Photopolymerization Of Methyl Methacrylate Research Articles

Suspension Photopolymerization of Methyl Methacrylate and ATRP Grafting of Thermo‐Responsive Polymers Using a Perylediimide Derivative Photoinitiator

AbstractThe first aim of this study is to develop a photo‐ATRP process using methyl methacrylate (MMA) by employing a novel perylenediimide derivative (PDI) as photoinitiator. The analysis of the MMA photopolymerization process kinetics is performed in solution and in bulk, demonstrating control over the reaction progress even if the polymerizations display a slow initiation step. The photo‐ATRP process for MMA in suspension is also developed and the obtained PMMA particles are further used to reinitiate the ATRP polymerization of thermoresponsive polymers (different molecular weights poly(ethylene glycol) methyl ether methacrylate and poly(N‐isopropylacrylamide)) (PNIPAM) in solution and surface‐initiated processes. The synthesized polymers by surface‐initiated process display a bimodal molecular weight distribution with a clear modification of the signal areas ratio depending on the grafted monomer and on the reaction conditions. The grafting process can take place on the surface of the polymer particles (Mn2), or it can also involve polymer chains located further at the interior of the polymer particles (Mn1). The lower critical solution temperature (LCST) transition is demonstrated for the PNIPAM functionalized polymer particles.

A Photoreactor-Interfaced Mass Spectrometer: An Online Platform to Monitor Photochemical Reactions.

An experimental platform is reported that allows for the online characterization of photochemical reactions by coupling a continuous flow photoreactor, equipped with LED light irradiation and a dual-tipped ESI source, directly to a mass spectrometer with electrospray ionization. The capabilities of this platform are demonstrated with two classes of photoreactions: (1) the photopolymerization of methyl methacrylate and (2) photocatalyzed alkyne insertion into a 1,2,3-benzotriazinone. The online technique provides rapid information to inform the underlying photochemical mechanism and evaluate the overall photochemistry.

Thioxanthonation of 2-naphthalene-thioacetic acid as a visible-light photoinitiator: The investigation of photophysical and photochemical properties

Thioxanthonation of naphthalene thioacetic acid (TXNPSCH2COOH) resulted a visible light photoinitiator with the high molar absorptivity (ε405: 5680 L.mol−1.cm−1) in the visible spectral region and made this compound an attractive photoinitiator for free radical polymerization reactions. Low fluorescence quantum yield (ΦF: 0.06 in 2-MeTHF) and comparatively low triplet energy (186 kJ/mol in 2-MeTHF) was in favorable for efficient intersystem crossing to the triplet state which is necessary for production of initiating radicals. Indeed, photopolymerization of methyl methacrylate along with TXNPSCH2COOH (1 × 10−3 M) and a tertiary amine namely MDEA yielded nearly 25% conversion of monomer to polymer. All spectrophotometric studies including laser flash photolysis which gives triplet lifetime of initiator which is very important information for initiation mechanism of photoinitiators, indeed a long enough triplet lifetime of TXNPSCH2COOH (τT: 1000 ns) allows for efficient reactions with co-initiators to generate radicals.

Neutral Red and Safranin Т in the Photopolymerization of Methyl Methacrylate and Other (Meth)Acrylate Monomers

Neutral Red and Safranin Т in the Photopolymerization of Methyl Methacrylate and Other (Meth)Acrylate Monomers

Neutral Red and Safranin Т in the Photopolymerization of Methyl Methacrylate and Other (Meth)Acrylate Monomers

Features of the polymerization of methyl methacrylate and a number of other (meth)acrylate monomers in the presence of catalytic systems based on phenazine dyes (Neutral Red and Safranin Т) under visible light irradiation are investigated. It is shown that amines of various structure as well as air oxygen affect the kinetic features of polymerization and the molecular weight characteristics of polymers. It is found that polymerization may proceed in the controlled mode up to high conversions at room temperature and a low photocatalyst concentration, among them without preliminary degassing of the reaction medium.

Mechanical Characterization of UV Photopolymerized PMMA with Different Photo-Initiator Concentration

Polymethyl methacrylate (PMMA) is one among few known photo-polymeric resin useful in lithography for fabricating structures having better mechanical properties to meet the requirement in electronics and biomedical applications. This study explores the effect of Photo Initiator (PI) concentration and also curing time on strength and hardness of Polymethyl methacrylate (PMMA) obtained by UV photopolymerization of Methyl methacrylate (MMA) monomer. The UV LED light source operating at the wavelength of 364 nm is used with Benzoin Ethyl Ether (BEE) as photo initiator. The curing of PMMA resin is supported with peltier cooling device placed at the bottom of the UV light source. The characterisation study of UV photo cured PMMA is analysed through nano indenter (Agilent Technologies-G200). The current work investigates the influence of PI concentration and curing time in achieving maximum mechanical properties for UV photopolymerized PMMA.

Influence of the photoinitiating system on the properties of photopolymerized methylmethacrylate: the role of the ketyl radical in type II photoinitiators

The photopolymerization of methylmethacrylate using different initiating systems strongly affects its glass transition temperature and dispersity.

Photopolymerization kinetics of methyl methacrylate with reactive and inert nanogels.

The enhanced in situ photopolymerization kinetics of methyl methacrylate (MMA) to poly(methyl methacrylate) (PMMA) through the incorporation of both inert and reactive nanogel (NG) fillers under ambient conditions has been demonstrated. In addition to the polymerization kinetics, the physical and chemical properties of the prepolymeric NG were also utilized to tune the thermoplasticity and mechanical properties of the PMMA polymer network. The protocol followed in this study imparts superior MMA photopolymerization kinetics (≥ 60% double-bond conversion within 15 min for > 35 wt% nanogel loadings and ≥ 95% double-bond conversion in < 60 min for all NG concentrations) when compared with traditional polymerization mechanisms. PMMA remained a glassy material following the incorporation of both inert and reactive NG as demonstrated by the glass transition temperature (Tg) of the ultimate networks. Network linearity is uncompromised following incorporation of inert NG additives, thereby preserving the thermoplasticity of the PMMA network. As the non-functionalized, inert NG content increases, the maintenance of thermoplasticity occurs at the expense of mechanical properties (10× reduction of maximum strength at 25 wt% loading). These effects are less pronounced when reactive nanogels are employed (no significant reduction of maximum strength at 25 wt% loading with minimal crosslinking). The incorporation of NGs enable high chemical tunability within linear polymer networks. Given the wide range of monomers available for the synthesis of NGs, the methodology detailed in this study offers a scheme for the optimization of linear networks for specific targeted applications, hitherto deemed unrealistic under established polymerization protocols.

Conducting polymer networks synthesized by photopolymerization-induced phase separation

Polymer mixtures composed of double networks of a polystyrene derivative (PSAF) and poly(methyl methacrylate) (PMMA) were alternatively synthesized by using ultraviolet (UV) and visible (Vis) light. The PSAF networks were generated by UV irradiation to photodimerize the anthracene (A) moieties labeled on the PSAF chains, whereas PMMA networks were produced by photopolymerization of methyl methacrylate (MMA) monomer and the cross-link reaction using ethylene glycol dimethacrylate (EGDMA) under Vis light irradiation. It was found that phase separation process of these networks can be independently induced and promptly controlled by using UV and Vis light. The characteristic length scale distribution of the resulting co-continuous morphology can be well regulated by the UV and Vis light intensity. In order to confirm and utilize the connectivity of the bicontinuous morphology observed by confocal microscopy, a very small amount, 0.1 wt%, of multi-walled carbon nanotubes (MWCNTs) was introduced into the mixture and the current–voltage (I–V) relationship was subsequently examined. Preliminary data show that MWCNTs are preferentially dispersed in the PSAF-rich continuous domains and the whole mixture became electrically conducting, confirming the connectivity of the observed bi-continuous morphology. The experimental data obtained in this study reveal a promising method to design various scaffolds for conducting soft matter taking advantages of photopolymerization-induced phase separation.

Simple Photochemical Route to Block Copolymers via Two‐Step Sequential Type II Photoinitiation

AbstractA simple method for the preparation of block copolymers by a two‐step sequential Type II photoinitiation is described. In the first step, amine functionalized poly(methyl methacrylate) (PMMA‐N(Et)2) is prepared by photopolymerization of methyl methacrylate at λ = 350 nm using benzophenone and triethyl amine as photosensitizer and hydrogen donor, respectively. Subsequent benzophenone‐sensitized photopolymerization of tert‐butyl acrylate using PMMA‐N(Et)2 as hydrogen donor yielded poly(methyl methacrylate)‐block‐poly(tert‐butyl acrylate). The obtained hydrophobic block copolymer is readily converted to amphiphilic polymer by hydrolysis of the tert‐butyl ester moieties of the block copolymer as demonstrated by contact angle measurements. All polymers are characterized by NMR, Fourier transform infrared and UV–vis spectroscopies, and differential scanning calorimetry (DSC) thermal analyses.

Magnetic Levitation To Characterize the Kinetics of Free-Radical Polymerization.

This work describes the development of magnetic levitation (MagLev) to characterize the kinetics of free-radical polymerization of water-insoluble, low-molecular-weight monomers that show a large change in density upon polymerization. Maglev measures density, and certain classes of monomers show a large change in density when monomers covalently join in polymer chains. MagLev characterized both the thermal polymerization of methacrylate-based monomers and the photopolymerization of methyl methacrylate and made it possible to determine the orders of reaction and the Arrhenius activation energy of polymerization. MagLev also made it possible to monitor polymerization in the presence of solids (aramid fibers, and carbon fibers, and glass fibers). MagLev offers a new analytical technique to materials and polymer scientists that complements other methods (even those based on density, such as dilatometry), and will be useful in investigating polymerizations, evaluating inhibition of polymerizations, and studying polymerization in the presence of included solid materials (e.g., for composite materials).

Redox-active poly(ionic liquid)-engineered Ag nanoparticle-decorated ZnO nanoflower heterostructure: A reusable composite catalyst for photopolymerization into high-molecular-weight polymers

A two-step wet chemical method is described for the preparation of spherical silver nanoparticle-decorated flower-shaped zinc oxide (ZnO@Ag) heteronanostructures using a newly designed redox-active poly(ionic liquid)(PIL), poly(1-vinyl-3-butylimidazolium ascorbate) (P[VBuIm][As]). The first step is the generation of ZnO nanoflower using P[VBuIm][As] in water followed by its decoration with in situ formed Ag nanoparticles (AgNPs) by the reduction of AgNO3 with surface adsorbed ascorbate ion. P[VBuIm][As] plays a triple role as shape-directing-cum-capping agent, mediator for Ag+ reduction and inducing the formation of spherical AgNPs. The composite ZnO@Ag heteronanostructures are thoroughly characterized by FESEM, TEM and XRD. The as-synthesized ZnO@Ag heteronanostructures is found to be excellent composite photocatalyst towards photopolymerization of methyl methacrylate (MMA) to very high-molecular-weight poly(methyl methacrylate) (PMMA) (Ca. ∼2 × 105) with very high (82%) conversion in bulk and in solution without any photoinitiator under UV light irradiation (λmax = 350 nm). The ZnO@Ag composite is also an efficient photocatalyst for styrene polymerization in bulk and N-isopropylacrylamide polymerization in water. The photopolymerization with neat ZnO nanoflower catalyst also produces PMMA, but molecular weights are comparatively low with a low conversion. The ZnO@Ag composite photocatalyst is easily isolable by centrifugation after polymerization, is stable and is reusable for four cycles of polymerization of MMA in bulk condition without losing its original activity.

Photo Polymerization Of Methyl Methacrylate In Homogeneous Aqueous Medium By Host-Guest Complexation With Β- Cyclodextrin

Photo polymeruization of Methyl Methacrylate (MMA) by host-guest complexation with β-cyclodextrin was investigated in homogeneous aqueous medium. Vinyl monomers like MMA, Styrene etc. become water soluble due to complexation with β-CD and can easily be polymerized in aqueous solution in the presence of free radical initiator. Polymerization was also carried out with uncomplexed monomer and in presence of organic solvent. A systematic study of the kinetics of photosensitized polymerization of MMA with dye (acriflavin) , reducing agent(ascorbic acid) under buffered condition (Na2HPO4 – citric acid) in presence of β-CD in aqueous solution has been made against the different variables like concentration of monomer, dye, ascorbic acid, time and temperature. Presence of β-CD showed obviously effects on the polymerization, so as to increase the rate of polymerization and percentage conversion of monomer, increase of molecular weight of polymer. The mechanism of polymerization and kinetic scheme proposed was examined in the light of the experimental results. Thermal degradation pattern of the polymer sample was studied by thermo gravimetric analysis.

Photodimerization of thioxanthone–anthracene: formation of monochromophoric Type II initiator

Thioxanthone–anthracene (TX-A) was previously synthesized and used as an initiator for the polymerization of acrylates and methacrylates in air atmosphere. Photodimerization of TX-A was carried out in benzene under light irradiation of >350 nm, and dimer (diTX-A) formation was followed by UV–vis, fluorescence and phosphorescence spectroscopy. The conjugation of anthracene was destroyed after dimerization, and the thioxanthone group was left behind. Therefore, the typical thioxanthone absorption spectrum was seen at 380 nm. TX-A itself does not have phosphorescence emission; however, diTX-A displayed phosphorescence emission spectrum similar to thioxanthone. IR and 1H NMR spectrophotometric techniques also helped to determine the structure of diTX-A. Furthermore, photopolymerization of methyl methacrylate (MMA) in the presence of dimer (diTX-A) was another proof of the photodimerization of TX-A. diTX-A initiated polymerization of MMA as good as thioxanthone in the nitrogen atmosphere and displayed typical Type II initiator behaviour.

Stereocontrol of Methyl Methacrylate during Photoinduced Nitroxide-Mediated Polymerization in the Presence of Photosensitive Alkoxyamine

Photosensitive alkoxyamine 2,2,6,6-tetramethyl-1-(1-phenylethoxy)piperidin-4-yl quinoline-2-carboxylate (PE-TEMPO-Q) was synthesized. Photochemical properties of PE-TEMPO-Q were studied to develop photoinduced nitroxide-mediated polymerization of methyl methacrylate (MMA). Rapid and facile polymerization at ambient temperature with PE-TEMPO-Q as an initiator was confirmed to proceed in a controlled mechanism based on the linear growth in molecular weight combined with relative narrow polydispersity index (1.4–1.8) of the resulting polymers. The stereochemistry of obtained polymers was also investigated, and the syndiotacticity slightly increased compared with the typical photopolymerization. Dual-controlled photopolymerization of MMA was achieved in the presence of synthesized alkoxyamine.

Synthesis of hybrid materials via photopolymerization of benzoin functionalized silica nanoparticles

• Covalent functionalization of silica nanoparticle was achieved. • Silica nanoparticles were formed as macro-photoinitiators. • Covalent grafting from surface of silica nanoparticles under UV radiation was achieved. • Spherical form was preserved in the growth of PMMA-silica nanoparticles. Photopolymerization of methyl methacrylate (MMA) was achieved on the surface of silica nanoparticles by “Grafting from” method. Well defined spherical silica nanoparticles prepared by Stöber method was functionalized with isocyanate groups of toluene di-isocyanate in order to achieve both improved dispersion of nanoparticles in organic solvents and further attachment of benzoin photoinitiator moieties onto the surface of silica nanoparticles. FTIR spectroscopy analysis confirmed the covalent bonding of the functional moieties and grafting of polymethylmethacrylate (PMMA) onto the surface of silica nanoparticles. Thermogravimetric analysis indicated the ratios of attached functionalities and PMMA grafting with a good agreement of SEM observations.

Photopolymerization of methyl methacrylate: effects of photochemical and photonic parameters on the chain length

The effects of photochemical and photonic parameters are investigated on the chain length of poly(methylmethacrylate) (PMMA) as formed by the free radical photopolymerization process.

Mechanistic studies of thioxanthone–carbazole as a one-component type II photoinitiator

A mechanistic study concerning photoinitiated free radical polymerization using Thioxanthone–Carbazole (TX–Cz) as a one-component Type II photoinitiator was performed. TX–Cz presented visible initiator characteristics with absorptions at 434 and 414nm where the molar absorption coefficients were 2014 and 1754Lmol−1cm−1, respectively. Fluorescence and phosphorescence spectroscopy, as well as laser flash photolysis was employed to study the photophysical properties of TX–Cz. In addition, photopolymerization of methyl methacrylate (MMA) showed that TX–Cz is efficient photoinitiator. To explain the initiation mechanism of TX–Cz, fluorescence and phosphorescence emission spectra of poly (methyl methacrylate) (PMMA) were also taken to see whether the initiator covalently bonded to the polymer. The postulated mechanism is based on inter- molecular reaction of the triplet, 3(TX–Cz)⁎ with the carbazole moiety at ground state, TX–Cz. The photoinitiation efficiency of TX–Cz during gelation of multifunctional acrylates was also investigated by Photo-Differential Scanning Calorimetry (Photo-DSC) technique and high polymerization rates were obtained.

Thioxanthone–Diphenyl Anthracene: Visible Light Photoinitiator

7,12-Diphenyl-14H-naphto[2,3-b]thioxanthen-14-one (TX-DPA) was synthesized and characterized as a potential visible light photoinitiator for radical polymerization. TX-DPA has an excellent absorption character in the visible region and the photophysical properties of TX-DPA were investigated by fluorescence and laser flash photolysis studies and the photopolymerization of methyl methacrylate in air atmosphere helped to understand the initiation mechanism of TX-DPA. Moreover, it is possible that the production of singlet oxygen from the quenching of 3TX-DPA by molecular oxygen resulted in the reaction of singlet oxygen with TX-DPA to form an endoperoxide: decomposition of endoperoxide leads to initiating radicals.

Photo-polymerizable gold nanorods / methyl methacrylate composite for plasmonic optical application

ABSTRACTWe prepared a photo-polymerizable compound of Au nanorods and methyl methacrylate (MMA). An irradiation of ultraviolet (UV) light onto the compound induces photo-polymerization of MMA, resulting in a formation of an Au nanorods/PMMA composite. Au nanorods were synthesized by seed-mediated growth method in aqueous solution. Hydrophobically functionalized Au nanorods were dispersed into MMA with a small amount of photosensitizer and initiator. We investigated the stability and the uniformity of the dispersion of Au nanorods during the photo-polymerization process through VIS-NIR absorption spectroscopy. We also demonstrated the use of the compound for two-photon micro/nanolithography.