Chemical imaging of self-assembling structures in Langmuir–Blodgett films of polymer blends

Abstract

The ability of tailoring surface properties is crucial in a large number of applications, so that a wide range of surface engineering techniques has been developed in the last decades. Among these techniques, those based on the surface functionalization by means of self-assembled monolayers and Langmuir–Blodgett (LB) films are peculiarly attractive because of, simplicity, versatility. In particular, this work concerns the functionalization of insulating surface with macromolecular systems disguised as LB films. In particular, we will show that patterned LB films of poly(2-vinylpyridine) (P2VP) and polystyrene (PS) blends can be obtained by careful control of the ratio of polymer components in the blend. Surface separation phase phenomena, crucial to the patterning purposes, can be evidenced by ToF-SIMS chemical imaging. Furthermore, the film morphology can be thoroughly examined by means of scanning probe microscopies (SPM) techniques. It will be shown that three main types of structures can be obtained by changing the ratio between two polymers. In particular, by increasing the relative amount of PS, structures with different shapes can be fabricated. Round-shaped structures have been obtained by using low relative quantity of PS, single wires and entangled wires have been obtained by using relative intermediate quantity of PS and high relative quantity of PS, respectively.