Surface Modification Of Polymers Research Articles

Surface modification to enhance photo-stability of polymers

Photo-degradation is an irreversible alteration in the chemical, mechanical and physical properties of polymers, these alterations are a result of photon absorption from sunlight. UV-light is considered to be the main factor for initiating photo-degradation process of polymers. To extend the lifetime of polymers, their durability, overall minimization of the rate of photo degradation and protection of polymers against environmental factors, stabilizers are introduced to polymers. In addition, since the interaction of the polymer with its environment occurs mainly at the surface of the polymer, therefore surface modification of polymers is used to enhance the UV photo-stabilization. This method can also provide a more durable, weather resistant and photo-stable polymers.

Nanosecond pulse-driven atmospheric-pressure plasmas for polymer surface modifications: Wettability performance, insulation evaluation and mechanisms

Epoxy resin (EP) is one of the most widely-used insulating support materials in electrical power systems, with its insulating performance playing an important role in high-voltage engineering. In this study, a nanosecond pulse-driven Ar/Octamethylcyclotetrasiloxane (OMCTS) plasma jet is developed for fabricating nanocomposite dielectric materials to enhance their EP properties. It is demonstrated that the plasma-enabled polymerization effectively modifies the physical morphology and chemical composition of EP surfaces, where the surface roughness greatly increases with the deposition of less-polar silicon-containing films. Moreover, with an increased OMCTS carrier gas flow rate, the surface conductivity of the EP increases by two orders of magnitude, which is directly related to the appearance of shallow traps in the dielectric surface after Ar/OMCTS plasma treatment. Results show that the trap depth of the electron decreases from 1.21 to 0.99 eV post-treatment, with the OMCTS fragments becoming shallow trap points for charge detrapping and transportation processes. Moreover, the addition of a controlled amount of OMCTS increases the plasma discharge intensity, promotes silicon film deposition, and thus significantly improves the insulation and wettability performance, with higher flashover voltages and water contact angles (WCA). By contrast, excessive addition of OMCTS inhibits the plasma discharge due to the absorption and consumption of energetic electrons by OMCTS molecules. Quantum chemistry calculations are further developed to explore the mechanisms of plasma-induced surface modifications. Overall, the proposed plasma polymerization strategy offers a promising fabrication technique and provides guiding insights into the fabrication of nanocomposite dielectric materials in electrical engineering.

STUDY OF THE EFFECT OF LOW-TEMPERATURE PLASMA BETWEEN ELECTROLYTIC ELECTRODES ON POLYMER SURFACES

In the modern world, polymers are used in almost all areas. Modification of polymer surfaces is an urgent task. Increasing adhesion and wettability is one of the important parameters. There are many different methods for increasing adhesion and wettability. The electrolytic plasma method is one of them. After processing the surface of the polymer by this method, the wettability of the surface of modified polymers with water was studied by measuring the size of a drop of technical water on the surface of the polymer. As a result of experimental studies, the modification of polyethylene terephthalate decreased the wetting angle by 11-24%.

High throughput laser surface micro-structuring of polystyrene by combining direct laser interference patterning with polygon scanner technology

Laser-based processing techniques have proven to be an effective option of modifying polymer surfaces. In this context Direct Laser Interference Patterning in conjunction with the polygon scanner technique is used to fabricate textured polystyrene surfaces through ultra-fast beam deflection. This is achieved by using a high-average power picosecond laser in combination with a polygon mirror-based scanning system. The two-beam DLIP optical configuration leads to the formation of line-like structures with a spatial period of 21.0 µm. The influence of the scanning speed and the repetition rate on the structure formation is investigated, allowing structure heights up to 23 µm. The formation of the micro-structure was found to result from swelling and ablation mechanisms. By applying scanning speeds of 350 m/s, a throughput of 1.1 m2/min is reported for the first time using this method.

Carbon deposition and argon post-treatment of polyurethane surface: Structural-mechanical and fracture properties

Modification of polymeric surface by plasma ions has perspectives in creating flexible functional materials; their deformation behavior is one of the most important properties, as poor fracture resistance cancels all advantages. Carbon ions were deposited on the surface of elastic polyurethane with subsequent argon treatment. Created carbon-containing nanolayer has increased wettability and nonuniform local mechanical properties. Uniaxial extension to strains >100% induces discontinuous microcracks of carbon-modified surfaces but their propagation is constrained by inhomogeneities of the modified layer. Argon post-treatment improves wettability further but makes local mechanical properties uniform that decreases the fracture resistance. Multi-cycle uniaxial loading to 50% doesn't damage the surface but forms in the modified layer weakened domains – precursors of failure; this improves crack resistance at strains >100% a mesh of disordered microcracks appears preventing propagation of long cracks.

Facile and tunable method for polymeric surface modification of magnetic nanoparticles via RAFT polymerization: Preparation, characterization, and drug release properties

Herein, the facile and tunable technique for the preparation of novel multi-stimuli-responsive nanocomposites via RAFT polymerization for DOX delivery is reported. The influence of the molecular weight of pH- and thermo-sensitive poly (acrylic acid-co-NIPAM) (PNAx), as a macro-RAFT agent, on the nanocomposites size and drug release rate was investigated. The outcome of this study reveals that macro-RAFT agent with lower molecular weight can be attached to the surface of magnetic nanoparticles with higher content of polymeric layer than can macro-RAFT agent with higher molecular weight. Also, it was observed that the particle size, polymer grafting density, DOX loading capacity, and DOX release rate could well be influenced by the molecular weight of PNAx. The in vitro drug release of doxorubicin was examined in various conditions (pH and temperature) and the results established a strong pH and thermal dependence. The order of drug-loading and releasing level rate for synthesized nanocarriers toward PNAx molecular weight are PNA3 < PNA2 < PNA1. These magnetic nanocarriers displayed excellent biocompatibility, stability, and dispersibility in aqueous solutions. Therefore, experimental data and results showed that nanocarriers synthesized with various molecular weights of PNAx by RAFT polymerization could be deployed for practical biomedicine applications and that the RAFT polymerization ushers in an excellent technique for tunable and facile surface modification of various nanoparticles with distinct sizes and morphologies.

Does Plasma Treatment Effective for Surface Modification of Polymer? An Overview of Treatment Effect on Adhesive and Tribological Properties

Surface modification with plasma has been widely applied to polymeric materials. This treatment is intended to improve the surface properties of the polymer including its wettability and adhesiveness. The aim of this paper is to provide a review of the literature on the surface treatment of polymers with plasma, which focuses on the effects of adhesive and surface tribology properties. The related surface properties are also reviewed in order to strengthen the review of adhesive properties and tribology. Various types of plasma treatments that have been reviewed reported that plasma can be effectively used to improve surface properties, especially adhesive and tribological properties. On a small surface treatment has been developed plasma jet treatment which has been widely applied in biomedical applications.

Plasma Surface Modification of Epoxy Polymer in Air DBD and Gliding Arc

We studied the epoxy polymer surface modification using air plasma treatment in a Gliding Arc (GA) plasma reactor and a pulsed Dielectric Barrier Discharge (DBD). We employed optical emission spectroscopy (OES) measurements to approximate the vibrational and rotational temperatures for both plasma sources, as well as surface temperature measurements with fiber optics and IR thermography to corelate with the corresponding hydrophilization of the epoxy material. Water contact angle measurements revealed a rapid hydrophilization for both plasma sources, with a slightly more pronounced effect for the air DBD treatment. Ageing studies revealed stable hydrophilicity, with water contact angle saturating at values lower than 50°, corresponding to a &gt;50% decrease compared to the untreated epoxy polymer. ATR-FTIR spectroscopy studies showed an additional absorption band assigned to carbonyl group, with its peak intensity being higher for the DBD treated surfaces. The spectra were also correlated with the surface functionalization via the relative peak area ratio of carbonyl to oxirane and benzene related bands. According to SEM imaging, GA plasma treatment led to no apparent morphological change, contrary to DBD treatment, which resulted in nano-roughness formation. The enhanced surface oxidation as well as the nano-roughness formation on epoxy surface with the air DBD treatment were found to be responsible for the stable hydrophilization.

Surface Modification of Low-Background Polymers by Applying Nitrogen Ion Implantation for Electronic Substrates of Rare Event Detection

Surface Modification of Low-Background Polymers by Applying Nitrogen Ion Implantation for Electronic Substrates of Rare Event Detection

Super-Hydrophilic Zwitterionic Polymer Surface Modification Facilitates Liquid Transportation of Microfluidic Sweat Sensors.

The transportation of sweat in an epidermal sweat sensor is critical for the monitoring of biochemical compositions of human sweat. However, it is still a challenge to engineer microfluidic devices with super-wetting channels for such epidermal sweat sensors. Herein, a zwitterionic poly (2-methacryloyloxyethyl phosphorylcholine) (PMPC) modified microfluidic device with super-wetting and good liquid transport ability via an azo coupling reaction of PMPC onto the surface of polydimethylsiloxane microfluidic devices is reported. The obtained PMPC-modified microfluidic device can be integrated with flexible electrochemical sensor to measure the ion compositions of human sweat in real-time. The super-hydrophilic zwitterionic polymer surface modification can greatly facilitate the transportation of body fluids in microfluidic sensors for the detection of various biomarkers. Such microfluidic sensors have great potential for next-generation personalized healthcare.

A STUDY ON THE RELATION BETWEEN MORPHOLOGICAL AND CHEMICAL CHANGES AND WETTABILITY MODIFICATION OF POLYETHERSULFONE SURFACE AFTER IRRADIATION WITH A PULSED KrF LASER

Laser irradiation is used for surface modification of polymers aiming to improve their properties for different applications. The wettability of a polymeric surface can significantly affect its performance for biological applications. In this paper, the interaction of high-energy KrF laser photons in the two above- and below-threshold regimes with polyethersulfone polymer is studied. The role of morphological and chemical changes of the irradiated polymer and their correlation in the modification of the wetting property of this polymer is investigated. The obtained results show that the morphological parameter of surface roughness is the dominant mechanism in the below-threshold regime, while in the above-threshold region, the competition between this parameter and the carbonization amount of the surface determines the final hydrophilic response.

Polyurethane Treated in Ar/C2H2/Ar Plasma: Towards Deformable Coating with Improved Albumin Adsorption

Plasma modification of soft polymeric surfaces has many prospects in creating biomedical devices. The deformability of the obtained coatings should be studied, as the usage of such materials implies mechanical loads. Polyurethane (a two-phase synthetic polymer) treated in argon/acetylene plasma, with post-treatment in argon plasma, was investigated. A carbon-containing nanocoating (discontinuous mesh-like structures) with structural–mechanical inhomogeneities is formed by the action of Ar/C2H2 plasma. The heterogeneities of the coating are due to the complex structure of the initial substrate and short duration of treatment; as the treatment time increases, the coatings become homogeneous, but their stiffness rises. The treated surfaces in the uniaxial tensile state have micro and/or nanocracks in certain cases of plasma treatment. This is associated with an increased elastic modulus of the coatings. The coatings without cracks have regions with sufficiently alternating stiffness. Post-treatment in argon plasma increases wettability and free surface energy, positively affecting the adsorption of albumin. The stiffness of such coatings increases, becoming more homogeneous, which slightly reduces their crack resistance. Thus, plasma coatings on soft polymers operating under mechanical loads without causing damage should have sufficiently low stiffness, and/or structural-mechanical heterogeneities that provide redistribution of stress.

Combination of AFM and Electrochemical QCM-D for Probing Zwitterionic Polymer Brushes in Water: Visualization of Ionic Strength and Surface Potential Effects.

The surface modification of soft zwitterionic polymer brushes with antifouling properties represents a facile approach to enhancing the performance of bioelectronics. Ionic strength and applied potentials play a crucial role in controlling polymer brushes' conformation and hydration states. In this study, we quantitatively investigated and compared poly(2-methacryloyloxyethyl phosphorylcholine) (PMPC) and poly(sulfobetaine methacrylate) (PSBMA) brushes at different salt concentrations and applied surface potentials. Initiator-containing poly(3,4-ethylenedioxythiophene) films (poly(EDOT-Br)) were prepared by electropolymerization. After the conducting polymer was deposited, polymer brushes grew from the electrode surface through surface-initiated atom-transfer radical polymerization (SI-ATRP). Polymer brushes were carefully characterized for their surface morphologies using an atomic force microscope (AFM). The force volume method measured using AFM enabled the analysis of the Young's modulus of the two polymer brushes. Hydration states and protein binding behaviors of polymer brushes were examined using quartz crystal microbalance with dissipation (QCM-D). We further integrated a potentiostat with the QCM-D to conduct an electrochemical QCM-D study. The energy dissipation and frequency changes corresponded to the ion adsorption on the film surface under different ionic strengths. The results of both hydration states and nonspecific protein binding behavior indicate that PMPC brushes have greater ionic strength independency, implying the conformation of the unchanged PMPC brushes. Moreover, we illustrated how the surface potential influences nonspecific and specific binding behavior on PMPC brushes on PEDOT films compared with electrified poly(EDOT-PC) electrodes. We concluded that PMPC brushes exhibit unique behaviors that are barely affected by ion concentration, and that the brushes' modification results in less influence by surface potential due to the finite Debye length influencing the electrode surface to outer environment in an NaCl aqueous solution.

Study on CO2-based plasmas for surface modification of polytetrafluoroethylene and the wettability effects

Surface modification of polymers is an attractive way to endow them with new interfacial properties while maintaining desirable bulk properties, thus expanding their possible applications. In the present work, CO2/N2 DBD plasma was applied for the surface modification of polytetrafluoroethylene (PTFE) membranes by using acrylic acid as the precursor. Systematic experiments has been carried out to investigate the influence of the plasma gas composition and the plasma exposure time to the composition, morphology, and wettability performance of the PTFE membranes. It is shown that acrylic acid has been successfully grafted on the surface of PTFE to form carboxylic functional groups by the plasma technique, leading to improved hydrophilicity. The increase of the CO2 content in CO2/N2 mixtures results in enhanced generation of CO, CO, and CC species, suggesting CO2 has been converted to functional groups on the surface of PTFE membranes. Moreover, at plasma exposure time of 0˜60 s, the hydrophilicity of the PTFE membranes can be improved, while longer plasma exposure time would lead to the degradation of the formed coating, leading to reduced hydrophilicity. This is also demonstrated by the quality of printed text on the corresponding PTFE membranes. The CO2-based plasma method was further extend to the surface modification of substrates like polyethylene (PE), polyvinylidene fluoride (PVDF), and plexiglass, suggesting high versatility of the process to alter their wettability performance. This study provides useful insight for the utilization and conversion of CO2 into value-added carboxylic groups on polymers via plasma technique.

Water-Resistant Surface Modification of Hydrophobic Polymers with Water-Soluble Surfactant Additives.

Water-soluble nonionic surfactant, pentaethylene glycol monododecyl ether, C12E5, spontaneously blooms to the surface of spin-cast hydrophobic polyisoprenes, generating hydrophilic surfaces. This system provides a simple model for hydrophilic chemical modification of rubbery polymers that demonstrates surprisingly rich, complex, and unexpected behaviour. The vertical depth profiles were quantified using neutron reflectometry (NR) using a novel procedure to account for undulations in the film thickness. Surface properties were characterized using contact angle analysis and atomic force microscopy (AFM). Despite the low surface tension of the toluene solvent used in film preparation and the low surface energy of the polyisoprene (PI) matrix, NR depth profiles revealed clear evidence of surfactant segregation. This surface layer was typically thicker than a monolayer, but incomplete, yet was remarkably stable with respect to dissolution, even when exposed to hundreds of thousands of times the volume of water required to dissolve all the surfactant on the surface. Despite the apparent resistance to removal from the surface, water exposure does alter the subsequent wettability of the surface, with a hydrophilic-to-hydrophobic transition occurring after rinsing. Complementary AFM images of these C12E5/cis-PI films showed unexpected strand-like features on the surface of the film, which we attribute to a non-uniform lateral distribution of some of the surfactant. This surface structure becomes more evident after rinsing, and it appears that there are two distinct populations of surfactant on the PI film surface. We conclude that some of the bloomed surfactant exists as layers, which are relatively inert with respect to rinsing or surface modification, and some is laterally inhomogeneous. This latter population is primarily responsible for surface wetting behaviour but is not detected by specular NR.

Tailoring the working gas flow to improve the surface modification of plasma-treated polymers

The paper aims to comparatively investigate the plasma-induced effects − under different discharge regimes: stationary and flowing gas (He and He + 0.5%O2) − on the surface properties of four types of polymers, with a distinct structure, degree of oxidation, and functionality. A pulsed dielectric barrier discharge is used to produce homogenous non-thermal atmospheric-pressure plasma for uniform, efficient, reproducible chemical surface processing. The discharge characteristics, specific to each mode of operation, were analyzed in correlation with the changes in the surface characteristics found following plasma exposure. The plasma treatment increases the surface hydrophilization of all tested polymers, regardless of the discharge mode of operation. Nevertheless, the optimum discharge regime for surface functionalization is correlated with the polymer structure and discharge characteristics. Thus, polypropylene and polystyrene present the maximum wettability in trapping gas mode, while poly(methyl methacrylate) and polysulfone, in the flowing gas mixture. The experimental results demonstrate that working in trapping gas mode is advantageous due to enhanced (>15÷40%) incorporation onto the surface of functional groups related to both oxygen and nitrogen species.

Polyurethane coated with polyvinylpyrrolidones via triazole links for enhanced surface fouling resistance

Surfaces with hydrophilic and antimicrobial properties are very attractive for cardiovascular device-associated applications. The aim of this study was to prepare and coat a hydrophilic polymer containing a functional group capable of forming triazole functionality onto the surface of polyurethane (PU). The modified surfaces were assessed with cell adhesion, bacterial adhesion and bacterial viability. Mouse fibroblast cells (NIH-3T3) and three bacterial species were used for assessment. The results showed that the modified surface not only exhibited a significant reduction in cell adhesion with a 25%–59% decrease to mouse fibroblast but also showed a significant reduction in bacterial attachment with 26%–67%, 24%–61% and 23%–57% decrease to Staphylococcus aureus, Escherichia coli and Pseudomonas aeruginosa, respectively, as compared with original PU. Furthermore, the polymer-modified surface exhibited a significant antibacterial function by inhibiting bacterial growth with reduction of 49%–84%, 44%–79% and 53%–79% to S. aureus, E. coli and P. aeruginosa, respectively, as compared with original PU. These results indicate that covalent polymer attachment enhanced the antibacterial and antifouling properties of the PU surface.

The Effect of Additional Polyethylene Glycol (PEG) as Coating Fe3O4 for Magnetic Nanofluid Applications

Background &amp; Objective: Magnetic nanofluid is a special class of nanofluid that exhibits both magnetic and fluid properties. The main purpose of using magnetic nanofluid as a heat transfer medium is the possibility of controlling the flow and the heat transfer process through an external magnetic field. This research aims at identifying the effect of adding polyethylene glycol (PEG) to magnetite (Fe3O4) nanoparticles for magnetic nanofluid applications. Method: The nanofluid was prepared by synthesizing Fe3O4 nanoparticles using the chemical precipitation method and then dispersing them in distilled water using a sonicator. Results: The result of XRD is that nanoparticles had inverse spinel structures, and the smallest crystallite size is found in the Fe3O4@PEG-6000 samples. FE-SEM and TEM show that the addition of PEG can reduce the Fe3O4 agglomeration, and the smallest particle size is found in the Fe3O4@PEG-6000 samples. The result of FT-IR shows that there is a surface modification of Fe3O4 nanoparticles and PEG polymer. The result of VSM shows the coercivity value is small; hence, the sample is a superparamagnetic material. The addition of PEG increases the thermal conductivity of Fe3O4 nanoparticles. Conclusion: The addition of PEG makes particle size smaller, reduce the agglomeration and increases the thermal conductivity, so that it is potential for magnetic nanofluid applications.

Polymer surface modification using He/O2 RF remote low‐pressure plasma

In this study, He/O2 plasma mixture, induced in a radio frequency (RF) low‐pressure remote plasma system, has been characterized and employed for polymer surface modification. Actinometry optical emission spectroscopy (AOES) and Langmuir probe techniques were used to evaluate the plasma active species contributing to polymer surface modification. These active species involve the atomic oxygen [O] and the electrons (ne). Five different polymers (poly(methyl methacrylate) [PMMA], polytetrafluoroethylene [PTFE], polyethylene [PE], polyvinyl chloride [PVC], and polystyrene [PS]) were plasma treated and subsequently characterized for etching rate, surface morphology using atomic force microscopy (AFM) technique, and chemical elemental composition using X‐ray photoelectron spectroscopy (XPS) technique.

Long-term surface modification of PEEK polymer using plasma and PEG silane treatment

Despite the several advantages of the Polyetheretherketone (PEEK) polymer, its wide application is limited due to its hydrophobic nature and poor surface adhesion performance. The plasma treatment can effectively transform the hydrophobic surface to hydrophilic. However, their effects are for a short duration, and the modified surfaces gradually lose their wetting and surface adhesion properties. In this work, we have reported a combined effect of plasma and PEG Silane treatment for permanent hydrophilic modification and improved adhesion strength of PEEK surfaces. The time-dependent changes in the contact angles, XPS, and ATR-FTIR spectra results were carefully recorded to investigate the surface properties of the modified surfaces. It was observed that the functional groups and polar component of surface energy played a pivotal role in long-term modification of PEEK surfaces. The Plasma and PEG Silane treated PEEK surface retained a very low contact angle and high content of hydroxide, carboxylic acid, and peroxide groups as compared to the plasma-treated PEEK surfaces. The lap shear test confirms the long-term effects of Plasma and PEG Silane treatment on adhesion properties with high bonding strength after 48 days of sample storage, which was dropped for Plasma treated surface just after 7 days of storage.