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SynopsisA group of natural materials having anhydroglucose units linked by glycosidic bonds, as well as other related compounds, were irradiated with plasmas generated by a radio frequency field (13.56 MHz). Reactive sites created were characterized by electron spin resonance, chemiluminescence, infrared, and x-ray photoelectron spectroscopy. The free radicals are related to the number of glycosidic bonds, and their decays result in chemiluminescence. In the absence of moisture and oxygen, however, the radicals are stable. During plasma irradiation, carbonyl groups as well as free radicals are formed on surfaces, and the atom ratio of oxygen to carbon on surfaces increases. Within the reactor, thin films of polymers can be deposited on cotton fabrics by allowing the monomer to enter the reactor above the fabric that is in a horizontal position downstream from the external electrodes.

Radiofrequency (rf) cold plasmas of argon, nitrogen, and air were used to modify cotton fabrics and yarns. Changes in surface characteristics were detected by application of the techniques of electron emission spectroscopy for chemical analyses (ESCA), electron spin resonance, and chemiluminescence. Examples of polymerization of selected monomers and depolymerization of chemically modified cottons within rf plasmas have been used to illustrate potentials of combinations of plasmas and ESCA in cellulose chemistry.

Cotton printcloth was treated with low-temperature, low-pressure argon plasma created by passing argon gas through a radiofrequency electric field of 13.56 MHz. Fabrics were exposed to plasma for 0–90 min. Pressure was maintained at 100 millitorrs and RF power at 40 watts. Plasma-treated cottons wetted readily and uniformly with water and aqueous dye solutions. Loss of weight on relatively long plasma treatment was greater than that due to usual removal of moisture under reduced pressure. Spectral changes observed by x-ray photoelectron-emission spectroscopy and infrared spectroscopy indicated surface oxidation of the cotton, and electron-spin-resonance spectra showed presence of free radicals. Although surface oxidation occurred, gross topographical changes of the cotton surface were not evident, even when viewed under the scanning electron microscope. The rate of wetting of argon-activated cotton was significantly greater than it was prior to plasma treatment. At comparable immersion times the amount of water wicked into an argon-activated cotton fabric was about twice that taken up by untreated material. The rate of drying was also faster after plasma treatment.

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