Abstract
In this work, a polyvinyl alcohol (PVA) thin film was modified by exposure to a dielectric barrier discharge argon plasma. The plasma was generated by a sinusoidal power supply with discharge voltage of 4.75 kV (rms), and frequency of 30 kHz at duty cycle 6.13%. The effect of the plasma on the PVA thin film was investigated by analyzing the contact angle, scanning electron microscopy, atomic force microscopy, X-ray photoelectron spectroscopy, and UV–visible spectroscopy. After the plasma treatment, the contact angle was found to be decrease from 29.6 ± 0.4° to 14.5 ± 0.2°, which implied that the surface property had changed to a hydrophilic state caused by an increase in the surface roughness and introduction of oxygen, including a polar carbonyl group. It was found that the plasma-treated hydrophilic PVA thin film exhibited excellent antifogging and highly transparent characteristics, making it an appropriate material for food packaging and green houses.
Highlights
IntroductionPolymers as structural materials have tremendous attention in the industrial[1,2] and biomedical field[1,2,3] owing to their excellent material properties such as low density, high flexibility, and high chemical resistance.[4] Despite these excellent characteristics, polymers are often unsuitable for certain applications because of their low surface free energy,[2,4,5,6,7] leading to poor wettability and poor adhesion.[8] It has been suggested that the reason polymer films have such low wettability and adhesion is the lack of surface polar groups.[9] Various methods such as wet chemical processing, flame spraying, radiation,[10] plasma processing,[11] and ion implantation[12] are available for modifying the surface properties of polymers.[1] all the aforementioned techniques may not be sustainable; the ecological requirements demand a search for an eco-friendly method.[6,13,14] In the last two decades, plasma treatment of polymers has been gaining more attention as a surface modification technique because it does not require the use of chemicals.[15] it can be considered as an environmentally beneficial technology.[6,16] The plasma method is a low-temperature,[11] nontoxic, low-cost, easy to handle, flexible, and effective process.[17,18]
Over the few decades, polymers as structural materials have tremendous attention in the industrial[1,2] and biomedical field[1,2,3] owing to their excellent material properties such as low density, high flexibility, and high chemical resistance.[4]
After 10 minutes of plasma treatment, the water contact angle is significantly decreased to 14.5 ± 0.2○, as depicted in Fig. 3(c), exhibiting that plasma treatment can be used for the improvement of the surface wettability[43] of polyvinyl alcohol (PVA) thin films
Summary
Polymers as structural materials have tremendous attention in the industrial[1,2] and biomedical field[1,2,3] owing to their excellent material properties such as low density, high flexibility, and high chemical resistance.[4] Despite these excellent characteristics, polymers are often unsuitable for certain applications because of their low surface free energy,[2,4,5,6,7] leading to poor wettability and poor adhesion.[8] It has been suggested that the reason polymer films have such low wettability and adhesion is the lack of surface polar groups.[9] Various methods such as wet chemical processing, flame spraying, radiation,[10] plasma processing,[11] and ion implantation[12] are available for modifying the surface properties of polymers.[1] all the aforementioned techniques may not be sustainable; the ecological requirements demand a search for an eco-friendly method.[6,13,14] In the last two decades, plasma treatment of polymers has been gaining more attention as a surface modification technique because it does not require the use of chemicals.[15] it can be considered as an environmentally beneficial technology.[6,16] The plasma method is a low-temperature,[11] nontoxic, low-cost, easy to handle, flexible, and effective process.[17,18]
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