Photo-Induced Grafting of Monomers on Prewetted Fiber Substrates

Abstract

Photo-induced graft polymerization of acrylic monomers on fiber surfaces pre-wetted with water or aprotic polar solvents is reviewed. The role of solvent-induced fiber swelling and monomer penetration in the grafting process is examined. The role of dyes, biacetyl, metal oxides, polar solvents, and hydrogen donors as accelerants in photo-grafting is explored. Grafting of monomers introduced as vapors is compared with grafting of monomers applied from wetting solution, and the nature of polymer deposition is considered for both systems. The physical and chemical properties of the resultant fiber grafts are examined and compared with untreated fibers. Grafting is shown to have a marked effect on the dyeing and color characteristics of the fibers. Photo-induced vapor phase grafting of acrylic monomers on pre-wetted fibers is shown to proceed rapidly with little homopolymer formation or interfiber bonding to give modified fabrics that retain major aesthetic characteristics and yet have improved properties dependent on the polymer grafted. Dye-Sensitized Photografting on Fibers Immersed in Monomer SolutionsDye-sensitized photopolymerizations of moderate to high concentrations (>10%) of acrylic monomers have been studied extensively (1-10); however, until 1967 little was known concerning dye-sensitized graft photopolymerizations onto fibers.In general, dye-sensitized photopolymerizations at low monomer concentrations required the presence of small quantities of oxygen and a mild reducing agent (added or as part of the dye-moiety) to give photosensitized initiation of polymerization by dyes. The rate of dyesensitized photopolymerizations was proportional to the square of the monomer concentration Ç2, 7_ 9 8), so photopolymerizations of low monomer concentrations (>5%) proceeded very slowly if at all and essentially no polymerization of monomer was noted after 4