PMMA Surface Research Articles

Study of lamination quality of solar modules with PMMA front layer

Purpose The photovoltaic modules with front glass as a protective layer are the most popular type in the industry, but for some applications it can be considered as too heavy. One of the approaches is to laminate the cells using PMMA [Poly(methyl methacrylate)] as the front layer. This polymer has good mechanical strength and optical properties but exhibits low adhesion to lamination foil. To increase adhesion between these two materials, PMMA surface treatment may be required. Design/methodology/approach To examine the PMMA treatment influence on the sample, adhesion samples’ surfaces were modified by grinding and laser cutting. Also two types of PMMA available in the market were tested, namely, smooth and satin types. The quality of lamination was determined using two methods, namely, tear test with recorded maximal tear force achieved for the samples, and environment chamber tests, in which the system resistance against the cyclic temperature variation was evaluated. Findings Additional treatment of the PMMA surface lead to increased adhesion of the lamination foil used. Ethylene-vinyl acetate foil in the PMMA system is sensitive to temperature variation, which can lead to system delamination, whereas polyvinyl butyral foil exhibits better environmental performance and even its adhesion to PMMA is lower. Originality/value This paper presents atypical surface modification methods that contributed to higher adhesion of lamination systems in glass-free solar modules. Glass front sheet and polymeric backsheet were replaced with PMMA. As the adhesion mechanism in the PMMA-lamination foil system differs from that in the traditional glass system, different PMMA surface treatments need to be evaluated.

How alkali-activated Ti surfaces affect the growth of tethered PMMA chains: a close-up study on the PMMA thickness and surface morphology

Abstract The alkali-activation of titanium (Ti) surfaces performed in a heated sodium hydroxide (NaOH) aqueous solution, results in a porous layer rich in hydroxyl (OH) groups, the structure and porosity of which strongly depend on the reaction time and NaOH concentration used. In this study, a polymerization initiator is covalently grafted on the alkali-activated Ti substrates by using a phosphonic acid as coupling agent and the resulting surfaces are used as scaffolds to drive the growth of tethered poly(methyl methacrylate) (PMMA) chains via a surface initiated atom transfer radical polymerisation (SI-ATRP). A close-up investigation of how different treatment times (1 h, 3 h, 6 h, 12 h, and 24 h) and NaOH concentrations (0.1 M, 0.5 M, 1 M, 2 M, and 5 M) affect the final PMMA morphology and thickness are presented.

Surface Activation of Poly(Methyl Methacrylate) with Atmospheric Pressure Ar + H2O Plasma

The atmospheric pressure of Ar + H 2 O plasma jet has been analyzed and its effects on the poly(methyl methacrylate) (PMMA) surface has been investigated. The PMMA surface treatment was performed at a fixed gas flow-rate discharge voltage, while varying the plasma treatment time. The Ar + H 2 O plasma was studied with optical emission spectroscopy (OES). Optimum plasma conditions for PMMA surface treatment were determined from relative intensities of Argon, hydroxyl radical (OH), oxygen (O) I emission spectra. The rotational temperature T rot of Ar + H 2 O plasma was determined from OH emission band. The PMMA surfaces before and after plasma treatment were characterized by contact angle and surface free energy measurements, X-ray photoelectrons spectroscopy (XPS), atomic force microscope (AFM) and UV-spectroscopy. The contact angle decreased and surface free energy increased with plasma treatment time. XPS results revealed the oxygen to carbon ratio (O/C) on plasma-treated PMMA surfaces remarkably increased for short treatment time ≤60 s, beyond which it has weakly dependent on treatment time. The carbon C1s peak deconvoluted into four components: C–C, C–C=O, C–O–C and O–C=O bonds and their percentage ratio vary in accordance with plasma treatment time. AFM showed the PMMA surface roughness increases with plasma treatment time. UV-visible measurements revealed that plasma treatment has no considerable effect on the transparency of PMMA samples.

Effect of Free Surface Layer and Interfacial Zone on Glass-Transition Behavior of PMMA/CNT Nanocomposite

The glass-transition behaviors of the nanocomposites comprised of poly(methyl methacrylate) (PMMA) and multiwalled carbon nanotubes (MWCNTs) were investigated. The average glass-transition temperatures (Tg) of PMMA/CNT nanocomposites strongly depend on the nanocomposite structure or the orientation of CNTs in composites. The coexistence of the polymer layer with high mobility at the free surface of PMMA coating on CNT sidewalls and low-mobility PMMA chains in the interfacial zone locally in contact with CNTs leads to the local heterogeneity of polymer dynamics. In the PMMA/CNT nanocomposite with vertically aligned and densified CNT arrays (DCNTA), the PMMA chains with reduced dynamics in the interfacial zone near CNT sidewalls dominate the average Tg and lead to an increase in Tg. In the PMMA/CNT nanocomposite with randomly distributed CNTs (RCNT), a polymer layer with high mobility at the free surface of PMMA coating on CNT sidewalls causes a decrease in average Tg. The PMMA/CNT nanocomposites also exhib...

Improving Polymethyl Methacrylate Resin Using a Novel Titanium Dioxide Coating.

The objective of this study was to improve the surface characteristics of poly (methyl methacrylate) (PMMA) by developing a novel, thin film coating process and to characterize the resulting coated surface. An atomic layer deposition (ALD) technique was developed to deposit a titanium dioxide (TiO2 ) nano-thin film on PMMA. The surface wettability for both coated and uncoated PMMA was determined by measuring water contact angle. Wear resistance was assessed using a mechanical tooth-brushing device with a 50 g load for 6000 strokes after 5 months of water storage. A denture cleanser challenge test was performed by using sonication in 3.8% sodium perborate for 1 hour with aged specimens. X-ray photoelectron spectroscopy (XPS) was used before and after the brushing test and challenge test to analyze the PMMA surface chemical composition. The mechanical strength of coated and uncoated PMMA was measured using a three-point bending test. Surface microbial interactions were also evaluated by assessing Candida albicans biofilm attachment. Nano-TiO2 coating (30 nm thick) was successfully deposited on PMMA at 65°C. After coating, water contact angle decreased from 70° to less than 5°. After brushing test, the coating remained intact. XPS analysis revealed no loss of TiO2 from coated specimens following brushing and denture cleanser sonication for 1 hour. There was no statistically significant difference in mechanical strength (MPa) (mean ± SD) between PMMA (139.4 ± 11.3) and TiO2 -PMMA (160.7 ± 37.1) (p = 0.0995). C. albicans attachment decreased by 63% to 77% on the coated PMMA surface. ALD is a promising technique to modify surface properties of PMMA and resulted in a stable adherent thin film. By depositing a TiO2 coating, PMMA surface properties may lead to significantly reduced microorganism adhesion and easier pathogen removal from PMMA. For patients who wear dentures, reducing the oral microbial biofilm burden using a TiO2 -coated PMMA surface could positively impact their oral and systemic health.

Intumescent fire‐retardant coatings for plastics based on poly(vinylphosphonic acid): Improving water resistance with comonomers

ABSTRACTCoatings based on the in situ photopolymerization of vinyl phosphonic acid (VPA) with triallyl cyanurate as a crosslinking agent are shown to be effective not only for fire‐protecting glass fiber‐reinforced epoxy resin (GRE) composites but also poly(methyl methacrylate) (PMMA), a typical meltable and flammable thermoplastic. Dry adhesion of polyVPA coatings to PMMA surfaces is excellent but, as with coatings on GRE, adhesion following water‐soak tests is poor. Copolymerizing VPA with more hydrophobic monomers improves wet adhesion, albeit with some impairment of fire performance, with copolymers of VPA and acrylonitrile giving the best results. © 2019 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2020, 137, 47601.

Design and direct additive manufacturing of three-dimensional surface micro-structures using material jetting technologies

The ability to directly print 3D microstructures across the surface of large dimension substrates opens up numerous possibilities not feasible with conventional 2D or 2.5D printing or coating techniques. Demonstrated herein is a method to print 3D microstructures onto clear poly(methyl methacrylate) (PMMA) plates using material jetting technologies. Contact angle and profilometry analysis indicated that the VeroCyan™ photopolymer had enhanced wetting of the PMMA surface leading to greater droplet spreading affecting the geometries printed compared to VeroCyan™ integrated models. Strategies to manipulate the interfacial interactions and hence adhesion of the VeroCyan™ photopolymer were investigated by varying PMMA surface free energy through physio-chemical and chemical techniques including (i) corona discharge, followed by post-treatments with 3-(trimethoxysilyl)propyl methacrylate, polyethyleneimine graft chemicals, and (ii) plasma treatments with air and plasma polymerisation of 1,7-octadiene. The surface chemistry and wetting behaviour played a crucial role in influencing interfacial interactions with the VeroCyan™ photopolymer hence its adhesion to the PMMA surface.

An ultrasensitive acoustic wave resonator device enabled by gluing a replaceable micropillar film

Traditional acoustic wave based sensing devices such as quartz crystal microbalance (QCM) rely on the thin films coated on the piezoelectric substrates as the sensing films for chemical and biological detection. This study demonstrates that significant sensitivity enhancement over traditional film based QCM (QCM-F) devices can be achieved by simply attaching a poly(methylmethacrylate) (PMMA) micropillar film onto a QCM substrate (QCM-P) by using a UV-curable glue. Humidity absorption measurements shows that the unique resonance occurred between the micropillars and the piezoelectric substrate improved the mass sensitivity of the QCM sensor by more than eight-fold. In addition, the newly developed QCM-P sensor and traditional QCM-F were utilized to detect bovine serum albumin (BSA) protein immobilization on PMMA surfaces. It was found that the glued QCM-P was capable of measuring BSA at a much lower concentration (200 nM) in comparison to QCM-F (1500 nM). The glue-based micropillar QCM device showed great potential for improving the sensitivity, simplifying the fabrication process, and reducing the cost of QCM sensors for various biosensing and chemical usages.

Impact of trifluoromethyl groups on the control of surface and optical properties of poly(methyl methacrylate)

Poly(methyl methacrylate) (PMMA) is a widely used polymer, but its surface properties are often not ideal for coating applications. Here, a wide range of surface and optical properties of PMMA were achieved by controlling the copolymer type, poly(trifluoroethyl methacrylate) (PTFEMA)-X, where X is the feed ratio (mol %) of trifluoroethyl methacrylate (TFEMA), where TFEMA includes hydrophobic –CF3 moiety. Four different PTFEMA-X samples (i.e. PTFEMA-5, -10, -20, and -40) were prepared by changing the monomer ratio between MMA and TFEMA. The surface energies, surface compositions, transmittances, and refractive indices of the samples were compared to those of PMMA and PTFEMA. The results showed a linear relationship between these properties and TFEMA content, demonstrating a potential method for controlling the surface and optical properties of PMMA. This is interesting as the only difference between MMA and TFEMA is that TFEMA has –CF3 moiety.

Preparation of Fluoroalkyl End-Capped Oligomers/Hexagonal Boron Nitride Nanocomposites Possessing No Weight Loss Behavior in Nanocomposites Even after Calcination at 800°C

Fluoroalkyl end-capped acrylic acid oligomer [RF-(ACA)n-RF]/hexagonal boron nitride (h-BN) nanocomposites [RF-(ACA)n-RF/h-BN] were prepared by reaction of the corresponding oligomer with h-BN nanoparticles (mean diameter: 50 nm) under non-catalytic or alkaline conditions, respectively. Fluoroalkyl end-capped N,N-dimethylacrylamide oligomer/h-BN nanocomposites [RF-(DMAA)n-RF/h-BN] were also obtained under similar conditions. It was demonstrated that RF-(ACA)n-RF/h-BN nanocomposites, which were prepared under alkaline conditions, afforded a clear weight loss in proportion to the contents of the oligomer in the composites after calcination at 800°C; however, the non-catalytic conditions enabled the RF-(ACA)n-RF/h-BN nanocomposite to give no weight loss behavior corresponding to the contents of the oligomer even after calcination. In fact, it was demonstrated that the RF-(ACA)n-RF/h-BN nanocomposites possessing a clear weight loss property could afford the fluorescent peak around 370 nm related to h-BN in the composites; however, the same fluorescent intensity of this nanocomposite after calcination at 800°C as that of the original h-BN was observed, indicating that this nanocomposite could give a clear weigh loss behavior corresponding to the content of the oligomer during the calcination process. In contrast, the RF-(ACA)n-RF/h-BN nanocomposites possessing no weigh loss behavior were found to exhibit the similar fluorescent intensity before and even after calcination at 800°C, suggesting that the corresponding nanocomposites could provide no weight loss ability corresponding to the contents of the oligomer in the composites even after calcination. Similarly, RF-(DMAA)n-RF/h-BN nanocomposites, which were prepared under non-catalytic or alkaline conditions, were found to provide no weight loss corresponding to the contents of the oligomer even after calcination, respectively. These fluorinated h-BN nanocomposites were applied to the surface modification of PMMA [poly(methyl methacrylate)] to exhibit an oleophobic property on the modified PMMA surface. RF-(ACA)n-RF/h-BN nanocomposites possessing a clear weight loss behavior, whose composites were calcinated at 800°C, afforded not oleophobic but oleophilic property on the modified PMMA surface, quite similar to that of the pristine PMMA film surface; however, more interestingly, we found that RF-(ACA)n-RF/ and RF-(DMAA)n-RF/h-BN nanocomposites possessing no weight loss characteristic, whose composites were calcined at 800°C, could supply a good oleophobic property related to the fluoroalkyl segments in the composites on the modified PMMA surfaces, respectively.

Effect of dielectric and conductive targets on plasma jet behaviour and thin film properties

A double layer DBD plasma jet driven by a pulsed generator is used for SiOx thin film deposition. The effects of dielectric and conductive targets on discharge behavior and film properties are analyzed. Different fraction of N2 is added to the working gas (argon) to modulate film growth rate. The electrical property and optical emission of the plasma jet at different positions are characterized. Film surface morphology, composition and thickness are measured for different targets. The excitation temperature (Texc), vibrational temperature (Tvib) and rotational temperature (Trot) are calculated. The relationship between the discharge behavior and the film properties is studied. Results show that the relative optical emission intensities of Si, O, Ar and N2, as well as Texc, Tvib and Trot are higher for the PMMA target between the high voltage electrode and the grounded electrode (referred to as the H–G region). However, Tvib and Trot appear to be higher on the surface of the copper (conductive) target. The morphology of SiOx film is different: nanoparticles are formed on the PMMA (dielectric) target while dense amorphous film is formed on the copper target. With the same depositing parameters, the thickness of the SiOx film is higher on the copper target. The presence of PMMA at the downstream of the plasma can be considered as a small capacitor with a large resistance, which inhibits the current into the primary circuit passing through the H–G region. Although the presence of a dielectric target enhances the discharge in the H–G region, the charge accumulation on the PMMA surface limits the film growth. These results may contribute to the development of next-generation plasma surface modification technologies for diverse applications in electronics, material synthesis and other related areas.

Spray-Assisted Coil-Globule Transition for Scalable Preparation of Water-Resistant CsPbBr3 @PMMA Perovskite Nanospheres with Application in Live Cell Imaging.

Despite their impressive optical properties, lead halide perovskite quantum dots (PQDs) have not realized their potential, especially in bioimaging applications, as they suffer from poor moisture and thermal stability, solvent incompatibility, and significant toxicity. Here, a spray-assisted coil-globule transition method for encapsulating CsPbBr3 (CPB) PQDs into poly(methyl methacrylate) (PMMA) polymer nanospheres is reported. Polyvinylpyrrolidone-capped CPB PQDs are synthesized via the ligand assisted reprecipitation method in dichloromethane. After dissolving PMMA, the above precursor solution is sprayed into petroleum ether under high pressure N2 . High-pressure nebulization restricts the interactions between PMMA polymer chains, resulting in the formation of ≈112 nm nanoscale composite spheres after a coil-globule transition. The CPB@PMMA nanospheres not only possess 73% quantum yields but retain 81% of fluorescence intensity after the exposure to water for over 80 days. Due to their confined size and biocompatible encapsulation, they are readily available for cellular uptake and exhibit no toxicity on live HeLa cells. Furthermore, the PMMA surface allows for functional surface modification, carrying the possibility of targeting specific biological species and processes.

Fabrication and Characterizations of Metallic Mg Containing PMMA-Based Partially Degradable Composite Bone Cements

Inadequate strength at the bone/cement interface is one of the main drawbacks of poly(methylmethacrylate) (PMMA) bone cement in the current orthopedic surgeries. In the present work, a partially degradable PMMA/Mg composite bone cement (PMC) was developed for enhancing the bone/cement interfacial strength, which is proposed to be accomplished by increasing the osteo-conductivity of PMMA and enhancing the mechanical interlocking between bone tissue and the porous PMMA surface formed by the degradation of Mg on the surface of the cement. PMCs were prepared with various concentrations of Mg particles with different sizes and alloy compositions. The effects of Mg particle size, composition and content on the injectability, mechanical and degradation properties, and biocompatibility of PMCs were evaluated. The results show that these parameters affected the properties of the PMCs simultaneously. The good injectability and compressive strengths of PMMA were preserved, while the compatibility to osteoblasts was enhanced when adding Mg particles in a proper manner. The PMCs degraded at the surface with time and formed porous surface structures in the physiological environment, while maintaining the original compressive strengths. This preliminary study shows that the PMC is promising for minimally invasive orthopedic surgery; however, it still requires to be optimized and evaluated in the future.

Novel Concept to Endow Poly(Methyl Methacrylate) Surfaces with Reactive Surface Groups

AbstractThe surface modification of poly(methyl methacrylate) (PMMA) moldings with poly(vinylamine) (PVAm) was performed to produce a novel composite material with a reactive surface, which can be subsequently functionalized to be (bio)compatible. The synthetic potential of the composite material was achieved by endowing the surface with a high density of primary amino groups. To graft the PVAm layer onto PMMA, an interlayer of polymerized dopamine (PDA) was deposited on the PMMA surface. This PDA layer acted as a reactive adhesion promoter. When varying the oxidizing agents, the oxidative polymerization of dopamine was extensively studied concerning deposition rate and homogeneity. Dess‐Martin periodinane possess a mean PDA deposition rate of 14.6 nm⋅h−1 and was the well suited oxidizing agent. The composite surfaces were characterized by atomic force microscopy (AFM), transmission electron microscopy (TEM), and X‐ray photoemission spectroscopy (XPS). The phenomenological surface properties were studied by electrokinetic measurements.

Wetting behavior of superhydrophobic poly(methyl methacrylate)

Superhydrophobic PMMA surfaces were prepared by spin-coating and doctor blade coating of PMAA/hydrophobic silica (1/10 by weight) dispersions in toluene onto glass substrates. Influence of the number of coating layers applied and gauge thickness of the doctor blade used on surface properties were investigated. Formation of dual scale, micro/nano surface topographies were demonstrated by scanning electron microscopy, atomic force microscopy and white light interferometry studies. Roughness factor (r) and average surface roughness (Ra) values of the surfaces were determined. Wetting behavior of superhydrophobic PMMA surfaces obtained by introducing micro-nano, hierarchical roughness to inherently hydrophilic smooth PMMA films cannot be explained by Wenzel model. Therefore, wetting behavior of these surfaces were analyzed using Cassie-Baxter model and area fraction of surface protrusions were estimated.

Toll-like Receptor 2-Dependent NF-κB/AP-1 Activation by Damage-Associated Molecular Patterns Adsorbed on Polymeric Surfaces.

The foreign body reaction is a chronic inflammatory response to an implanted biomaterial that ultimately leads to fibrous encapsulation of the implant. It is widely accepted that the host response to implanted biomaterials is largely dependent on the species and conformations of proteins adsorbed onto the material surface due to the adsorbate's role in mediating cellular interactions with the implanted material. While the cellular response to adsorbed serum-derived proteins has been studied extensively, the presence of endogenous, matrix- and cell-derived mediators of inflammation within the adsorbed protein layer and their impact on cell-material interactions is not well-understood. Damage associated molecular patterns (DAMPs) are endogenous ligands released by stressed or damaged tissues to stimulate sterile inflammatory responses via Toll-like receptors (TLRs) and other pattern recognition receptors. The present study investigated the potential role of tissue-derived, pro-inflammatory stimuli in macrophage responses to biomaterials using cell lysate as a complex source of cell-derived DAMPs and poly(methyl methacrylate) (PMMA) and polydimethylsiloxane (PDMS) films as model biomaterials. We show that lysate-adsorbed PMMA and PDMS surfaces strongly induced NF-κB/AP-1 transcription factor activity and pro-inflammatory cytokine secretion in the RAW-Blue macrophage cell line compared to serum-adsorbed surfaces. Lysate-dependent NF-κB/AP-1 activation and cytokine expression were strongly attenuated by TLR2 neutralizing antibodies, while TLR4 inhibition resulted in a modest reduction. These data suggest that DAMPs, in their adsorbed conformations on material surfaces, may play a significant role in macrophage activation through TLR signaling, and that TLR pathways, particularly TLR2, merit further investigation as potential therapeutic targets to modulate host responses to implanted biomaterials.

One-step selective-wettability modification of PMMA microfluidic devices by using controllable gradient UV irradiation (CGUI)

Poly (methyl methacrylate) (PMMA) has become increasingly popular to fabricate microfluidic devices. In a microfluidic device, different functional areas usually require different wettability to achieve a better performance. However, most of the existing wettability modification methods have been applied to the whole PMMA surface making the device have minimum wettability difference. In this paper, a controllable gradient UV irradiation (CGUI) method was presented. In this method, a series of quartz plates sputtered with different thickness of Cu were arranged on top of the PMMA surface. By controlling the thickness of Cu film, the UV irradiation, which transmitted though the quartz plates onto the PMMA surface, can be adjusted making the modification performance able to be varied accordingly. The validation of the proposed CGUI was conducted through contact angle measurements. Our results showed that through 5 min CGUI process, the contact angle for different parts of the PMMA surface can be varied from 45.48° to 77.41° continuously with a long-term stability of 60 days. To demonstrate this method, a fully integrated Point-of-Care Test (POCT) device was designed and fabricated for the detection of cardiac Troponin I achieving the lower detection limit of 85 pg/ml within 10 min.

Fabrication of Mesoscopic Structure on PMMA Surface by Atomic Hydrogen and Evaluation of the Surface Functionality

Fabrication of Mesoscopic Structure on PMMA Surface by Atomic Hydrogen and Evaluation of the Surface Functionality

An experimental and numerical study of thermal and chemical structure of downward flame spread over PMMA surface in still air

This study presents the results of a comprehensive experimental investigation and numerical simulation of the downward flame spread over PMMA slabs. For the first time, in the case of downward flame spread over PMMA slab 9.6 mm thick, temperature and species concentration fields in the gas-phase flame, temperature profiles in the condensed phase and dependence of the heat flux to the burning surface on the distance from the flame front were obtained. A coupled model of heat and mass transfer involving two-dimensional elliptic conservation equations both for gas phase and solid fuel has been used with the fuel surface approximation of the samples burnout. This allowed us to state, for the indefinite intermediate mode (in terms of the sample thickness, which are not neither thermally thin nor thermally thick), a mathematical model ensuring good agreement between the experimental and calculated macro parameters of combustion. The results of comparing the experimental and calculated data allowed us to determine a number of facts, which, despite the satisfactory agreement between the simulation and the experimental data in the main macro parameters, indicate the necessity of further improvement of the model derived. Such facts are: the increasing disagreement between the calculation and the experiment in the position of the maxima of the temperature in the gas phase as the distance from the flame front grows; essential difference in the width of the MMA and O2 consumption zone between the calculation and the experiment; identification in the experiment of CO as an intermediate product. Further improvement of the model should be aimed at more detailed development of the combustion reaction mechanism, which should consider at least two steps.

Periodic nanostructures formed on a poly-methyl methacrylate surface with a femtosecond laser for biocompatibility improvement

Poly(methyl methacrylate) (PMMA) is widely used as a biomaterial. The formation of periodic nanostructures on the surface is necessary to improve the biocompatibility. A method was proposed and developed to form periodic nanostructures on a PMMA surface. A PMMA plate was placed on titanium (Ti) plate, and then the Ti plate was irradiated with a laser through the PMMA plate. We try to effectively produce periodic nanostructures on PMMA with a femtosecond laser at a fundamental wavelength by increasing the contact pressure and using titanium (Ti) plate. The contact pressure between PMMA and Ti required to form a periodic nanostructure is 300 kPa, and for a contact pressure of 2400 kPa, periodic nanostructures are formed in 62% of the laser-irradiated area on the PMMA surface. These results suggest that the formation efficiency of the periodic nanostructure depends on the laser conditions and the contact pressure.