine for the Synthesis of β-Nitro Alcohols

In order to compare the activity and selectivity for the synthesis of β-nitro alcohols, piperazine was functionalized directly and after surface modification into the ordered mesoporous SBA-15 framework. The materials were characterized by powder X-ray diffraction, N2-adsorption–desorption isotherm, FT-IR, SS-NMR and scanning electron microscopy. The catalyst synthesized via surface modification under solvent free conditions showed very high activity and selectivity of β-nitro alcohols compared to the one synthesized by direct functionalization of SBA-15. Finally the possible reaction pathways were explained mechanistically. Surface modification of SBA-15 was achieved by radical polymerization of monomers followed by functionalization with piperazine to achieve the selective nitro alcohols in nitroaldol condensation

Mechanism of poly(methyl methacrylate) film formation by pulsed laser deposition

The formation of poly(methyl methacrylate) films during pulsed laser deposition was studied by deposition at different substrate temperatures and by using targets with defined molecular mass and tacticity. At room temperature, the films (deposited from high-molecular weight polymer targets) mainly consist of macromolecules with average molecular masses of about 8000g∕mol. Up to substrate temperatures of 100°C, this average mass remains constant, suggesting the transport of larger polymeric fragments from the target to the substrate surface. This hypothesis is also confirmed by experiments using target material of lower molecular weight and of defined tacticity. At temperatures above 100°C and thus at conditions of enhanced mobility, the substrate molecular weight increases with temperature. The experiments indicate that the films are formed by deposition and reaction of macromolecular species. Radical polymerization of monomers described in the literature as a dominating film formation process plays no significant role.

Reactions of fluoroalkanoyl peroxides with single‐walled carbon nanotubes: application to sidewall modification of single‐walled carbon nanotubes with the introduction of fluoroalkyl groups

AbstractFluoroalkanoyl peroxides reacted with single‐walled carbon nanotubes (SW‐CNTs) to afford fluoroalkylated SW‐CNT derivatives under very mild conditions. Fluoroalkylated SW‐CNT derivatives [RF‐(SW‐CNT)s] thus obtained exhibited no solubility in aqueous and traditional organic media; however, RF‐(SW‐CNT)s were solubilized into water more effectively than the parent SW‐CNT by the use of fluoroalkyl end‐capped homooligomers. However, fluroalkyl end‐capped SW‐CNT cooligomers were obtained by the reactions of fluroalkanoyl peroxides with SW‐CNTs in the presence of radical polymerizable monomers, and these fluoralkylated SW‐CNT cooligomers were found to exhibit a good solubility in aqueous and organic media. Copyright © 2006 John Wiley & Sons, Ltd.

Solubilization of fullerene into ionic liquids by the use of fluoroalkyl end‐capped oligomers

AbstractFluoroalkyl end‐capped oligomers were solubilized into a variety of ionic liquids such as N‐methylpyrazolium tetrafluoroborate, 3‐methylpyrazolium tetrafluoroborate and 1‐butyl‐3‐methylimidazolium hexafluorophosphate, and these fluorinated oligomers were able to reduce the surface tension of these ionic liquids. Interestingly, these fluorinated oligomers were able to solubilize fullerene into ionic liquids effectively. Fluoroalkyl end‐capped fullerene co‐oligomers, which were prepared by the oligomerizations of fluoroalkanoyl peroxides with radical polymerizable monomers such as acryloylmorpholine in the presence of fullerene, were more effective in solubilizing fullerene into ionic liquids compared to the corresponding fluoroalkyl end‐capped homo‐oligomers possessing no fullerene units. Fluoroalkyl end‐capped fullerene co‐oligomers/fullerene/ionic liquid complexes thus obtained were applied to the arrangements of fullerenes above the poly(methyl methacrylate) (PMMA) surface, and the higher fluorescent intensity of fullerene was obtained in the modified PMMA surface, although the reverse side of this modified film surface afforded an extremely weak fluorescent intensity. Copyright © 2005 John Wiley & Sons, Ltd.

Synthesis and properties of novel fluoroalkyl end-capped oligomers having adamantane units in the main chains via a radical process

Fluoroalkanoyl peroxides were reacted with adamantane in the presence of radical polymerizable monomers such as acrylic acid, acryloylmorpholine, and N,N-dimethylacrylamide to afford fluoroalkyl end-capped oligomers having adamantane units in the main chains via a radical process under very mild conditions. Thermal stability of these new fluorinated adamantane co-oligomers thus obtained became higher than that of the corresponding fluorinated homo-oligomers having no adamantane units. Interestingly, these fluorinated adamantane co-oligomers exhibited good solubility in traditional organic solvents such as methanol, ethanol, tetrahydrofuran, chloroform, benzene, dimethylsulfoxide and N,N-dimethylformamide including water, although the parent adamantane exhibited no solubility in water, methanol and dimethylsulfoxide. Furthermore, these adamantane co-oligomers were able to reduce the surface tension effectively to form the nanometer size-controlled self-assembled fluorinated molecular aggregates. Copyright © 2005 John Wiley & Sons, Ltd.

Kinetics of Radical Polymerization of a Monomer Derived from Monoethanolamine Vinyl Ether and 1,4-Benzoquinone: A Polarographic Study

Radical polymerization of a disubstituted monomer derived from monoethanolamine vinyl ether and 1,4-benzoquinone was studied by classical polarography. The optimal conditions for the synthesis of the redox polymer were found. The polymerization rate constants, preexponential term in the Arrhenius equation, and activation energy were calculated.

Cyclodextrins in polymer synthesis: Dimethyl-β-cyclodextrin as thermosensitive retardant for the radical polymerization of N-methacryloyl-L-tyrosine derivatives in water

AbstractThe synthesis and characterization of N-methacryloyl-L-tyrosine methyl ester (3a) and ethyl ester (3b), and their acetyl derivatives O-acetyl-N-methacryloyl- L-tyrosine methyl ester (4a) and ethyl ester (4b) are described. Monomers 3 and 4 were complexed with RAMEB (randomly methylated ß-cyclodextrin) yielding water soluble host-guest complexes 5a-d. The radical polymerization of monomers 3 and 4 was investigated in the presence as well as in the absence of RAMEB in aqueous medium at room temperature and also at 60°C. It is shown that the polymerization tendency of complexes 5a-d at room temperature is lower, leading to polymers of higher molecular weight, compared to the free monomers 3 and 4. Furthermore, the polymerization of monomers 3 and 4 was carried out in homogenous organic solution using 2,2’-azoisobutyronitrile as initiator, and the results are discussed.

New polymethacrylates having a carbonate linkage between the spacer and the mesogenic unit in the side chain

New side chain homo- and copolymethacrylates with a carbonate linkage between the spacer and the mesogenic unit were prepared by the free radical polymerization of monomers having 4-cyanobiphenyl and/or 4′-methoxybenzylideneaniline as mesogens, whose structures were confirmed by FTIR and 1H-NMR spectra and elemental analyses. Thermal and mesogenic properties of the monomers and the polymers were evaluated by differential scanning calorimetry, X-ray analyses and polarizing microscopy. It was discovered that only the homopolymer with 4′-methoxybenzylideneaniline as a mesogen formed nematic mesophase, but the others had no thermotropic LC phases. This might be due to introduction of a carbonate linkage which shows an unusual geometry.

Synthesis of ethylene-propylene rubber graft copolymers by borane approach

This paper describes a new method to prepare graft copolymers which have an EP rubber backbone and several free radical polymerized polymers grafted thereto. The process involves hydroboration of commercial EPDM rubbers, such as poly(ethylene-co-propylene-co-1,4-hexadiene) and poly(ethylene-co-propylene-co-5-ethylidene-2-norbornene), with 9-borabicyclononane (9-BBN). The resulting secondary alkyl-9-BBN moieties in the EPDM copolymer were then exposed to oxygen in the presence of free radical polymerizable monomers. Under certain conditions, the selective autoxidation reaction of secondary alkyl-9-BBN took place to create desirable polymeric radicals which can in situ initiate free radical polymerization. High graft efficiency was observed with controllable copolymer compositions. The graft copolymer of EP-g-PMMA is used to show the chemistry as well as some of the physical properties.

Polymer Inclusion Compounds by Polymerization of Monomers in β-Cyclodextrin Matrix in DMF Solution

Abstract The investigations of the synthesis of polyrotaxanes by the radical polymerization of monomers (vinylidene chloride, methyl acrylate, styrene, and methacrylonitrile) in DMF in the presence of β-cyclodextrin have been carried out. The possibility of formation β-cyclodextrin inclusion compounds with some vinyl monomers or some other organic substances in DMF solution has been established. We assume that the inclusion in presence of the solvent is related to the unusual phenomenon of β-cyclodextrin crystallization in hot DMF solutions. The polymerization of vinyl monomers in DMF solution at increased temperatures in the presence of β-cyclodextrin leads to compounds containing a great amount of cyclic compounds (up to 80%). Similar results have been obtained for monomers introduced as previously prepared adducts with β-cyclodextrin. Stable compounds of polymer and β-cyclodextrin have been obtained in the case of vinylidene chloride. The lack of carbohydrate moieties in the product obtained by polymer...