SURFACE CHARACTERISTICS OF FLUOROALKYLSILICONE - POLY(METHYL METHACRYLATE) BLOCK COPOLYMERS AND THEIR PMMA BLENDS

Surface properties of fluoroalkylsilicone—poly(methyl methacrylate) block copolymers and their poly(methyl methacrylate) (PMMA) blends have been intensively studied to draw a relationship between surface segregation behavior and adhesion performance. The fluoroalkylsilicone—PMMA block copolymers containing thre kinds of fluoroalkyl side chains (i.e., 3,3,3‐trifluoropropyl) (CF3CH2CH2−, abbreviated as TFP), tridecafluoro‐1,1,2,2‐tetrahydrooctyl [F3C(CF2)5CH2CH2−, TFO], and heptadecafluoro‐1,1,2,2‐tetrahydrodecyl groups [F3C(CF2)7CH2CH2−, HFD] on the siloxane chains were prepared according to the macroazoinitiator method. Contact angle measurement and X‐ray photoelectron spectroscopy (or ESCA) were used to obtain structural information on the surface of the solution‐cast films. A significant effect of fluroalkyl groups on the surface accumulation not only in silicon but also fluorine atoms were observed for relatively long fluoroalkyl side chains (i.e., TFO and HFD). On the contrary, TFP group was found to be effective to orient to the hydrophilic surfaces (i.e. glass‐side surfaces). The surface accumulation of fluoroalkyl groups in the films was also reflected by the 180° peel strength against pressure‐sensitive adhesives as a measure of the adhesion performance. These results indicated that incorporation of relatively long fluoroalkyl groups much enchanced the surface hydrophobicity (and/or oleophobicity) of solution‐cast films in addition to that of the siloxane‐enriched surfaces. The composition and orientation of the functional groups on the surface were also speculated based on ESCA data. Copyright © 1990 John Wiley & Sons, Inc.