Spreading Behavior of Poly(<i>N</i>-(polyfluoroalkyl)acrylamide) Monolayers and Langmuir−Blodgett Film Formation

Abstract

The spreading behavior of monolayers of poly( N -(polyfluoroalkyl)acrylamide)s having various fluorocarbon chain lengths at the air−water interface was investigated by measurement of surface pressure−surface area isotherms to prepare fluorinated polymer LB films. The monolayer properties strongly depend on the length of the fluorocarbon chains. The monolayer of N -(1H,1H-heptafluorobutyl)acrylamide polymer (C 3 F 7 AA) formed an expanded monolayer, N -(1H,1H-pentadecafluorooctyl)acrylamide polymer (C 7 F 15 AA) and (2-(perfluorooctyl)ethyl)acrylamide polymers (C 8 F 17 AA) formed liquidlike fluid condensed monolayers, and the (2-(perfluorodecyl)ethyl)acrylamide (C 10 F 21 AA) monolayer was rigid crystalline. The polymer monolayers except C 10 F 21 AA can be transferred onto solid substrates, and uniform polymer LB films can be prepared. The wettability and the surface structure of the LB films were also investigated by measuring the static contact angle (θ) of water on the surface. The surface structure was discussed from the critical surface tension, which was estimated by measuring the contact angles of several n -alkanes on the film surface.