Homopolymers PMMA Research Articles

Mechanochemically Promoted Functionalization of Postconsumer Poly(Methyl Methacrylate) and Poly(α‐Methylstyrene) for Bulk Depolymerization

We describe a methodology of post‐polymerization functionalization to enable subsequent bulk depolymerization to monomer by utilizing mechanochemical macro‐radical generation. By harnessing ultrasonic chain‐scission in the presence of N‐hydroxyphthalimide methacrylate (PhthMA), we successfully chain‐end functionalize polymers to promote subsequent depolymerization in bulk, achieving up to 81% depolymerization of poly(methyl methacrylate) (PMMA) and poly(α‐methylstyrene) (PAMS) within 30 min. This method of depolymerization yields a high‐purity monomer that can be repolymerized. Moreover, as compared to the most common methods of depolymerization, this work is most efficient with ultra‐high molecular weight (UHMW) polymers, establishing a method with the potential to address highly persistent, non‐degradable all‐carbon backbone plastic materials. Lastly, we demonstrate the expansion of this depolymerization method to commercial cell cast PMMA, achieving high degrees of depolymerization from post‐consumer waste. This work is the first demonstration of applying PhthMA‐promoted depolymerization strategies in homopolymer PMMA and PAMS prepared by conventional polymerization methods.

Mechanochemically Promoted Functionalization of Postconsumer Poly(Methyl Methacrylate) and Poly(α-Methylstyrene) for Bulk Depolymerization.

We describe a methodology of post-polymerization functionalization to enable subsequent bulk depolymerization to monomer by utilizing mechanochemical macro-radical generation. By harnessing ultrasonic chain-scission in the presence of N-hydroxyphthalimide methacrylate (PhthMA), we successfully chain-end functionalize polymers to promote subsequent depolymerization in bulk, achieving up to 81% depolymerization of poly(methyl methacrylate) (PMMA) and poly(α-methylstyrene) (PAMS) within 30 min. This method of depolymerization yields a high-purity monomer that can be repolymerized. Moreover, as compared to the most common methods of depolymerization, this work is most efficient with ultra-high molecular weight (UHMW) polymers, establishing a method with the potential to address highly persistent, non-degradable all-carbon backbone plastic materials. Lastly, we demonstrate the expansion of this depolymerization method to commercial cell cast PMMA, achieving high degrees of depolymerization from post-consumer waste. This work is the first demonstration of applying PhthMA-promoted depolymerization strategies in homopolymer PMMA and PAMS prepared by conventional polymerization methods.

Model Membranes and Antimicrobial Activities of pH-Sensitive Copolymers

Polymers are options as antimicrobials for skin protection, antifouling surfaces, and fabrics. Here we analyzed the interaction of polymers based on poly(methacrylate) (PMMA) and poly((dimethylamino ethyl) methacrylate) (PDMAEMA) with model membranes and bacteria. We used the homopolymers PMMA, PDMAEMA, and the diblock copolymer(s) prepared with different PMMAm:PDMAEMAn ratios (m/n). The interactions of PDMAEMA and PMMAm-b-PDMAEMAn with large unilamellar vesicles (LUVs) prepared with phosphatidylcholine and phosphatidylglycerol at different pHs, were analyzed by nuclear magnetic resonance (NMR), dynamic light scattering, and zeta potential. These polymers promoted LUVs leakage of a fluorescent probe (5,6-carboxyfluorescein) localized exclusively in the internal aqueous compartment. Interestingly, all copolymers exhibit a bell-shaped pH dependence for the polymer-induced LUVs leakage. The interaction of the positively charged polymers and the pH effect was also demonstrated using giant unilamellar vesicles. These copolymers inhibited bacterial growth in the micromolar range and can be used to prevent bacterial growth on surfaces.

Correlating Optical Reflectance with the Topology of Aluminum Nanocluster Layers Growing on Partially Conjugated Diblock Copolymer Templates.

Large-scale fabrication of metal cluster layers for usage in sensor applications and photovoltaics is a huge challenge. Physical vapor deposition offers large-scale fabrication of metal cluster layers on templates and polymer surfaces. In the case of aluminum (Al), only little is known about the formation and interaction of Al clusters during sputter deposition. Complex polymer surface morphologies can tailor the deposited Al cluster layer. Here, a poly(methyl methacrylate)-block-poly(3-hexylthiophen-2,5-diyl) (PMMA-b-P3HT) diblock copolymer template is used to investigate the nanostructure formation of Al cluster layers on the different polymer domains and to compare it with the respective homopolymers PMMA and P3HT. The optical properties relevant for sensor applications are monitored with ultraviolet-visible (UV-vis) measurements during the sputter deposition. The formation of Al clusters is followed in situ with grazing-incidence small-angle X-ray scattering (GISAXS), and the chemical interaction is revealed by X-ray photoelectron spectroscopy (XPS). Furthermore, atomic force microscopy (AFM) and field emission scanning electron microscopy (FESEM) yield topographical information about selective wetting of Al on the P3HT domains and embedding in the PMMA domains in the early stages, followed by four distinct growth stages describing the Al nanostructure formation.

Design and fabrication of a transparent, tough and UVC screening material as a substitute for glass substrate in display devices

A series of copolymers P(MMAx-co-ANy) constituting of methyl methacrylate (MMA) and acrylonitrile (AN) monomer unit and a homopolymer PMMA have been synthesized by solution polymerization method. The foremost purpose of this research is to obtain tough, transparent, lightweight materials, which will be able to substitute glass in all display devices. Complete characterizations of all the polymers have been carried out along with their absorption properties to understand the effect of introduction of AN comonomer unit on MMA backbone. Among all synthesized copolymers, P(MMA70-co-AN30) is found to be the best composition based on both mechanical and optical properties compared to the same of the other polymers. The optical study of this polymer shows only 5% transmittance at wavelength 256 nm, which is almost equivalent to UV-shielding properties of glass, and this selective UV-screening is achieved without addition of any additives or fillers in copolymer matrix.

Fundamental study of the separation of homopolymers from block copolymers by liquid chromatography with preloaded adsorption promoting barriers

A fundamental study of the separation of homopolymers from polystyrene-block-polymethylmethacrylate (PS-b-PMMA) by liquid chromatography with preloaded discrete and continuous adsorption promoting barriers was performed. The impact of barrier composition on the separation of block copolymers (BCP) was studied by a dual detection (ultraviolet (UV) and evaporated light scattering (ELSD) detectors) system that enabled monitoring both barrier composition and BCP separation simultaneously. The separation of homopolymers from BCP by preloaded discrete adsorption promoting barriers was validated via a series of control experiments by blending known amounts of homopolymers PS or PMMA with PS-b-PMMA, and the resulting chromatograms were free from co-elution of homopolymers and BCP. Quantitation of homopolymers and BCP by ELSD was also demonstrated. The influence of BCP chemical composition on the separation by preloaded discrete adsorption promoting barriers was investigated. Results showed a PS-b-PMMA having 90wt% PMMA co-eluted with homopolymer PMMA, whereas PS-b-PMMA samples having lower amounts of PMMA block could be separated from homopolymer PMMA, successfully. Attempts at using a preloaded solvent gradient for separating homopolymers from block copolymers were unsuccessful. UV detection of the solvent gradient revealed significant deviation in solvent composition compared to the nominally loaded gradient. This deviation was due to the interaction of strong desorption solvent with column stationary phase. As such, the barrier composition in the preloaded gradient method was not as expected. Therefore, one can obtain undesired separation results by preloaded solvent gradients.

Synthesis, characterization and antifouling performance of ABC-type fluorinated amphiphilic triblock copolymer

In this paper, a series of ABC-type fluorinated amphiphilic triblock copolymer composed of hydrophilic block (PEG block), hydrophobic “anchoring” block (poly(methyl methacrylate) (PMMA) block), and nonpolar hydrophobic block (poly(2-perfluorooctylethyl methacrylate) (PFMA) block) were prepared by atom transfer radical polymerization and characterized. By manipulating the bulk composition and annealing treatment, the films with various surface compositions were prepared and then the adsorption behaviors of human plasma fibrinogen (HFg) and bacterial (Escherichia coli) adhesion on these surfaces were investigated by X-ray photoelectron spectroscopy (XPS) and scanning electron microscopy (SEM). The antifouling performances of the amphiphilic triblock copolymers after incorporation of fluorinated block are enhanced compared to PMMA-b-PEG and homopolymer PMMA. The surface compositional heterogeneities with special content of hydrophilic and fluorinated moieties play a significant role in antifouling properties. When the percentage of hydrophobic fluorinated moieties is 21 % and the percentage of hydrophilic ether group is 9.5 % on the surface, the copolymer surface is most unfavorable for protein adsorption. The bacterial adhesion experiment shows the similar results. These results demonstrate the desirable antifouling performance from the ABC-type fluorinated amphiphilic triblock copolymers and provide further realization of the effect of amphiphilic surface structures on the protein adsorption and bacterial adhesion behavior.

Morphology control of PS-b-PB-b-PMMA/PMMA blends by silica nanoparticles

The effect of the silica nanoparticles on the morphology of a blend consisting of poly(methyl methacrylate) (PMMA) and the poly(styrene)-b-poly(butadiene)-b-poly(methyl methacrylate) (SBM) triblock copolymer was studied. Upon blending PMMA with SBM, macrophase separation between the block copolymer and homopolymer occurred, in which the higher molar mass chains of homopolymer separate into homopolymer-rich domains due to the ‘dry-brush’ regime, whereas the lower molar mass chains of homopolymer tend to be selectively solubilized in the block copolymer-rich domains due to the ‘wet-brush’ regime. Upon adding the hydrophilic silica nanoparticles to the PMMA/SBM blend, a significant suppression effect on the extent of macrophase separation between the homopolymer and block copolymer can be observed. It was shown that the silica particles are preferentially localized in the PMMA phase due to the strong hydrogen bonding interaction between the hydroxyl groups on the surface of silica nanoparticles with the carbonyl groups of the PMMA. The suppression effect of the silica particles may be related to the selective adsorption of the high molar mass PMMA on the surface of the silica particles, which may force the system into the ‘wet-brush’ regime, but this was only observed for the systems with a low silica content. For the systems with a high silica content, both the homopolymer PMMA and the PMMA block of the SBM block copolymer interact with the silica surface, which becomes the connecting part between both polymers, thereby suppressing the extent of macrophase separation.

Synthesis and photoluminescence properties of a Dy(III)-containing copolymer in a WLED device

The copolymer poly(MMA-co-Dy(4-BBA)2(TPPO)2(UA)) was obtained by free-radical copolymerization of the synthesized reactive Dy(III)-containing complex Dy(4-BBA)2(TPPO)2(UA) with methyl methacrylate monomer. The structure, morphology, and microcell composition of the copolymer were characterized by FT-IR and UV–visible spectroscopy, SEM, and EDS. The thermal properties were investigated by TG–DTG and DSC analysis, and the photoluminescence properties were investigated by acquisition of fluorescence spectra. The results show that the copolymer (Dy complex content 0.41 %) furnished characteristic Dy(III) peaks at 480 nm $$ \left( {^{4} {\text{F}}_{9/2} \to^{6} {\text{H}}_{15/2} } \right) $$ and 572 nm $$ \left( {^{4} {\text{F}}_{9/2} \to^{6} {\text{H}}_{13/2} } \right) $$ and retained the excellent luminescence of the complex. Its Commission Internationale De L’Eclairage (CIE) coordinates were calculated as x = 0.315 and y = 0.369, which were located at the edge of the white light region. Compared with the homopolymer PMMA, the copolymer increased the glass transition temperature (T g) from 105 to 132 °C. TG–DTG analysis indicated the copolymer was stable up to 228 °C, thus meeting the operating temperature requirement of LEDs.

Viscoelastic and adhesive properties of PMMA-b-PtBA with tackifier

The study of adhesive behavior of poly(methyl methacrylate)-b-poly(t-butyl acrylate) (PMMA-b-PtBA) diblock copolymers is rare in literature. In this study, we prepared a PMMA-b-PtBA diblock copolymer (B-16) by the anionic polymerization technique and compounded it with various amounts of tackifier (Staybelite Ester 3 synthetic resin of Hercules Inc., a triethylene glycol ester of partially hydrogenated wood rosin). The B-16 contained 10 parts of tackifier per hundred parts of polymer (phr), which has a better storage modulus (G') at 120°C and 0.1rad/s than counterpart homopolymer PMMAs of different average molecular weights, containing the same phr of tackifier. Increasing the molecular weight of homopolymer PMMA samples (containing 10phr of tackifier), the G' value at 120°C increases toward the optimum region. The peel performance relates rather well to the viscoelastic property.

Poly(methyl methacrylate)-block-polystyrene and polystyrene-block-poly(n-butyl acrylate) as compatibilizers in PMMA/PnBA blends

Abstract The influence of the addition of poly(methyl methacrylate)-blockpolystyrene (PMMA-b-PS) and PS-b-poly(n-butyl acrylate) (PS-b-PnBA) diblock copolymers on the structure and the mechanical properties of PMMA/PnBA polymer blends was investigated. In binary polymer blends of PMMA and PS, and PS and PnBA, and in the ternary system the corresponding diblock copolymers caused a significantly higher distribution of the dispersed phase and an appreciable narrowing of the particle size distribution as shown by scanning force microscopy using the pulsed force mode technique. Transmission electron microscopy images proved that in the ternary system the two diblock copolymers formed no own separate phase but are arranged as a ring layer at the interface between the two homopolymers PMMA and PnBA. Charpy tests demonstrated that the impact strength of the ternary blends is increased by the two diblock copolymers even at low amounts of the latter. The influence on mechanical properties like Young’s modulus, yield stress, and tensile strength at break was less marked as strainstress measurements showed. The major effect seems to be exerted on the elongation at break.

Contribution of the comonomers to the bulk and surface properties of methacrylate copolymers

Relationships between formulation, bulk properties, and surface properties are investigated on series of copolymers prepared with hydroxyethylmethacrylate (HEMA), methylmethacrylate (MMA), and ethylmethacrylate (EMA) monomers, and on the homopolymers PMMA and PHEMA. The bulk water content, swelling ratio, and static (sessile drop and captive bubble) and dynamic (Wilhelmy plate technique) contact angles and the electrokinetic potential (streaming potential) are measured. The bulk water content and swelling ratio of HEMA copolymers are proportional to the amount of HEMA and are linearly correlated to the contact angle hysteresis. Periodic instabilities in the wetting cycles, similar to Haines jumps, are observed with HEMA copolymers and support a bidirectional relaxation of the hydrophilic groups respectively towards external water and capillary water. The origin of the electrokinetic potential of these nonionizable polymers is attributed to specific adsorption of OH − ions. Its dependence on surface hydrophobicity and statistical length of the side-chains is interpreted in terms of the properties of water molecules near the interface.

Thermal and oxidative degradation of vinyl triethoxy silane – methyl methacrylate copolymers

Methyl methacrylate (MMA) was copolymerized with vinyl triethoxy silane (VTES) using 60CO- γ radiaton at varying ratios of the monomers. The homopolymers PMMA and PVTES were also prepared by the same method. The thermal stabilities and activation energies for the thermal and oxidative degradation reactions of these samples were studied by thermogravimetry. It was observed that the incorporation of PVTES segments in the copolymers decreased the thermal stability of PMMA, as confirmed by thermogravimetric analysis. The activation energies for the degradation process in both N 2 and O 2 atmospheres of copolymers calculated by Freeman – Carroll method with Jeres correction decreased with increasing mole fraction of VTES.

Composition of γ-ray induced triethoxyvinylsilane-methyl methacrylate copolymers determined by XPS

Methyl methacrylate (MMA) was copolymerized with triethoxyvinylsilane (TEVS) using 60Co-γ radiation at varying masses of the liquid monomers in the feed. Their homopolymers PMMA and PTEVS were also prepared by the same method. Thin copolymer and homopolymer blend films were prepared by dissolving the polymers in tetrahydrofuran and casting on clean Teflon or glass substrates. Analysis of the surface composition of these films using XPS indicated that the surfaces of the blend films were completely covered by PTEVS after 10% composition by weight. Similar analysis on the copolymer films, however, revealed that the surfaces of the copolymers contain comparable amounts of PMMA and PTEVS in agreement with the bulk analysis using infrared spectrometry. Hence, use of PMMA/PTEVS copolymers for stone preservation seems feasible by radiation induced polymerization.

Morphological studies of binary homopolymer/block copolymer blends: effect of molecular weight

Morphological investigations of solvent-cast polymer blend films, containing dilute dispersions of poly(methyl methacrylate-block-styrene) (PMMA- b-PS) in a matrix of either poly(methyl methacrylate) (PMMA) or poly(vinyl chloride) (PVC) are described. PMMA and PVC species having molecular weights ranging from 25 000 to 400 000 and from 120 000 to 500 000, respectively, were blended with PMMA- b-PS copolymers of molecular weight 20 000, 65 000, 283 000, and 680 000 at a composition of 80:20 w/w. The PMMA/PMMA- b-PS blends exhibit a variety of micellar morphologies (viz. spherical, cylindrical, vesicular, and lamellar structures) which can be systematically modified by varying the molecular weight ratio of homopolymer PMMA to block segment PMMA, λ = M H/ M A. For blends in which λ ⪡ 1, spherical micelles of uniform size are formed. On increasing λ, the micellar size increases initially, and then a transition from spherical to cylindrical to vesicular and lamellar morphology occurs, provided λ remains less than 1. Further increase of λ to values larger than 1 produces morphologies in which macrophase separation accompanies microphase formation. The PVC/PMMA- b-PS blends exhibit microphase formation, even at λ > 1, due to the strong exothermic interaction between PVC and PMMA. The morphology of this blend system was studied as a function of λ and of the product Nχ PVC-PS, where χ PVC PS is the PVC-PS Flory-Huggins interaction parameter, and N = N PVC N PS /(N PVC 1 2 + N PS 1 2 ) 2 . Macrophase formation is observed when λ ⪢ 1 and also occurs when λ < 1, if Nχ PVC-PS becomes very large. Microphase morphology in the PVC/PMMA- b-PS blends is insensitive to the value of λ because of the dominant role played by the exothermic interaction in determining coronal swelling of the block copolymer.

Dependence of flory-Huggins ? parameters on the copolymer composition for solutions of poly(methyl methacrylate-ran-n-butyl methacrylate) in cyclohexanone

Intermolecular interactions in random copolymer systems depend on the copolymer composition as being observed as a miscibility window in the random copolymer blends. The copolymer composition dependencies of the Flory-Huggins χ parameter and the heats of mixing ▵HM(∞) at infinite dilution were studied for the solutions of poly(methyl methacrylate-ran-n-butyl methacrylate) (MMAnBMA) in cyclohexanone (CHN). The copolymer composition dependencies of χ obtained from osmotic pressures and of ▵HM(∞) measured with a microcalorimeter were concave curves. This suggests that the random copolymers MMAnBMA interact with CHN more attractively than do the homopolymers PMMA and PnBMA. This is caused by the repulsion effect between the MMA and nBMA segments. The equation-of-state theory extended to the random copolymer systems by us reproduced fairly well these thermodynamic properties. The χ parameter for the PMMA/PnBMA blends was calculated using the equation-of-state theory with the MMA/nBMA intersegmental parameters employed for the above random copolymer solutions in CHN. The χ value calculated thus was in satisfactory agreement with that obtained from the random copolymer solutions using the Flory-Huggins theory extended to multicomponent systems. © 1996 John Wiley & Sons, Inc.

Miscibility of linear low density polyethylene (LLDPE)‐graft‐poly(methyl methacrylate) with poly(vinylidene fluoride) (PVF2) and its application as compatibilizer LLDPE/PVF2 blends

AbstractDifferential scanning calorimetry (DSC), Fourier‐transform infrared spectroscopy (FTIR), scanning electron microscopy (SEM), and X‐ray photoelectron spectroscopy (XPS) were used to study the miscibility of blends of a graft copolymer of poly(methyl methacrylate) on linear low density polyethylene (LLDPE‐g‐PMMA, G‐3) with poly(vinylidene fluoride)Systematic name: poly(1,1‐difluoroethylene). (PVF2) and the compatibilization of blends of LLDPE/PVF2. The specific interaction between PMMA side chains and PVF2 in G‐3/PVF2 binary blends is weaker than that between the homopolymers PMMA and PVF2. There are two states of PVF2 in the melt of a G‐3/PVF2 (60/40, w/w) blend, one as pure PVF2 and the other interacting with PMMA side chains. The miscibility between PMMA side chains and PVF2 affects the crystallization of PVF2. LLDPE‐g‐PMMA was demonstrated to be a good compatibilizer in LLDPE/PVF2 blends, improving the interfacial adhesion and dispersion in the latter. Diffusion of PMMA side chains into PVF2 in the interfacial region reduces the crystallization rate and lowers the melting point (Tm) and the crystallization temperature (Tc) of PVF2 in the blends.

Microphase and macrophase separation in blends with a two-block copolymer

The miscibility behaviour of blends A αβ of a homopolymer A and a symmetric two-block copolymer αβ, where the chains A and the blocks α are chemically the same and immiscible with the blocks β, is analysed theoretically and experimentally. The blends are compared with corresponding blends A αβ′ , where the copolymer αβ′ is random. The styrene (S)/methyl methacrylate (MMA) model systems investigated consist of a copolymer P(S- b-MMA) (two-block) or P(S- co-MMA) (random) and a homopolymer PMMA of varying chain length. The process of phase separation during film casting at different temperatures was analysed by mean-field calculations, and the morphologies of the cast films were studied by transmission electron microscopy. The block copolymer blends exhibit both microphase and macrophase separation, which develop in two steps in the order microphase-macrophase or macrophase-microphase. Which sequence is preferred can be predicted from the homopolymer-copolymer chain-length ratio.

Gas-to-liquid permeation in silicon-containing, crosslinked, glassy copotymers of methyl methacrylate

Copolymers of methyl methacrylate with disiloxane derivatives have been proposed as biomaterials for contact lens applications. Although glassy, these copolymers exhibit high oxygen permeability and adequate wettability so that they can be used for manufacture of hard, extended wear lenses. CrossHnked copolymers of poly(methyl methacrylate-co-1,3-bis(methacryloxymethyl)-1,1,3,3-tetramethyl-disiloxane), P(MMA-co-BMTDS), containing from 0.085 to 0.53 mole fraction of BMTDS were prepared and tested for oxygen permeation using a novel apparatus which simulates the atmosphere/lens/cornea conditions. The gas-to-liquid dissolved oxygen permeability, P gd , was determined and it was found to increase with BMTDS content Permeability values for P(MMA-co-BMTDS) at 34°C were significantly higher than for pure homopolymer PMMA, although these copolymers were glassy at this temperature. The increased oxygen permeation was attributed to increased oxygen solubility in the copolymers due to the presence of the -Si-0-bonds.