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Surface modification of superparamagnetic Fe3O4 nanoparticles using polymers (polyaniline/polypyrrole) was done by radio frequency (r.f.) plasma polymerization technique and characterized by XRD, TEM, TG/DTA and VSM. Surface-passivated Fe3O4 nanoparticles with polymers were having spherical/rod-shaped structures with superparamagnetic properties. Broad visible photoluminescence emission bands were observed at 445 and 580 nm for polyaniline-coated Fe3O4 and at 488 nm for polypyrrole-coated Fe3O4. These samples exhibit good fluorescence emissions with L929 cellular assay and were non-toxic. Magnetic hyperthermia response of Fe3O4 and polymer (polyaniline/polypyrrole)-coated Fe3O4 was evaluated and all the samples exhibit hyperthermia activity in the range of 42–45 °C. Specific loss power (SLP) values of polyaniline and polypyrrole-coated Fe3O4 nanoparticles (5 and 10 mg/ml) exhibit a controlled heat generation with an increase in the magnetic field.

In order to improve bacterial antifouling property, titanium (Ti) surfaces were functionalized through the plasma polymerization (PP) technique with diethyl allyl phosphate (DAP) as amphoteric precursor. Antifouling properties of the surfaces were evaluated in vitro by Escherichia coli (ATCC® 25922™) and Staphylococcus aureus (ATCC® 25923™) strain, and results showed that 75.00% and 81.25% bacterial reduction achieved on functionalized surfaces, respectively. In vitro cell culture studies were carried out with BJ normal human skin fibroblast (ATCC® CRL-2522™) cell line. These findings revealed that amphoteric plasma polymer prepared from DAP offers promising solution for preventing Biofilm formation on Ti.

In this manuscript has investigated the synthesis of plasma-polymerized pyrrole (C4H5N) nano-particles prepared by the proposed atmospheric pressure nonequilibrium plasma jet through the parametric studies, particularly gas flow rate (0.5, 1 and 1.5 L/min). The plasma jet which used operates with alternating voltage 7.5kv and frequency 28kHz. The plasma-flow characteristics were investigated based on optical emission spectroscopy (OES). UV-Vis spectroscopy was used to characterize the oxidization state for polypyrrole. The major absorption appears around 464.1, 449.7 and 435.3 nm at the three flow rate of argon gas. The chemical composition and structural properties of the contained samples which synthesized at 0.5 L/min as a argon flow rate were analyzed by scanning electron microscopy (SEM), Fourier transformation infrared spectroscopy (FTIR), Raman spectroscopy and X-ray diffraction (XRD). SEM point to a uniform distribution of polypyrrole (PPY) nanoparticles matrix. XRD technique showed a semicrystalline pattern for PPY)thin film. It is expected, that the high-quality plasma polymer grown by atmospheric pressure plasma jet method contributes to serving as conducting materials.

Increase in hydrophilicity of the filtration membrane could attribute to the fouling reduction and overall filtration performance. In this study, we employ a surface modification on polyamide (PA) membrane by using plasma polymerization with acrylic acid as the precursor by varying the deposition time from 1 to 10 min to induce hydrophilic surface of the membrane without changing the bulk properties of PA membrane. Cross-flow filtration of humic acid using the modified PA membrane was conducted to measure permeates flux and rejection. We calculate the fouling tendencies of each membrane and the result indicates the best performance from sample with 7 min deposition time in terms of permeate flux, rejection and the lowest fouling tendencies. Therefore, this proposed technique could be useful to further improve the commercial filtration membrane; without changing the membrane fabrication process.

This work investigates the antifungal effect of plasma polymer films produced by low-pressure RF-generated plasma system using acrylic acid, 2-hydroxyethyl methacrylate, and diethyl phosphite (DEP). Unmodified and plasma-modified polystyrene (PS) microplate wells were tested by 30 biofilm-positive Candida spp. isolated from blood samples and two control strains using a quantitative plaque assay method. Regardless of the precursors and plasma parameters, biofilm formation was inhibited for all plasma-modified microplate wells. The most significant anti-biofilm effect was observed on PS modified by DEP at 90 W plasma power with the inhibition of all Candida species' biofilm formation.

The effect of Atmospheric Pressure Plasma-Enhanced Chemical Vapor Deposition (AP-PECVD) on Ethylene Propylene Diene Terpolymer (EPDM) with the precursors hexamethyldisiloxane (HMDSO) and tetraethyl orthosilicate (TEOS) on roughness, chemical composition as well as wetting and friction properties has been investigated. For the first time, topography analysis like Scanning Electron Microscopy (SEM), White Light Interferometry (WLI), Digital Microscopy as well as surface analytical methods by using X-ray Photoelectron Spectroscopy (XPS) and Time-of-Flight Secondary Ion Mass Spectrometry (ToF-SIMS) were combined with contact angle and friction experiments to obtain a detailed analysis of plasma polymer surfaces. This work shows that different plasma coatings can be utilized to tailor wettability, surface energies and reduce friction of EPDM rubber, which are important for various applications. Wettability investigations have shown that both coatings are more polar compared to the untreated surface but less polar than the surface activated EPDM without precursor. The carbon content is decreased, and the content of oxygen and silicon is increased after plasma polymerization as shown by XPS investigations. ToF-SIMS investigations have revealed that the ion spectra of both coatings are very similar with a comparable surface chemistry. A lower penetration depth is considered for the contact angle measurements in contrast to the other surface-sensitive methods. The surface energy of the activated EPDM surface without precursor increases significantly compared to the untreated EPDM due to the incorporation of polar groups in the elastomer surface. Both coatings with the corresponding precursors also have a higher surface energy compared to the uncoated EPDM, whereas the TEOS coating reveals a higher surface energy than the HMDSO coating. However, both coatings have lower surface energies than the activated EPDM. The coefficient of friction and the stick-slip phenomenon can be significantly reduced using plasma polymer coatings based on organosilicon precursors sliding on glass substrates. The lowest friction values with absence of stick-slip on EPDM were achieved by using the precursor TEOS as friction partner.

Integration of two or more biomolecules with synergetic and complementary effects on a material surface can help to obtain multi-functions for various biomedical applications. However, the amounts of biomolecules integrated and their physiological functions are compromised due to the limited surface anchoring sites. Herein, we propose a novel concept of film engineering strategy “from surface to bulk synergetic modification”. This new concept is realized by employing the surface amine groups of plasma polymerized allylamine (PPAm) film for grafting a molecule e.g., thrombin inhibitor, bivalirudin (BVLD), meanwhile its bulk amine groups is used as a universal depot for storing and releasing therapeutic nitric oxide (NO) gas as supplement to the functions of BVLD. It is demonstrated that such a “from surface to bulk synergetic modification” film engineering can impart the modified-substrates with anti-platelet and anti-coagulant dual functions, giving rise to a highly endothelium-mimetic thromboresistant property. We believe that our research provides a very promising strategy to deliver multifunctional surface versatilely that require NO release in combination with other properties, which will find broad biomedical applications in blood-contacting devices, and et al. Moreover, it also provides a brand-new film engineering strategy for tailoring surface multi-functionalities of a wide range of materials., Graphical abstract Image 1, Highlights • A concept of “from surface to bulk synergetic modification” is proposed for tailoring surface multi-functionalities. • The surface amine groups of plasma polymerized allylamine (PPAm) film were used for grafting bivalirudin. • The bulk amine groups of PPAm film is utilized as the universal depots for storing and releasing nitric oxide.

The experimental data of the thermal conductivity of high density polyethylene composites filled with as-received and modified graphite particles by ethylene plasma polymerization were compared with the theoretical values obtained after applying the following micromechanical analytical models: the series model, the Maxwell model, as well as the Nielsen and the Agari models. The experimental thermal conductivity of the composites was determined by Modulated Differential Scanning Calorimetry. The theoretical results of each model adjusted to a greater or lesser extent to the experimentally obtained data. However, the Agari’s model was the one that most closely approximates the experimental values while the series model is the one with the least precision.

Hydrophobic and oleophilic Si-based cotton fabrics have recently gained a lot of attention in oil/water separation due to their high efficiency. In this study, we present the effect of O2 plasma pre-treatment on the final properties of two Si-based cotton membranes obtained from dip coating and plasma polymerization, using polydimethylsiloxane (PDMS) as starting polymeric precursor. The structural characterizations indicate the presence of Si bond on both the modified cotton surfaces, with an increase of the carbon bond, assuring the success in surface modification. On the other hand, employing O2 plasma strongly changes the cotton morphology, inducing specific roughness and affecting the hydrophobicity durability and separation efficiency. In particular, the wettability has been retained after 20 laundry tests at 40 °C and 80 °C, and, for separation efficiency, even after 30 cycles, an improvement in the range of 10–15%, both at room temperature and at 90 °C can be observed. These results clearly demonstrate that O2 plasma pre-treatment, an eco-friendly, non-toxic, solvent-free, and one-step method for inducing specific functionalities on surfaces, is very effective in enhancing the oil/water separation properties for Si-based cotton membranes, especially in combination with plasma polymerization procedure for Si-based deposition.

Recently, new plasma polymerization-based techniques emerged to deposit chemically functional coatings for various applications. However, little is known on the aging of these layers. Therefore, this study aims to investigate the physicochemical properties of aerosol-assisted atmospheric pressure plasma deposited (3-aminopropyl)triethoxysilane-based (AAPD-APTES) coatings and compare their aging behavior to APTES-modified plasma polymerized hexamethyldisiloxane-based coatings (ppHMDSO-APTES). X-ray photoelectron spectroscopy (XPS), attenuated total reflection-Fourier transform infrared spectroscopy (ATR-FTIR), water contact angle (WCA) and atomic force microscopy (AFM) measurements indicated that the applied power had an insignificant impact on the wettability, chemistry and morphology of the AAPD-APTES films. A complex nitrogen-containing organosilicon layer was obtained with significant preservation of the Si-O-C-bonds. For the ppHMDSO-APTES coatings, XPS indicated that these layers had a significantly higher amount of preserved primary amines and a different surface morphology. Oxidation and hydrolysis of Si-O-C-bonds were the most prevalent aging processes for the AAPD-APTES coatings, while protonation of primary amines was most important for the ppHMDSOAPTES films. This study indicates that further research is needed to examine the differences in coating chemistry and aging of other AAPD-based and conventional plasma polymers. Additionally, it provides a reference to decide which coating type and associated aging processes are preferred for certain applications.

Surface roughness plays an important role in regulating protein adsorption to biomaterial surfaces and modulating the subsequent inflammatory response. In this study, we examined the role of surface nanotopography on albumin adsorption, unfolding and subsequent immune responses. To achieve the objectives of the study, we create model surfaces of hill-like nanoprotrusions by covalently immobilizing gold nanoparticles (AuNPs) of predetermined sizes (16, 38, and 68 nm) on a functional plasma polymer layer. The amount of adsorbed albumin increased with the increase in surface area caused by greater surface nanotopography scales. Circular dichroism spectroscopy was used to evaluate albumin conformational changes and pointed to loss of α-helical structure on all model surfaces with the greatest conformational changes found on the smooth surface and the surface with largest nanotopography features. Studies with differentiated THP-1 cells (dTHP-1) demonstrated that immune cells interacted with surface adsorbed albumin via their scavenger receptors, which could bind to exposed peptide sequences caused by surface induced unfolding of the albumin. Pre-adsorption of albumin resulted in an overall decrease in the level of expression of pro-inflammatory cytokines from dTHP-1 cells. On the other hand, pre-adsorption of albumin led in an increase in the production of anti-inflammatory markers, which suggests a switch to the M2 pro-healing phenotype. The knowledge obtained from this study could instruct the design of healthcare materials where the generation of targeted surface nanotopography and pre-adsorption of albumin may enhance the biomaterial biocompatibility and lead to faster wound healing. Refereed/Peer-reviewed

Biofilm formation on food-contact surfaces is a matter of major concern causing food safety and spoilage issues to this sector. The aim of this study was to assess the durability of the anti-biofilm capacity of a plasma-polymerized coating composed of a base coating of (3-aminopropyl)triethoxysilane (APTES) and a functional coating of acrylic acid (AcAc). Coated and uncoated AISI 316 stainless steel (SS) plates were subjected to five sanitization cycles with sodium hypochlorite (0.05%) and peracetic acid (0.5%). The effectiveness of the coating for the inhibition of multi-strain Listeria monocytogenes biofilm formation was confirmed using a three-strain cocktail, which was grown on the SS plates at 12 °C for 6 days. Compared to the uncoated SS, relative biofilm productions of 14.6% on the non-sanitized coating, 27.9% on the coating after sanitization with sodium hypochlorite, and 82.3% on the coating after sanitization with peracetic acid were obtained. Morphological and physicochemical characterization of the coatings suggested that the greater anti-biofilm effectiveness after sanitization with sodium hypochlorite was due to the high pH of this solution, which caused a deprotonation of the carboxylic acid groups of the functional coating. This fact conferred it a strong hydrophilicity and negatively charged its surface, which was favorable for preventing bacterial attachment and biofilm formation.

This work demonstrates the efficacy in performing an electrochemical pretreatment on carbon fibres to improve the effect of plasma polymerization of acrylic acid on these surfaces. Modified samples demonstrated improve physical properties including tensile strength and Young’s modulus, as well as an increase in composite performance as measured by the interfacial shear strength. The electrochemical pretreatment was shown to enhance the advantages observed when coating fibres using plasma polymerization.

Basalt fibres are becoming a promising alternative to synthetic fibres as a green reinforcement phase in polymeric matrix composites, showing excellent mechanical, chemical and thermal properties. In this work we synthetized tetravinylsilane (TVS) or a mixture formed by tetravinylsilane and different percentages of oxygen on the surface of unsized basalt fibres through the Plasma-Enhanced Chemical Vapor Deposition (PECVD) technique for improving the fibre/matrix adhesion. Single fibre tensile test proved the effectiveness of the process, without any degradation of the mechanical properties of modified basalt fibres. Finally, through pull out tests, the interfacial properties of basalt fibres were studied, measuring increases up to 80% of the IFSS for modified fibres compared to neat fibres. This result is the consequence of a greater chemical compatibility between the fibres and the matrix, thanks to the presence of a higher number of Si-O-C groups, and of a mechanical interlocking effect promoted by the increased surface roughness of the plasma-modified fibres.

The morphological and chemical properties of polyaniline (PANI) nanocomposite films after adding small amounts of auxiliary gases such as argon, nitrogen, and oxygen during atmospheric pressure (AP) plasma polymerization are investigated in detail. A separate gas-supply line for applying an auxiliary gas is added to the AP plasma polymerization system to avoid plasma instability due to the addition of auxiliary gas during polymerization. A small amount of neutral gas species in the plasma medium can reduce the reactivity of monomers hyperactivated by high plasma energy and prevent excessive crosslinking, thereby obtaining a uniform and regular PANI nanocomposite film. The addition of small amounts of argon or nitrogen during polymerization significantly improves the uniformity and regularity of PANI nanocomposite films, whereas the addition of oxygen weakens them. In particular, the PANI film synthesized by adding a small amount of nitrogen has the best initial electrical resistance and resistance changing behavior with time after the ex situ iodine (I2)-doping process compared with other auxiliary gases. In addition, it is experimentally demonstrated that the electrical conductivity of the ex situ I2-doped PANI film can be preserved for a long time by isolating it from the atmosphere.

Macrophage differentiation into M1 (inflammatory) and M2 (healing) phenotypes plays a vital role in determining the fate of biomaterials. The biophysical properties of the extracellular matrix are known to affect macrophage behavior. Mimicking these special biophysical properties of the extracellular matrix has led to increasing interest in biomaterial constructs with tailor-engineered surface nanotopographical and chemical properties. However, a significant gap of knowledge exists in the role played by the combinational effect of surface nanotopography and chemistry. To address this gap, we have fabricated nanoporous surfaces of controlled pore size (30, 65, and 200 nm) and lateral spacing with uniform outermost surface chemistry tailored with amines (NH2), carboxyl (COOH−) and hydrocarbon (CH3−) functionalities. We show that the combinatory effects of surface properties can direct the differentiation of macrophages to the pro-healing M2 phenotype. This is most evident on the surface featuring nanopores of 200 nm and −COOH functionality. Overall, the concentration of pro-inflammatory cytokines significantly decreases, while the concentration of anti-inflammatory cytokines increases many folds on nanotopographically, and chemically, modified surfaces compared to their planar counterparts. Our data provide pioneering knowledge that could provide pathways to tuning inflammatory and foreign body responses and instruct the design of tailor-engineered biomaterial implants to enable better clinical outcomes. usc Refereed/Peer-reviewed

Lack of suitable surface properties in biomaterials is an acute challenge for their utilization in nucleic acid delivery, since surface plays a vital role in cell adhesion/uptake and immunity. Low pressure cold plasma is a promising technology for functionalization and surface modification of materials, in an effective, environment friendly and economical way. In this investigation we have modified the surface of silver nanoparticles (AgNPs) with chitosan biopolymer, using plasma treatment, to extend their application scope in intracellular DNA delivery. The plasma functionalized; chitosan modified AgNPs (MetaloPolymeric Nanocarriers; MPNCs) possessed superior biocompatibility compared to unmodified AgNPs. Carboxylic groups were incorporated on the surface of nanosilver using 3600 rotating pulsed plasma reactor and acrylic acid vapors were used as precursor gas. Pulsed plasma polymerization process was optimized with respect to working pressure of the system, duty cycle for pulsing, time of treatment and flow rate. Biocompatibility of the plasma functionalized nanosilver was enhanced by coupling it with Chitosan Oligosaccharide (COS), using EDC (1-Ethyl-3-(3-dimethylaminopropyl) carbodiimide) to form amide linkages. The resulting MPNCs showed high cell viability and bio-stability, which was attributed to plasma processing of nanosilver and its association with COS. In vitro cellular studies illustrated significant uptake of nanoplexes. The study suggested the potential of plasma functionalization for manipulating surfaces of metallic nanoparticles to enhance their application in intracellular gene delivery.

The assembly of nano- and micro-scale building blocks on surface has been the focus of intense interest in materials science for years. In this work, (3-aminopropyl)triethoxysilane (APTES) carrying one primary amino group was deposited on various substrate surfaces using the plasma polymerization method. The key plasma parameters i.e. pressure and power were varied to obtained the highest density of primary amino groups. The influence of such parameters on the characteristics of deposited layers (e.g. chemical structure, adhesion strength, growth rate, etc.) was systemically investigated using various characterization methods such as XPS, FTIR, ellipsometry and so on. Meanwhile, three types of particles (AuNPs, zeolites and gold@zeolites) with sizes from nano- to submicro-range were synthesized and further used as model building blocks. Subsequently, the prepared particles were deposited onto cyclic olefin copolymer (COC) substrate surfaces, which were pre-functionalized by deposition of the plasma polymer layer using the parameters of pressure = 1.0 mbar and power = 30 W. The results confirmed the formation of membrane structures consisting of highly packed particles on the COC surface, and such immobilized structures showed high stability against flowing water, evidencing the good immobilization ability of deposited APTES layers with amino groups.

The plasma polymerization of amide-based precursors is a nearly unexplored research area, which is in contrast with the abundance of reports focusing on amide-based surface modification using wet c...

Deposition chemistry from plasma is highly dependent on both the chemistry of the ions arriving at surfaces and the ion energy. Typically, when measuring the energy distribution of ions arriving at surfaces from plasma, it is assumed that the distributions are the same for all ionic species. Using ethyl acetate as a representative organic precursor molecule, we have measured the ion chemistry and ion energy as a function of pressure and power. We show that at low pressure (

Titanium implants have been widely used for orthopedic and trauma surgery, while they often encounter the predicament of implant-associated infection, which leads to surgery failure. To address thi...

The plasma polymerization processes during hybrid PVD-PECVD deposition, structure, hydrogenation, hybridization, hardness and coefficients of friction in W-C:H coatings prepared by direct current magnetron sputtering (DCMS), High Power Impulse Magnetron Sputtering (HiPIMS) and High Target Utilization Sputtering (HiTUS) were reviewed as a function of acetylene (0–12 sccm C2H2) and hydrogen (0–20 sccm H2) additions into Ar atmosphere. The addition of acetylene resulted in the increase of carbon and hydrogen contents in the matrix via incorporation of CxHy fragments with the C2H, 2C and CH radicals being the “primary” source for growth. The level of hydrogenation in the carbon matrix was found to be related to the level of sp3 hybridization and cross-linking as well. Hardness and coefficient of friction of the studied W-C:H coatings were found to be affected not only by hydrogenation and hybridization, but also by the sputtering technique. HiPIMS provided the best combination of hybridization, hydrogenation and cross-linking in the carbon structure resulting in W-C:H coatings with reasonably high (~20 GPa) hardness and simultaneously sufficiently low (≤0.1) coefficients of friction. Thus, HiPIMS applied to hybrid PVD-PECVD W-C:H coatings expands the range of their mechanical and tribological properties compared to DCMS and HiTUS.

This study aims at deposition and characterization of antibacterial, hydrophobic and semitransparent metal/plasma polymer nanocomposite coating, containing Ag nanoparticles, onto cotton fabrics intended to be used in medical applications. The nano composite coatings were obtained via a simple, one step and ecofriendly plasma based co-deposition approach where silver was magnetron sputtered simultaneously with plasma polymerization of hexamethyldisiloxane (HMDSO) monomer. The nanocomposite thin films containing different concentration of silver were deposited either by varying silver sputter rate or thickness of the plasma polymer matrix to obtain a good balance between optical properties of the coated fabric and its long term antibacterial performance. The obtained coatings were investigated in detail with respect to their composition, morphology, optical properties, nanoparticle size distribution, silver ion release efficiency, antibacterial performance, water contact angle and washing stability of the coating. The thickness of the plasma matrix was found to be more important in controlling the release of silver ions as well as affecting the optical properties of the coating. The water contact angle on the coated fabric was up to 145°, close to super hydrophobicity. The coating showed effective antibacterial efficacy against Staphylococcus epidermidis (a Gram positive bacterium) which was present even when fabric was subjected to 10 repeated washing cycles indicating good washing stability of the coating.

We report here the dry, one-step, and low-temperature modification of FTO surfaces using pulsed plasma polymerization of allylamine (PPAAm). PPAAm/FTO surfaces were characterized by X-ray photoelectron spectroscopy, spectroscopic ellipsometry, and contact angles to understand the morphological, structural, and optical properties. FTO were coated with a very thin layer of adherent cross-linked, pinhole-, and additive-free allylamine plasma polymer resistant to hydrolysis and delamination, and characterized by a high density of positively charged amino groups. Electrochemical studies revealed that PPAAm/FTO electrodes show wide range pH stability and reaction rates tuned by the duration of plasma treatment. We show how the modification of plasma treatment duration between 72 s and 288 s affects the chemical structure and thickness of the obtained modification, having a strong influence on the charge transfer kinetics. In particular, XPS revealed the occurrence of the reduction processes under long-term plasma exposure proving the need for monitoring of this key factor. This covalent immobilization of amine compounds on FTO surface using rapid process in microwave pulsed-plasma makes it a promising electrode for future applications in electrochemical biosensors and optoelectronic devices.

Plasma polymerization experiments are typically conducted by sustaining a non-thermal plasma in a gas flow containing monomer molecules. Recently, it was however observed that plasma polymerization can also occur in a nitrogen/2% ethanol vapor dielectric barrier discharge operated at medium pressure (5.0 kPa). To obtain a better understanding of this peculiar plasma polymerization behavior, a detailed parameter study is conducted in this work. The influence of plasma exposure time at fixed discharge power on the coating properties is investigated as well as the influence of discharge power applying a fixed energy density. Results reveal that at a discharge power ≥ 3.0 W, very hydrophilic (WCA values

Hydroxy (-OH) and primary amino groups (-NH2) are important as anchoring points at polymer surfaces for covalent coupling of molecules used in bio-medicine or components in polymer composites. O2 and NH3 plasmas or the coating of polyolefin surfaces with thin films of plasma polymers from allyl alcohol and allylamine are most often used for generation of OH and NH2 groups. The analysis of polyolefin surfaces exposed to oxygen and noble gas plasma treatments has shown very similar spectra of O-functional groups when the plasma treated samples were post-plasma exposed to air. Therefore, it was not surprising that the variety of O-functional groups formed by the two types of plasmas corresponds well to that of chemical auto-oxidation. This oxidation proceeds via formation of radicals, attachment of molecular oxygen, generation of peroxy radicals, and decomposition of hydroperoxide groups to many types of O-functional groups, among them only a few OH groups are formed. Coating of polyolefins with allyl alcohol plasma polymer leads to a surface with higher concentration of OH groups. It is assumed that many OH groups of the monomer survive the plasma polymerization process and additional OH groups are formed by post-plasma auto-oxidation on exposure to air. Ammonia plasma treatment produces also a low yield in desired NH2 groups at a polyolefin surface, due to unfavorable thermodynamics. Moreover, several side reactions are observed, such as hydrogenation at the topmost surface as well as in subjacent layers, dehydrogenation by UV irradiation, polyene formation, crosslinking and post-plasma extensive auto-oxidation on exposure to air in deeper layers. Allylamine plasma polymerization is characterized by a strong loss in NH2 groups of allylamine and extensive side-reactions, such as dehydrogenation to imine and nitrile groups (-CH2-NH2→CH=NH→C≡N). The auto-oxidation of plasma polymer introduces many O-functional groups. Yield, selectivity, advantages, limitations and drawbacks of the above-mentioned processes for polyolefin surface modification with OH or NH2 groups are discussed in some detail with respect to the mechanism, kinetics and thermodynamics of reactions. In conclusion, introduction of functional groups into the polymer surface is always a compromise between attachment of different types of functional groups and simultaneous degradation and decomposition of the surface region of polymer substrates with weakening of its mechanical strength.

International audience; The affinity and repartition of silver nanoparticles in different plasma polymer matrices are studied according to the polymer functional groups. The polymer layers are synthesized by plasma polymerization of allyl alcohol (AAl), aniline (ANI), or heptadecafluoro-1-decene (HDFD). The matrix is then impregnated in a metallic salt solution and a reducing one. When plasma polymerized (pp) ANI is used as matrix, a higher amount of silver nanoparticles (AgNPs) is introduced compared to the other two polymer matrices. Otherwise, with pp-AAl, smaller AgNPs with narrower size distribution are inserted. Finally, different plasma polymer/AgNPs interaction mechanisms are proposed according to the polymer functional groups. Moreover, the sensing behavior of pp-ANI, well-known as sensitive layer towards ammonia, is markedly enhanced by the presence of AgNPs.

In this study, hexamethyldisiloxane was polymerized on the biaxially oriented polypropylene films by low-pressure radio frequency (RF) plasma. The samples were polymerized by using RF plasma in the frequency range of 13.56 MHz at the different polymerization times. The surface properties and chemical structure of samples were examined by contact angle measurement, atomic force microscopy, scanning electron microscopy and Fourier transformation infrared (FTIR). Also, the scratch behavior and the mechanical properties of samples were evaluated by using SPM lithography. In this work, some distinguishing changes were observed in properties of polymerized samples in comparison with raw sample. Results showed that the scratch resistance increased by prolonging polymerization time, whereas the surface energy decreased dramatically. It can be inferred from SPM and FTIR data that there is a direct relationship between scratch resistance and chemical composition of samples. Scratch resistance is mostly affected by silicon compounds deposited on the samples. Plasma polymerization causes changes in the chemical structure and surface properties of samples.

In the present study, low-temperature plasma combined with allylamine polymerization approach was used to coat amino-groups on oxide layer of plasma-oxidized biomedical titanium (Ti) for protein immobilization. Scanning electron microscopy, X-ray diffractometer, transmission electron microscopy, X-ray photoemission spectroscopy, secondary ion mass spectrometer and 2, 4, 6-trinitrobenzenesulfonic acid assay were utilized to investigate the surface and microstructural properties of the plasma-oxidized, plasma-polymerized and protein-immobilized samples. Analytical results indicated that the presence of a nanostructured rutile-TiO2 thin layer could be found on the plasma-oxidized samples. The thickness of nanostructured rutile-TiO2 layer increased with increasing plasma treatment power and period. As the plasma-oxidized samples underwent plasma polymerization with allylamine, amino-groups (NH2) were uniformly coated on nanostructured rutile-TiO2 layer. It was also found that Ti surface with thick oxide layer exhibited higher amounts of amino-groups deposition. After protein immobilization, the plasma-polymerized samples presented a formation of uniform streak-like immobilized protein clusters. Therefore, biomedical Ti with nanostructured rutile-TiO2 layer is a promising biomaterial that can be applied to cross-link with other biomolecules for promoting the bone healing and regeneration.

This work explores the synthesis and properties alteration of new composite membrane system based on polyvinyl chloride (PVC) grafting with polyacrylic acid (PAA) using argon (Ar) plasma. The membranes of PVC were synthesized by solution-casting method, where PAA was deposited onto PVC using dielectric barrier discharge (DBD) at atmospheric pressure with different carrier gases such as (O2, Ar, N2, air) to get the optimum condition for grafting process of acrylic acid. Physicochemical properties were investigated as function of varied carrier gas for grafting process of PAA. ATR-FTIR has provided information on details of chemical structure of membrane, while morphological changes are characterized by scanning electron microscope (SEM). Moreover, mechanical properties of the membranes were studied using tensile strength (TS). Surprising, the wettability behavior of modified PVC membrane with AA vapor (plasma polymerization) is closed to such membranes those treated with O2 plasma-AA liquid. An ultra-thin, pin hole free films of PAA were deposited onto PVC membranes leading to the increase of the wettability feature of the membranes. Meanwhile, ion exchange capacity (IEC) of such membranes was investigated by volumetric method and it is directly dependent on the electrochemical properties of membranes. The IEC values in case of grafting with PAA in vapor phase are promising and maybe related to the special structure of plasma deposited polymers. The grows in the electronegativity of the grafted and sulfonated membranes is an indication to the proton permeability. Therefore, such membranes may be used as polyelectrolyte membranes (PEM) in direct methanol fuel cell (DMFC).

In this study, polycaprolactone (PCL) nanofibrous mats (O: 144.2 ± 3.4 nm) were fabricated by electrospinning and subsequently exposed to a low-pressure plasma polymerization treatment using 1-propanethiol as monomer. Surface characterization was performed utilizing several techniques: X-ray photoelectron spectroscopy (XPS) for surface chemical analysis, water contact angle (WCA) measurements for wettability examination, scanning electron microscopy (SEM) for morphological characterization as well as atomic force microscopy (AFM) for visualization of the topography of individual nanofibers before and after the plasma polymerization process. Moreover, the biocompatibility of the untreated and plasma-modified nanofibers was also evaluated by seeding bone marrow stem cells (BMSTs) on the samples and examining cell adhesion and proliferation using live/dead fluorescence imaging and MTT assays. The obtained results revealed that plasma exposure time significantly affected the morphology as well as the surface chemical composition of the electrospun mats, while surface wettability was largely maintained. A short exposure time of 5 s was found to maintain the advantageous nanofibrous morphology as only a very thin coating layer was deposited (range of a few nms), while longer exposure times resulted in a gradual loss of the nanofibrous structure due to the inhomogeneous deposition of thicker coatings. Moreover, also the sulphur amount was found to gradually increase with increasing exposure time resulting from the gradual growth of the deposited thiol-rich coating on the nanofibers with a maximum of 14% of sulphur, correlating with a 6.7% SH concentration after a plasma polymerization step of 1 min. As the nanofibrous structure is highly advantageous for cell growth, a 5 s plasma exposure time was selected for the cell studies, which proved that the deposition of a very thin thiol-rich coatings was able to positively affect BMSTs adhesion and proliferation. These enhanced cellular responses can be attributed to the presence of thiol groups on the nanofibers which are known to significantly increase the adhesion of culture medium proteins. It can thus be concluded that the incorporation of thiol functionalities via plasma polymerization can positively affect the cellular response of nanofibrous meshes and thus have large potential in tissue engineering applications.

Plasma-enhanced chemical vapor deposition (PECVD) is a cost-effective and green process of plasma polymer synthesis that can be used as a gentle but powerful tool for the surface modification of fibers and retains their bulk properties. This paper introduces the notion of a compact and modular device consisting of low-pressure reactor segments that have a specialized function and are adapted for the continuous modification of fiber surface. A roll-to-roll device, designed on an industrial scale, with a PECVD reactor was used for continuous plasma pretreatment and plasma polymerization coating on 1600 glass fibers in a bundle, with the fibers used as reinforcements in a glass fiber/polyester composite. Optimization of the plasma-processing conditions allowed for the improvement of interfacial adhesion between the glass fibers and polymer matrix, resulting in an increase in the shear strength of the polymer composite by 14%, compared to industrially sized fibers coated by wet chemical processes.