Microstructure and surface state of plasma-treated high-density polyethylene elucidated by energy-tunable positron annihilation and water contact angle measurements

Abstract

Positron gamma ray spectroscopy coupled with an energy-tunable positron beam was utilized to the study of the microstructure in polyethylene (PE) modified by the radio-frequency (RF) plasma. The energy dependence of the line-shape S parameter, a measure of the Doppler broadening of the positron radiation, confirmed that the change in the hydrophilic state of the PE surface after plasma modification was due to the altered chemical structure in the near-surface region. Moreover, only a region at a depth shallower than 700 nm was influenced by the plasma modification. The recovery in the surface hydrophobicity after plasma modification was observed through contact angle measurements. The variation of the contact angle of water can be fitted by a two-factor decay model, suggesting that the surface recovery is caused by the diffusion of two different groups.

Anticoagulant Polyethylene Terephthalate Surface by Plasma-Mediated Fucoidan Immobilization

“…Heparin is a well-known anticoagulant polysaccharide for avoiding blood thrombus, but its biggest drawbacks are hemorrhage and thrombocytopenia. Furthermore, it may cause animal-based infections since it is mostly obtained from animals [29,30,31,32,33].…”

A New Route of Fucoidan Immobilization on Low Density Polyethylene and Its Blood Compatibility and Anticoagulation Activity

“…Some of the polymeric materials (such as polyolefins) have low surface energy and lack adequate enough bonding interfaces which makes them challenging substrates for further surface modification; as such, surface treatment is essential [ 15 , 16 ]. Functionalization of biomaterials by means of surface treatment is possible by several methods, such as corona discharge, UV irradiation, wet chemistry, flame treatment, ozone induced treatment, flame treatment, and plasma treatment [ 17 , 18 , 19 ].…”

“…Altering the plasma parameters, such as diversity of used gas with its flow rate, reactor type and pressure, generated power, and frequency creates different types of plasma for individual applications like sterilization, deposition, chain scission, ion etching, cross-linking, polymerization, surface activation, etc. [ 15 , 17 , 20 ]. Controlling the process efficiency is possible by changing the exposure time.…”

“…Thrombus inhibition by anticoagulant fucoidan is a promising strategy to avoid thrombus formation. Heparin is another polysaccharide (see Figure 1 a) that has been used as an anticoagulant for several years [ 15 , 25 , 26 ]. The biggest drawback of heparin is hemorrhaging and thrombocytopenia [ 25 , 26 , 27 ].…”