ABSTRACT
Photocatalytic lithography is proved for the realization of micropatterned polymer brushes. Initiator-functionalized titanium dioxide or silicon surfaces are respectively exposed directly to near-UV light through a photomask (direct approach) or through a transparent photoactive TiO2 film (remote approach). Initiator patterns are then amplified as polymer brushes with SI-ATRP. Features down to 10 µm could be obtained using simple equipment. The process is intrinsically parallel, has high throughput and scalable to wafer size, making it powerful for microfabrication purposes.
ABSTRACT
The assessment of the surface free energy (SFE) of a material permits to control and predict a large number of physicochemical properties of a solid surface and its reactivity. Here, the surface energies of a series of bare and fluorinated silanes are determined by means of different semi-empirical models on the grounds of contact angle determinations for different solvents. Literature data are also considered in order to produce a series of films with increasing SFE. Wetting envelopes (WE) are obtained for the various surfaces in order to predict the wettability of the films by numerous commonly employed solvents. The polar and disperse components of the surface energies are obtained by the Owens-Wendt-Rabel-Kaelbe (OWRK) method; the values of the polar components are compared with gas-phase dipole moments obtained by theoretical calculations employing semi-empirical Hamiltonians. The sequences of the polar components of the SFE and of the calculated dipole moments for the different molecules are strictly the same. The interplay between theoretical and experimental approaches proves efficient in predicting the behavior of different systems and it could be employed in tuning the SFE of a solid surface with respect to its final applications.
