Mh. Hung et Rr. Burch, FUNCTIONALIZATION AND METALLIZATION OF FLUOROPOLYMER SURFACES THROUGHREDUCTION, Journal of applied polymer science, 55(4), 1995, pp. 549-559
Fluoropolymer films, such as Teflon(TM)-TFE [poly(tetrafluoroethylene)
], Teflon(TM)-FEP [copolymer of tetrafluoroethylene and hexafluoroprop
ylene], Teflon(TM)-PFA [copolymer of tetrafluoroethylene and perfluoro
(propyl vinyl ether)], and PCTFE [poly(chlorotrifluoroethylene)], are
reduced by the mild reducing agent benzoin dianion/DMSO, while Teflon(
TM)-AF [copolymer of tetrafluoroethylene and perfluoro-2,2-dimethyl-1,
3-dioxole] is unreactive. The reduction makes the films adherable towa
rd epoxy resins, the adhesive strength decreasing in the order PCTFE >
PFA greater than or equal to FEP > PTFE. Surprisingly, Teflon(TM)-AF
films are totally inert except when the TFE content is high, and in th
ese cases, the adhesive strength of Teflon(TM)-AF is close to that of
PTFE. The surfaces of PTFE, FEP and PFA films are further modified by
first treating these films with the benzoin dianion/DMSO reagent and t
hen with an excess of sodium salts of mercaptans. Reactive PTFE films
that are light colored with a metallic luster are formed rather than t
he dark, metallic color typical of PTFE surface reduction without merc
aptan treatment. These films have poor adhesion toward epoxy resins bu
t good adhesion toward gold applied by sputtering. FEP and PFA films b
ehaved similarly. These results are attributed to the incorporation of
sulfur onto the reduced surface. Unreduced fluoropolymer films reacte
d with only sodium mercaptan fail to show C-S bond incorporation. This
newly developed method can be used to selectively metallize the fluor
opolymer film surface with gold layers and affords very high conductiv
ity of the metallized regions. (C) 1995 John Wiley and Sons, Inc.