Low Temperature Plasma Polymerization Research Articles

Low temperature plasma polymerization: An effective process to enhance the basalt fibre/matrix interfacial adhesion

The interface of fibre reinforced composite materials is deeply affected by the type of sizing applied to the surface of the fibres. In this study, a polymer film based on pure tetravinylsilane (TVS) or its mixture with two different oxygen amounts was deposited on the surface of unsized basalt fibres by plasma enhanced chemical vapor deposition. At first, the influence of the plasma process was investigated through a single fibre tensile test characterization, which did not show any strength degradation of the modified fibres. Subsequently, single fibre pull-out tests were performed to study interfacial strength with an epoxy matrix. The presence of oxygen within the polymer film mixture allowed to increase the interfacial shear strength (IFSS) by 79% compared to untreated basalt fibres, highlighting an excellent fibre/matrix interface for the micro composite. After the interfacial adhesion tests, scanning electron microscopy confirmed the strong bond between the fibre surface and the deposited silane sizing.

Self-healing super-hydrophobically coated fiber prepared by plasma treatment

The ultra-durable, self-healing superhydrophobic polyester fabric based on ZnO@PDMS nanoparticle composite coating (PET-g-PDMS@ZnO fiber) is prepared by low-temperature plasma polymerization. The influences of the preparation process on the superhydrophobicity, self-healing property, durability and stability of the coating are studied. The results show that the water contact angle on the surface of PET-g-PDMS@ZnO fabric can reach 162.7°, and the sliding angle is 7.5°. After 300 washing cycles and 1300 rubbing cycles, the superhydrophobic property is still maintained. Both plasma method and heating method are used to repair the worn coating, and it is found that the repair effect of plasma is obvious, while the heating repair is effective only in the case of small loads. Moreover, scanning electron microscope, nanoindentation and X-ray photoelectron spectroscopy measurement are used to explore the self-healing mechanism. This research provides the theoretical and technical support for the development and application of plasma technology in the preparation of superhydrophobic fabrics.

Low-temperature plasma polymerized fluorocarbon coating promotes surface charge dissipation in polystyrene

Polystyrene (PS) is a common insulating material in pulsed power devices, which has excellent and reliable insulation properties. However, the charge accumulation on the insulator surface seriously threatens its surface insulation property. Surface modification has been verified as an effective way for inhibiting surface charge accumulation. In this paper, plasma polymerized fluorocarbon (PPFC) coating was prepared by low-temperature plasma polymerization in the mixture of methyl-methacrylate and dodecafluoroheptyl-methacrylate (DFHMA). Compared with the untreated PS, the surface charge dissipation rate of PPFC coating is increased by more than 6 times. The introduction of DFHMA makes the coating have no obvious ageing effect after the storage, and has good reusability after the surface flashover. This work provides a new method for modification of polymer dielectrics and a novel way for the preparation of high-charge-dissipation polymers in other related fields.

Preparation of a Biofunctionalized Surface on Titanium for Biomedical Applications: Surface Properties, Wettability Variations, and Biocompatibility Characteristics

This study developed a promising approach (low-temperature plasma polymerization with allylamine) to modify the titanium (Ti) surface, which helps the damaged tissue to heal faster. The Ti surface was first cleaned by argon (Ar) plasma, and then the functional amino-groups were coated on the Ti surface via plasma polymerization. The topography characteristics, wettability, and optimal plasma modification parameters were investigated through atomic force spectroscopy, secondary ion mass spectroscopy, and response surface methodology (RSM). Analytical results showed that the formation of a porous surface was found on the Ar plasma-modified Ti surfaces after Ar plasma modification with different parameters. The Ar plasma modification is an effective approach to remove surface contaminants and generate a porous topography on the Ti surface. As the Ti with Ar plasma modification was at 100 W and 190 m Torr for 12 min, the surface exhibited the maximum hydrophilic performance. In the allylamine plasma modifications, the contact angle values of the allylamine plasma-modified Ti surfaces varied between 70.15° and 88.26° in the designed parameters. The maximum concentration of amino-groups (31.58 nmole/cm2) can be obtained from the plasma-polymerized sample at 80 W and 150 mTorr for 22 min. Moreover, the cell response also demonstrated that the allylamine plasma-modified Ti sample with an optimal modification parameter (80 W, 22 min, and 150 mTorr) possessed great potential to increase cell adhesion ability. Thus, the optimal parameters of the low-temperature plasma polymerization with allylamine can be harvested using the RSM design. These data could provide new scientific information in the surface modification of Ti implant.

Carboxyl-Functionalized Nanoparticles Produced by Pulsed Plasma Polymerization of Acrylic Acid.

Carboxyl-enriched and size-selected polymer nanoparticles (NPs) may prove to be very useful in biomedical applications for linker-free binding of biomolecules and their transport to cells. In this study, we report about the synthesis of such NPs by low-pressure low-temperature pulsed plasma polymerization of acrylic acid. Gas aggregation cluster source was adapted to operate plasma with a constant pulse period of 50 μs and with varying duty cycle. The NPs were produced with the size ranging from 31 ± 5 to 93 ± 14 nm and with retention of the carboxyl groups ranging from 4.0 to 12.0 atom %. Two regimes of the NP formation were identified. In the large duty cycle regime, the NP growth was interfered with by positive ion bombardment which resulted in the ion-driven detachment of the carboxyl species and in the formation of carboxyl-deficient NPs. In the small duty cycle regime, the NP growth was accompanied by the radical-driven chain propagation with the attachment of intact monomer molecules. Improved efficacy of the monomer retention resulted in increased concentration of the carboxyl groups.

Flexible electrochromic tungsten/titanium mixed oxide films synthesized onto flexible polyethylene terephthalate/indium tin oxide substrates via low temperature plasma polymerization

An investigation has been taken on enhancing lithium electrochromic performances of mixed organotungsten oxide (WOyCz)/organotitanium oxide (TiOyCz) films, co-synthesized onto 60 Ω/square flexible polyethylene terephthalate (PET)/indium tin oxide (ITO) substrates by a low temperature plasma polymerization method at various mixed concentrations of precursors tungsten hexacarbonyl W(CO)6 and titanium n-butoxide Ti(C4H9O)4. The plasma polymerized-organo‑tungsten‑titanium oxides (WTixOyCz) films possess notable electrochromic performances while switch tested by a potential sweep from −1 V to 1 V at a scan rate of 50 mV/s and from 1 V to −1 V at a scan rate of −50 mV/s for 200 cycles of reversible Li+ ion intercalation and de-intercalation in a 1 M LiClO4-PC electrolyte, still after bended 360o around a 2.5 cm diameter rod for 1000 cycles. Optical modulation (ΔT) of 74.8% for WOyCz films at a wavelength of 850 nm is appreciably progressed of up to 82.7% for WTixOyCz films as co-deposited by a low temperature plasma polymerization method.

Drug loaded nanoparticle coating on totally bioresorbable PLLA stents to prevent in-stent restenosis.

Biodegradable polymer poly (dl-lactide) (PDLLA) has been used as drug coating material for drug-eluting stents due to its excellent biocompatibility and sustained drug release ability. However, the uniform thin layer drug eluting coating on a stent not only inhibits the blood vessel's smooth muscle cell overgrowth but also delay the endotheliation process which is often associated with the occurrence of acute thrombosis. Therefore, in this study, we developed a novel coating method using PDLLA nanoparticles (NPs) as a coating to overcome this issue. The average 300 nm sized sirolimus-loaded PDLLA nanoparticles were prepared by a conventional emulsion solvent evaporation method. A low temperature plasma polymerization technology to graft hydrophilic polymers on to poly (l-lactide) stent was used to increase the surface coating efficiency of nanoparticles on the stent. Results showed that sirolimus-loaded nanoparticles can be successfully coated on to the stents with sustained drug release properties. In vitro cell culture study showed the drug loaded nanoparticle coating effectively inhibited the proliferation of smooth muscle cells while still allowed a faster proliferation of endothelial cells, suggesting that the new NP coated bioresorbable stents have the potential to reduce both the occurrence of in-stent restenosis and acute thrombosis. © 2016 Wiley Periodicals, Inc. J Biomed Mater Res Part B: Appl Biomater, 106B: 88-95, 2018.

Effects of O 2 gases addition on enhanced lithium ion intercalation and conduction of flexible-transparent-lithiated tantalum oxide thin films synthesized by an atmospheric pressure plasma jet

Abstract Flexible-transparent-lithiated-lithium tantalum oxide (Li x TaO y C z ) films deposited onto 40 Ω/□ flexible polyethylene terephthalate/indium tin oxide substrates by low temperature plasma polymerization with an atmospheric pressure plasma jet (APPJ) at various flow rates oxygen gases are investigated. Precursors [lithium tert -butoxide, (CH 3 ) 3 COLi] and [tantalum ethoxide, Ta(OC 2 H 5 ) 5 ] 2 ] vapors are carried by argon gas, mixed by oxygen gas and injected into air plasma torch for fast synthesis of Li x TaO y C z films by short durations of the substrates, 33–37 s, exposed in the plasmas. The flexible-transparent Li x TaO y C z films possess the notable Li + ion intercalation and conduction performance for 200 cycles of reversible Li + ion intercalation and de-intercalation in a 1 M LiClO 4 -propylene carbonate electrolyte by switching measurements with a potential sweep from − 1.25 V to 1.25 V at a scan rate of 50 mV/s, even after being bent 360° around a 2.5 cm diameter rod for 1000 cycles. The Li + ionic diffusion coefficient and conductivity are respectively of up to 1.2 × 10 − 10 cm 2 /s and 1 × 10 − 8 S/cm for Li x TaO y C z films synthesized using an APPJ with a certain O 2 gases addition of 9 sccm.

Enhanced electrochromic performance of flexible WFexOyCz films by O2 gas addition using low temperature plasma polymerization

An investigation was conducted into the prominent lithium electrochromic performance of flexible organo-tungsten-iron oxide (WFexOyCz) films deposited onto flexible (60 Ω/□ polyethylene terephthalate/indium tin oxide) substrates. The simple one-step low temperature (∼23 °C) plasma polymerization method was used to inject the precursors tungsten hexacarbonyl [W(CO)6] and biscyclopentadienyl iron [Fe(C5H5)2] into the plasma chamber, whilst being mixed with O2 gases at various gas flow rates. The plasma-polymerized WFexOyCz films at a certain addition of oxygen gases achieved outstanding lithium electrochemical reversibility of Li+ ion intercalation and de-intercalation proven by a potential sweep switching between −1 V and 1 V at a scan rate of 50 mV/s in a 1 M LiClO4-propylene carbonate electrolyte. High values for optical transmittance modulation (ΔT) of up to 83.2%, optical density (ΔOD) of up to 1.08 and color efficiency (η) of up to 62.3 cm2/C at a wavelength of 854.9 nm were obtained for the amorphous WFexOyCz films synthesized by the addition of oxygen gases at a flow rate of 17 sccm. The results verified that the proper addition of oxygen gas provides a suitable routine to enhance the electrochromic properties of plasma-polymerized WFexOyCz films.

Direct one-step synthesis of flexible electrochromic tungsten/iron mixed oxide films onto flexible PET/ITO substrates using low temperature plasma polymerization

An investigation has been undertaken into the improved lithium electrochromic performance of flexible tungsten oxide films by the addition of iron oxides via one step synthesis onto flexible 60 Ω/square polyethylene terephthalate/indium tin oxide substrates using a low temperature plasma polymerization method. The flexible organic–inorganic hybrid nanocomposite WOyCz, WFexOyCz and FeOyCz films are synthesized by injecting the precursors tungsten carbonyl [W(CO)6] and/or ferrocence [Fe(C5H5)2] into the plasma chamber. The capable fractions of the nano-grain boundaries between the nano-grains produced in the WOyCz and WFexOyCz films assure the reversible Li+ intercalation and deintercalation properties. The addition of iron oxides into tungsten oxide films at a certain Fe gas flow ratio enhances the optical modulation (ΔT) from 74.4 to 80.7 %, increases the optical density (ΔOD) from 0.71 to 0.92, and raises the color efficiency (η) from 48.8 to 56.6 cm2/C, respectively, at a wavelength of 721 nm, even after 200 cycles of reversible Li+ ion intercalation/de-intercalation in a 1 M LiClO4-propylene carbonate electrolyte.

Surface modification of SERS substrates with plasma-polymerized trimethylsilane nanocoating

Surface-enhanced Raman scattering (SERS) substrates were modified by depositing a nanometer-thick polymer coating on top of SERS-active surface. This thin hydrophobic nanocoating, achieved by low temperature plasma polymerization of trimethylsilane, was found to reduce surface energy of SERS substrate and in turn help relieve the analyte spreading on the surface of SERS substrates. Detection of melamine molecules with these surface-modified SERS substrates showed that this plasma nanocoating improved, not significantly though, SERS sensitivity in comparison with unmodified SERS substrates. It is believed that the increased hydrophobicity induced by this plasma nanocoating had two folds of beneficial effects on SERS sensitivity. First, the as-produced hydrophobic surface gave rise to preconcentration effect due to the reduced contact area between analyte molecules and the substrate surface. Second, the decreased surface energy of SERS substrates was helpful in placing analyte molecules in SERS hot spots. These two combined gains were deemed to outweigh the loss of SERS sensitivity caused by enlarged distance between metal surface and analyte molecules.

Enhanced endothelialization guided by fibronectin functionalized plasma polymerized acrylic acid film

The plasma polymerized acrylic acid (PPAA) films with high carboxyl concentration were fabricated by low temperature plasma polymerization technology. Vacuum thermal treatment was used to modify the PPAA films. The stability of the PPAA film was evidenced by scanning electron microscopy (SEM). The result of toluidine blue-O (TBO) method showed that the –COOH concentration on the surface of the PPAA films decreased from 20.73nM to17.90nM after vacuum thermal treatment. Fibronectin (Fn) was successfully covalently immobilized onto the modified surface PPAA via a covalent bond reacted with carboxyl groups. Diffuse reflectance Fourier infrared transform spectroscopy (DRFTIR) and X-ray photoelectron spectroscopy (XPS) were utilized to characterize the layer-by-layer PPAA surface modification. From the evaluation of immunostaining for actin and Cell Counting Kit-8 (CCK-8), the surface of Fn-immobilized thermal treated PPAA films could be used to enhance the adhesion and proliferation of human umbilical vein endothelial cells (HUVECs). Especially, the exposure of RGD domain existing in the immobilized Fn was ascertained by ELISA, which was one of main improvement factors of HUVEC's adhesion and proliferation. This study demonstrated a promising surface modification used for vascular devices.

Development of Blood Compatible Alpha-lipoic acid Coated Stent with a Good Adhesive by Low Temperature Plasma Polymerization

ABSTRACTNeointimal hyperplasia is a main cause for in-stent restenosis after stent-implantation and is triggered by inflammatory response to foreign materials. It can be inhibited if the stent is modified to have good blood compatibility by coating drug compounds. Low temperature plasma polymerization of 1, 2-diaminocyclohexane was performed to prepare more adhesive polymeric thin film onto the metallic stent. Then, the chemical grafting of α-lipoic acid (ALA) was carried out to improve blood compatibility of stent. Drugs containing carboxylic groups can be chemically grafted through the formation of amide bond in the presence of 1-ethyl-3-(3-dimethylaminopropyl) carbodiimide methiodide onto the DACH deposited stent surface. ALA grafted film showed good mechanical stability and blood compatibility.

Characteristics of polyimide-based composite membranes fabricated by low-temperature plasma polymerization

Composite membranes were prepared by the deposition of plasma-polymerized allylamine films onto a porous polyimide substrate. The relationship between the plasma conditions and the membrane characteristics was described in terms of monomer flow rate, plasma discharge power, plasma polymerization time, and so on. Scanning electron microscope (SEM) images indicate that the thickness of the plasma polymer layer increased and the membrane skin pore size decreased gradually with the increasing of plasma polymerization time. Fourier transform infrared (FTIR) spectra demonstrate the appearance of amine groups in the plasma deposited polymer and the contact angle measurements indicate that the hydrophilicity of the membrane surfaces increased significantly after plasma polymerization. The composite membranes can reject salt from sodium chloride feed solution, and membrane separation performance depends strongly on the plasma conditions applied during the preparation of the plasma deposited polymer films.

Microstructure and Mechanical Properties of SiC-Al<sub>2</sub>O<sub>3</sub> Nanocomposite Prepared by Surface Modified SiC Nanopowders

SiC nanopowders were surface modified by low temperature plasma polymerization. 5vol% SiC-Al2O3 nanocomposite was prepared by adding the surface modified SiC nanopowders into the matrix of Al2O3.The influence of surface modified SiC nanopowders on the properties and structure of SiCAl2O3 nanocomposite was studied. The surface modified SiC-Al2O3 nanocomposite had higher density and nicer mechanical properties than untreated SiC- Al2O3 nanocomposite because of the improvement of dispersion. The hardness and toughness of the SiC- Al2O3 nanocomposite were higher than monolithic Al2O3 but the ultimate bending strength was not perfect because of retardation of the densification and formation of unsintered pores caused by the induced oxygen during the process of powder treatment.

Preparation of CIM Feedstock of Al<sub>2</sub>O<sub>3</sub>-SiC Nanocomposite

The ceramic injection molding feedstock of Al2O3-SiC nanocomposite were prepared and studied in detail. Three ways of surface modification including surfactant pre-coating, surface emulsion polymerization and surface low temperature plasma polymerization were used to modify the surface of SiC powders in order to reduce the agglomeration, improve the dispersion and the compatibility with organic media. CIM feedstock with different SiC content and solid loading were prepared through mixing surface modified SiC powders with Al2O3 powders and organic binders. The effect of three ways of surface modification on the viscosity of CIM feedstock were studied and the way of surface emulsion polymerization developed the best action in increasing dispersion, reducing viscosity and improving the solid loading of CIM feedstock.

A study of the low temperature plasma polymerization on enhancing interface of painted cold rolled steel in salt bath

Enhanced corrosion protection of painted cold rolled steel (CRS) by low temperature plasma polymerization was investigated. It was found that the surface treatment on CRS prior to painting by plasma cleaning with hydrogen plasmas and then plasma coating by plasma polymerization with tetraethyl orthosilicate (TEOS) plasmas in room temperature (23 °C) can be used for improving the corrosion protection of painted CRS. Tape adhesion tests (ASTM 3359 Method) demonstrated this improvement, with a rating of “0” for untreated CRS for aging at 3.5% NaCl solution for 6 days and “5” for hydrogen plasma-cleaned and TEOS plasma-deposited CRS at certain plasma conditions even for aging at 3.5% NaCl solution for 10 days. The results of this study indicated the performance of corrosion protection on painted CRS was dependent on the surface characteristics of CRS, the wettability of CRS and the work of adhesion of paint to CRS. In this study, the work of adhesion of paint to CRS and the wettability of CRS were calculated from the surface free energy of paint and CRS. The surface free energy of paint and CRS were calculated by the contact angle measurement using sessile drop method, the surface characteristic such as surface morphology of CRS was monitored by atomic force microscopy (AFM) and the surface composition of CRS was characterized by using Electron Spectroscopy for Chemical Analysis (ESCA).

Electrochemical characterization of plasma polymer coatings in corrosion protection of aluminum alloys

Low-temperature plasma polymerization is a promising pretreatment technique to create environmentally friendly coating systems for corrosion protection of aluminum alloys. In this study, the pretreatment effects of plasma treatment and plasma polymerization on corrosion properties of alclad aluminum alloy 2024-T3 ([2A]) were investigated using electrochemical characterization techniques, including cyclic polarization (CP) and electrochemical impedance spectroscopy (EIS). The [2A] panels were coated with an ultrathin layer (∼50nm) of plasma polymers in a direct current (dc) glow discharge of trimethylsilane or its mixtures with one of two diatomic gases (O2 and N2). The CP measurement results showed that the plasma polymer coated [2A] panels exhibited more negative corrosion potentials (Ecorr), smaller corrosion currents (Icorr), and no surface passivation when compared with uncoated [2A] control panels. The lower values of Icorr imply a higher corrosion resistance on the plasma polymer coated [2A]. When investigated using EIS, these plasma polymer coated [2A] panels exhibited higher impedance (∣Z∣) at lower frequency when first immersed in electrolyte solution, yet degraded quickly to a similar level as uncoated controls within 1day of immersion. These results illustrated that thin plasma polymer films provided a certain but very limited corrosion resistance to [2A] substrate; their dominant role in plasma interface engineered coating systems still relied mostly on their adhesion enhancement at metal∕paint interface as observed in our previous studies.

Enhanced corrosion protection of cold rolled steel by low-temperature plasma cleaning and plasma polymerization

This study investigates the enhanced corrosion protection of cold rolled steel (CRS) by low-temperature plasma cleaning and plasma polymerization. It is found that the surface treatment on CRS, prior to painting, by a combination of plasma cleaning with argon–hydrogen plasmas and then plasma coating by plasma polymerization with tetraethyl orthosilicate (TEOS)–hydrogen plasmas at room temperature (23 °C), can be used for improving the corrosion protection of painted-CRS. The corrosion test demonstrates this improvement, with the mean corrosion creepage of painted-CRS decreasing from 2 mm for untreated CRS to 0.02 mm for CRS pretreated by a combination of Ar–H 2 plasma cleaning and TEOS–H 2 plasma polymerization at certain plasma conditions after immersion in 3.5% NaCl solution for 10 days. The corrosion protection performance of painted-CRS is highly dependent on the surface characteristics of the CRS and the work of adhesion of paint to CRS.

Surface Modification of Ultrafine Ceramic Powders by Low Temperature Plasma Polymerization

Surface Modification of Ultrafine Ceramic Powders by Low Temperature Plasma Polymerization