Pulsed plasma polymerization of hexamethyldisiloxane onto wool : control of moisture vapor transmission rate and surface adhesion

A new fabric with potential in medical textiles has been developed by application of a surface coating on wool using pulsed plasma polymerization of HMDSO. This coating enabled a controllable MVTR and surface adhesion. MVTR in the range recommended for optimum wound healing was obtained by varying frequency, monomer pressure and deposition time. Lower surface adhesion was achieved. Peeling tests, contact angle measurements, SPM force curves and ATR FT-IR were used to characterize the surfaces for both wool and a PE model substrate. All these results were consistent with a decrease in surface energy after PP-HMDSO treatment. ATR FT-IR results showed a siloxane film with less organic Si(CH₃)_n groups and more SiOSi cross-links.

Reducing the pilling propensity of wool knits with a three-step plasma treatment

A three-step plasma treatment, including surface activation with argon, surface functionalization with oxygen and then thin film deposition using a pulsed plasma polymerization of hexamethyldisiloxane (HMDSO), was used in low-pressure plasma to improve the pilling resistance of knitted wool fabric. The pilling propensity of the treated samples was investigated and compared with the pilling propensity of untreated, argon activated and oxygen functionized samples and argon and oxygen plasma-treated samples that were afterwards subject to continuous wave plasma polymerization of HMDSO. With the three-step treatment, a pilling grade of four was achieved for the treated wool fabric, while that of untreated and other plasma-treated was two and three, respectively. For the three-step plasma-treated sample, a uniform HMDSO polymer coating of 300 nm thickness was obtained; X-ray photoelectron spectroscopy (XPS) showed the presence of the silicone element, and Fourier transform infrared (FTIR) spectroscopy confirmed the chemical structure of the coating. No apparent differences were found in the whiteness index between the treated and untreated wool knits, but there was deterioration in the bursting strength and handle of the plasma-treated wool samples.