PMMA Copolymer Research Articles

Incorporation of Benzoxazine Pendants in Polymer Chains: A Simple Approach to Add‐Up Multi‐Responsive Functions

AbstractExternal stimuli responsive polymers can be derived from the functional side group in copolymers. Benzoxazine dimer is a good candidate for expressing multi‐responsive properties based on the type of phenol in combination with its metal complexation. The present work proposes a vinyl monomer containing a benzoxazine pendant, which contains an azo group as the functional monomer. The copolymerization with methylmethacrylate (MMA) via atom transfer radical polymerization leads to a block copolymer, specifically, PA‐Azo‐C3‐b‐PMMA, which forms uniform nanoparticles. The ring opening of benzoxazine monomer results in dimer pendants. The copolymer obtained, PA‐Azo‐C3‐b‐PMMA, shows multi‐responsive functions in terms of metal ion complexation, and UV responsiveness through the dimer pendants and azobenzene groups. The UV exposure results in loss of uniformity of the nanoparticles as well as a decrease in size. This work demonstrates the role of benzoxazine pendants in developing PMMA copolymer showing external stimuli responsive functions.

Highly Fluorescent Merocyanine and Cyanine PMMA Copolymers.

Polymerizable merocyanine and cyanine dye monomers are synthesized and applied in a statistical copolymerization with methylmethacrylate, giving a series of highly fluorescent poly(methyl methacrylate) (PMMA) copolymers. Photophysical properties of yellow to red merocyanine- and of pink to dark purple cyanine-containing copolymers are studied by fluorescence spectroscopy in solid state as well as in different solvents. The highest quantum yield measured in the solid state is observed for copolymers with the lowest dye content: 16% for merocyanine-based and 13% for cyanine-based copolymers, respectively. Fluorescence properties in solution show positive solvatochromism for both merocyanine monomer and copolymer. Copolymer, in comparison to monomer, is hypsochromically shifted to lower wavelengths which point toward H-aggregation of the chromophores in the copolymer matrix.

Strong Hydrogen Bonding with Inorganic Pendant Polyhedral Oligomeric Silsesquioxane Nanoparticles Provides High Glass Transition Temperature Poly(methyl methacrylate) Copolymers.

We report a series of poly(methyl methacrylate) (PMMA) copolymers containing small amounts of methacrylamide (MAAM) and pendant polyhedral oligomeric silsesquioxane (POSS) methyl acrylate (MAPOSS) segments. The hydrogen bonding interactions of the MAAM monomer units and the inorganic POSS nanoparticle units improved the thermal and mechanical properties of the PMMA copolymers. For example, PMMA copolymerization with 5 wt% PMAAM and 5 wt% PMAPOSS monomers could enhance the glass transition temperature to 142°C, with higher modulus, higher water contact angle, and reasonably high transparency. Such copolymers have potential to replace PMMA homopolymers in optical applications.

Alteration of the refractive index of polyacrylate and poly(styrene-co-acrylate) films via molecular structure modification

The alteration in the refractive index (RI) of the polyacrylate and poly(styrene-co-acrylate) films was performed in order to produce a gradient index in the polymeric RI profiles. Such gradient is imperative especially in realizing the fabrication of the polymeric multilayer optical filters and the graded-refractive-index polymeric-based antireflection films. In this study, the highest RI obtained is 1.528 with the poly(styrene-co-acrylate) film which consists of 25 wt% of styrene (Sty), 70 wt% of butyl acrylate (BA) and 5 wt% of acrylic acid, with 8 wt% of divinyl benzene (DVB) which can be utilized to alter the flexibility or the hardness of the polymeric materials. Replacing Sty with methyl methacrylate (MMA) in the copolymer without DVB gives the lowest RI of 1.472 and a difference of RI of 0.056. The Sty copolymer system that contains 8 wt% of DVB has been identified to be one of the effective factors, which yields a refractive index of approximately 0.040 higher than that obtained from the PMMA copolymer system when the same amount of DVB was used. The incorporation of the DVB up to 8.5 wt% has resulted in an increase of the refractive index of approximately 0.013 in the poly(MMA-co-BA-co-AA) copolymer. The refractive index of the polyacrylate copolymer film does not change significantly with the increasing amount of up to 7 % of TMVS in both acidic and alkaline environment. The difference of the refractive index of the film under both mediums is in the order of 10−3.

Synthesis and thermal decomposition kinetics of poly(methyl methacrylate)-b-poly(styrene) block copolymers

Two diblock copolymers of poly(methyl methacrylate)- block-poly(styrene) with chlorine as terminal group (PMMA- b-PS-Cl) were synthesized via two-step atom transfer radical polymerization. The structures of the block copolymers were characterized by Fourier transform infrared spectroscopy, proton nuclear magnetic resonance, and gel permeation chromatography. Thermal properties including glass transition temperature ( Tg) and thermal stability were studied by differential scanning calorimetry and thermogravimetric analysis (TGA), respectively. The block copolymers of PMMA- b-PS-Cl exhibited two glass transitions, which were attributed to the Tgs of PMMA and PS segments, respectively. According to TGA, thermal decompositions of PMMA macro-initiator and PMMA- b-PS-Cl block copolymers had two stages. The weight loss ratio in the second stage was more significant than that in the first stage, which may be attributed to the separation of the halogen atom from the terminal group and the formation of a double bond. The breaking down of the backbone dominates in the second stage in which the weight loss ratio was more than 70%, represented the main stage of pyrolysis. It was found that the introduction of the PS chain remarkably enhanced the thermal stability of the copolymer, thus endowing the block copolymers high activation energy for thermal decomposition. On the other hand, the remaining two pyrolysis procedures further indicated that thermodynamic mechanism didn’t change due to the introduction of PS segments.

Synthesis of Amylopectin Macro-Initiator for Graft Copolymerization of Amylopectin-g-Poly(Methyl Methacrylate) by ATRP (Atom Transfer Radical Polymerization)

Graft copolymer of Amylopectin and PMMA was synthesized by atom transfer radical polymerization (ATRP) method. The hydroxyl groups of amylopectin partially substituted with tert-butyl a-bromoisobutyrate to form tert-butyl a-bromoisobutyrate (TBBiB ) groups. This compound is known as an efficient macro-initiator for ATRP process. This research, aimed to obtain a bio based polymer of Amylopectin, in which the amylopectin was used as macro-initiator in the ATRP of MMA. The experiment was carried out in the homogeneous system under temperature range of 40 – 70°C in DMSO solution using TEA as catalyst. The modified amylopectin-TBBiB then was grafted to methyl methacrylate trough ATRP. Product characterization indicates that the graft copolymer Amylopectin-g-PMMA is efficient and the obtained product owns well defined structures

Photosensing Properties of Pentacene OFETs Based on a Novel PMMA Copolymer Gate Dielectric

In the present work, bottom-gate top-contact organic field effect transistors (OFETs) were fabricated by evaporating a pentacene semiconductor film on top of a new insulating poly(methyl methacrylate) (PMMA) copolymer containing methacrylate units. The PMMA copolymer was synthesized in order to combine the well-known insulating properties of PMMA with the possibility to be efficiently photocured enabling photopatterning-based organic circuitry integration processes. The properties of the pentacene layer deposited on ITO/PMMA copolymer stack were studied through morphological and structural analyses. Device photoresponses and photoexcitated transients were investigated and compared to reference devices based on standard PMMA gate dielectric.

EVA thin film with thermo- and moisture-stable luminescent copolymer beads composed of Eu(III) complexes for improvement of energy conversion efficiency on silicon solar cell

Luminescent beads composed of Eu(hfa)3(TPPO)2 (hfa: hexafluoroacetylacetonate, TPPO: triphenylphosphine oxide) in PMMA copolymer (polymethylmethacrylate- styrene and polymethylmethacrylate–trifluoromethylmethacrylate copolymers), PMMA–St–Eu and PMMA–TF–Eu have been reported for improvement of energy conversion efficiency on silicon solar cell. The PMMA–St–Eu and PMMA–TF–Eu beads are prepared using radical initiator AIBN (2,2-azobisisobutyronitrile) without BPO (Benzoyl peroxide) which promotes decomposition of Eu(hfa)3(TPPO)2. The emission properties of EVA (ethylene vinyl acetate) film with PMMA–St–Eu or PMMA–TF–Eu beads are characterized by the emission spectra and lifetimes. Thermo- and moisture-stabilities of the EVA films are performed under high temperature and high moisture condition (85°C85%RH). Increase percentage the solar cell short circuit current efficiency in the solar cell modulation using with EVA film containing PMMA–St–Eu beads with size in 70μm was estimated to 1.2%. Thermo- and moisture-stable PMMA–St–Eu and PMMA–TF–Eu beads for solar sealing film are demonstrated for the first time.

Morphology Control of Polymer Microspheres Containing Block Copolymers with Seed Polymerization

Microspheres based on binary polymer blend consisting of polystyrene (PSt), poly (methyl methacrylate) (PMMA), block copolymer comprising PSt and PMMA subunits, and ternary polymer blend consisting of PSt, PMMA, and block copolymer were fabricated by a solvent evaporation method, in which a polymer solution in dichloromethane was dispersed in water phase with the aid of a homogenizer to obtain an O/W emulsion followed by solvent evaporation with agitation to solidify the polymer. In the case of ternary blend, the effect of block copolymer content on the morphology of resulting spheres was investigated. Ternary blends afforded the bi-compartmental morphologies, the intermediate morphology between Janus and core-shell, which was confirmed by TEM observation. Seed polymerization of St or MMA was also carried out utilizing the resulting microspheres as seed particles in order to control the shape, and the surface morphology of particles. The particles with snowman-like morphology were obtained by seed polymerization of St using PSt/PMMA binary blend microspheres as seed particles. Surface roughness was controlled by the polymerization of MMA in the block copolymer seed, and that of St in the ternary blend seed.

CO2 nano-foaming of nanostructured PMMA

PMMA-based nano-cellular materials were produced using a gaseous CO2 foaming process. PMMA has been investigated because of its CO2-philic behaviour, which allows high CO2 uptake during the foaming process and facilitates the nucleation phenomenon. Nevertheless, one way to further increase the nucleation rate during the foaming process is to create a heterogeneous nucleation inside a polymer/nucleating agents system, while controlling the foaming process parameters. The addition of acrylate-based copolymers as potential nucleating agents to PMMA is the method chosen here to increase the nucleation rate. This study focuses on the foaming of blends of PMMA and acrylate-based copolymers with a batch process using gaseous CO2 and presents the influence of the initial microstructure of the blends on their final foam structures. Under certain conditions, nano-cellular materials with an average cell size lower than 100 nm were obtained, a hundred times lower compared with PMMA foam.

Synthesis of MA POSS–PMMA as an intraocular lens material with high light transmittance and good cytocompatibility

Poly(methyl methacrylate) (PMMA) has been widely used for intraocular lenses (IOL) but may lead to posterior capsule opacification (PCO) after implantation due to its undesirable hydrophilicity and surface morphology. A novel methacrylisobutyl polyhedral oligomeric silsesquioxane-co-poly methyl methacrylate copolymer (MA POSS–PMMA) was synthesized by a free radical polymerization method to improve its material properties and cytocompatibility. Fourier transform infrared spectroscopy (FT-IR), X-ray diffraction (XRD) and proton nuclear magnetic resonance spectroscopy (1H NMR) measurements demonstrated the successful synthesis of MA POSS–PMMA copolymer. The incorporation of MA POSS greatly changed the crystal structure, surface wettability, optical transmission and cytocompatibility of PMMA. XRD peaks at 2θ ∼ 38.5, 44.7 and 66.1° indicated that a portion of the MA POSS molecules had aggregated and crystallized. Furthermore, larger aggregates are formed at higher MA POSS contents. The optical transmission of the copolymers was up to 99%, which was better than pure PMMA. The hydrophilicity and morphology of the IOL surface were characterized by static water contact angle and atomic force microscopy. Results revealed that MA POSS rendered the surface more hydrophobic and with higher roughness than the pure PMMA. Biocompatibility of copolymers with human lens epithelial cells (HLECs) was further evaluated by morphology and activity measurements in vitro. More HLECs adhesion and better spreading morphology on the surfaces of MA POSS–PMMA copolymers than that on PMMA was shown.

Characterization of poly(2-vinylpyridine)-block-poly(methyl methacrylate) copolymers and blends of their homopolymers by liquid chromatography at critical conditions.

Poly(2-vinylpyridine)s (P2VPs) are important polymers with extensive applications in modern day material science. P2VP is an exceptional case for liquid chromatography because of certain polar interactions with most of the stationary phases. In the present study, we establishedthe critical adsorption point (CAP) of P2VP for the first time. The effectiveness of the method is demonstrated by analyses of blends and block copolymers of P2VP and PMMA. The CAP of PMMA is established for determination of molar mass of P2VP component of above mentioned blends and block copolymers. The methods successfully demonstrate the separation of both types of homopolymers from the rest of the samples in conjunction with the determination of molar mass distribution of noncritical block or component.

Mechanical properties of a rubber-reinforced block copolymer PMMA: Effect of the nanostructuration on tribological performances

The effect of a nanostructured architecture of a rubber-reinforced block copolymer PMMA on both volume and surface mechanical properties is studied. The rubber inclusions ordered at the nanoscale enhance the ductile behavior of the triblock copolymer. This acrylic glass can therefore be easily thermoformed even. Besides, polymeric surfaces are sensitive to scratches which have direct influence on optical transparency. Scratches, which left irreversible grooves on the surface, appear at higher strains with rubber inclusion ordered at the nanoscale compared to classical PMMA or high impact cast PMMA. Eventually, the studied rubber-reinforced block copolymer PMMA is a good candidate to acrylic glass dedicated to automotive glazing.

Hydrophobic modification of polymethyl methacrylate as intraocular lenses material to improve the cytocompatibility

The development of posterior capsule opacification (PCO) after intraocular lenses (IOL) implantation for dealing with cataract is mainly due to the severe loss of the human lens epithelial cells (HLECs) during surgery contact. A novel poly (hedral oligomeric silsesquioxane-co-methyl methacrylate) copolymer (allyl POSS–PMMA) was synthesized by free radical polymerization method to promote the adhesion of HLECs. FT-IR and 1H NMR measurements indicated the existence of POSS cage in the product, which demonstrated the successful synthesis of allyl POSS–PMMA copolymer. Effect of allyl POSS in the hybrids on crystal structure, surface wettability and morphology, optical transmission, thermodynamic properties and cytocompatibility was investigated in detail. X-ray diffraction peaks at 2θ∼11° and 12° indicated that POSS molecules had aggregated and crystallized. Thermogravimetric analysis-differential scanning calorimeter and optical transmission measurements confirmed that the allyl POSS–PMMA copolymer had high glass transition temperatures (more than 100°C) and good transparency. The hydrophilicity and morphology of PMMA and copolymers surfaces were characterized by static water contact angle and atomic force microscopy. The results revealed that the surface of the allyl POSS–PMMA copolymer displayed higher hydrophobicity and higher roughness than that of pure PMMA. The surface biocompatibility was evaluated by morphology and activity measurement with HLECs in vitro. The results verified that the surface of allyl POSS–PMMA copolymer films had more HLECs adhesion and better spreading morphology than that of PMMA film.

Temperature dependant structural changes in thin films of random semifluorinated PMMA copolymers

Semifluorinated (SF) side chain polymers show phase separation between polymer backbone and SF side chains. Due to strong interaction between SF segments the side chains determine the structure behaviour strongly, often resulting in layered structures in which backbones and layers of SF side chains alternate. The interest in this work was directed to find out the dependence of these structures on concentration of SF side chains. Thin films of random copolymers consisting of methylmethacrylate (MMA) and semifluorinated side chain methacrylate (SFMA) segments and with different fluorine content in the perfluoroalkyl side chains (abbreviated as H10F10 and H2F8) were prepared by spin-coating. Phase separation and structure changes were initiated by external subsequent annealing. Corresponding bulk material served as basic information. Generation of ordered structures and variation of film parameters were observed using different X-ray scattering methods (XRR, GIWAXS, and GISAXS). The phase behaviour in bulk is governed by the SF side chain amount and their specific fluorine content which control the self-organization tendency of SF side chains. Additionally, the confinement in thin films generates an orientation of side chains normally to film surface.

High Efficiency Platinum Acetylide Nonlinear Absorption Chromophores Covalently Linked to Poly(methyl methacrylate)

We report three platinum acetylide acrylate monomers containing known two-photon absorption (TPA) chromophores and their covalent incorporation into polymers via free radical polymerization with methyl methacrylate. The photophysical properties of the platinum acetylide monomers and resulting poly(methyl methacrylate) (PMMA) copolymers were investigated to determine if the one- and two-photon photophysical properties of the chromophores were maintained in the copolymers. The photophysical properties of the series of copolymers were studied in solution and solid state with minimum shifts exhibited in the ground state absorption, photoluminescence, and triplet-triplet transient absorption spectra. The polymer films displayed markedly stronger phosphorescence and longer triplet excited state lifetimes than the polymers in solution or the monomers. The incorporation of the platinum acetylide chromophores into the PMMA copolymers allows the materials to be cast as thin films or into free-standing monoliths. Films with ~3.6 μm in thickness and monoliths with 1 mm path length were fabricated and examined. The nonlinear absorption responses of the polymers in solution were measured via the nanosecond z-scan method, and the solid state polymer monoliths were measured via nonlinear transmittance. Both measurements indicate that the polymers exhibited strong transmittance attenuation at input pulse energies exceeding 100 μJ.

Photo-attaching functional polymers to cellulose fibers for the design of chemically modified paper

We introduce a novel approach for preparing polymer-modified and chemically microstructured paper substrates by a photo-chemical attachment of functional polymers to cellulose microfibers inside model filter papers. Poly(methyl methacrylate), PMMA copolymers, which carry a defined amount of photo-reactive benzophenone functional groups, are adsorbed to paper substrates from solution by a simple dip coating process, followed by covalent attachment of the physisorbed polymers through UV-light irradiation. Non-bound macromolecules can be removed from paper sheets by simple solvent extraction, and the resulting polymer-modified substrates were analysed with respect to chemical identity, attached polymer mass, and homogeneity of the polymer attachment. The amount of paper-attached polymers can be conveniently controlled in a wide range from a few mg/g cellulose fiber up to several tenth of mg/g cellulose fiber, by adjusting the polymer concentration in the coating solution. Polymers are being attached by photo-chemical means, and chemical micro patterns on paper can be designed by lithographical means. In first proof-of-concept studies, millimeter-scale channels were prepared that can be used to control fluid penetration by capillary actions. Because of the modularity in the design of photo-reactive polymers, a number of different chemically microstructured papers can be envisioned which may become potentially interesting in lab-on-paper devices.

Comparative effects of denture cleansers on physical properties of polyamide and polymethyl methacrylate base polymers

The purpose of this study was to evaluate the effect of denture cleansers on the surface roughness, hardness and color stability of two polyamides (Valpast, Deflex), a butadiene styrene copolymer PMMA (Rodex), and PMMA polymer as a control group (Paladent). Each material was divided into 5 sub-groups (n=7) as two control and three test groups. Three test groups were immersed for 20 days in commercially available three denture cleansers (CO-Corega, PR-Protefix, VA-Valclean). Two-way analysis of variance and Tukey's post hoc HSD test were used to evaluate surface roughness and hardness data (α=0.05). ΔE, ΔL*, Δa*and Δb* mean values were used for ANOVA, Tamhane test was used as post hoc. Polyamides showed low hardness and high roughness before and after immersion. A significant decrease in hardness was observed for all resins except Rodex after immersion (p<0.05). The denture cleansers changed the roughness, hardness and color of some resins.

Potential transparent PLA impact modifiers based on PMMA copolymers

Two parallel routes were employed to prepare potential transparent impact modifiers for polylactide(PLA). Poly(butadiene-co-methyl methacrylate-co-butyl methacrylate-co-hydroxyethyl methacrylate) or poly(butadiene-co-methyl methacrylate-co-butyl acrylate-co-hydroxyethyl methacrylate) (collectively abbreviated as BMBH copolymer) was prepared by free radical method, possessing polybutadiene domain as rubbery segment to absorb impact energy. It also contained another segment which was composed of methyl methacrylate based polymers to provide optical transparency. Compound of PLA and BMBH copolymers showed an increase of impact strength of only 12% compared to virgin PLA. The other copolymer, poly(butadiene-co-lactide-co-methyl methacrylate-co-butyl methacrylate) (abbreviated as BLMB), consisted of not only polybutadiene and methyl methacrylate based polymer, but also polylactide segment to ascertain compatibility with the PLA matrix. Addition of BLMB copolymers increased the impact strength of PLA up to 25%, while retaining optical transparency.

MesoDyn simulation study on the phase morphologies of miktoarm PS‐b‐PMMA copolymer doped by nanoparticles

AbstractThe compatibility of six groups 12 miktoarm polystyrene‐block‐poly(methyl methacrylate) copolymers is studied at 383, 413, and 443 K via mesoscopic modeling. The values of the order parameters depend on both the architectures of the block copolymers and the simulation temperature, whereas the change tendency of the order parameters is nearly the same at 413 and 443 K. Obviously, temperature presents more obvious effect on long and PMMA‐rich chains. A study of plain copolymers doped with nanoparticles shows that the microscopic phase is influenced by not only the properties of the nanoparticles, such as the size, number, and density, but also by the composition and architecture of copolymers. Increasing the size and the number of the nanoparticles used as a dopant plays the most significant role on the phase morphologies of the copolymers at lower and higher temperatures, respectively. Especially, the 13214‐type copolymers, which are PMMA‐rich composition, present microscopic phase separation as varying degrees of lamellar phase morphologies at 443 K, alternated with PS and PMMA component. © 2012 Wiley Periodicals, Inc. J. Appl. Polym. Sci., 2013