Excimer laser induced surface photochemical reaction of 1,2-diaminoethane with poly(tetrafluoroethylene)

Poly(tetrafluoroethylene) (PTFE or Teflon) is notable for its nonadhesive and nonreactive character. Successful surface photochemical modification of Teflon using liquid 1,2-diaminoethane and lambda = 193 nm ArF excimer laser light was demonstrated. The surfaces were analyzed by X-ray photoelectron spectroscopy (XPS), atomic force microscopy, and liquid contact angle and gluing tensile strength measurements. Due to the photomodification the originally poor adhesive property of the PTFE surface was dramatically improved. Surfaces were glued by epoxy resin and the tensile strength of gluing increased by 150 times over that of the unirradiated samples. The surface was metalized electrolessly with silver on selected areas following patterned phototreatment. As a result of the photochemical reaction, hydrophilic and oleophilic property developed on the surfaces at the same time. The water and benzene contact angles decreased from 94 degrees to 40 degrees and from 31 degrees to 0 degrees, respectively. The removal of fluorine and the incorporation of both alkyl groups and nitrogen were identified on XPS spectra. The reaction cross section was determined from water contact angle and XPS results. It was found to be as high as (1.3-1.6) x 10(-17) cm(2). A radical or a photoinduced electron transfer mechanism is suggested to describe the photoreaction.