Preparation of poly(methyl methacrylate) macromonomer by radical polymerization in the presence of methyl α-(bromomethyl)acrylate and copolymerization of the resultant macromonomer

Radical polymerization of methyl methacrylate (MMA) in the presence of methyl -(bromomethyl) acrylate yielded poly-(MMA) bearing the 2-methoxycarbonylallyl end group through chain reaction involving bimol ecular termination. The molecular weight of the resultant polymer was effectively controlled with a small amount of the bromomethylacrylate added; the chain transfer constant was estimated to be 0.9. The poly (MMA) with the unsaturated end group (

Mechanical properties of transparent poly(methyl methacrylate) nanocomposites reinforced with core–shell polyacrylonitrile/poly(methyl methacrylate) nanofibers

Having considered the mechanical and optical properties related to microstructure, the authors of the present work did a study of the in situ interface formation between polyacrylonitrile/poly(methyl methacrylate) (PAN/PMMA) core–shell nanofibers and PMMA resin so as to prepare reinforced PMMA nanocomposites (NCs). The NCs were produced using the dip-coating method. The core–shell nanofibers were generated via phase separation of PAN/PMMA solution during the conventional electrospinning. The results of attenuated total reflection-Fourier transform infrared spectroscopy, transmission electron microscope, and energy dispersive X-ray spectrometer confirmed the formation of core–shell structure of the PAN/PMMA nanofibers. According to the findings of the study, the NCs reinforced with 1.7% volume fractions (v _f) of the core–shell nanofibers, having the composition of 50/50 (PAN/PMMA), had the highest tensile and bending properties. The obtained results showed that by increasing the v _f of nanofibers from 1.7 to 2.9%, the tensile and bending moduli increased by 29.9 and 44.2%, respectively. Increasing v _f to 5.7% decreased the just-mentioned properties. Moreover, the transparency of NCs decreased by less than 1, 10, and 18%, respectively, when the aforementioned volume fractions were applied. The theoretical values for the tensile modulus were calculated using the models proposed by Manera, Pan, and Halpin–Tsai–Nielsen. The best prediction was made when the model proposed by Halpin–Tsai–Nielsen was applied.     

Preparation of poly[(vinyl alcohol)-co-(methyl methacrylate)] by oxidative transformation of C–Si bond in poly[di(isobutoxy)phenylvinylsilane-co-(methyl methacrylate)]

Radical copolymerization of di(isobutoxy)methylvinylsilane 1 and di(isobutoxy)phenylvinylsilane 2 with methyl methacrylate (MMA) and n-butyl acrylate (n-BA) was carried out, and the oxidative cleavage of Si–C bonds in the resulting copolymers was examined to prepare copolymers having repeating units of vinyl alcohol (VA). Although the incorporation of 1 and 2 in the copolymerization of these alkoxyvinylsilanes with MMA was not so effective (1 or 2 content < 18 mol%), MCPBA-induced oxidative transformation of a poly(2-co-MMA) with 9.0 mol% of 2 content proceeded efficiently, giving a poly[(vinyl alcohol)-co-MMA]. On the other hand, whereas poly(1 or 2-co-n-BA)s with relatively higher 1 or 2 contents (up to 45 mol%) can be prepared by the radical copolymerization of 1 or 2 with n-BA, oxidation of the copolymers afforded insoluble products.     

Synthesis of structurally well-controlled ω-vinylidene functionalized poly(alkyl methacrylate)s and polymethacrylonitrile by organotellurium,organostibine, and organobismuthine-mediated living radical polymerizations

The reaction of poly(methyl methacrylate) (PMMA), poly(i-butyl methacrylate), poly(2-hydroxyethyl methacrylate), and polymethacrylonitrile bearing organotellurium, organostibine, and organobismuthine ω-living polymer end groups with 2,2,6,6-tetramethylpiperidine 1-oxy (TEMPO) under thermal or photochemical conditions gave the corresponding ω-vinylidene functionalized polymethacrylates and polymethacrylonitrile with high end group fidelity. Treatment of the PMMA with ethyl 2-[(tributylstannyl)methyl]acrylate also gave a PMMA bearing the same ω-vinylidene end functionality. ¹H NMR, GPC, MALDI TOF MS, and thermogravimetric analyses revealed the highly controlled and defined structure of poly(alkyl methacrylate)s and polymethacrylonitrile in terms of molecular weight, molecular weight distribution, and the ω-polymer end structure.     

Synthesis of ω-mercapto-poly(alkylene oxide) by the Mitsunobu reaction

Summary An efficient way to transform ω-hydroxy-poly(alkylene oxide) in ω-mercapto-poly(alkylene oxide) in two steps is described : the Mitsunobu reaction with thiolacetic acid followed by the reduction of the thiol ester. Yields are quantitative with water soluble polymers. Received: 20 September 2000/Revised version: 10 December 2000/Accepted: 10 December 2000     

Modeling of interdiffusion in poly(vinyl acetate)–poly(methyl methacrylate)–toluene multicomponent systems

Work on interdiffusion has been mainly carried out in binary systems in the past, and this work has focused on polymer–solvent (S) systems and polymer blends. To understand and predict the interdiffusion of two solids in the presence of one S, we present a new mathematical model based on the Onsager approach. Within our model, interdiffusion kinetics are described with a modification of the reptation model for long polymer chains, and the chemical potential gradient is used as the driving force behind mass transfer. The chemical potential is calculated with a Flory–Huggins approach. The model was validated with 29 Raman spectroscopy experiments in poly(vinyl acetate)–poly(methyl methacrylate)–toluene systems at 20 °C. Monomer mobilities (L _i,0s) were determined for both polymers to show the independence of L _i,0 from the chain length. The L _i,0s were found to be strongly dependent on the S content. With the knowledge of phase equilibria and L _i,0s, interdiffusion in the ternary polymer–polymer–S system could be predicted by the introduced model. © 2018 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2019 , 136, 47092.     

Thermodynamic and kinetic studies of crystal violet dye adsorption with poly(methyl methacrylate)–graphene oxide and poly(methyl methacrylate)–graphene oxide–zinc oxide nanocomposites

We successfully prepared poly(methyl methacrylate) (PMMA)–graphene oxide (GO) and PMMA–GO–zinc oxide (ZnO) nanocomposites and characterized them using different techniques. The adsorption performances of the as-prepared composites were investigated for crystal violet (CV) dye removal. The contact time as a main factor affecting the adsorption process by adsorbents was studied. Because the adsorption capacity value for CV was found to show no extensive changes after 35 min, 35 min was selected as the best contact time for our system. The adsorption results revealed that the best capacity of CV adsorption onto the PMMA–GO and PMMA–GO–ZnO nanocomposites occurred at pH 12 and 298 K. The respective entropies (−0.208 and −0.168 kJ mol⁻¹ K⁻¹) and enthalpies (−72.86 kJ/mol, and −55.54 kJ/mol) for PMMA–GO and PMMA–GO–ZnO and Gibbs energy revealed that the process of adsorption was exothermic. In addition, the Elovich, pseudo-first-order, intraparticle diffusion, and pseudo-second-order (four types) models were applied to our kinetic study. Our results indicate that CV adsorption onto PMMA–GO and PMMA–GO–ZnO was good with the pseudo-second-order (type 1) and pseudo-first-order models because of the low χ² value and the high correlation coefficient value. © 2019 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2019 , 136, 47495.     

Effects of liquid–liquid phase separation on crystallization of poly(ethylene glycol) in blends with isotactic poly(methyl methacrylate)

To analyze the interplay between crystallization and liquid–liquid phase separation (LLPS), isothermal crystallization behavior of poly(ethylene glycol) (PEG) in blends with isotactic poly(methyl methacrylate) (i-PMMA) was investigated by differential scanning calorimetry (DSC). The blend system had an upper critical solution temperature (UCST) type phase diagram. When the crystallization occurred simultaneously with LLPS, the overall crystallization rate was enhanced at high crystallization temperatures T_c, relatively compared with that of neat PEG. This behavior was interpreted by the combination of the effects of spinodal quench depth ?T_s and usual supercooling degree ?T_c, according to the theory of Mitra and Muthukumar, namely, the crystallization rate is enhanced by the concentration fluctuation-assisted nucleation at high T_c. In the crystallization after LLPS proceeded, on the other hand, the overall crystallization rate was slow and less dependent on the blend composition. In addition, it was revealed by small-angle X-ray scattering measurements that amorphous i-PMMA was excluded from the interlamellar region of PEG crystals in SQ as well as WQ.     

Synthesis of α-hydroxy-ω-amino poly(ethylene oxide) and its use in reaction injection moulding (RIM)

Summary Computer simulations show that oligomers with two different terminal groups with dissimilar reactivities for isocyanates give a delayed viscosity rise in polyurethanes. This is a desired behaviour for RIM processes. Therefore, an -hydroxy--amino poly(ethylene oxide) (HAPEO) has been prepared. The synthesis was carried out by the ethoxylation of 2-hydroxyethyl phthalimide as a blocked amine. Hydrazinolysis appears to be the best way to obtain the deblocked oligomer. The product properties were compared with an oligomeric diamine ether (Jeffamine D2000). The gel time of HAPEO (M_n=500) and JAD2000 (M_n=2000) was the same (2 sec.). The product with HAPEO had a higher modulus, a comparable impact and tensile strength and a lower elongation at break.     

Preparation in supercritical CO2 of porous poly(methyl methacrylate)–poly(l-lactic acid) (PMMA–PLA) scaffolds incorporating ibuprofen

Partially biodegradable porous scaffolds incorporating bioactive molecules prepared by clean techniques posses an enormous interest in tissue engineering applications. Poly(methyl methacrylate)–poly(l-lactic acid) (PMMA–PLA) blends were submitted to CO₂ supercritical conditions (P = 160–260 bar, T = 60 °C) after certain time and then rapidly depressurized to obtain porous structures that have been related with the supercritical parameters and to the polymer blend composition. In some cases ibuprofen was also incorporated to the formulations previously to the CO₂ treatment and studied the appropriate conditions for avoiding its extraction in SCCO₂. Scaffolds purity, thermal transitions, swelling and degradation behaviour, and the ibuprofen release were also studied to determine the appropriate scaffolds with a desired porosity for cell seeding. Cell culture was performed on the selected porous scaffolds using human fibroblast examined by scanning electron microscopy (SEM).     

Acoustical,damping and thermal properties of polyurethane/poly(methyl methacrylate)-based semi-interpenetrating polymer network foams

In the present study, the interpenetrated polymer networks (IPN) foams of polyurethane (PU) and poly(methyl methacrylate) (PMMA) with different ratio of PU/PMMA (i.e. 85/15, 75/25 and 65/35) were prepared using the polymerisation process. The acoustical, damping and thermal properties of synthesised IPN foams with regard to different compositions were studied. As indicators of effective damping capability, viscoelastic parameters including loss factor (tan δ), glass transition temperature (T_g) and effective damping interval (tan δ?>?0.3) were also determined. The results show that the T_g shifted to higher temperature ranges, and the damping temperature range (tan δ?>?0.3) increased when the IPN was formed. The sound absorption coefficient results show that because of the formation of IPN, the sound-absorbing capacity of prepared samples increased at a certain frequency, and the resonance frequency shifted to lower frequencies by increasing the PMMA content in IPN foams.     

High-pressure solution blending of poly(?-caprolactone) with poly(methyl methacrylate) in acetone + carbon dioxide

The miscibility of blends of poly(?-caprolactone) (PCL, M_w = 14,300) with poly(methyl methacrylate) (PMMA, M_w = 15K or 540K) in acetone + CO₂ mixed solvent has been explored. The liquid-liquid phase boundaries at different temperatures have been determined for mixtures containing 10 wt% total polymer blend, 50 wt% acetone and 40 wt% CO₂. The PCL and PMMA contents of the blends were varied while holding the total polymer concentration at 10 wt%. The polymer blend solutions all displayed LCST-type behavior and required higher pressures than individual polymer components for complete miscibility. Complete miscibilities were achieved at pressures within 40 MPa. The DSC scans show that the blends are microphase-separated. The blends display the melting transition of PCL and the glass transition temperature of the PMMA phases. The presence of PMMA is found to influence the crystallization and melting behavior of PCL in the blends. The DSC results on heat of melting and the FTIR spectra, specifically the changes at 1295 cm⁻¹ band show the changes (decrease) in overall crystallinity of the blend upon addition of PMMA.     

Development of oral-fluid-impervious and fracture-resistant silver–poly(methyl methacrylate) nanoformulations for intra-oral/extra-oral rehabilitation

Poly(methyl methacrylate) (PMMA) based dental prosthetic materials have an inferior transverse resistance value and a high water-retention capacity. These drawbacks cause frequent prosthesis fractures both inside and outside the mouth, which require the remaking or repair of the prosthesis. The mechanical and physical durability of the polymer matrix can be improved by the incorporation of a multifunctional filler. In this study, we focused on the reinforcing effect of silver nanoparticles (AgNPs) on the flexural properties of PMMA. Apart from that, the transport behavior of water and saliva through this composite matrix was also studied extensively. Morphological analyses with scanning electron microscopy (SEM) and atomic force microscopy imaging techniques confirmed the uniform distribution of nanoparticles in the matrix with an increased surface roughness proportionate to the amount of AgNPs. The flexural strength and modulus were enhanced by the addition of up to 5 wt % AgNPs (p < 0.05); we also observed a significant increase in the fracture resistance. The SEM micrographs of the fractured ends of AgNP-reinforced groups had smaller cracks compared to the large multidirectional cracks in the unreinforced group. The diffusion of oral fluid through the composite was investigated in detail as a function of the AgNP content, the nature of the solvent (water or saliva), and the temperature (5, 28, 37, or 60°C). The water and saliva uptake, diffusion, sorption, and permeation constants were investigated and were found to decrease with increasing AgNP loading. The transport properties could have been related to the morphology of the nanocomposites and followed the Korsmeyer–Peppas model. At high concentrations, the AgNPs formed a local filler–filler network in the polymer matrix. This network hindered the transport of water and saliva through the polymer. The outcome deduced from this study confirmed that the reinforced nanocomposites improved the durability of the denture base and could be an effective replacement for the conventional denture base. © 2019 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2019 , 136, 47669.     

Influence of ionic liquid on glass transition,dynamic rheology,and thermal stability of poly(methyl methacrylate)/silica nanocomposites

The nanofiller dispersion greatly influences the properties of nanocomposites. Herein an ionic liquid, 1-ethyl-3-methylimidazolium tetrafluoroborate, is introduced in poly(methyl methacrylate) (PMMA) nanocomposites for mediating dispersion of silica filler. As elucidated by rheology, the ionic liquid is able to improve the degree of retardation of chains diffusion induced by silica although it eliminates the elevation of glass transition. Simultaneously, the ionic liquid incorporated can improve thermal and thermal-oxidative stability of PMMA due to trapping of radicals and blocking oxygen penetration. © 2019 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2019 , 136, 48007.     

Preparation and characterization of the poly(2-hydroxyethyl methacrylate)–salicylic acid conjugate

A new polymeric system containing hydrolysable ester bond linked to salicylic acid to be used for controlled drug release was synthesized. Poly(2-hydroxyethyl methacrylate) (PHEMA) functionalized with chloroacetate groups was obtained by the reaction between PHEMA and chloroacetyl chloride using the N,N-dimethylacetamide/5% lithium chloride system as a solvent and pyridine as a catalyst. The degree of substitution was calculated from the chlorine content and ranged from 32.2 to 98.1 mol.% depending on the ratio of chloroacetyl chloride to PHEMA. The coupling of salicylic acid to PHEMA functionalized with chloroacetate groups was carried out by the reaction between PHEMA and the sodium salt of salicylic acid. The structures of chloroacetylated PHEMA and PHEMA–salicylic acid conjugates were determined by means of FTIR, ¹H-NMR and ¹³C-NMR spectra. The hydrolysis in the heterogeneous system of PHEMA–salicylic acid conjugates were performed in buffer solutions (pH 7.6 and 8.5) at 37 °C and showed that the release of the drug (sodium salicylate) from tablets was dependent on the hydrophilic character of conjugate as well as on the pH value of the medium.     

Synthesis and characterization of polyrotaxanes comprising α-cyclodextrins and poly(ε-caprolactone) end-capped with poly(N-isopropylacrylamide)s

Biodegradable polyrotaxane (PR)-based triblock copolymers were synthesized via the atom transfer radical polymerization (ATRP) of N-isopropylacrylamide (NIPAAm) initiated with polypseudorotaxanes (PPRs) consisting of a distal 2-bromopropiomyl bromide end-capping poly(ε-caprolactone) (Br-PCL-Br) and a varying amount of α-cyclodextrins (α-CDs) in the presence of Cu(I)Br/PMDETA at 25 °C in aqueous solution. The copolymers were featured by relatively higher yields from 46.0% to 82.8% as compared with previous reports. Their structure was characterized in detail by using ¹H NMR, ¹³C CP/MAS NMR, GPC, WXRD, DSC and TGA analyses. When a feed molar ratio of NIPAAm to Br-PCL-Br was changed from 50 to 200, the degree of polymerization of PNIPAAm blocks attached to two ends of PPRs was in a range of 158–500. About one third of the added α-CDs were still entrapped on the central PCL chain after the ATRP process. Attaching PNIPAAm rendered the copolymers soluble in aqueous solution showing the thermo-responsibility as evidenced by turbidity measurements.     

The preparation and characteristics of poly(methyl methacrylate–methylacrylate acid)/nano-ZnO composite latex particles

In this work, poly(methyl methacrylate-co-methylacrylate acid)/ZnO (poly(MMA–MAA)/ZnO) composite latex particle was synthesized by three steps The first step was to synthesize poly(MMA–MAA) copolymer latex particles by soapless emulsion polymerization. Following the first step, the second step was to polymerize MMA, MAA and 3,3-(trimethoxysilyl) propyl methacrylate (MPS) in the presence of poly(MMA–MAA) seed latex particles to form the poly(MMA–MAA)/poly(MMA–MAA–MPS) core–shell latex particles. In the third step, the poly(MMA–MAA)/poly(MMA–MAA–MPS) latex particles reacted with ZnO nanoparticles, which were synthesized by a traditional sol gel method, to form the polymer/inorganic poly(MMA–MAA)/poly(MMA–MAA–MPS)/ZnO composite latex. In this study, MPS with silanol groups essentially was used as the coupling agent to couple with ZnO nanoparticles, while the results of the study showed that there was not covalent bond existed between ZnO particles and polymer latex. The ZnO particles were adsorbed on the surface of polymer latex by electrostatic interaction. Besides, the linear poly(MMA–MAA)/crosslinking poly(MMA–MAA–MPS) core–shell latex particles which were synthesized in the second step were heated in the presence of ammonia to form the hollow poly(MMA–MAA–MPS) latex particles. The factors of heating time and concentration of crosslinking agent significantly influenced the morphology of hollow poly(MMA–MAA–MPS) latex particles.