Deposition of Copper on Polyester Knitwear Fibers by a Magnetron Sputtering System. Physical Properties and Evaluation of Antimicrobial Response of New Multi-Functional Composite Materials

: In this study, copper ﬁlms were deposited by magnetron sputtering on poly(ethylene terephthalate) knitted textile to fabricate multi-functional, antimicrobial composite material. The modiﬁed knitted textile composites were subjected to microbial activity tests against colonies of Gram-positive ( Staphylococcus aureus ) and Gram-negative ( Escherichia coli ) bacteria and antifungal tests against Chaetomium globosum fungal molds species. The prepared samples were characterized by UV / VIS transmittance, scanning electron microscopy (SEM), tensile and ﬁltration parameters and the ability to block UV radiation. The performed works proved the possibility of manufacturing a new generation of antimicrobial textile composites with barrier properties against UV radiation, produced by a simple, zero-waste method. The speciﬁc advantages of using new poly(ethylene terephthalate)-copper composites are in biomedical applications areas. deposition of coatings carried out in the atmosphere of argon, the distance between a copper target and the sputtering substrate was equal to 15 cm, the applied powers varied from 350 to 1000 W. The established optimal sputtering conditions were: the power discharge—700 W; the time of deposition—10 min; the resulting power density—0.72 W/cm 2 and the working pressure 2.0 × 10 − 3 mbar. The applied parameters were chosen on the basis of the previous research concerning the deposition of copper on the Polylactide (PLA) nonwoven fabrics. A preliminary study was performed for the purpose of another publication, which has recently published [111]. In order to choose the appropriate deposition parameters, the authors varied the sputtering power of the magnetron


Magnetron Sputtering
The knitted PETE samples were modified using a DC magnetron sputtering system produced by P.P.H. Jolex s. c. (Czestochowa, Poland), schematically presented in Figure 2. The deposition of coatings was carried out in the atmosphere of argon, the distance between a copper target and the sputtering substrate was equal to 15 cm, the applied powers varied from 350 to 1000 W. The established optimal sputtering conditions were: the power discharge-700 W; the time of deposition-10 min; the resulting power density-0.72 W/cm 2 and the working pressure 2.0 × 10 −3 mbar. The applied parameters were chosen on the basis of the previous research concerning the deposition of copper on the Polylactide (PLA) nonwoven fabrics. A preliminary study was performed for the purpose of another publication, which has been recently published [111]. In order to choose the appropriate deposition parameters, the authors varied the sputtering power of the magnetron

Magnetron Sputtering
The knitted PETE samples were modified using a DC magnetron sputtering system produced by P.P.H. Jolex s. c. (Czestochowa, Poland), schematically presented in Figure 2.

Magnetron Sputtering
The knitted PETE samples were modified using a DC magnetron sputtering system produced by P.P.H. Jolex s. c. (Czestochowa, Poland), schematically presented in Figure 2. The apparatus was developed for the Lukasiewicz Research Network-Textile Research Institute in Lodz, Poland-for the purpose of the project Envirotex -PO IG no. 01.03.01-00-006/08 cofinanced from the funds of European Regional Development Fund within the framework of the Operational Programme Innovative Economy 2007-2013. It allows the semi-continuous deposition of metallic coatings on different fabrics (up to 60 cm wide).
The deposition of coatings was carried out in the atmosphere of argon, the distance between a copper target and the sputtering substrate was equal to 15 cm, the applied powers varied from 350 to 1000 W. The established optimal sputtering conditions were: the power discharge-700 W; the time of deposition-10 min; the resulting power density-0.72 W/cm 2 and the working pressure 2.0 × 10 −3 mbar. The applied parameters were chosen on the basis of the previous research concerning the deposition of copper on the Polylactide (PLA) nonwoven fabrics. A preliminary study was performed for the purpose of another publication, which has been recently published [111]. In order to choose the appropriate deposition parameters, the authors varied the sputtering power of the magnetron The apparatus was developed for the Lukasiewicz Research Network-Textile Research Institute in Lodz, Poland-for the purpose of the project Envirotex-PO IG no. 01.03.01-00-006/08 co-financed from the funds of European Regional Development Fund within the framework of the Operational Programme Innovative Economy 2007-2013. It allows the semi-continuous deposition of metallic coatings on different fabrics (up to 60 cm wide).
The deposition of coatings was carried out in the atmosphere of argon, the distance between a copper target and the sputtering substrate was equal to 15 cm, the applied powers varied from 350 to 1000 W. The established optimal sputtering conditions were: the power discharge-700 W; the time of deposition-10 min; the resulting power density-0.72 W/cm 2 and the working pressure 2.0 × 10 −3 mbar. The applied parameters were chosen on the basis of the previous research concerning the deposition of copper on the Polylactide (PLA) nonwoven fabrics. A preliminary study was performed for the purpose of another publication, which has been recently published [111]. In order to choose the appropriate deposition parameters, the authors varied the sputtering power of the magnetron target from 350 up to 1000 W. At the same time, the sputtering time was changed from 10 to 30 min. The upper limit of the applied power was set as a result of our previous experiments showing Appl. Sci. 2020, 10, 6990 4 of 21 that higher values of power have destructive effect on the PLA substrate. The preliminary analysis of antimicrobial activity was carried out for the obtained samples. The results exhibited no antibacterial and antifungal effect for the sputtering power lower than 700 W. Taking into consideration the possible cytotoxicity of copper, the authors decided to choose the minimal sputtering power for which the antimicrobial activity was observed for further research. This allows us to minimize the content of copper and thus, minimizes the risk of cytotoxicity. In order to enable the comparison of results obtained for different materials, the authors decided to apply the same deposition parameters for the PETE substrate as for the PLA substrate. Since for the PLA nonwovens the observed antibacterial activity did not vary substantially between the samples subjected to 10 and 30 min of copper deposition, the authors decided to choose the lower deposition time in order to further limit the Cu content. Therefore, the final deposition parameters applied in this work were established at 700 W and 10 min for each side of the substrate.
In order to vary the copper content in the PETE-Cu (0) , composites two different deposition variants were applied, namely: 10 min single-sided deposition of copper on PETE (sample name: PETE-Cu (0) -1) and 20 min two-sided deposition of PETE (10 min for the upper and 10 min for the lower side of the sputtering fabric; sample name: PETE-Cu (0) -2; PETE-Cu (0) -2.1 and PETE-Cu (0) -2.2).

SEM/EDS-Scanning Electron Microscopy/Energy-Dispersive X-ray Spectroscopy
The microscopic analysis of fibers was performed on a Tescan Vega 3 scanning electron microscope (Tescan Analytics, Brno, Czech Republic) with the EDS (Oxford Instruments, Abingdon, UK) X-ray micro analyzer. The SEM microscopic examination of the surface topography was carried out in a high vacuum using the energy of the probe beam 20 keV. The layer of gold (approx. 3.5 nm), as a conductive substance, was sputtered on the samples before SEM analysis using a Quorum Technologies Ltd. (Lewes, UK) vacuum dust extractor. The instrument is fitted with a 57 mm diameter quick-change magnetron sputter target. Gas supplies: Argon. Vacuum: 5 × 10 −5 mbar. Magnifications of SEM applied were in the range from 500× to 20,000×. The performance of an EDS system was evaluated by measuring the resolution of a known set of elemental standards (Oxford Instruments, Abingdon, UK) in line with the ISO 15632:2012 [112].

FAAS-Flame Atomic Absorption Spectrometry
For the determination of copper content in PETE-Cu (0) , samples were assessed by prior sample mineralization (Figure 3), using a single-module Magnum II microwave mineralizer from Ertec (Wroclaw, Poland), followed by the determination of copper (II) ions by atomic absorption spectrometry with flame excitation using the Thermo Scientific Thermo Solar M6 (LabWrench, Midland, ON, Canada) spectrometer equipped with a 100 mm titanium burner, coded lamps with a single-element hollow cathode, background correction: D2 deuterium lamp.
Appl. Sci. 2020, 10, x 4 of 21 target from 350 up to 1000 W. At the same time, the sputtering time was changed from 10 to 30 min. The upper limit of the applied power was set as a result of our previous experiments showing that higher values of power have destructive effect on the PLA substrate. The preliminary analysis of antimicrobial activity was carried out for the obtained samples. The results exhibited no antibacterial and antifungal effect for the sputtering power lower than 700 W. Taking into consideration the possible cytotoxicity of copper, the authors decided to choose the minimal sputtering power for which the antimicrobial activity was observed for further research. This allows us to minimize the content of copper and thus, minimizes the risk of cytotoxicity. In order to enable the comparison of results obtained for different materials, the authors decided to apply the same deposition parameters for the PETE substrate as for the PLA substrate. Since for the PLA nonwovens the observed antibacterial activity did not vary substantially between the samples subjected to 10 and 30 min of copper deposition, the authors decided to choose the lower deposition time in order to further limit the Cu content. Therefore, the final deposition parameters applied in this work were established at 700 W and 10 min for each side of the substrate. In order to vary the copper content in the PETE-Cu (0) , composites two different deposition variants were applied, namely: 10 min single-sided deposition of copper on PETE (sample name: PETE-Cu (0) -1) and 20 min two-sided deposition of PETE (10 min for the upper and 10 min for the lower side of the sputtering fabric; sample name: PETE-Cu (0) -2; PETE-Cu (0) -2.1 and PETE-Cu (0) -2.2).

SEM/EDS-Scanning Electron Microscopy/Energy-Dispersive X-Ray Spectroscopy
The microscopic analysis of fibers was performed on a Tescan Vega 3 scanning electron microscope (Tescan Analytics, Brno, Czech Republic) with the EDS (Oxford Instruments, Abingdon, UK) X-ray micro analyzer. The SEM microscopic examination of the surface topography was carried out in a high vacuum using the energy of the probe beam 20 keV. The layer of gold (approx. 3.5 nm), as a conductive substance, was sputtered on the samples before SEM analysis using a Quorum Technologies Ltd. (Lewes, UK) vacuum dust extractor. The instrument is fitted with a 57 mm diameter quick-change magnetron sputter target. Gas supplies: Argon. Vacuum: 5 × 10 −5 mbar. Magnifications of SEM applied were in the range from 500× to 20,000×. The performance of an EDS system was evaluated by measuring the resolution of a known set of elemental standards (Oxford Instruments, Abingdon, UK) in line with the ISO 15632:2012 [112].

FAAS-Flame Atomic Absorption Spectrometry
For the determination of copper content in PETE-Cu (0) , samples were assessed by prior sample mineralization (Figure 3), using a single-module Magnum II microwave mineralizer from Ertec (Wroclaw, Poland), followed by the determination of copper (II) ions by atomic absorption spectrometry with flame excitation using the Thermo Scientific Thermo Solar M6 (LabWrench, Midland, Canada) spectrometer equipped with a 100 mm titanium burner, coded lamps with a singleelement hollow cathode, background correction: D2 deuterium lamp.  The total copper content of the sample M [mg/kg; ppm] was calculated according to the formula [113]: here:

UV-VIS Analysis and Determination of the Protective Properties Against UV Radiation
Changes of the physical properties as transmittance [%T] of samples occurring during modifications were assessed using a double beam Jasco V-550 UV-VIS spectrophotometer (Jasco, Tokyo, Japan) with an integrating sphere attachment in the range 200-800 nm. The same apparatus was used to determine the Ultraviolet Protection Factor (UPF) of samples, according to EN 13758-1:2002 standard [114], using the formula: where: E(λ)-the solar irradiance; ε(λ)-the erythema action spectrum (measure of the harmfulness of UV radiation for human skin); ∆λ-the wavelength interval of the measurements; T(λ)-the spectral transmittance at wavelength λ.
The UPF value of the samples was determined as the arithmetic mean of the UPF values for each of the samples, reduced by the statistical value depending on the number of measurements performed, at a confidence interval of 95%.

Filtration Parameters
Air permeability of the PETEknitted fabrics and PETE-Cu (0) composites was determined according to the EN ISO 9237:1998 standard [115]. An FX 3300 TEXTEST AG (Klimatest, Wrocław, Poland) permeability tester was applied. During the test, air at a pressure of 100 Pascal and 200 Pascal was passed through a fabric area of 20 cm 2 . Air permeability was determined as an average of 10 measurements for each type of sample.

Tensile Testing
Tensile testing of the PETE knitted fabrics and PETE-Cu (0) composites was performed in accordance with the EN ISO 10319:2015 standard [116]. A H5KS (Hounsfield, Redhill, UK) testing machine was used. The cross-head stretching speed was equal to 100 mm/min, the support spacing was 100 mm, while the width of the sample was 50 mm. The initial pressure force was set at 0.5 N. Measurements were carried out for both longitudinal and horizontal directions.

Thickness
Thickness measurements of the PETE knitted fabrics and PETE-Cu (0) composites were conducted in accordance with the EN ISO 5084:1999 standard [117]. The thickness of each sample was calculated as an average of 10 measurements. The area of the tested samples was equal to 20 cm 2 . The measurements were performed using a GM-70 thickness gauge (IW, Lodz, Poland) at the pressure of 1 kPa.

Thermal Resistance, Steam Resistance and Steam Permeability
Thermal resistance, steam resistance and steam permeability of the PETE knitted fabrics and PETE-Cu (0) composites were measured according to the EN ISO 11092:2014-11 [118] using a KONTECH apparatus (IW, Lodz, Poland). The application of this measurement technique is restricted to a maximum thermal resistance and water-vapour resistance e.g., 2 m 2 ·K/W and 700 m 2 ·Pa/W respectively. The airflow speed was set to 1.0 m/s.

Bacterial Activity
The antibacterial activity of PETE-Cu (0) composites was tested according to the PN-EN ISO 20645:2006 [119] against a colony of Gram-negative bacteria (Escherchia coli, ATCC 25922) and Gram-positive bacteria (Staphylococcus aureus, ATCC 6538), using the agar diffusion method of Muller Hinton. The test was initiated by pouring agar on to sterilized Petri dishes and it was allowed to solidify. The surfaces of agar media were inoculated by overnight broth cultures of bacteria (ATCC 25922: 1.2 × 10 8 CFU/mL, ATCC 6538: 1.7 × 10 8 CFU/mL) and kept at 4 • C before analysis. In order to establish the bacterial concentration inside the overnight culture the assessment of turbidity of bacterial suspension as well as the culture method were used. The density of the bacterial suspension was firstly determined using a calibrated densitometer. Then, using a series of ten-fold dilutions, the number of colonies grown on the plates was calculated from the appropriate dilutions and relevant calculations were made.
Discs of PETE-Cu (0) composites (10 mm) were placed onto the inoculated agar and incubated at 37 • C for 24 h. The diameter of the clear zone around the discs was measured as an indication of inhibition of the microbial species. Each side of the sample was tested in duplicate (four tests were performed for each sample). Simultaneously, the same tests were carried out for control samples-unmodified PETE samples.

Antifungal Activity
The procedure applied was partly identical with the procedure above. Thus, the antifungal activity of PETE-Cu (0) composites was tested according to PN-EN 14119:2005 [120] against a Chaetomium globosum (ATCC 6205). Discs of the tested PETE-Cu (0) composites (20 mm) were placed onto the inoculated with Chaetomium globosum fungal moulds species agar (pH:6.2) plates and incubated at 29 • C for 14 days. Both sides of PETE-Cu (0) composites were tested. The level of antifungal activity was assessed by examining the extent of fungal growth: in the contact zone between the agar and the specimen, on the surface of specimens and, if present, the extent of the inhibition zone around the specimen. All tests were carried out in duplicate. Simultaneously, the same tests were carried out for control samples (unmodified PETE). Hinton. The test was initiated by pouring agar on to sterilized Petri dishes and it was allowed to solidify. The surfaces of agar media were inoculated by overnight broth cultures of bacteria (ATCC 25922: 1.2 × 10 8 CFU/mL, ATCC 6538: 1.7 × 10 8 CFU/mL) and kept at 4 °C before analysis. In order to establish the bacterial concentration inside the overnight culture the assessment of turbidity of bacterial suspension as well as the culture method were used. The density of the bacterial suspension was firstly determined using a calibrated densitometer. Then, using a series of ten-fold dilutions, the number of colonies grown on the plates was calculated from the appropriate dilutions and relevant calculations were made. Discs of PETE-Cu (0) composites (10 mm) were placed onto the inoculated agar and incubated at 37 °C for 24 h. The diameter of the clear zone around the discs was measured as an indication of inhibition of the microbial species. Each side of the sample was tested in duplicate (four tests were performed for each sample). Simultaneously, the same tests were carried out for control samplesunmodified PETE samples.

Antifungal Activity
The procedure applied was partly identical with the procedure above. Thus, the antifungal activity of PETE-Cu (0) composites was tested according to PN-EN 14119:2005 [120] against a Chaetomium globosum (ATCC 6205). Discs of the tested PETE-Cu (0) composites (20 mm) were placed onto the inoculated with Chaetomium globosum fungal moulds species agar (pH:6.2) plates and incubated at 29 °C for 14 days. Both sides of PETE-Cu (0) composites were tested. The level of antifungal activity was assessed by examining the extent of fungal growth: in the contact zone between the agar and the specimen, on the surface of specimens and, if present, the extent of the inhibition zone around the specimen. All tests were carried out in duplicate. Simultaneously, the same tests were carried out for control samples (unmodified PETE).

Copper Determination in PETE-Cu (0) /Composites
Copper determination in PETE-Cu (0) composites was achieved using EDS spectroscopy (determination of surface located copper) and FAAS spectrometry (determination of bulk copper).

Copper Determination by Energy-Dispersive X-Ray Spectroscopy EDS
Comparison of the EDS analyses of PETE and PETE-Cu (0) composites are presented in Table 1.

Copper Determination in PETE-Cu (0) /Composites
Copper determination in PETE-Cu (0) composites was achieved using EDS spectroscopy (determination of surface located copper) and FAAS spectrometry (determination of bulk copper).

Copper Determination by Energy-Dispersive X-Ray Spectroscopy EDS
Comparison of the EDS analyses of PETE and PETE-Cu (0) composites are presented in Table 1.

Copper Determination in PETE-Cu (0) /Composites
Copper determination in PETE-Cu (0) composites was achieved using EDS spectroscopy (determination of surface located copper) and FAAS spectrometry (determination of bulk copper).

Copper Determination by Energy-Dispersive X-ray Spectroscopy EDS
Comparison of the EDS analyses of PETE and PETE-Cu (0) composites are presented in Table 1.  These differences can be caused by the different morphology of both sides of the knitted PETE textile (weave: interlock right) used for the copper sputtering deposition [121], influencing on a type of deposited copper. The Flame Atomic Absorption Spectrometry results advocate for the proportional increase of deposition of copper during the deposition. We also consider the influence of the already-formed copper layer on the copper diffusion inside bulk during sputtering of the second side of the textile (PETE-Cu (0) -2.2).
Is worth admitting that the distribution and penetration of the Cu atoms into the polymer beneath the interface, and the exact nature of the Cu-O-C bonds formed during polyarylamide PAMX D6 copper sputtering, are still unclear since Legois' work [122].

Copper Determination by Flame Atomic Absorption Spectrometry-FAAS
The results of copper content in PETE-Cu (0) composite samples determined by the FAAS method are listed in Table 2. The results inform about the whole copper concentration in starting PETE knitwear fibers and PETE-Cu (0) composites. These revealed that composites are practically null of copper in the starting PETE (0.003: %; m: 0.0004) with only 0.7% to 1.4% of copper in PETE-Cu (0) composites; in detail there was 0.67% (0.105 molal) of copper in one side of the sputtered knitwear fibers PETE-Cu (0) -1 and twice as high a copper concentration in the case of two-sided sputtering mode PETE-Cu (0) -2 (140%; 0.221 molal).
Taking into account the results of copper determination in PETE-Cu (0) -2.2 by EDS and in PETE-Cu (0) -2 by FAAS it can be assumed that during sputtering of the second side of PETE-Cu (0) -2 (PETE-Cu (0) -2 → PETE-Cu (0) -2.2) the diffusion of copper from the sputtering surface (PETE-Cu (0) -2.2) into bulk of polymer occurs, and there is copper diffusion in the polymer, analogous to earlier works on PET metallization [123][124][125].

UV-VIS Analysis and Determination of the Protective Properties Against UV Radiation
Poly(ethylene terephthalate) is transparent for UV, undergoing itself a surface modification under deep UV irradiation (e.g., [126,127]). The importance of protection against ultraviolet radiation (UV) is increasing daily. Investigations on poly(ethylene terephthalate) fibers' protection against solar ultraviolet radiation (UVR) have been frequently undertaken (e.g., [128][129][130]). The property of UVR protection exhibited by PETE-Cu (0) composites was investigated using a UV spectrophotometer by measuring the transmittance of UV-rays through the fabrics.
Thus, the transmittance spectra [%T] of starting PETE knitted textile and PETE-Cu (0) composites in the range λ = 200-800 nm are presented in Figure 6.

UV-VIS Analysis and Determination of the Protective Properties Against UV Radiation
Poly(ethylene terephthalate) is transparent for UV, undergoing itself a surface modification under deep UV irradiation (e.g., [126,127]). The importance of protection against ultraviolet radiation (UV) is increasing daily. Investigations on poly(ethylene terephthalate) fibers' protection against solar ultraviolet radiation (UVR) have been frequently undertaken (e.g., [128][129][130]). The property of UVR protection exhibited by PETE-Cu (0) composites was investigated using a UV spectrophotometer by measuring the transmittance of UV-rays through the fabrics.
Thus, the transmittance spectra [%T] of starting PETE knitted textile and PETE-Cu (0) composites in the range λ = 200-800 nm are presented in Figure 6. As shown in Figure 6, the transmittance of UV-rays of the PETE fabrics, PETE-Cu (0) -1 and PETE-Cu (0) -2 composites were different in the wavelength range examined. Thus, the PETE transmittance curve exhibited a complexed shape, with a sharp decrease in the 200-250 nm range from ca 14%T to ca 1.5 %T, then a slow increase from 1.5% T (310 nm) to 7% T (380 nm), a rapid decrease to 26%T at 420 nm and the plateau region to 600 nm and a further gradual increase to 29%T at 700 nm with the plateau to 800 nm. The PETE-Cu (0) -1composite exhibited null transmittance in the wavelength range 200 to 720 nm, with an increase to 3%T at the 720-800 nm range. The PETE-Cu (0) -2composite exhibited null transmittance in the full examined wavelength range 200 to 800 nm. As a result, the property of UVR protection of the both PETE-Cu (0) composites had improved significantly in almost the full wavelength range (excluding the 250-300 nm gap: 0%T for PETE-Cu (0) vs 1.5%T for PETE). As shown in Figure 6, the transmittance of UV-rays of the PETE fabrics, PETE-Cu (0) -1 and PETE-Cu (0) -2 composites were different in the wavelength range examined. Thus, the PETE transmittance curve exhibited a complexed shape, with a sharp decrease in the 200-250 nm range from ca 14%T to ca 1.5 %T, then a slow increase from 1.5% T (310 nm) to 7% T (380 nm), a rapid decrease to 26%T at 420 nm and the plateau region to 600 nm and a further gradual increase to 29%T at 700 nm with the plateau to 800 nm. The PETE-Cu (0) -1composite exhibited null transmittance in the wavelength range 200 to 720 nm, with an increase to 3%T at the 720-800 nm range. The PETE-Cu (0) -2composite exhibited null transmittance in the full examined wavelength range 200 to 800 nm. As a result, the property of UVR protection of the both PETE-Cu (0) composites had improved significantly in almost the full wavelength range (excluding the 250-300 nm gap: 0%T for PETE-Cu (0) vs 1.5%T for PETE).
The transmittance (%T) spectra of PETE and PETE-Cu (0) composites in the range λ = 290-400 nm (UV A and UV B) are presented in Figure 7.
Appl. Sci. 2020, 10, x 10 of 21 The transmittance (%T) spectra of PETE and PETE-Cu (0) composites in the range λ = 290-400 nm (UV A and UV B) are presented in Figure 7. On the basis of these transmittance measurements obtained for PETE knitted textile and PETE-Cu (0) composites at λ = 290-400 nm, corresponding UPF values have been calculated [114]. UPF values of PETE knitted textile and PETE-Cu (0) composites, calculated on the basis of transmittance measurements for λ = 290-400 nm ( Figure 6), have been listed in the Table 3. The results have been measured in triplicate and presented as a mean value with. ±deviation approximately 2%.
These data revealed that both PETE-Cu (0) composites possess UPF(PETE-Cu(0)) values > 50 in comparison with, UPF(PETE) values ~37 indicating that the magnetron sputtering modification performed imparts proper barrier properties of PETE knitted textile against UV radiation.

Technical Parameters
From several technical parameters affecting fabric behavior [131], we applied for PETE-Cu (0) composites utility verification analyses of filtration parameters, tensile strength, thickness as well as thermal resistance, steam resistance and steam permeability.

Filtration Parameters
Filtration parameters, expressed by the air permeability, present one of the major properties of textile materials and are governed by factors like the fabric structure, density, thickness and surface characteristics. The comparisons of air permeability of PETE-Cu (0) composites vs. PETE fabric are shown in Table 4. The obtained results indicated that the modification of PETE fabrics with copper On the basis of these transmittance measurements obtained for PETE knitted textile and PETE-Cu (0) composites at λ = 290-400 nm, corresponding UPF values have been calculated [114]. UPF values of PETE knitted textile and PETE-Cu (0) composites, calculated on the basis of transmittance measurements for λ = 290-400 nm ( Figure 6), have been listed in the Table 3. The results have been measured in triplicate and presented as a mean value with. ±deviation approximately 2%.
These data revealed that both PETE-Cu (0) composites possess UPF (PETE-Cu(0)) values > 50 in comparison with, UPF (PETE) values~37 indicating that the magnetron sputtering modification performed imparts proper barrier properties of PETE knitted textile against UV radiation.

Technical Parameters
From several technical parameters affecting fabric behavior [131], we applied for PETE-Cu (0) composites utility verification analyses of filtration parameters, tensile strength, thickness as well as thermal resistance, steam resistance and steam permeability.

Filtration Parameters
Filtration parameters, expressed by the air permeability, present one of the major properties of textile materials and are governed by factors like the fabric structure, density, thickness and surface characteristics. The comparisons of air permeability of PETE-Cu (0) composites vs. PETE fabric are shown in Table 4. The obtained results indicated that the modification of PETE fabrics with copper coating moderately (16%-18%) decreases the air permeability from 65.5 mm/s to 54.5 mm/s at 100 Pa and from 147 mm/s to 123 mm/s at 200 Pa. Moreover, a slightly further reduction in the air permeability (51.8 mm/s at 100 Pa and 117 mm/s at 200 Pa) was observed for the sample coated with copper on both sides. Therefore, it may be concluded that the coating of PETE with copper minimally affected filtration parameters. Observed results may be associated with the changes of porosity of the sample due to the presence of the copper coatings on the surface.

Tensile Strength
The results of tensile testing, i.e., tensile strength [kN/m] and elongation at maximum load [%], of PETE fabric and PETE-Cu (0) composites, determined in longitudinal and horizontal modes, are listed in Table 5. The results have been measured in triplicate and presented as a mean value.
The results presented opposite tendencies regarding as well elongation determined for PETE and PETE-Cu(0) in longitudinal and horizontal modes. Thus, ca 10% increase of tensile strength in longitudinal mode for PETE-Cu (0) in comparison with starting PETE fibre (7.8-7.6 vs 7.0 [kN/m]) is accompanied by corresponding ca 3% decrease in horizontal mode (6.0 vs 6.2 [kN/m]), respectively. At the same time, the differences of tensile strengths, measured for PETE-Cu (0) -1 and PETE-Cu (0) -2 in both modes are negligible.
Similarly, the elongation at maximum load increases ca 6% from 375% for PETE to 396%-403% for PETE-Cu (0) fabrics in longitudinal mode and decreases ca 5% from 421% for PETE to 405%-413% for PETE-Cu (0) fabrics in horizontal mode, respectively. At the same time, the differences in the elongations at maximum load, measured for PETE-Cu (0) -1 and PETE-Cu (0) -2 are negligible (lay in error limit).

Thickness
The data of thickness of the unmodified PETE fabrics and PETE-Cu (0) composites are listed in Table 6. These data displayed negligible differences with the average values of measured thickness at 1 kPa in the range of 0.66-0.67 mm. The results have been measured in triplicate and presented as a mean value, estimated to two decimal point.

Thermal Resistance
The measured thermal resistance, steam resistance and steam permeability of PETE fabric and PETE-Cu (0) composites are listed in Table 7. The results have been measured in triplicate and presented as a mean value, estimated to three decimal points.
The obtained results of thermal resistance exhibited a 1.75-2.25 fold increase of PETE-Cu (0) composites in comparison with starting PETE fabrics, namely from 0.004 m 2 K/W for PETE to 0.007 m 2 K/W for PETE-Cu (0) -1 (the one-side metaled sample) and 0.009 m 2 K/W for PETE-Cu (0) -2 (the sample coated on both sides), respectively.
Recapitulating, the metallization of PETE fabrics increased the thermal resistance and steam resistance of obtained composites PETE-Cu (0) in comparison with the starting PETE fabrics in degrees dependent on the copper content. The opposite trend was observed for steam permeability, with a decrease of permeability increasing with the copper content.

Antibacterial Activity
The PETE-Cu (0) samples were subjected to antimicrobial activity tests against Gram-negative Escherichia coli (ATCC11229) and Gram-positive Staphylococcus aureus (ATCC 6538). The inhibition experiment results for PETE and PETE-Cu (0) are presented in Figure 8. The similar pictures have been obtained for PETE and PETE-Cu (0) against Staphylococcus aureus species.
The results of tests on the antibacterial activity of PETE-Cu (0) composites against Escherichia coli and Staphylococcus aureus are illustrated in Table 8. The results revealed strong visible inhibition zones of bacterial growth on Petri dishes ( Figure  8), and therefore proved antimicrobial protection of metallized surface of PETE-Cu (0) against representative Gram-negative (Escherichia coli) and Gram-positive (Staphylococcus aureus) bacteria (Table 8).

Antifungal Activity
Results of antifungal activity tests against a colony of Chaetomium globosum (ATCC 6205) of PETE fabrics and PETE-Cu (0) composites are illustrated in Figure 9 and listed in Table 9. The similar pictures have been obtained for PETE and PETE-Cu (0) against Staphylococcus aureus species.
The results of tests on the antibacterial activity of PETE-Cu (0) composites against Escherichia coli and Staphylococcus aureus are illustrated in Table 8. The results revealed strong visible inhibition zones of bacterial growth on Petri dishes (Figure 8), and therefore proved antimicrobial protection of metallized surface of PETE-Cu (0) against representative Gram-negative (Escherichia coli) and Gram-positive (Staphylococcus aureus) bacteria (Table 8).

Antifungal Activity
Results of antifungal activity tests against a colony of Chaetomium globosum (ATCC 6205) of PETE fabrics and PETE-Cu (0) composites are illustrated in Figure 9 and listed in Table 9.

Antifungal Activity
Results of antifungal activity tests against a colony of Chaetomium globosum (ATCC 6205) of PETE fabrics and PETE-Cu (0) composites are illustrated in Figure 9 and listed in Table 9.
(a) (b) (c)  The results revealed strong visible inhibition zones of fungal growth on Petri dishes (Figure 9), and therefore proved antifungal protection of metallized surface of PETE-Cu (0) against Chaetomium globosum ( Table 9).
The results revealed that the unmodified PETE sample induced the strong fungal growth-covering of the entire surface of the control sample (Figure 9a). At the same time PETE-Cu (0) composites equipped with copper layers/clusters on the composite surface provided antifungal properties for both-PETE-Cu (0) -1 and PETE-Cu (0) -2 composites.
(2) The structural characterizations of the new PETE-Cu (0) polymer composites obtained, were characterized by Scanning Electron Microscopy (SEM) and UV/VIS transmittance. The chemical compositions of the PETE-Cu (0) composites obtained were achieved using Energy-Dispersive X-ray Spectroscopy, EDS (C, O, Cu surface analysis) and Atomic Absorption Spectrometry with Flame Excitation, FAAS (Cu content in the bulk).
(3) The application utility of the PETE-Cu (0) composites was established by determination of their technical parameters, including filtration parameters, tensile strength, thickness, thermal and steam resistance, steam permeability, the barrier properties against UV radiation and also antimicrobial tests against Escherichia coli, Staphylococcus aureus and Chaetomium globosum fungus species.
(4) SEM images of PETE-Cu (0) composites revealed that the applied magnetron sputtering of the starting PETE textile did not exhibit substantial destruction of the textile structure. Moreover, the described PETE-Cu (0) composites have shown improvement of the technical parameters, including air permeability and thermal and steam resistance. PETE-Cu (0) composites exhibited improvement of barrier properties against UV radiation in comparison with the unmodified PETE sample.
(5) Determined antimicrobial properties of PETE-Cu (0) composites revealed the significant antibacterial action of both PETE-Cu (0) -1 as well as PETE-Cu (0) -1 composites against Escherichia coli, Staphylococcus aureus and Chaetomium globosum fungus species. (6). Recapitulating, the PETE-Cu (0) composites obtained, due to exhibited beneficial antibacterial and also technical properties, can find an application in a medical sector, for example, as a microbial barrier material.