Methacrylate Double Bonds Research Articles

Photoinduced Polymerization of Eugenol-Derived Methacrylates.

Biobased monomers have been used to replace their petroleum counterparts in the synthesis of polymers that are aimed at different applications. However, environmentally friendly polymerization processes are also essential to guarantee greener materials. Thus, photoinduced polymerization, which is low-energy consuming and solvent-free, rises as a suitable option. In this work, eugenol-, isoeugenol-, and dihydroeugenol-derived methacrylates are employed in radical photopolymerization to produce biobased polymers. The polymerization is monitored in the absence and presence of a photoinitiator and under air or protected from air, using Real-Time Fourier Transform Infrared Spectroscopy. The polymerization rate of the methacrylate double bonds was affected by the presence and reactivity of the allyl and propenyl groups in the eugenol- and isoeugenol-derived methacrylates, respectively. These groups are involved in radical addition, degradative chain transfer, and termination reactions, yielding crosslinked polymers. The materials, in the form of films, are characterized by differential scanning calorimetry, thermogravimetric, and contact angle analyses.

MOF-Based Erodible System for On-Demand Release of Bioactive Flavonoid at the Polymer-Tissue Interface.

Plant-derived compounds incite applications virtually on every biomedical field due to the expedient antioxidant, anti-inflammatory and antimicrobial properties in conjunction with a natural character. Here, quercetin (QCT), a flavonoid with therapeutic potentials relevant to the oral environment, was encapsulated within metal-organic frameworks (MOFs) to address the concept of on-demand release of phytochemicals at the biointerface. We verified the applicability of a microporous MOF (ZIF-8) as a controlled-release system for QCT, as well as investigated the incorporation of QCT@ZIF-8 microparticles into a dental adhesive resin for desirable therapeutic capabilities at the tooth-restoration interface. QCT was encapsulated within the frameworks through a water-based, one-step synthetic process. The resulting QCT@ZIF-8 microparticles were characterized with respect to chemical composition, crystal structure, thermal behavior, micromorphology, and release profile under acidic and physiological conditions. A model dental adhesive formulation was enriched with the bioactive microparticles; both the degree of conversion (DC) of methacrylic double bonds and the polymer thermal behavior were accounted for. The results confirm that crystalline QCT@ZIF-8 microparticles with attractive loading capacities, submicron sizes, high thermal stability and responsiveness to environmental pH change were successfully manufactured. The concentration of QCT@ZIF-8 in the resin system was a key factor to maintain an optimal DC plateau and rate of polymerization. Essentially, one-step encapsulation of QCT in biocompatible ZIF-8 matrices can be easily achieved, and QCT@ZIF-8 microparticles proved as smart platforms to carry bioactive compounds with potential use to prevent microbial and enzymatic degradation of hard tissues and extracellular matrix components.

Synthesis of methacrylate pendant polyelectrolyte as water-soluble multifunctional cross-linker

A new cationic polyelectrolyte, constituting with quaternary poly(4-vinyl pyridine) (PVPy) backbone and methacrylate pendant groups was prepared by spontaneous polymerization methodology. Thus, action of 2-bromoethyl methacrylate (BEMA) on 4-vinyl pyridine resulted in spontaneous polymerization of vinyl pyridine monomer, without initiator, while methacrylate double bonds remaining unreacted. The resulting water-soluble polymer (QMEP); poly(2-methacryloyloxyethyl 4-vinyl pyridinium bromide) was demonstrated to undergo rapid gelation in concentrated aqueous solutions via self-crosslinking of the methacrylate pendant groups by radical polymerization (The abbreviation QMEP stands for quaternary methacrylate functional polymer). Crosslinking densities of QMEP hydrogels estimated by “Phantom Network Model” using equilibrium swelling values, revealed 62.5% of the residual methacrylate double bonds. QMEP was also employed as multifunctional crosslinker for synthesis of highly swelling hydrogels derived from a set of monomers, such as acrylic acid, acrylamide, N-vinyl formamide and N-vinyl pyrrolidinone.

Highly adjustable biomaterial networks from three-armed biodegradable macromers

Biocompatible material platforms with adjustable properties and option for chemical modification are warranted for site-specific biomedical applications. To this end, three-armed biodegradable macromers of well-defined chemical characteristics were prepared from trivalent alcohols with different degrees of ethoxylation and different lengths of oligoester domains. A platform of 15 different macromers was established. The macromers were designed to exhibit different hydrophilicities and molecular weights and contained various types of oligoesters such as d,l-lactide, l-lactide and ε-caprolactone. Macromers chemical composition was determined and molecular weights ranged from 900 to 3000Da. Thermally induced cross-linking of methacrylated macromers was monitored by oscillation rheology. A novel variant of the solid lipid templating technique was established to fabricate macroporous tissue engineering scaffolds from these macromers. Scaffold properties were thoroughly investigated regarding mechanical properties, compositional analysis including methacrylic double bond conversion, microstructure and porosity. Material properties could be controlled by macromer chemistry. By variation of the fabrication procedure and processing parameters scaffold porosity was increased up to 88%. Basic cytocompatibility was assessed including indirect and direct contact methods. The established macromers hold promise for various biomedical purposes. Statement of SignificanceSpecific biomedical applications require tailored biomaterials with defined properties. We established a macromer platform for preparation of tissue engineering scaffolds with adjustable chemical and mechanical characteristics. Macromers were composed of trivalent core alcohols with different degrees of ethoxylation to which biodegradable domains – lactide or ε-caprolactone – were oligomerized before final methacrylation. The solid lipid templating technique was adapted to fabricate macroporous scaffolds with controlled pore structure and porosity from the developed macromers, which can also be processed by solid freeform fabrication techniques. The material platform relies on clinically established chemistries of the biodegradable domains and the macromer concept enables the fabrication of networks in which cross-polymerization kinetics, mechanical properties and surface hydrophobicity is predefined by macromer chemistry. Cytocompatibility was confirmed by indirect and direct cell contact experiments.

Controlled Divinyl Monomer Polymerization Mediated by Lewis Pairs: A Powerful Synthetic Strategy for Functional Polymers.

Lewis pair cooperation provides a facile approach for polymerizing dissymmetric divinyl polar monomers such as 4-vinylbenzyl methacrylate in excellent regioselectivity and high reactivity at mild conditions, affording soluble polymers bearing pendant active vinyl groups with high molecular weight (up to 6.4 × 105 g/mol) and narrow polydispersity (PDI < 1.5). ESI-TOF MS study demonstrated that the polymerization process only concerned the methacrylic double bond and selectively remained the pendant allylic or styrene C═C bond.

Synthesis of Allyl-Functionalized Polymers via Selective Reversible Addition-Fragmentation Chain Transfer (RAFT) Polymerization

Allyl-functionalized copolymers with well-defined structure have been successfully prepared via selective reversible addition-fragmentation chain transfer (RAFT) copolymerization of styrene and allyl methacrylate possessing a higher reactive methacrylate and a lower reactive allyl. By employing a fast RAFT equilibrium, the polymerization for AMA completely occurred in methacrylate double bonds, whereas allyl double bonds remained intact and were introduced into the side-chains. GPC and 1H NMR analyses have confirmed the high chain-end functionality of the resultant copolymer.

The effect of the crosslinking agent on the performance of propranolol imprinted polymers

Molecularly imprinted polymers (MIPs) of propranolol were synthesized by bulk polymerization. Methacrylic acid (MAA) was selected as the functional monomer and symmetrical dimethacrylate crosslinkers of different length between the double bound as well as an asymmetrical crosslinker containing an allylic and a methacrylic double bond were investigated in this study. The rebinding experiments were carried by radioligand experiments in presence of [3H]-(S)-propranolol. The microstructure of MIPs (morphology, crosslinking density and surface properties) were analysed by B.E.T. surface, SEM images and swelling experiments. MIPs containing 1,6 hexanediol dimethacrylate (HDDMA) and allyl methacrylate (AMA) improved the binding results of MIPs having the most common crosslinking agent ethylene glycol dimethacrylate (EGDMA).In addition, methyl methacrylate (MMA) was included in the formulation to decrease the crosslinking density. The binding specificity decreased except for MIPs containing AMA as crosslinking agent, which showed a similar specificity to MIPs without MMA.

Chitin-Methacrylate: Preparation, Characterization and Hydrogel Formation.

Chitin-methacrylate (CM) was prepared by the reaction of methacrylic acid on chitin in 5% LiCl/DMAc in the presence of N,N’-dicyclocarbodiimide and dimethylaminopyridine. The resultant chitin-methacrylate product was isolated in 61% yield and was found to be readily water-soluble. The derivative was found to be a mixture of methacrylate and methacrylic-dimethylaminopyridine complex substituents at the C-6 position in approximately equal amounts. In order to evaluate the activity of the methacrylate double bond, a chitin-methacrylate water solution was photo-crosslinked in the presence of Irgacure 2959 photo-initiator to generate CM-hydrogel. The CM-hydrogel was evaluated for its biodegradability characteristics by enzymatic degradation with lysozyme solutions of varying concentrations. Completely water-soluble products were obtained within 48 h. In vitro cytotoxicity assays of the CM-hydrogel and its extract against three cell lines, NCTC clone 929, IMR-90 and MG-63, indicated the hydrogel was non-cytotoxic with cells able to adhere and proliferate well on the hydrogel.

Enhancement of scratch-resistance properties of methacrylated UV-cured coatings

Methacrylic based organic–inorganic hybrid coatings containing silica, titania or alumina domains, were generated in situ combining a UV-induced polymerization reaction with a sol–gel process of metal alkoxide precursors. While the presence of TEOS and ALP did not influence significantly the rate of curing and the final methacrylic double bond conversion, a certain effect is evident when TIP is added as inorganic precursor both on UV-curing rate and final double bond conversion. An increase of the rigidity of the cured coating was achieved in the presence of the inorganic fillers with an increase of T g values by increasing the metal alkoxide content in the photocurable formulations. Scratch test showed a general increase of first and second critical load values for hybrid coatings together with an increase in the Persoz hardness values.

(Meth)acrylate vinyl ester hybrid polymerizations

In this study vinyl ester monomers were synthesized by an amine catalyzed Michael addition reaction between a multifunctional thiol and the acrylate double bond of vinyl acrylate. The copolymerization behavior of both methacrylate/vinyl ester and acrylate/vinyl ester systems was studied with near-infrared spectroscopy. In acrylate/vinyl ester systems, the acrylate groups polymerize faster than the vinyl ester groups resulting in an overall conversion of 80% for acrylate double bonds in the acrylate/vinyl ester system relative to only 50% in the bulk acrylate system. In the methacrylate/vinyl ester systems, the difference in reactivity is even more pronounced resulting in two distinguishable polymerization regimes, one dominated by methacrylate polymerization and a second dominated by vinyl ester polymerization. A faster polymerization rate and higher overall conversion of the methacrylate double bonds is thus achieved relative to polymerization of the pure methacrylate system. The methacrylate conversion in the methacrylate/vinyl ester system is near 100% compared to only ~60% in the pure methacrylate system. Utilizing hydrophilic vinyl ester and hydrophobic methacrylate monomers, polymerization-induced phase separation is observed. The phase separated domain size is on the order of ~1 μm under the polymerization conditions. The phase separated domains become larger and more distinct with slower polymerization and correspondingly increased time for diffusion.

A novel dispersant for preparation of high loading and photosensitive carbon black dispersion

AbstractHigh loading of stable carbon black (CB) dispersion in organic solvent, PGMEA, was prepared by a ball‐milling process when using poly(styrene‐EHA‐HEMA)‐block‐poly(styrene‐EHA‐HEMA‐DMAEMA) (P(SEH)‐b‐P(SEHD)) as a dispersant. The P(SEH)‐b‐P(SEHD) containing P(SEH) as a steric chain and P(SEHD) as an anchoring chain was prepared by TEMPO‐mediated polymerization. The tertiary amine group of DMAEMA in P(SEHD) chain could be adsorbed onto CB by the interaction with the carboxylic acid group on surface of CB and the P(SEH) chain could provide sufficiently steric repulsion force to avoid the aggregation of CB. In addition, a photosensitive dispersant, P(SEH)‐b‐P(SEHD)CC, containing the methacrylate double bond side group was also synthesized and was used to prepare stable CB dispersion in PGMEA. The effects of the molecular weight between steric and anchoring chains, the content of tertiary amine, and the amount of methacrylate double bond in the dispersant on the particle size of CB were investigated. Furthermore, the influences of various surface properties of CB, such as specific surface area, content of carboxylic acid group, and size of primary particle, on the particle size of CB in dispersion were also discussed. Finally, the photosensitivity of P(SEH)‐b‐P(SEHD)CC/CB composite was monitored by a photodifferential scanning calorimeter. © 2008 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 46: 6185–6197, 2008

Characterization of negative-type photoresists containing polyhedral oligomeric silsesquioxane methacrylate

A series of negative-type photoresists made by blending with various contents of polyhedral oligomeric silsesquioxane (POSS) methacrylate were prepared and characterized. These POSS macromers tend to crystallize or aggregate to form their own domains within the photoresist matrix. Sensitivity of the POSS modified photoresist is significantly improved with the increase of the POSS content. Results from photo-DSC analyses indicate that both induction time and peak maximum of heat flux are reduced by blending with POSS macromer. Addition of the proper amount (<13 wt%) of POSS can effectively increase photo-polymerization rate and exothermic heat. Hydrogen bonding interaction between the hydroxyl of photoresist and the siloxane of POSS tends to attract methacrylate double bonds surrounding POSS particles locally and thus enhances the rate of photo-polymerization and sensitivity.

Copolymerization of two bromine containing methacrylate monomers with methylmethacrylate. Determination of reactivity ratios by in situ quantitative 1H NMR monitoring

AbstractAn important method used to make medical implants radiologically visible is based on introduction of radiopaque bromine or iodine containing methacrylic monomers. Thus, 2-(2-bromopropionyloxy) propyl methacrylate (BPPM) and 2-(2-bromoisobutyryloxy) propyl methacrylate (BIPM) were synthesized with the aim to use them as radiopaque agents. The free radical initiated copolymerization of BPPM and BIPM with methyl methacrylate (MMA) were performed directly in a thermostatic cell of the NMR spectrometer. The copolymer compositions obtained from 1H NMR spectra led to the determination of the reactivity ratios (rMMA = 1.08 ± 0.12; rBPPM = 1.01 ± 0.13 and rMMA = 0.95 ± 0.09; rBIPM = 0.95 ± 0.1). The reactivity ratios of these two monomers is similar to that of MMA suggesting that the length of the bromine containing monomers side chain does not affect significantly the reactivity of the methacrylic double bond. From the results we conclude the copolymers to have random structure.

A Novel Approach to Magnetic Nanoadsorbents with High Binding Capacity for Bovine Serum Albumin

AbstractMagnetic nanoadsorbents using Fe3O4 nanoparticles as cores and poly(methyl acrylic acid) (PMAA) as ionic exchange groups were prepared through our novel approach. Two steps were involved in this approach: the first was to functionalize the magnetic nanoparticles (MNPs) with methacrylate double bonds via the combination of ligand exchange and condensation of methacryloxypropyltrimethoxysilane(MPS); the second was to graft PMAA chains onto the surface of MNPs through radical polymerization. The success of the various surface functionalization steps was ascertained using FTIR and XPS. The as‐synthesized PMAA‐coated MNPs were effective in binding bovine serum albumin (BSA) with a high capacity of 1 300 mg · g−1.magnified image

Macrophage response to methacrylate conversion using a gradient approach

Incomplete conversion, an ongoing challenge facing photopolymerized methacrylate-based polymers, affects leachables as well as the resulting polymer network. As novel polymers and composites are developed, methods to efficiently screen cell response to these materials and their properties, including conversion, are needed. In this study, an in vitro screening methodology was developed to assess cells cultured directly on cross-linked polymer networks. A gradient in methacrylate double bond conversion was used to increase the experimental throughput. A substrate of 2,2-bis[4-(2-hydroxy-3-methacryloxypropoxy)phenyl] propane (BisGMA) and triethylene glycol dimethacrylate (TEGDMA) was prepared with a conversion ranging from 43.0% to 61.2%. Substrates aged for 7 days had no significant differences in surface roughness or hydrophilicity as a function of conversion. Leachables were detectable for at least 7 days using UV absorption, but their global cytotoxicity was insignificant after 5 days of aging. Thus, RAW 264.7 macrophage-like cells were cultured on aged substrates to evaluate the cell response to conversion, with possible contributions from the polymer network and local leachables. Conversions of 45% and 50% decreased viability (via calcein/ethidium staining) and increased apoptosis (via annexin-V staining). No significant changes ( p > 0.05) in tumor necrosis factor-α and interleukin-1β gene expression, as measured by quantitative, real-time reverse transcription-polymerase chain reaction, were seen as conversion increased. Thus, conversions greater than 50% are recommended for equimolar BisGMA/TEGDMA. The ability to distinguish cell response as a function of conversion is useful as an initial biological screening platform to optimize dental polymers.

Self-Organization-Induced Three-Dimensional Honeycomb Pattern in Structure-Controlled Bulky Methacrylate Polymers: Synthesis, Morphology, and Mechanism of Pore Formation

Here we report, for the first time, a novel molecular design for three-dimensional honeycomb structures through a self-organization of hydrogen-bonded bulky anchoring group in a methacrylic polymer backbone. The polymerizable monomer design includes a methacrylic double bond linked to various hydrophobic anchoring units such as ethane, n-decane, tricyclodecane (TCD), and adamantane via a hydrogen-bonded cycloaliphatic urethane linkage. The structures of the polymers were confirmed by nuclear magnetic resonance (NMR) and the molecular weights of the polymer were determined by gel permeation chromatography (GPC). The methacrylate polymers having tricyclodecane and adamantane bulky anchoring groups self-organized to produce three-dimensional honeycomb patterns in tetrahydrofuran-water solvent mixture at ambient conditions, whereas its linear analogues (ethane, n-decane) failed to produce any micropattern. The scanning electron microscopy (SEM) analysis of the above-prepared polymer films revealed that the structure of the polymer played a major role in the formation of the honeycomb patterns. The solution Fourier transform infrared (FTIR) measurements confirmed that the bulky tricyclodecane and adamantane polymers have strong hydrogen-bonding interaction compared to that of their linear analogues, which is the driving force for the micropatterns. Transmission electron microscopy (TEM) and atomic force microscopy (AFM) analysis of the bulky polymers revealed that the polymers exist as vesicles or micelles in the solution, which leads to the formation of the honeycomb pattern. The honeycomb pattern formation in the bulky polymer systems suggests that two cooperative factors such as hydrogen-bonding interaction and hydrophobicity of bulky anchoring units are necessary to induce three-dimensional honeycomb structures. To investigate the effect of molecular weights and its distribution on the self-organization process, both benzoyl peroxide (BPO) initiated free radical and atom transfer radical polymerization (ATRP) techniques were employed for the polymerization. Micropores formed irrespective of differences in molecular weight and polydispersity index (PDI); however, the pore size distribution was influenced by both molecular weights and PDI. Low molecular weight samples afforded polydisperse pores with the ATRP samples with more narrow PDI producing pores with large dimensions. The approach has also been investigated for polystyrene-bulky methacrylic copolymer, and the results revealed that uniform honeycomb patterns were produced for copolymers having more than 50 mol % incorporation of bulky units.

Polyhedral Oligomeric Silsesquioxane Containing Copolymers for Negative‐Type Photoresists

AbstractSummary: A series of methacrylate copolymers containing polyhedral oligomeric silsesquioxane (POSS) was synthesized from the free radical copolymerization of methacrylic acid, methyl methacrylate, and isobutyl propylmethacryl polyhedral oligosilsesquioxanes, and then were modified with glycidyl methacrylate to serve as negative‐type photoresists. The UV/Vis spectroscopy reveals that the incorporation of POSS moiety into the copolymer results in a slight decrease in transparency from 99 to 92.5% (at wavelength = 365 nm). The photosensitivity in terms of resist sensitivity (D), contrast (γ), and photopolymerization rate are significantly increased with increase in the POSS content. In addition, the induction time is reduced from 0.520 to 0.515 min after incorporating the POSS unit based on photo‐DSC analyses. These observed results can be rationalized as due to hydrogen bonding interactions between siloxane and hydroxyl groups in copolymers which tend to attract the methacrylate double bonds surrounding POSS units to crosslink, thereby enhancing the photopolymerization rate and sensitivity. We further evaluate the lithographic property of a photoresist under a collimated exposure.Compact double bonds zone induced via hydrogen bonding.magnified imageCompact double bonds zone induced via hydrogen bonding.

Hydrogen bonding and rate enhancement in the photoinduced polymerization of telechelic urethane methacrylates based on a cycloaliphatic system: Tricyclodecane dimethanol

AbstractA new class of telechelic urethane methacrylic crosslinkers, based on a cycloaliphatic system (tricyclodecane dimethanol and tricyclodecane monomethanol), was synthesized. The synthesis was achieved by a two‐step condensation of 1,6‐hexamethylene diisocyanate or isophorone diisocyanate with tricyclodecane dimethanol and capping with hydroxyethyl methacrylate. Samples of hexanediol diacrylate, tricyclodecane monomethacrylate, and tricyclodecane dimethacrylate were used as non‐hydrogen‐bonding monomers for comparative studies of the curing kinetics. The photopolymerization of these telechelic systems was investigated with UV irradiation in the presence of 2,2‐diethoxy acetophenone as the photoinitiator, and the kinetics were followed by the monitoring of the double‐bond conversion at 815 cm−1 with Fourier transform infrared spectroscopy. The hydrogen‐bonded crosslinkers had higher double‐bond conversions than their non‐hydrogen‐bonded counterparts under identical conditions. The higher cure rate could be explained by hydrogen‐bonding preassociation in these systems, which brought the methacrylate double bonds within close proximity. The temperature effects on the hydrogen bonding were also investigated. A decrease in the extent of the double‐bond conversion with increasing temperature was observed for the hydrogen‐bonded crosslinker, in contrast to an increased conversion with temperature for hexanediol diacrylate and tricyclodecane dimethacrylate. This was directly indicative of a reduction of hydrogen bonding at elevated temperatures leading to lower conversions. © 2006 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 44: 4384–4395, 2006

Simulation of conversion profiles within dimethacrylate thick material during photopolymerization. Validation of the simulation by thermal analysis data. Application to the synthesis of a gradient structure material

In a previous paper, a new synthesis method of gradient structure materials from a homogeneous system of monomers was described. These materials were made in two steps. The first one consisted in creating a photopolymerization gradient in methacrylic double bonds under UV exposure thanks to the decay of UV light intensity through the sample thickness. The second one consisted in setting the obtained gradient by a thermal crosslinking reaction. Here, we focussed our attention on the first step, i.e. the creation of the conversion gradient. The knowledge of this gradient is of fundamental importance to predict the final properties of the material. Unfortunately, the measurement of this parameter all over the thickness during the photopolymerization is impossible because no suitable technique is available. A numerical simulation based on the general heat equation transfer was developed on a dimethacrylate model system to calculate this conversion gradient. To describe the true conditions of kinetic experiments, some necessary parameters were measured, like conversion, reaction rate, spectral irradiance of the Hg vapour lamp, dimethacrylate spectral absorbance. The validation of the model by comparison between numerical simulation and experimental temperature results was checked. Finally, influence of physical and chemical parameters on the conversion gradient was discussed.

Radical copolymerization studies of an amphiphilic macromonomer derived from Triton X-100. Reactivity ratios determination by in situ quantitative 1H 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.