Polypropylene Surface Research Articles

Loading characteristics of streptavidin on polypropylene capillary channeled polymer fibers and capture performance towards biotinylated proteins.

The development of higher-throughput, potentially lower-cost means to isolate proteins, for a variety of end uses, is of continuing emphasis. Polypropylene (PP) capillary-channeled polymer (C-CP) fiber columns are modified with the biotin-binding protein streptavidin (SAV) to capture biotinylated proteins. The loading characteristics of SAV on fiber supports were determined using breakthrough curves and frontal analysis. Based on adsorption data, a 3-min on-column loading at a flow rate of 0.5 mL min-1 (295.2 cm h-1) with a SAV feed concentration of 0.5 mg mL-1 produces a SAV loading capacity of 1.4 mg g-1 fiber. SAV has an incredibly high affinity for the small-molecule biotin (10-14 M), such that this binding relationship can be exploited by labeling a target protein with biotin via an Avi-tag. To evaluate the capture of the biotinylated proteins on the modified PP surface, the biotinylated versions of bovine serum albumin (b-BSA) and green fluorescent protein (b-GFP) were utilized as probe species. The loading buffer composition and flow rate were optimized towards protein capture. The non-ionic detergent Tween-20 was added to the deposition solutions to minimize non-specific binding. Values of 0.25-0.50% (v/v) Tween-20 in PBS exhibited better capture efficiency, while minimizing the non-specific binding for b-BSA and b-GFP, respectively. The C-CP fiber platform has the potential to provide a fast and low-cost method to capture targeted proteins for applications including protein purification or pull-down assays.

Microfabrication of Thermoplastic Polypropylene Surface Structures via Thermal Imprinting for Controlling the Adhesion of Easy Peel Package.

Micropatterns were fabricated on polypropylene (PP) surfaces using the hot embossing technique with various temperatures ranging from 160 to 175 °C and applying force conditions from 100 to 300 N. To evaluate the replication quality, an effective filling ratio of 1 indicates that the volume of the formed pattern is similar to the mold cavity volume. From the results, the filling ratio increased with increasing the embossing temperature. For instance, under a constant force of 100 N, the filling ratio of polypropylene (PP) with small square arrays (pattern SS) increased from 0.08 to 0.41 when the embossing temperature was raised from 160 to 175 °C, respectively. With the increase of applied force, the filling ratio also increased. At an imprinting temperature of 175 °C and an applied force of 300 N, the highest effective filling ratio that was achieved was approximately 0.99. Furthermore, the effect of PP with different melt flow indexes (MFIs) on the filling ratio was investigated. For food packaging applications, a micropatterned PP sheet was heat-sealed with a biaxially oriented polypropylene (BOPP) film. The micropatterned PP sheet demonstrated easy-opening properties by varying sealing contact areas and micropattern geometries between the sheet and the BOPP film. All micropatterned PP sheets with an MFI of 25 g/10 min exhibited an easy peel property with adhesive failure characteristics at a heat-sealing temperature of 150 °C and a dwell time of 3 s. There was no residue on the PP substrate surface. The overall findings are beneficial in understanding the hot embossing technology for fabricating micropatterns on polymer surfaces, and it can be applied in an easy peel property for packaging applications.

Antibacterial HPL‐DOSS surface coating for commercial plastics

AbstractBacterial colonization and biofilm formation on the surface of materials can lead to serious bacterial infections and are highly detrimental to our health. Here, we prepared a water‐insoluble HPL‐DOSS complex by compounding hyperbranched polylysine (HPL) with docusate sodium salt (DOSS) and coated HPL‐DOSS onto the surfaces of the commercial polypropylene (PP) and thermoplastic polyurethane (TPU) plastics to afford antibacterial PP‐HD and TPU‐HD plastics. PP‐HD and TPU‐HD showed excellent antibacterial activities against both Escherichia coli and MRSA. In addition, the bacterial residues on the PP‐HD and TPU‐HD surfaces were significantly reduced compared with the pristine PP and TPU surfaces, indicating that the HPL‐DOSS surface coating had good anti‐adhesive property against bacteria and helped to reduce the formation of biofilms. Meanwhile, both PP‐HD and TPU‐HD exhibited excellent biocompatibility, indicating that the HPL‐DOSS complex could be used as a safe antimicrobial coating material to reduce bacterial infections on plastic surfaces.

Photochemical Metallization: Advancements in Polypropylene Surface Treatment.

The work was devoted to the development of technology for applying metal coatings to the surface of polypropylene products. At the same time, the main stages of the technology were carried out using the influence of electromagnetic waves of light radiation. So, to obtain an electrically conductive silver layer, after mechanical treatment, etching and activation, the polymer was immersed for several minutes in a solution containing 10-20 g/L of silver nitrate and equivalent amounts of ascorbic acid, and a thin layer of solution was obtained on the surface of the polymer. A sample with such a sorption film was exposed to electromagnetic waves of light radiation at a flux density of 700-1100 W/m2. The small thickness of the sorption film facilitated the penetration of these waves directly onto the polymer surface and ensured the photochemical process of silver reduction with the formation of active centers. At the same time, electromagnetic waves acting on ascorbic acid transferred it to an excited state. As a result, the chemical reduction of silver in the space between the active centers became possible. In this case, the film obtained within 15-20 min had the necessary electrical conductivity. The suitability of these films for galvanic metallization of the polymer surface was shown.

Effect of ginger essential oil and 6-gingerol on a multispecies biofilm of Listeria monocytogenes, Salmonella Typhimurium, and Pseudomonas aeruginosa.

The objective of this study was to evaluate the potential antimicrobial and antibiofilm effect of ginger essential oil (GEO) and 6-gingerol on a multispecies biofilm formed by Listeria monocytogenes, Salmonella Typhimurium, and Pseudomonas aeruginosa on a polypropylene surface. The minimum inhibitory concentration concentrations obtained for GEO were 100 and 50mg/mL and for 6-gingerol 1.25mg/mL. Sessile cell counts ranged within 5.35-7.35 log CFU/cm2 in the control biofilm, with the highest sessile growth at 72h. GEO treatments acted on the total population regardless of concentration at 1 and 48h. L. monocytogenes behaved similarly to the total population, showing GEO action at 1h and keeping the same pattern at 48, 72, and 96h. Better action on S. Typhimurium was obtained at times of 1, 72, and 96h. P. aeruginosa showed logarithmic reduction only when treated with GEO 50mg at 24h. As for 6-gingerol, in general, there was no significant action (p > 0.05) on the evaluated sessile cells. GEO showed antimicrobial activity againstL. monocytogenes, S. Typhimurium, and P. aeruginosa, acting as an inhibitor of biofilm formation. As for 6-gingerol, it was considered a possible antimicrobial agent but without efficacy during biofilm formation.

Enhanced Dyeing of Polypropylene Using Fluorine–Oxygen Gas Mixtures

Surface fluorination with pure F2 gas can easily make the surface on PP (polypropylene) hydrophobic, and it causes limited dyeability, as reported in a previous paper. In this study, to produce a more hydrophilic surface, surface fluorination of PP was performed at 25 °C, total gas pressure of 13.3 kPa, and reaction time of 1 h using F2 and O2 mixtures with different proportions of F2 gas. The surface roughness of the fluorinated PP samples was about 1.5 times higher than that of the untreated sample (5 nm). Fourier-transform infrared spectroscopy and X-ray photoelectron spectroscopy (XPS) results showed that the PP-derived bonds (-C-C- and -CHx) decreased because they were converted into polar groups (-C–O, -CHF-, and -CFx), which increased the surface electronegativity of the PP. The variation in the F2 gas proportion in the gas mixture significantly affected the hydrophilicity and surface composition of the PP. At F2 gas proportions of <70%, the hydrophilicity of the fluorinated PP samples was increased. Notably, the hydrophilic and negatively charged PP surface enhanced the dyeing of the polymer with basic methylene blue (MB). In contrast, at F2 gas proportions of >90%, the PP surface became hydrophobic owing to increased numbers of hydrophobic -CF3 bonds. Thus, enhanced PP dyeing can be controlled based on the composition of the F2 and O2 gas mixture.

Polydopamine and calcium functionalized fiber carrier for enhancing microbial attachment and Cr(VI) resistance

The formation of biofilm determines the performance and stability of biofilm system. Increasing the hydrophilicity of the carrier surface could efficiently accelerate the attachment and growth of microorganisms. Here, the surface of polypropylene (PP) fiber carrier was modified with polydopamine (PDA) and calcium (Ca(II)) to enhance microbial attachment and toxicity resistance. The results of surface characteristic confirmed the self-polymerization of PDA and the chelation mechanism of Ca(II). Subsequently, the biofilm formation experiments were conducted in sequencing batch biofilm reactors using both normal and chromium-containing wastewater. The biofilm on the surface of the modified carrier exhibited better nitrogen removal and Cr(VI) reduction ability. The biomass of the modified carrier was significantly increased, and the maximum microbial attachment amounts in normal wastewater and chrome-containing wastewater were 1153.34 and 511.78 mg/g carrier, respectively. Furthermore, the confocal laser scanning microscope (CLSM) indicated that the modified carrier coated with PDA and Ca(II) were both biocompatible, and the cell activity was significantly increased. 16S rRNA sequencing results showed that the modified carrier efficiently enriched both denitrification bacteria (Thauera and Flavobacterium) and chrome-reducing bacteria (Simplicispira and Arenimonas) to improve system stability and Cr(VI) resistance. Microbial phenotype prediction based on BugBase analysis further verified the enrichment effect of modified carriers on microorganisms responsible for biofilm formation and oxidative stress resistance. Overall, this work proposed a novel functional carrier that could provide references for advancing the application of biofilm systems in wastewater treatment.

Circular Production, Designing, and Mechanical Testing of Polypropylene-Based Reinforced Composite Materials: Statistical Analysis for Potential Automotive and Nuclear Applications.

The circularity of polymer waste is an emerging field of research in Europe. In the present research, the thermal, surface, mechanical, and tribological properties of polypropylene (PP)-based composite produced by injection molding were studied. The pure PP matrix was reinforced with 10, 30, and 40% wt. of pure cotton, synthetic polyester, and polyethylene terephthalate post-consumer fibers using a combination of direct extrusion and injection molding techniques. Results indicate that PP-PCPESF-10% wt. exhibits the highest value of tensile strength (29 MPa). However, the values of tensile and flexural strain were lowered with an increase in fiber content due to the presence of micro-defects. Similarly, the values of modulus of elasticity, flexural modulus, flexural strength, and impact energy were enhanced due to an increase in the amount of fiber. The PP-PCCF-40% wt. shows the highest values of flexural constant (2780 MPa) and strength (57 MPa). Additionally, the increase in fiber loadings is directly proportional to the creation of micro-defects, surface roughness, abrasive wear, coefficient of friction, and erosive wear. The lowest average absolute arithmetic surface roughness value (Ra) of PP and PP-PCCF, 10% wt., were 0.19 µm and 0.28 µm. The lowest abrasive wear value of 3.09 × 10-6 mm3/Nm was found for pure PP. The erosive wear value (35 mm3/kg) of PP-PCCF 40% wt. composite material was 2 to 17 times higher than all other composite materials. Finally, the single-step analysis of variance predicts reasonable results in terms of the p-values of each composite material for commercial applications.

Surface Modification of PP and PBT Nonwoven Membranes for Enhanced Efficiency in Photocatalytic MB Dye Removal and Antibacterial Activity.

In this study, we developed highly efficient nonwoven membranes by modifying the surface of polypropylene (PP) and poly(butylene terephthalate) (PBT) through photo-grafting polymerization. The nonwoven membrane surfaces of PP and PBT were grafted with poly(ethylene glycol) diacrylate (PEGDA) in the presence of benzophenone (BP) and metal salt. We immobilized tertiary amine groups as BP synergists on commercial nonwoven membranes to improve PP and PBT surfaces. In situ Ag, Au, and Au/Ag nanoparticle formation enhances the nonwoven membrane surface. SEM, FTIR, and EDX were used to analyze the surface. We evaluated modified nonwoven membranes for photocatalytic activity by degrading methylene blue (MB) under LED and sunlight. Additionally, we also tested modified membranes for antibacterial activity against E. coli. The results indicated that the modified membranes exhibited superior efficiency in removing MB from water. The PBT showed the highest efficiency in dye removal, and bimetallic nanoparticles were more effective than monometallic. Modified membranes exposed to sunlight had higher efficiency than those exposed to LED light, with the PBT/Au/Ag membrane showing the highest dye removal at 97% within 90 min. The modified membranes showed reuse potential, with dye removal efficiency decreasing from 97% in the first cycle to 85% in the fifth cycle.

Chitosan and TiO2 functionalized polypropylene nonwoven fabrics with visible light induced photocatalytic antibacterial performances

Chitosan/TiO2 functionalized polypropylene (CS/TiO2/PP) nonwoven fabrics were fabricated through crosslinking of chitosan with glutaraldehyde followed by loading of TiO2 nanoparticles. The functionalized CS/TiO2/PP has super hydrophilicity and excellent visible light induced photocatalytic antibacterial properties owing to the synergistic effects of CS and TiO2. The photocatalytic degradation performance was determined by assessing the degradation of methyl blue under simulated visible light irradiation and its recyclability was also evaluated. In addition, SEM images demonstrated that TiO2 nanoparticles were distributed evenly on the surface of the 2 g/L CS/TiO2/PP. Meanwhile, the polypropylene surface showed a significant increase in hydrophilicity after being treated with chitosan and TiO2. The photocatalytic degradation results revealed that CS/TiO2/PP had higher photocatalytic properties than those of pure PP under visible light, and the degradation rate of methylene blue reached 96.4 % after 90 min of light exposure. Compared to pure PP, the antibacterial properties of CS/TiO2/PP significantly increased, and the bacterial reduction percentages were increased to 98.7 % and 96.3 %, against E. coli and S. aureus, respectively. The functionalized CS/TiO2/PP composites exhibited promising potential in environmentally friendly antibacterial materials.

Assessing the Quality of Oxygen Plasma Focused Ion Beam (O-PFIB) Etching on Polypropylene Surfaces Using Secondary Electron Hyperspectral Imaging.

The development of Focused Ion Beam-Scanning Electron Microscopy (FIB-SEM) systems has provided significant advances in the processing and characterization of polymers. A fundamental understanding of ion-sample interactions is still missing despite FIB-SEM being routinely applied in microstructural analyses of polymers. This study applies Secondary Electron Hyperspectral Imaging to reveal oxygen and xenon plasma FIB interactions on the surface of a polymer (in this instance, polypropylene). Secondary Electron Hyperspectral Imaging (SEHI) is a technique housed within the SEM chamber that exhibits multiscale surface sensitivity with a high spatial resolution and the ability to identify carbon bonding present using low beam energies without requiring an Ultra High Vacuum (UHV). SEHI is made possible through the use of through-the-lens detectors (TLDs) to provide a low-pass SE collection of low primary electron beam energies and currents. SE images acquired over the same region of interest from different energy ranges are plotted to produce an SE spectrum. The data provided in this study provide evidence of SEHI's ability to be a valuable tool in the characterization of polymer surfaces post-PFIB etching, allowing for insights into both tailoring polymer processing FIB parameters and SEHI's ability to be used to monitor serial FIB polymer surfaces in situ.

Developing chemical interaction and achieving mechanical interlock to manufacture high-reliability Polypropylene/A6061-T6 aluminum alloy FAW joints

Polypropylene (PP) is wildly used to light the weight of advanced cars and vehicles due to its good resistance to abrasion and wear, high flexibility, and excellent impact strength. However, PP macromolecules consist of long chains of carbon atoms attached to hydrogen atoms. The non-functional surfaces of PP make it hard to achieve stable hybrid structures with metals. Current work reported an interfacial design strategy to manufacture high-reliability PP/A6061-T6 aluminum alloy (6061) hybrid structures by friction assisted welding (FAW). To achieve this, carboxy group (COOH) was grafted on PP while the surficial microstructure was built on 6061. The introducing carboxy group reacted with 6061 to develop interfacial covalent and hydrogen bonds. The built surface microstructures of 6061 not only realized the mechanical interlock at PP/6061 interfaces but also improved the compatibility between PP and 6061. The surface microstructures enabled the good wetting and fast spread of melt PP to provide sufficient reaction area and time for the development of interfacial chemical interaction. Compared with other developed methods, our interfacial design strategy enhances the reliability of metal-thermoplastic hybrid structures with low equipment, process, materials, and environmental costs, making it a promising candidate for industrial applications. Current work provides a simple yet attractive strategy for achieving high-reliability joints between dissimilar metals and thermoplastics.

Comparing efficiencies of polypropylene treatment by atmospheric pressure plasma jets

AbstractPlasma treatment of polypropylene (PP) is a well‐established method of improving its surface properties. However, the efficiencies of different plasma discharges are seldom compared. Herein, we discuss the differences in PP treated by three arc‐based commercial plasma jets working in dry air, Plasmatreat rotating plasma jet (PT‐RPJ), AFS PlasmaJet® (AFS‐PJ), and SurfaceTreat gliding arc jet (ST‐GA), and by the low‐temperature RF plasma slit jet (RF‐PSJ) working in argon. The AFS‐PJ has a significantly different reactive species composition dominated by nitrogen oxides. It induced higher thermal loads leading to surface damage. The other arc‐based jets (PT‐RPJ and ST‐GA) created the PP surface with higher oxygen and nitrogen concentration than the low‐temperature RF‐PSJ. It induced a higher adhesion strength measured on PP‐aluminum joints.

Deciphering the role of fungus in degradation of polypropylene from hospital waste.

Health and environmental consequences are unavoidable when it comes to management of hospital waste (HW) disposables. In order to eradicate the HW, this study isolated a novel fungus SPF21 from a hospital dumping yard to degrade Polypropylene (PP). We measured the attributes of PP inoculated with fungus using mass loss, Fourier trans-form infrared (FTIR), contact angle (CA), and scanning electron microscopy (SEM). The weight of PP exposed to SPF21 was reduced by 25% in 90 days. The SEM images reveal that there are pores all over the sample surface; they alsocaused voids during the biodegradation of PP. FTIR analysis indicates that the spectra of treated mask pieces show the absence of peak at 1746cm-1 and the appearance of a new peak at 1643cm-1 . A period of 90-day exposure to the fungal isolate SPF21 reduced the CA of PP by 44.8% when compared to the nonexposed PP samples, suggesting that the surface of PP turned more hydrophilic after exposure. Moreover, our study on PP degradation by the fungus Ascotricha sinuosa SPF21 appears to be promising from the perspective of environmental, health, and economic hazards. Our results indicate that biodegradation greatly facilitates fungus deposition and changes PP film morphology and hydrophilicity.

Quantitative and selective study of the effect of O radicals on polypropylene surface treatment

Abstract Gaining a comprehensive understanding of the mechanisms underlying plasma-polymer surface treatments using atmospheric pressure plasmas can guide their industrial applications. To this end, a novel vacuum ultraviolet photodissociation reactive species supply (VUV PRS) method, which can quantitatively supply the desired type of reactive species to polymer surfaces, was developed in our previous study. In this study, the innovative approach is used to quantitatively study the effects of O radicals on polypropylene (PP) surface treatment. Specifically, water contact angle (WCA), attenuated total reflection-Fourier transform infrared (ATR-FTIR) spectroscopy, and atomic force microscopy (AFM) are used to characterize the surface modification. The results show that the surface treatment is dominated by O radicals under the present experimental conditions. The surface modification rate, characterized by the WCA decline rate, is linearly correlated with the concentration of O radicals, that is (surface modification rate) = (8.1 ± 0.4)[Os] + (0.13 ± 0.02) degrees s−1, where [Os] indicates the density of O radicals at PP surface (in ppm). The ATR-FTIR spectra shows that –OH and C=O functional groups are introduced onto the PP surface after the treatment, which results in a decrease in the WCA of the surface. Atomic force microscopy (AFM) analysis shows that the surface morphology of the treated PP remains almost unchanged. Low molecular weight oxidized materials (LMWOMs) on PP surface are generated when the O radical dose that arrives at the PP surface exceeds a certain threshold. More than 60% of the oxygen-containing functional groups exist as LMWOMs when the WCA saturates. The results presented in this paper indicate that the VUV PRS method has the potential to drive the understanding of plasma-polymer surface interactions at the atomic and molecular levels. Moreover, the measured roles of the O radicals on the polymer surface at atmospheric pressure can guide the industrial application of atmospheric pressure plasma treatment.

The effect of pulse voltage rise rate on the polypropylene surface hydrophilic modification by ns pulsed nitrogen DBD

The nanosecond (ns) pulsed nitrogen dielectric barrier discharge (DBD) is employed to enhance the hydrophilicity of polypropylene (PP) surface and improve its application effect. The discharge characteristics of the ns pulsed nitrogen DBD with different pulse rise times (from 50 to 500 ns) are investigated by electrical and optical diagnostic methods and the discharge uniformity is quantitatively analyzed by image processing method. To characterize the surface hydrophilicity, the water contact angle (WCA) is measured, and the physical morphology and chemical composition of PP before and after modification are analyzed to explore the effect of plasma on PP surface. It is found that with increasing pulse rise time from 50 to 500 ns, DBD uniformity becomes worse, energy efficiency decreases from 20% to 10.8%, and electron density decrease from 6.6 × 1011 to 5.5 × 1011 cm−3. The tendency of electron temperature is characterized with the intensity ratio of N2/N+ 2 emission spectrum, which decreases from 17.4 to 15.9 indicating the decreasing of T e with increasing pulse rise time from 50 to 500 ns. The PP surface treated with 50 ns pulse rise time DBD has a lower WCA (∼47°), while the WCA of PP treated with 100 to 500 ns pulse rise time DBD expands gradually (∼50°‒57°). According to the study of the fixed-point WCA values, the DBD-treated PP surface has superior uniformity under 50 ns pulse rise time (3° variation) than under 300 ns pulse rise time (8° variation). After DBD treatment, the increased surface roughness from 2.0 to 9.8 nm and hydrophilic oxygen-containing groups on the surface, i.e. hydroxyl (−OH) and carbonyl (C=O) have played the significant role to improve the sample’s surface hydrophilicity. The short pulse voltage rise time enhances the reduced electric field strength (E/n) in the discharge space and improves the discharge uniformity, which makes relatively sufficient physical and chemical reactions have taken place on the PP surface, resulting in better treatment uniformity.

Recycled poly(propylene-co-methy1 methacrylate) as printing binder for photoluminescent textiles

Photochromic fabrics change color upon exposure to an external light source. Photoluminescent textiles can undergo phosphorescence or fluorescence emissions. Fluorescent textiles emit light only under an illumination light source, whereas phosphorescent textiles continue emitting light after switching the illumination light source off. Herein, an industrial spinning process was carried out to produce nonwoven fibrous mat from polypropylene plastic waste. Poly(propylene-co-methy1 methacrylate) binder was synthesized via free-radical polymerization of borane-containing polypropylene and methyl methacrylate. A screen-printing composite of rare-earth strontium aluminate nanoparticles and poly(propylene-co-methy1 methacrylate) binder was printed onto recycled nonwoven polypropylene fabrics to introduce photochromic and photoluminescent textiles. Direct application of aqueous pigment-binder composites comprising various ratios of inorganic pigment with outstanding thermal and photostability was deposited onto polypropylene textiles. Screen printing allowed for the application of a consistent photoluminescent layer onto polypropylene surface. The printed nonwoven polypropylene samples had their excitation tracked at 368 nm, and an emission wavelength at 519 nm. The printed cloth with lower phosphor concentrations were found to reversibly emit a green color only under ultraviolet light, demonstrating fluorescence emission. At greater phosphor concentrations, a reversible green emission was monitored under the excitation light source, and greenish-yellow afterglow in the dark. A number of analytical techniques were used to gather microscopic information on the morphology of pigment nanoparticles and printed polypropylene textiles. The phosphor nanoparticles were measured to have diameters of 8–23 nm as reported by transmission electron microscopy (TEM), while X-ray diffraction examination revealed a crystal size of 21 nm. Increasing the pigment ratio enhanced the fabric UV protection, antibacterial activity, and superhydrophobicity. Upon increasing the pigment ratio, the contact and sliding angles were observed to increase in the ranges of 127.5°–160.4° and 11-7°, respectively. The impacts of phosphor ratio on comfort and colorfastness were examined.

P22 Fabrication methodologies for antimicrobial polypropylene surfaces with leachable and non-leachable antimicrobial agents

Abstract Objectives Develop a methodology for the fabrication of antimicrobial polypropylene (PP) surfaces with (i) leachable copper (II) chloride dihydrate (CuCl2·2H2O) and (ii) non-leachable magnesium hydroxide (Mg (OH)2) biocides. Methods and results Two methodologies are used to develop antimicrobial PP surfaces. One method involves melt blending and subsequent injection moulding, where the biocide additives were compounded with PP and subsequently injection moulded. The other method involves the thermal embossing of antimicrobial agents on the surface of a PP substrate. The obtained biocide-bearing PP surfaces were evaluated against Escherichia coli K-12 MG1655 for 0, 4 and 24 h to evaluate their antimicrobial properties. The injection-moulded PP bearing 5% CuCl2·2H2O showed a 6-log reduction of E. coli K-12 MG1655 after 24 h, while only 1 log reduction was observed for PP bearing 5% Mg (OH)2. The thermally embossed PP surfaces bearing CuCl2·2H2O and Mg (OH)2 particles (at a concentration of 10 mg/mL) showed 3 log and 4 log reduction, respectively, against E. coli K-12 MG1655 after 24 h. Conclusions The results clearly demonstrate that CuCl2·2H2O conferred antimicrobial properties to PP surfaces that were prepared by both injection moulding and thermal embossing approaches owing to the presence of leachable copper ions. In contrast, the non-leachable Mg (OH)2 imparted antimicrobial properties only to the surface prepared via the thermal embossing technique. Significance and impact Plastics with leachable biocides are effective antimicrobial surfaces, but their toxicity is a major concern. This study provides a fabrication methodology for non-leachable PP-based antimicrobial surfaces that are potentially safer. In addition, this strategy can be extended to many other plastic substrates.

Antibacterial Effects of a Carbon Nitride (CN) Layer Formed on Non-Woven Polypropylene Fabrics Using the Modified DC-Pulsed Sputtering Method.

In the present study, the surface of non-woven polypropylene (NW-PP) fabric was modified to form CN layers using a modified DC-pulsed (frequency: 60 kHz, pulse shape: square) sputtering with a roll-to-roll system. After plasma modification, structural damage in the NW-PP fabric was not observed, and the C-C/C-H bonds on the surface of the NW-PP fabric converted into C-C/C-H, C-N(CN), and C=O bonds. The CN-formed NW-PP fabrics showed strong hydrophobicity for H2O (polar liquid) and full-wetting characteristics for CH2I2 (non-polar liquid). In addition, the CN-formed NW-PP exhibited an enhanced antibacterial characteristic compared to NW-PP fabric. The reduction rate of the CN-formed NW-PP fabric was 89.0% and 91.6% for Staphylococcus aureus (ATCC 6538, Gram-positive) and Klebsiella pneumoniae (ATCC4352, Gram-negative), respectively. It was confirmed that the CN layer showed antibacterial characteristics against both Gram-positive and Gram-negative bacteria. The reason for the antibacterial effect of CN-formed NW-PP fabrics can be explained as the strong hydrophobicity due to the CH3 bond of the fabric, enhanced wetting property due to CN bonds, and antibacterial activity due to C=O bonds. Our study presents a one-step, damage-free, mass-productive, and eco-friendly method that can be applied to most weak substrates, allowing the mass production of antibacterial fabrics.

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.