Radical polymerization of methyl methacrylate with ethane-1,1,2-triyltribenzene as an initiator and ethane-1,1,2-triyltribenzene-end polymers as macroinitiators

An unsymmetrical triphenylethane, ethane-1,1,2-triyltribenzene (ETB), was successfully prepared from phenyl lithium, trans-1,2-diphenylethylene, and methanol. Characterization of the compound was performed by ¹H and ¹³C nuclear magnetic resonance spectroscopy (NMR). The polymerization of methyl methacrylate (MMA) was performed in the presence of ETB at 85 °C or higher. The free radicals obtained were characterized by ultra-performance liquid chromatography coupled with quadrupole time-of-flight mass spectrometry (UPLC/Q-TOF MS). Gel permeation chromatography (GPC) traces of the average molecular weight of poly(MMA) (PMMA) showed a series of translations with increasing time. The average molecular weight of PMMA indicated narrow polydispersity, and a linear relationship was found between ln([M]₀/[M]) and polymerization time. These results indicated the “living” nature of the polymerization of MMA in the presence of ETB. The structure of ETB was also introduced to the end of polystyrene (PS), polyisoprene (PI), and polyisoprene-b-polystyrene (PIS) chains which were obtained by living anionic polymerization. Hence, they initiated radical polymerization of MMA as ETB-end-macroinitiators to obtain block copolymers. Thus, living anionic polymerization and this radical polymerization method were combined together to prepare block copolymers without the intermediate transformation step.     

ATRP of methyl methacrylate initiated with a bifunctional initiator bearing bromomethyl functional groups: Synthesis of the block and graft copolymers

This article reports the synthesis of the block and graft copolymers using peroxygen‐containing poly(methyl methacrylate) (poly‐MMA) as a macroinitiator that was prepared from the atom transfer radical polymerization (ATRP) of methyl methacrylate (MMA) in the presence of bis(4,4′‐bromomethyl benzoyl peroxide) (BBP). The effects of reaction temperatures on the ATRP system were studied in detail. Kinetic studies were carried out to investigate controlled ATRP for BBP/CuBr/bpy initiating system with MMA at 40 °C and free radical polymerization of styrene (S) at 80 °C. The plots of ln ([M_o]/[M_t]) versus reaction time are linear, corresponding to first‐order kinetics. Poly‐MMA initiators were used in the bulk polymerization of S to obtain poly (MMA‐b‐S) block copolymers. Poly‐MMA initiators containing undecomposed peroygen groups were used for the graft copolymerization of polybutadiene (PBd) and natural rubber (RSS‐3) to obtain crosslinked poly (MMA‐g‐PBd) and poly(MMA‐g‐RSS‐3) graft copolymers. Swelling ratio values (q_v) of the graft copolymers in CHCl₃ were calculated. The characterizations of the polymers were achieved by Fourier‐transform infrared spectroscopy (FTIR), ¹H‐nuclear magnetic resonance (¹H NMR), gel‐permeation chromatography (GPC), differential scanning calorimetry (DSC), thermogravimetric analysis, scanning electron microscopy (SEM), transmission electron microscopy (TEM), atomic force microscopy (AFM), and the fractional precipitation (γ) techniques. © 2010 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 48: 1364–1373, 2010     

Interactions and mobility of copper(II)-imidazole-containing copolymers

Poly(1-vinylimidazole-co-methyl methacrylate) copolymers (PVM) were obtained from copolymerization of 1-vinylimidazole and methyl methacrylate with 2,2^′-azobisisobutyronitrile as an initiator. The formation of random copolymers was substantiated by the glass transition temperature (T_g) and the proton spin-lattice relaxation time in the rotating frame (T^H_1ρ). Cu(II)-PVM complexes were prepared by mixing tetrahydrofuran solution of PVM and copper sulfate solution. The formation of coordination bond between PVM and Cu²⁺ ions was studied using differential scanning calorimetry, infrared and ¹³C solid-stated nuclear magnetic resonance spectroscopy. A single composition dependent T_g was obtained for the PVM copolymers, and that increased with increasing VI content. The T_g value of the Cu(II)-PVM complex was much higher than that of the PVM copolymer with the same composition. The T^H_1ρ of the VI units and MMA units in the copolymers and complexes had one value, and that in the complexes was much lower than that in the copolymers. The dramatic decrease in T^H_1ρ for the Cu(II)-PVM complexes was due to Cu(II) complexation and electron-nuclear dipolar interactions.     

Anti-microbial activity of anhydride copolymers and their derivatives prepared by ionizing radiation

Methyl methacrylate/maleic anhydride (MMA/MAn) copolymers were synthesized using gamma rays. Preparation conditions such as irradiation dose, comonomer composition and type of diluent affecting the degree of comonomer conversion were investigated. The suitable diluent for obtaining reasonable MMA/MAn copolymer yield was acetone. The higher copolymer yield was achieved when the amount of methyl methacrylate in comonomer feed solutions as well as irradiation dose increased. The effect of ZnCl₂ on the MMA/MAn copolymer yield and structure was studied. Characterization of the prepared MMA/MAn copolymers was performed using FTIR, and thermogravimetric and viscometric analysis. The derivatives of MMA/MAn copolymers were obtained by treating them with different reagents such as sulpha-drugs, hydroxylamine hydrochloride and 4-amino sodium salyciliate. The antimicrobial activity of MMA/MAn copolymers and their derivatives was examined. The activity of such copolymers against Staphylococcus aureus and Escherichia coli increased by increasing MAn content in the copolymer. The MMA/MAn copolymers treated with sulpha-drugs exhibited particularly high biological activity against different microorganisms. These results revealed that the prepared MMA/MAn copolymer and its derivatives have a broad antimicrobial activity.     

ABC triblock polymethacrylates: Group transfer polymerization synthesis of the ABC,ACB, and BAC topological isomers and solution characterization

ABC triblock copolymers of methyl methacrylate (MMA), (dimethylamino)-ethyl methacrylate (DMAEMA), and tetrahydropyranyl methacrylate (THPMA) consisting of 12 units of each type of monomer were synthesized by group transfer polymerization (GTP). These were the three topological isomers with differentblock sequences: DMAEMA₁₂-THPMA₁₂-MMA₁₂, DMAEMA₁₂-MMA₁₂-THPMA₁₂, and THPMA₁₂-DMAEMA₁₂-MMA₁₂. The molecular weights and molecular weight distributions of the copolymers were determined by gel permeation chromatography (GPC) in tetrahydrofuran, and their number-average degrees of polymerization and copolymer compositions were calculated by proton nuclear magnetic resonance spectroscopy (¹H-NMR). These molecular weights and degrees of polymerization corresponded closely to the values expected from the monomer/initiator ratios. The polydispersities were low as expected for GTP, and ranged from 1.09 to 1.25. The three triblocks were chemically modified by converting the THPMA units to methacrylic acid (MAA) units either by thermolysis or acid hydrolysis. The resulting ABC triblock poly-ampholytes were characterized by ¹H-NMR spectroscopy and hydrogen ion titration. Aqueous GPC studies in 1.0M NaCl at pH 8.5 showed that the triblock copolymers form micelles whose size depends on their block sequence. © 1998 John Wiley & Sons, Inc. J Polym Sci A: Polym Chem 36: 617–631, 1998     

Synthesis and characterization of amphiphilic triblock copolymers by iron‐mediated atom transfer radical polymerization

The atom transfer radical polymerization of methyl methacrylate (MMA) and n‐butyl methacrylate (n‐BMA) was initiated by a poly(ethylene oxide) chloro telechelic macroinitiator synthesized by esterification of poly(ethylene oxide) (PEO) with 2‐chloro propionyl chloride. The polymerization, carried out in bulk at 90 °C and catalyzed by iron(II) chloride tetrahydrate in the presence of triphenylphosphine ligand (FeCl₂ · 4H₂O/PPh₃), led to A–B–A amphiphilic triblock copolymers with MMA or n‐BMA as the A block and PEO as the B block. A kinetic study showed that the polymerization was first‐order with respect to the monomer concentration. Moreover, the experimental molecular weights of the block copolymers increased linearly with the monomer conversion, and the molecular weight distribution was acceptably narrow at the end of the reaction. These block copolymers turned out to be water‐soluble through the adjustment of the content of PEO blocks (PEO content >90% by mass). When the PEO content was small [monomer/macroinitiator molar ratio (M/I) = 300], the block copolymers were water‐insoluble and showed only one glass‐transition temperature. With an increase in the concentration of PEO (M/I = 100 or 50) in the copolymer, two glass transitions were detected, indicating phase separation. The macroinitiator and the corresponding triblock copolymers were characterized with Fourier transform infrared, proton nuclear magnetic resonance, size exclusion chromatography analysis, dynamic mechanical analysis, and differential scanning calorimetry. © 2005 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 43: 5049–5061, 2005     

<Superscript>2</Superscript>H-NMR investigation after a polymerisation-induced phase separation process*

Polymer-dispersed liquid crystals (PDLC) are composite materials consisting of micron-sized droplets of liquid crystal dispersed in a polymer matrix. The easiest method to obtain a PDLC film is the polymerisation-induced phase separation process (PIPS). The liquid crystal is mixed with a monomer of low molecular weight and polymerisation is induced by heat or UV light. The increasing molecular weight of the polymer causes the phase separation of liquid crystal from the polymer matrix as micron-sized droplets. In this work, we have studied the structural changes induced in the polymer matrix of a PDLC after the PIPS process by deuterium nuclear magnetic resonance. Two different selectively deuterated monomers have been synthesized and investigated: isobutyl methacrylate (IBMA-d₂) and methyl methacrylate (MMA-d₃). The main results were the disappearance of the characteristic two-site hop in poly-IBMA, due to liquid crystal molecules, and the lack of unreacted MMA molecules in the liquid crystal droplets. In this last case, we found that it is possible to confine temporarily the unreacted MMA molecules within liquid crystal droplets.Abbreviations MMA Methyl methacrylate - IBMA Isobutyl methacrylate - PDLC Polymer-dispersed liquid crystal - PIPS Polymerisation-induced phase separation - ²H-NMR Deuterium nuclear magnetic resonance*Dedicated to Professor V. Bertini for his 70^th birthday     

Synthesis, spectral and thermal properties of homo- and copolymers of 2-[(5-methylisoxazol-3-yl)amino]-2-oxo-ethyl methacrylate with styrene and methyl methacrylate and determination of monomer reactivity ratios

The methacrylate monomer, 2-[(5-methylisoxazol-3-yl)amino]-2-oxo-ethyl methacrylate (IAOEMA), was synthesized by reacting 2-chloro-N-(5-methylisoxazol)acetamide dissolved in acetonitrile with sodium methacrylate in the presence of triethylbenzylammoniumchloride (TEBAC). The free-radical-initiated copolymerization of IAOEMA, with styrene (ST) and methyl methacrylate (MMA) was carried out in dimethylsulphoxide (DMSO) solution at 65 °C using 2,2^′-azobisisobutyronitrile (AIBN) as an initiator with different monomer-to-monomer ratios in the feed. The monomer (IAOEMA) and copolymers were characterized by FTIR, ¹H- and ¹³C-NMR spectral studies. The copolymer composition was evaluated by nitrogen content in polymers led to the determination of reactivity ratios. The reactivity ratios of the monomers were determined by the application of Fineman-Ross and Kelen-Tüdös methods. The analysis of reactivity ratios revealed that ST and MMA are more reactive than IAOEMA, and copolymers formed are statisticalle in nature. The molecular weights (M_w and M_n) and polydispersity index of the polymers were determined using gel permeation chromagtography. Glass transition temperatures of the copolymers were found to increase with an increase in the mole fraction of IAOEMA in the copolymers. The apparent thermal decomposition activation energies (E_d) were calculated by Ozawa method using the SETARAM Labsys TGA thermobalance.     

Synthesis,characterization and release profiles of nanoparticles self‐assembled from poly (PEGMA‐co‐MMA‐co‐acryloyl‐β‐CD) copolymers

A novel amphiphilic copolymer was synthesized from poly (ethylene glycol) methyl ether methacrylate (PEGMA950), methyl methacrylate (MMA) and acryloyl‐β‐cyclodextrin (acryloyl‐β‐CD) using the composites of (NH₄)₂S₂O₈/NaHSO₃ as the oxidation–reduction initiators. The successful fabrication of poly(PEGMA‐co‐MMA‐co‐acryloyl‐β‐CD) copolymers was confirmed by Fourier transform infrared spectrometer (FTIR), ¹H‐nuclear magnetic resonance (¹H NMR) spectra. The amphiphilic copolymer could self‐assemble into nanoparticles (NPs), and their morphology and particle size distribution were characterized with transmission electron microscopy (TEM), atomic force microscope (AFM) and dynamic light scattering (DLS) methods. Ibuprofen (IBU) was encapsulated in the novel NPs, and the release profiles of IBU were investigated. FTIR and ¹H NMR spectra illustrated that the poly(PEGMA‐co‐MMA‐co‐acryloyl‐β‐CD) copolymers were synthesized without any residual monomers and initiators. TEM and AFM photographs suggested that the obtained NPs were spherical, and the DLS results indicated that the diameter of blank NPs was 157.3 ± 32.7 nm. The IBU release profile showed that the IBU‐loaded NPs had certain pH responsibility. Copyright © 2014 John Wiley & Sons, Ltd.     

Chain dynamics and thermal stability of boron-tris-containing copolymers

Poly(methyl methacrylate-co-glycidyl methacrylate-tris(hydroxymethyl)aminomethane) (PMGT) copolymers were obtained by copolymerization of methyl methacrylate (MMA) and a chelating monomer, glycidyl methacrylate-tris(hydroxymethyl)aminomethane (GMA-Tris), with potassium persulfate as an initiator. The glass transition temperature (T_g) and the proton spin-lattice relaxation time in the rotating frame () substantiated the formation of random copolymers. Borate-loaded PMGT (BPMGT) complexes were prepared by mixing PMGT and boric acid solution. The formation of coordination bond between PMGT and borate was studied using differential scanning calorimetry, infrared and ¹³C solid-state nuclear magnetic resonance spectroscopy. A single composition dependent T_g was obtained for the PMGT copolymers. The T_g value of BPMGT complex was much higher than that of PMGT copolymer with the same composition. The of the main chains in the PMGT copolymers and BPMGT complexes had one value, and that in the complexes was higher than that in the copolymers. The apparent activation energy (E_a) of the thermo-oxidative degradation of Tris units in complexes was larger than that in copolymers, whereas the E_a value of the MMA-GMA matrix was reversed.     

Preparation and characterization of copolymers of chloroprene and methyl methacrylate

The preparation of chloroprene–methyl methacrylate copolymers in the presence of Lewis acids (Et_1.5AlCl_1.5) in hydrocarbon solvent and the effect of Lewis acids concentration on copolymer composition are described. ¹³C NMR spectra were obtained on these copolymers. In samples of high MMA content, tactic placements of MMA were observed as well as several different kinds of sequences for chloroprene and MMA. In samples of low MMA content, no tactic placements of MMA were found but several different kinds of chloroprene sequences were observed. From the analysis of the ¹³C NMR spectra of the different copolymers examined, it is apparent that all the various kinds of chloroprene sequences in these copolymers can be determined.     

Synthesis and characterization of amphiphilic star copolymers of 2-(dimethylamino)ethyl methacrylate and methyl methacrylate: Effects of architecture and composition

Six amphiphilic star copolymers comprising hydrophilic units of 2-(dimethylamino)ethyl methacrylate (DMAEMA) and hydrophobic units of methyl methacrylate (MMA) were prepared by the sequential group transfer polymerization (GTP) of the two comonomers and ethylene glycol dimethacrylate (EGDMA) cross-linker. Four star-block copolymers of different compositions, one miktoarm star, and one statistical copolymer star were synthesized. The molecular weights (MWs) and MW distributions of all the star copolymers and their linear homopolymer and copolymer precursors were characterized by gel permeation chromatography (GPC), while the compositions of the stars were determined by proton nuclear magnetic resonance (¹H NMR) spectroscopy. Tetrahydrofuran (THF) solutions of all the star copolymers were characterized by static light scattering to determine the absolute weight-average MW () and the number of arms of the stars. The of the stars ranged between 359,000 and 565,000 g mol⁻¹, while their number of arms ranged between 39 and 120. The star copolymers were soluble in acidic water at pH 4 giving transparent or slightly opaque solutions, with the exception of the very hydrophobic DMAEMA₁₀-b-MMA₃₀-star, which gave a very opaque solution. Only the random copolymer star was completely dispersed in neutral water, giving a very opaque solution. The effective pKs of the copolymer stars were determined by hydrogen ion titration and were found to be in the range 6.5-7.6. The pHs of precipitation of the star copolymer solutions/dispersions were found to be between 8.8-10.1, except for the most hydrophobic DMAEMA_10-b-MMA₃₀-star, which gave a very opaque solution over the whole pH range.     

Copolymerizations of alkyl methacrylates with vinyltriacetoxysilane

Copolymerizations of methyl methacrylate (MMA) and butyl methacrylate (BMA) with vinyltriacetoxysilane (VTAS) have been carried out in bulk at 70°. The compositions of the copolymers were determined from their silicon contents; the reactivity ratios were calculated by the Kelen-Tüdo&#x030B;s method. For MMA/VTAS, r₁ = 7.75 ± 0.31 and for BMA/VTAS, r₁ = 4.62 ± 0.15; in both systems, r₂ is zero, indicating that VTAS does not homopolymerize under the experimental conditions. The influence of the silicon comonomer on properties of the copolymers, such as solubility annd thermal behaviour, was studied.     

Preparation,Characterization and Properties of Cellulose Acetate-Grafted-Poly(glycidyl methacrylate) Copolymers

The cellulose acetate-grafted-poly(glycidyl methacrylate) copolymers were synthesized successfully by free radical polymerization. The resulting copolymer was characterized by proton nuclear magnetic resonance (¹H-NMR), solid-state ¹³C-NMR, Fourier transform infrared spectroscopy (FTIR) and gel permeation chromatography (GPC). The crystallization behavior, thermal properties, specific particle surface area, moisture sorption behavior of the modified cellulose acetate were investigated by wide angle X-ray diffraction (WAXD), differential scanning calorimetry (DSC), thermogravimetric analysis (TGA), Brunauer-Emmett-Teller (BET) method and Dynamic Vapor Sorption (DVS) instrument. It was found that the poly(glycidyl methacrylate) (PGMA) grafting was effective in improving the water adsorption of cellulose acetate (CA) changing the specific surface area, and reducing the T_g of copolymers.     

Homopolymerization and copolymerization of isocyanatoethyl methacrylate

This article describes the homopolymerization of isocyanatoethyl methacrylate (IEM) and its copolymerization with methyl methacrylate (MMA) in acetonitrile in the presence of 2,2′‐azobisisobutyronitrile. The constant characteristic of IEM polymerizability (k_p²/k_te = 128 × 10^?3 L mol^?1 s^?1, where k_p is the propagation constant and k_te is the termination constant) was determined. The study of IEM reactivity toward MMA gave ratios of 0.88 and 1.20 for IEM and MMA, respectively. The physicochemical properties of the IEM homopolymer and IEM/MMA copolymers were also studied. The glass‐transition temperature of poly(isocyanatoethyl methacrylate) was found to be 47 °C. From the thermogravimetric analysis of the weight‐loss percentage corresponding to the first wave of the thermogram, it was shown that the degradation mechanism of the IEM/MMA copolymers started from the isocyanate group. © 2006 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 44: 4762–4768, 2006     

Atom Transfer Radical Polymerization of Methyl Methacrylate Using Telechelic Tribromo Terminated Polyurethane Macroinitiator

Novel telechelic tribromo terminated polyurethane (Br₃-PU-Br₃) was used as a macroinitiator in atom transfer radical polymerization (ATRP) of methyl methacrylate using CuBr as a catalyst and NN,N',N”,N”-pentamethyldiethylenetriamine (PMDETA) as a ligand. During the course of polymerization, poly(methyl methacrylate)-b-polyurethane-b-poly(methyl methacrylate) (PMMA-b-PU-b-PMMA) tri-block copolymers were formed. The resulting tri-block copolymers were characterized by gel permeation chromatography (GPC) and ¹H nuclear magnetic resonance (NMR) spectroscopy. Molecular weight of the tri-block copolymers increases with increasing conversion. This result shows Br₃-PU-Br₃/CuBr/PMDETA initiating system polymerized methyl methacrylate through ATRP mechanism. NMR spectroscopy results revealed that apart from bromine atom transfer from Br₃-PU-Br₃ to PMDETA-CuBr complex, bromine atom transfer from the initially formed tri-block copolymer to PMDETA-CuBr complex also takes place, and, as a result, double bond terminated copolymer formed. Mole ratio of polyurethane and poly(methyl methacrylate) present in the PMMA-b-PU-b-PMMA tri-block copolymers was calculated using ¹H-NMR spectroscopy and it was found to be comparable with the mole ratio calculated through GPC results. Differential scanning calorimetric results confirmed the presence of two different phases in the tri-block copolymers.     

Copolymers of methyl methacrylate and fluoroalkyl methacrylates: Effects of fluoroalkyl groups on the thermal and optical properties of the copolymers

Fluoroalkyl methacrylates, 2,2,2‐trifluoroethyl methacrylate ( 1 ), hexafluoroisopropyl methacrylate ( 2 ), 1,1,1,3,3,3‐hexafluoro‐2‐methyl‐2‐propyl methacrylate ( 3 ), and perfluoro t‐butyl methacrylate ( 4 ) were synthesized. Homopolymers and copolymers of these fluoroalkyl methacrylates with methyl methacrylate (MMA) were prepared and characterized. With the exception of the copolymers of MMA and 2,2,2‐trifluoroethyl methacrylate ( 1 ), the glass transition temperatures (T_gs) of the copolymers were found to deviate positively from the Gordon‐Taylor equation. The positive deviation from the Gordon‐Taylor equation could be accounted for by the dipole–dipole intrachain interaction between the methyl ester group and the fluoroalkyl ester group of the monomer units. These T_g values of the copolymers were found to fit with the Schneider equation. The fitting parameters in the Schneider equation were calculated, and R² values, the coefficients of determination, were almost 1.0. The refractive indices of the copolymers, measured at 532, 633, and 839 nm wavelengths, were lower than that of PMMA and showed a linear relationship with monomer composition in the copolymers. 2 and MMA have a tendency to polymerize in an alternating uniform monomer composition, resulting in less light scattering. This result suggests that the copolymer prepared with an equal molar ratio of 2 and MMA may have useful properties with applications in optical devices. © 2008 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 46: 4748–4755, 2008     

Synthesis and biocompatibility of phosphoryl polymer and relationship between biocompatibility and water structure

A series of copolymers, poly(methylmethacrylate-co-2-methacryloyloxyethyl phosphorylcholine), with various compositions of methyl methacrylate (MMA) and 2-methacryloyloxyethyl phosphorylcholine (MPC) were synthesized by radical copolymerization in a mixed solvent of ethanol and chloroform. The structures of the copolymers were confirmed by proton nuclear magnetic resonance and elemental analysis. The properties and morphologies of the copolymers were characterized by differential scanning calorimeter, scanning electron microscopy, and optical microscope. The adsorption of bovine serum albumin (BSA) and the adhesion of platelet on the surfaces of the copolymer membrane significantly decreased with increasing the MPC composition. The copolymers containing MPC above 18% showed excellent biocompatibility. Moreover, the relationship between the water structure and the biocompatibility was illustrated by changing quantity of the MPC in copolymers. The result showed that the amount of free water affected the platelet compatibility of the copolymer.     

Property modification of poly(methyl methacrylate) through copolymerization with fluorinated aryl methacrylate monomers

Copolymers of methyl methacrylate (MMA) with 2,3,5,6‐tetrafluorophenyl methacrylate (TFPMA), pentafluorophenyl methacrylate (PFPMA), and 4‐trifluoromethyl‐2,3,5,6‐tetrafluorophenyl methacrylate (TFMPMA) were investigated. All the three systems showed a random copolymerization character. The composition, glass transition temperature (T_g), and refractive index of the copolymers obtained were studied. T_gs of TFPMA/MMA and PFPMA/MMA copolymers were found to deviate positively from the Gordon–Taylor equation. However, T_gs of TFMPMA/MMA copolymers were well fit with the Gordon–Taylor equation. These results indicated the existence of interaction between MMA and either TFPMA or PFPMA units in copolymers. This interaction resulted in the enhancement of the T_g of MMA polymers through the copolymerization with TFPMA and PFPMA. The refractive index and the light transmittance of copolymers were close to those of PMMA. Copyright © 2007 John Wiley & Sons, Ltd.     

Photolysis of unsubstituted and p-methoxycarbonyl substituted 2-methyl-1-phenylprop-2-en-1-one copolymers in solution

A new monomer, methyl 4-(2-methyl-1-oxoprop-2-en-1-yl)benzoate (p-(methoxycarbonyl)phenyl isopropenyl ketone, MeOCO-PIPK), was synthesized and copolymerized with styrene and methyl methacrylate (MMA). The copolymers of MeOCO-PIPK and 2-methyl-1-phenylprop-2-en-1-one (phenyl isopropenyl ketone, PIPK) with styrene and MMA were photolyzed by deep-, mid- and near-UV light in dilute solution; and the quantum yields of scission, ϕ_g, and the UV absorption spectra were measured. The p-methoxycarbonyl substitution increased the molar extinction coefficients of the ketone monomer units extensively, but slightly lowered the ϕ_g values in styrene and MMA copolymers. This is expected to increase the net sensitivity of solid films of the polymers. The ϕ_g was found independent of the wavelength, despite the concurrent absorption by styrene units in the styrene copolymers. Larger ϕ_g values were obtained for the MMA copolymers than the corresponding styrene copolymers. Solvents with larger dielectric constants gave larger ϕ_g for the copolymer of MMA with PIPK; but when the dielectric constants were similar, lower ϕ_g values were observed in the solvents with more easily abstractable hydrogens. A large bleaching effect was seen in MMA copolymers, which should make possible the formation of resist patterns with steep profiles when used in photolithography. © 1996 John Wiley & Sons, Inc.