Surface Of Polypropylene Fibers Research Articles

Strengthening the fiber-cement matrix interface by introducing functional groups on fiber surface

Polypropylene (PP) fiber is widely used for reinforcing cement matrix to improve its cracking resistance, but the poor interaction between two materials caused localized cracks along the fiber thus adverse effect on the fiber reinforced composites. Thus, novel methods for strengthening the fiber-cement matrix interface were proposed in this study. Amidoxime and amine functional groups were successfully grafted onto PP fiber surface through a two-step chelating procedure. XPS, FTIR, iGC-SEA and TG were employed to characterize the modified fibers, and the results verified that the surface treatment significantly improved the surface roughness, specific surface area, hydrophily and thermostability of PP fiber. Moreover, single fiber pullout, uniaxial tensile and three-point bending were conducted to assess the efficiency of surface treatment in enhancing the bonding between fiber and cement matrix, as well as the tensile and flexural strength of composites incorporating PP fibers. The bonding strength was increased by 84.15%–90.08 % and the flexural strength at 28 days was increased by 23.7%–26.4 %. The change in PP fiber surface led to densified fiber-cement matrix ITZ, enhanced chemical bonding and mechanical interlocking thus stronger interaction between fiber and cement matrix. Overall, the proposed surface treatment method is of great potential to be used in producing high performance concrete due to its easy of application and high efficiency.

Polypropylene fabric of durable hydrophilic character using plasma-mediated surface coating with keratin

Polymeric hydrocarbons without functional groups, like polypropylene (PP), are hydrophobic in nature and have limited applications in textile and clothing fields. Due to its poor adhesive nature and high chemical barrier, PP is one of the most difficult polymeric materials to treat. In this investigation, an easy-to-apply eco-friendly method was adopted to impart certain desired properties and functions to PP fabric to make it suitable for clothing applications. PP surface was activated using N2-plasma discharge to create nitrogen-containing functional groups, making PP fabrics susceptible to bonding with keratin and anionic dyes. An eco-friendly biopolymer, namely, keratin, was applied to the plasma-pretreated PP fabrics using the pad-dry-cure or exhaustion method. Results of this investigation revealed that plasma/biopolymers-finished PP fabrics exhibited desirable properties, such as induced wettability and dyeability toward anionic dyes, as well as improved ultraviolet protection and enhanced resistance to the accumulation of electrostatic charge. The Fourier transform infrared spectroscopic analysis of the treated fabrics assured the creation of amino groups (primary, secondary, or tertiary) within the plasma-treated samples and the successful anchoring of carboxylic groups, occurring with the side-chains of glutamic and aspartic acid residues along keratin macromolecules, onto the newly created amino groups on the surface of PP fibers. The scanning electronic micrographs of the keratin-treated samples confirmed the coating of the PP fibers’ surface with keratin. No severe loss in the fabric’s strength was recorded in the treated samples.

Rapid Assessment of Biological Activity of Ag-Based Antiviral Coatings for the Treatment of Textile Fabrics Used in Protective Equipment Against Coronavirus.

Severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) and its variants have rapidly spread worldwide, causing coronavirus disease (COVID-19) with numerous infected cases and millions of deaths. Therefore, developing approaches to fight against COVID-19 is currently the most priority goal of the scientific community. As a sustainable solution to stop the spread of the virus, a green dip-coating method is utilized in the current work to prepare antiviral Ag-based coatings to treat cotton and synthetic fabrics, which are the base materials used in personal protective equipment such as gloves and gowns. Characterization results indicate the successful deposition of silver (Ag) and stabilizers on the cotton and polypropylene fiber surface, forming Ag coatings. The deposition of Ag and stabilizers on cotton and etched polypropylene (EPP) fabrics is dissimilar due to fiber surface behavior. The obtained results of biological tests reveal the excellent antibacterial property of treated fabrics with large zones of bacterial inhibition. Importantly, these treated fabrics exhibit an exceptional antiviral activity toward human coronavirus OC43 (hCoV-OC43), whose infection could be eliminated up to 99.8% when it was brought in contact with these fabrics after only a few tens of minutes. Moreover, the biological activity of treated fabrics is well maintained after a long period of up to 40 days of post-treatment.

Experimental Study on the Mechanical Properties, Water Absorption, and Fiber Degradation of Naturally Aged Glass Fiber and Polypropylene Fiber-Reinforced Concrete.

The main objective of this study is to better understand the performance changes of naturally aged glass fiber-reinforced concrete (GFRC) and polypropylene fiber-reinforced concrete (PPFRC), especially the degradation of fibers, which is of great significance for evaluating the durability of structures using these two types of composite materials. The mechanical properties, water absorption, and microstructures of GFRC and PPFRC at a curing age of three years, including their compressive strength, full curves of water absorption, fiber-matrix interaction, and fiber degradation, were systematically studied, and the related properties were compared with those at the curing age of 28 days. The degradation of fibers after freeze-thaw cycles was also studied. The results revealed the following. The water/binder ratio (w/b) affects the rate of increase of the long-term compressive strength of naturally aged concrete. In general, the water absorption of fiber-reinforced concrete (FRC) at the curing age of three years was found to be significantly reduced, but with the increases of w/b and the fiber content to the maximum values, the water absorption of the specimens cured for three years was higher than that of the specimens cured for 28 days. Moreover, with the increase of the curing age, the optimal glass fiber (GF) contents for reducing the water absorption decreased from 1.35% to 0.90% (w/b = 0.30), and from 0.90% to 0.45% (w/b = 0.35), respectively. The GF surface was degraded into continuous pits with diameters of about 200 to 600 nm, and the surface of the pits was attached with spherical granular C-S-H gel products with diameters of about 30 to 44 nm. The freeze-thaw cycles were found to have no significant effect on the pits on the GF surface and the granular C-S-H gel products attached to the pits, but caused a portion of the cement matrix covering the GF to fall off. The interfacial bonding between the polypropylene fiber (PPF) and the cement matrix exhibited almost no change in the PPFRC after three years of curing as compared with that after 28 days of curing. Furthermore, the cement hydration gel on the PPF surface was not significantly damaged by 150 freeze-thaw cycles.

The mechanical strength of sulphoaluminate cement-gypsum composite material reinforced with polypropylene fibers synergistically modified by KH570 and nano-SiO2

ABSTRACT The polypropylene (PP) fibers were modified by silane coupling agent (KH570) or synergistically modified by KH570 and nano-SiO2 in this paper. The modification effect of PP fibers was evaluated by SEM and FTIR. The reinforcing effect of PP fibers and the modified PP fibers on sulphoaluminate cement-gypsum composites (SGC) was investigated. The results show that KH570 can undergo an autohydrolysis reaction and wrap on the surface of the PP fibers, which makes the hydrophilicity of PP fibers improved. Nano-SiO2 can further improve the hydrophilicity and roughness of the PP fiber surface by polycondensation reaction with KH570. KH570 and nano-SiO2 synergistically modified PP (KH570-SiO2-PP) fibers obviously increase the compressive strength and flexural strength of the hardened SGC compared with PP fibers or KH570 modified PP (KH570-PP) fibers. The SEM images show that PP-KH570-SiO2 fibers have better adhesion with the matrix than PP fibers and KH570- PP fibers.

Tunable Antibacterial Activity of a Polypropylene Fabric Coated with Bristling Ti3C2Tx MXene Flakes Coupling the Nanoblade Effect with ROS Generation

Polypropylene (PP) is a thermoplastic polymer widely used as a medical textile in healthcare applications due to its low cost and superior performance. However, it does not show antibacterial properties leading to the possibility of pathogen transmission. Herein, we have developed an antibacterial medical fabric by facile self-assembly of delaminated two-dimensional (2D) Ti3C2Tx MXene flakes bristling on the surface of PP fibers. The increasing amount of MXene in the coating solution from 1 up to 32 mg/mL allowed for edge-on assembly of MXene flakes on the PP surface and tracking the evolution of the band gap for a restacked structure. Characterization of the PP/Ti3C2Tx nanocomposite has proven that it exhibited highly effective antibacterial, robust coating, and chemically/thermally stable properties. The in vitro microbiological studies against Gram-negative Escherichia coli and Gram-positive Staphylococcus aureus have shown that PP/Ti3C2Tx reduced the bacterial viability up to 100%, as driven by synergistic membrane stress mediated by physical contact and light-induced reactive oxygen species (ROS) generation. Moreover, the use of l-ascorbic acid for MXene stabilization allowed for achieving excellent thermal stability of the PP/Ti3C2Tx nanocomposite upon accelerated thermal aging. Collectively, this work provides a facile surface engineering strategy for designing medical fabrics with outstanding functional performances. By demonstrating the exceptional performance of the stabilized MXene in a self-assembly nanocomposite structure, we are opening the door for MXenes to be applied in other biomedical fields.

Modification of PP Fabric with Polyols by the Plasma Composite Technique

Abstract In order to endow polypropylene (PP) fabric with hydrophilic and antistatic properties, PP was grafted with polyols (sorbitol, maltitol and polyethylene glycol (PEG)) by the oxygen plasma treatment and subsequent bridging process, where ethylene glycol diglycidyl ether (EGDE) and trimethylolpropanetris (2-methyl-1-aziridinepropionate) (TTMA) were used as crosslinkers. The highest grafting rate was 7.48%. The chemical structure changes were analysed by Fourier transform infrared spectroscopy (FTIR). A scanning electron microscope (SEM) was used to observe the changes in polypropylene fiber surface morphology. The hydrophilicity was characterized by testing loose fiber suspension and moisture retention. The modified PP was more easily immersed in water and the desorption behaviour continued for 2h without equilibrium. The half-life of the grafted PP was reduced to 7s. The results showed that the modified PP with polyols possessed hydrophilicity and antistatic properties.

Functional Materials Based on Nanoparticle Modified Polypropylene Fibers

Background: The formation and modification of the surface of polypropylene fibers provide a versatile material for a variety of applications. Objective: This research examines the production of new materials by pneumatic spraying of a polypropylene melt jet, on the surface of which metal and metal oxide nanoparticles are prepared using the sol-gel technique and photoreduction followed by ultra-high frequency processing. We used the obtained materials to remove Bisphenol A in the photoreactor. Method: Based on an analysis of the obtained values of the numerical characteristics in the spray zone and the physical essence of the criteria under consideration, a mechanism for the destruction of the melt jet from the formation of a fiber-forming system is proposed. Analysis of the degradation of Bisphenol A was carried out by electron spectroscopy and fluorescence. Results: A composite active layer, “polymer – inorganic nanoparticles”, on the surface of polypropylene fibers has been demonstrated to create new photocatalytic materials. Bisphenol A in water was examined as a toxicant. Conclusion: Based on the analysis of the obtained values of the numerical characteristics in the spray zone and the physical essence of the considered criteria, it was found that the pressure drop in the nozzle, the nozzle critical section area, and the rheological properties of the melt are dominating factors in the influence on the morphology and size of the ultra-fine fibers obtained by pneumatic spraying. It was determined that materials based on a polypropylene carrier with the largest diameter of 6.71 μm have the best sorption capacity for Bisphenol A. A decrease in the concentration of bisphenol A in water by more than two times in 30 minutes of UV irradiation in the presence of polypropylene was achieved without additional injection of oxidants.

Effect of Surface Treatment of Polypropylene (PP) Fiber on the Sulfate Corrosion Resistance of Cement Mortar

Sulfate erosion is one of the most complex and harmful chemical corrosion actions. Following sulfate erosion, concrete expands, cracks, dissolves, peels off, and decreases in strength, which affects the durability of structures. Polypropylene fiber (PP) is widely used in various concrete structures because of its good mechanical properties and chemical corrosion resistance. However, PP fiber has a number of shortcomings, such as a smooth surface, poor hydrophilicity, lack of active groups in the molecular chain, and agglomeration and poor dispersion in cement-based materials. These issues limit its application in cement-based materials. Although the use of a silane coupling agent to modify the surface of PP fiber is effective, the influence of treated PP fiber on the sulfate resistance of cement-based materials is not significant. In this study, a PP fiber treated with a silane coupling agent was used to examine effects of different cement-to-sand ratios (C/S) and dosages of the treated PP fiber on the sulfate erosion resistance of cement mortar. Furthermore, the apparent morphology, mass loss rate, flexural strength, corrosion resistance coefficient, and microstructure of the concrete were investigated by X-ray diffraction (XRD) and scanning electron microscopy (SEM). The results revealed that the PP fiber became rough after modification. Active groups were introduced on the fiber surface, which were well dispersed in the mortar and formed a good network distribution structure in the cement mortar, thereby slowing the erosion rate of the PP fiber mortar in a sodium sulfate solution. At a C/S ratio of 1:1 and a treated fiber dosage of 0.6%, the treated fiber mortar has exhibited good sulfate resistance. In addition, the monofilament fiber immersion test revealed that a layer of sodium sulfate crystals was deposited on the fiber surface, thereby increasing the roughness of the fiber surface and the pull-out force of the fiber from the cement matrix, this result indicated that the interfacial adhesion between the treated PP fiber and cement matrix was improved, which in turn led to the improvement in the sulfate erosion resistance of the treated PP fiber.

Study of the effects of mineral salts on the biofilm formation on polypropylene fibers using three quantification methods.

The microbial biofilms are ubiquitous in nature and represent important biological entities that affect various aspects of human life. As such, they attracted considerable attention during last decades, with the factors affecting the biofilm development being among the frequently studied topics. In our work, the biofilm was cultivated on the surface of polypropylene fibers in a nutrient medium inoculated by the suspension of two unsterile soils. The effects of ionic strength and valence of salt on the amount of the produced biofilm and on composition of biofilm microbial communities were investigated. The effect of valence was significant in some OTUs: Arthrobacter/Pseudarthrobacter/Paenarthrobacter and Bacillus with positive response to monovalent salt (KCl) and Streptomyces, Lysinibacillus, Pseudomonas, and Ensifer with positive response to divalent salt (MgSO4). The significant preference for a certain concentration of salts was observed in the case of OTUs Agrobacterium, Bacillus (both 100mM), and Brevundimonas (30mM). A new quantification method based on measuring of oxidizable organic carbon in biofilm biomass, based on dichromate oxidation, was used. We compared the results obtained using this method with results of crystal violet destaining and measuring of extracted DNA concentration as proxies of the biofilm biomass. The dichromate oxidation is simple, inexpensive, and fast, and our results show that it may be more sensitive than crystal violet destaining. The highest biomass values tended to associate with high concentrations of the divalent salt. This trend was not observed in treatments where the monovalent salt was added. Our data confirm the importance of inorganic ions for biofilm composition and biomass accumulation.

Improving the bond between polypropylene fiber and cement matrix by nano calcium carbonate modification

Polypropylene (PP) fibers are commonly used for reinforcing cementitious composites due to their reasonable strength, good chemical stability and relatively low cost. However, chemically inert surface causes relatively inferior bond with cement matrix. Therefore, this study applies nano calcium carbonate to modify the surface of polypropylene fibers. After modification, the surface roughness increased and dense hydration product with high hydration degree can be generated around the fiber surface. Single-fiber pullout tests confirmed chemical bonding and bond strength of fiber/cement matrix interface were enhanced by modification. Although frictional bond between modified fibers and cement matrix decreased slightly, more energy can be absorbed than normal PP/cement matrix interface during fiber slippage. Flexural properties including peak resistance and energy absorption were improved when modified PP fibers were incorporated into cementitious composites. In summary, surface coating treatment by nano calcium carbonate is a promising approach to modifying surface properties of polypropylene fibers to enhance bond performance with cement matrix, which may facilitate the application of PP fibers in fiber-reinforced cementitious composites (FRCC) for enhanced strength and ductility.

In situ growth polydopamine decorated polypropylen melt-blown membrane for highly efficient oil/water separation

The removal of organic pollutants from water is highly desired because of the development of industrial and social economy. Superhydrophilic and underwater superoleophobic membranes are emerging materials for effective oil/water separation. In this paper, superhydrophilic and underwater superoleophobic polypropylene (PP) melt-blown membranes were prepared through melt-blown and in situ growth method, achieving highly efficient oil/water separation. After in situ growth, polydopamine (PDA) grows on the surface of PP fibers, and the addition of coupling agent (3-aminopropyltriethoxysilane, APTES) can improve the stability of the membrane in harsh environments (1 M HCl, 1 M NaOH, 1 M NaCl). The PDA/APTES@PP membrane could dramatically enhance the wetting (water contact angle ∼0, underwater oil contact angle∼154°) compare with the pristine PP melt-blown membrane (water contact angle ∼130°, underwater oil contact angle ∼0). Moreover, the filtration performance is at a high level (∼99%). The behaviors are comparable or even superior to the typical reported results in the references (such as the mussel-inspired superhydrophilic PVDF membrane and copper mesh). This method provides a facile route to prepared multi-functional membrane for highly efficiency oil/water separation and industrial oily wastewater remediation.

Conductivity and piezoresistivity of nano-carbon black (NCB) enhanced functional cement-based sensors using polypropylene fibres

The cement-based sensors have a great potential for structural health monitoring, especially functional sensors filled with nano-carbon black (NCB) particles. To improve the sensing efficiency of NCB filled cementitious composite, polypropylene (PP) fibres were premixed with NCB during the manufacturing of cement-based sensor. Although the compressive strength is slightly decreased, the electrical conductivity and piezoresistivity of the NCB filled cementitious composite are improved by PP fibres. Microstructural characterization indicated that NCB attached to the surface of PP fibres significantly promotes the generation of conductive paths and contact points in cement-based sensors. The results can provide a new insight into the application of nonconductive fibres to enhance the conductivity and piezoresistivity of spherical conductors filled cement-based sensor.

Application of bacterial nanocellulose fibers as reinforcement in cement composites

In this study, the potential effect of bacterial nano-cellulose on mechanical properties of cement mortar was evaluated. For this purpose, bacterial nano-cellulose (BNC) directly as powder and gel (0.1, 0.3, and 0.5 wt%), and indirectly as coated onto the polypropylene fibers were used in the preparation of cement paste in order to investigate the effect of each method on the flexural strength, compressive strength and water absorption of specimens. Results indicated that samples containing BNC gel and powder enhanced mechanical properties. However, BNC-gel indicated inferior properties compared to powder. The maximum increase in flexural strength between all samples was observed in the specimens containing 0.5% of BNC powder, which was 104%, compared to the control sample. In addition, utilizing nanofibers decreased the water absorption of cement mortar. The water absorption of specimens containing 0.1% of the gel fibers and 0.3% of powder was decreased by 26% and 37%, respectively. According to scanning electron microscopy (SEM) analysis, the roughness and specific surface of polypropylene fibers coated with BNC were increased. This can improve the interaction of these fibers with the cement matrix. The results show clearly that the application of BNC nanofibers improves the mechanical properties of cement paste and workability of polypropylene fibers.

How does adsorption behavior of polycarboxylate superplasticizer effect rheology and flowability of cement paste with polypropylene fiber?

Nowadays, polycarboxylate (PCE) superplasticizer and polypropylene fiber (PPF) are widely used to improve the flowability and ductility of modern concrete. In this study, the rheology and flowability of cement paste with PPF have been investigated. With increasing length and dosage of PPF, the apparent viocosties, plastic viscosities and the yield stress of the cement paste increase gradually. The flowability of the cement paste decreases irrespective whether PCE has been added to the cement paste. However, with increasing length and dosage of PPF, the flowability ratio (i.e. the flowability of cement paste with PCE divided by the flowability of cement paste without PCE) becomes higher. That means the dispersibility of PCE increases with increasing length and dosage of PPF. In this study, the independent, total and synergistic adsorption amount of PCE has also been investigated. It shows that with increasing length and dosage of PPF, both the independent adsorption amount of PCE on the surface of PPF, and the total adsorption amount of PCE on the surfaces of PPF and cement particles increase. When PPF was added into cement paste, they would be intertwined by themselves, more PCE was adsorbed by the three-dimensional mesh of PPF. Therefore, due to the electrostatic repulsion and steric hindrance effects of PCE, the dispersion of cement paste with PPF is improved by adding PCE, and the dispersibility of PCE increases with increasing length and dosage of PPF.

Surface Hydrophilic Modification of Polypropylene Fiber by Hydrolysis of Silane Coupling Agent

Silane coupling agent is applied to modify polypropylene fiber. The modification effectively transfers the hydrophobic surface of polypropylene fiber to hydrophilic surface. Results from FT-IR, SEM and contact angle meter suggest that that the surface functional groups, the morphology and hydrophilia of polypropylene fiber is changed during the hydrolysis reactions of silane coupling agent. The modification process not only improve the surface hydrophilia of polypropylene fiber, but also convert the smooth surface of unmodified fibers to rough surface of modified fibers which gives stronger interface bonding force between fiber and substrate in the field of composite applications.

Controlled Levofloxacin Release and Antibacterial Properties of β-Cyclodextrins-Grafted Polypropylene Mesh Devices for Hernia Repair.

Mesh infection is a major complication of hernia repair. After knitted mesh implantation, bacteria can grow within textile structures causing infection. In this work, polypropylene (PP) mesh devices were two-step grafted with hexamethylene diisocyanate (HDI) and β–cyclodexrins (CD) and then loaded with suitable antimicrobial levofloxacin HCL for hernia mesh-infection prevention. First, oxygen plasma was able to create surface roughness, then HDI was successfully grafted onto PP fiber surfaces. Afterwards, CD was covalently grafted onto the HDI treated PP meshes, and levofloxacin HCL (LVFX) was loaded into the CD cavity of the modified meshes. The modified devices were evaluated for sustained antibiotic properties and drug-release profiles in a phosphate buffer, and sustained drug release was observed between interfaces of meshes and aqueous environment. The antibiotic-loaded PP mesh samples demonstrated sustained antibacterial properties for 7 and 10 days, respectively, against both Gram-negative and Gram-positive bacteria. The CD-captured levofloxacin HCL showed burst release after 6 h but later exhibited sustained release for the next 48 h. Among all samples, the modified mesh LVFX-6 was more stable and showed more sustained drug release and could be employed in future clinical applications.

Nano-mechanical behavior of the interfacial transition zone between steel-polypropylene fiber and cement paste

The fiber-matrix interfacial transition zone (ITZ) at nanoscale plays an important role in determining the mechanical performance of hybrid steel-polypropylene fiber reinforced concrete at upper scales. This paper investigates the elastic behavior of the ITZ between steel/polypropylene fiber and pure cement paste through nanoindentation for different water/cement ratios. The microstructure mapping and gradient of ITZ were analyzed based on the elastic modulus (E) and hardness (H) distributions. The morphology of ITZs was observed with the help of Scanning Electron Microscope. In addition, to probe into the formation mechanism of ITZ, distinct phases in ITZ were statistically determined from the frequency density distributions of E and H values through the deconvolution technique. Results show that the thickness of fiber-matrix ITZ mainly depends on the fiber type, where the steel fiber and polypropylene fiber ITZ are about 30μm and 15μm in thickness respectively. It is also found from E distribution that a trough in the steel fiber ITZ exists at lower w/c ratios, whereas a gradual growth of E and H values is demonstrated away from polypropylene fiber surface for all cases shown. The ITZ’s chemical compositions at nanoscale suggest that the volume fractions of HD C-S-H, CH/C-S-H and porosity are noted to be the main determinants for the overall properties of ITZ. In comparison with steel fiber samples, a larger amount of porosity exists in the vicinity of polypropylene fiber surface. Finally, based on the test data, the ITZ formation mechanism was discussed with water/cement ratio effect considered.

Combination of low-temperature plasma processes in the design of a novel ampicillin-loaded surgical mesh for hernia repair

Event Abstract Back to Event Combination of low-temperature plasma processes in the design of a novel ampicillin-loaded surgical mesh for hernia repair Cédric Labay1, 2, José María Canal1, Martina Modic3, Uros Cvelbar3, Maite Quiles4, Manuel Armengol4, María Antonia Arbos4, Francesc Javier Gil2 and Cristina Canal2 1 Technical University of Catalonia (UPC-BarcelonaTech), Surfaces, Products and Textile Processes Research Group, Textile and Paper Engineering Dept., Spain 2 Technical University of Catalonia (UPC-BarcelonaTech), Biomaterials, Biomechanics and Tissue Engineering Group, Materials Science and Metallurgy Dept., Spain 3 Jozef Stefan Institute (IJS), Department F4, Slovenia 4 Universitat Autònoma de Barcelona (UAB), Vall d'Hebron Institute of Research (VHIR), Spain Introduction: One of the new trends in biomaterials research is to deliver active compounds locally in the surgical site from the medical device. One way to manage post-operatory infections associated with mesh implants in abdominal hernia repair surgery can be the loading of antibiotics to the surgical meshes. Plasma treatment of polymer fibers has been commonly employed to tailor surface adhesion and wetting properties by changing the surface chemical composition[1],[2]. Appropriate selection of the plasma source enables the introduction of diverse functional groups on the target surface to improve wettability, biocompatibility or to allow subsequent covalent immobilization or physical adsorption of various molecules such as dyestuffs, pharmaceutical or cosmetic active principles[3],[4]. Plasma can also be used for the deposition of polymer thin coatings by plasma polymerization process[5]. By modifying the process parameters of the plasma and the precursor, different kinds of biocompatible coatings can be produced, from cell-adhesive to antifouling coatings. Materials and Methods: A polypropylene (PP) mesh was functionalized in air plasma at atmospheric pressure by corona plasma (380W, 1.9A, <7.0s), before its loading with ampicillin (AMP) from an aqueous solution. Plasma polymerization of the AMP-loaded mesh was performed (0.4mbar, 200W, 13.56MHz, 2h) with Ar carrier gas, using Tetraglyme as precursor to obtain a PEG-like thin coating of the mesh. Characterization techniques such as AFM, SEM, XPS, etc. were employed to determine the effect of plasma treatment on the surface topography and chemical composition. To evaluate the biological behavior of the modified meshes, in vitro assays regarding cell proliferation, morphology, viability, chemotaxis and cell adhesion were carried out on the materials using NIH-3T3 fibroblasts and THP1 monocytes. Antibacterial assays and in vitro release experiments of the AMP from the fiber to an isotonic liquid media were also carried out. Results and Discussion: Combination of plasma functionalization and polymerization in the design of this textile-based drug delivery system is fully justified by the distinct effects produced by these two plasma treatments. As a first-step in the design of the AMP-loaded mesh, plasma functionalization of the polymer surface with polar O-groups was used to modify the PP fiber surface at nanometric level. Surface wettability was improved due to the increased availability of chemical bonds with the introduction of new C=O and COOH functional groups. This was employed for the subsequent attachment of AMP allowing an increase of its loading as function of the plasma treatment time. The chemical and morphological changes on the surface of PP fibers lead to a 3-fold improvement of the AMP loading in the meshes after only 3.5s of plasma treatment. However, this plasma treatment and the subsequent loading of AMP on the PP fibers were related with lower fibroblast adhesion, altered morphology and enhanced chemotaxis. Thus, plasma polymerization was used as dry method to create a thin coating of PEG with the aim of keeping the high antibiotic loadings obtained with plasma functionalization and to maintain essentially unchanged fibroblast properties such as chemotaxis or adhesion with respect to untreated meshes, fulfilling the requirement of biocompatible device for the finished AMP-loaded mesh. Conclusions: Combination of plasma processes has been used to tailor the surface properties of PP meshes to obtain high loadings of AMP, maintaining the biological adhesion and the antibacterial activity of the current surgical meshes[6]. Beyond the added value brought by the antibiotic loading of the mesh for its release directly to the surgical site, the use of plasma processes in the design of biomaterials brings an original approach to control simultaneously physical and chemical surface properties, but also regarding the treatment of the mesh without the use of any other chemicals for the binding of the active principle with the fiber. Authors acknowledge L'Oreal-Unesco programme for Women in Science, the Spanish Government for financial support through Ramon y Cajal fellowship of CC, Generalitat de Catalunya through SGR 2014-1075 and SGR 2014-1333, the Slovenian Research Agency (ARRS) and the European Commission through Cost Action MP1101 “Bioplasmas”

Impregnation of corona modified polypropylene non-woven material with thymol in supercritical carbon dioxide for antimicrobial application

This study discusses the possibility of impregnation of polypropylene (PP) and corona modified PP non-woven material with thymol in supercritical solvent in order to fabricate eco-friendly antimicrobial textile material. Carbon dioxide was used as a working fluid. The morphological changes on the PP fiber surface induced by corona treatment at atmospheric pressure as well as the presence of thymol on the fiber surface after impregnation were confirmed by FESEM analysis. Chemical changes were assessed by FTIR analysis. Antimicrobial activity of the modified PP non-woven material was tested against Gram-positive bacterium Staphylococcus aureus, Gram-negative bacterium Escherichia coli and fungus Candida albicans. Although both PP non-woven material impregnated with thymol and corona activated PP impregnated with thymol provided maximum microbial reduction, corona pre-treated material was much faster wetted, which could be an advantage in wound healing.