title: Thermal and UV Hydrosilylation of Alcohol-Based Bifunctional Alkynes on Si (111) surfaces: How surface radicals influence surface bond formation.
abstract: Using two different hydrosilylation methods, low temperature thermal and UV initiation, silicon (111) hydrogenated surfaces were functionalized in presence of an OH-terminated alkyne, a CF3-terminated alkyne and a mixed equimolar ratio of the two alkynes. XPS studies revealed that in the absence of premeditated surface radical through low temperature hydrosilylation, the surface grafting proceeded to form a Si-O-C linkage via nucleophilic reaction through the OH group of the alkyne. This led to a small increase in surface roughness as well as an increase in hydrophobicity and this effect was attributed to the surficial etching of silicon to form nanosize pores (~1-3 nm) by residual water/oxygen as a result of changes to surface polarity from the grafting. Furthermore in the radical-free thermal environment, a mix in equimolar of these two short alkynes can achieve a high contact angle of ~102°, comparable to long alkyl chains grafting reported in literature although surface roughness was relatively mild (rms = ~1 nm). On the other hand, UV initiation on silicon totally reversed the chemical linkages to predominantly Si-C without further compromising the surface roughness, highlighting the importance of surface radicals determining the reactivity of the silicon surface to the selected alkynes.
authors.affiliation: University of Milan-Bicocca, Department of Materials Science Via R. Cozzi 55, I-20125 Milan (Italy).|Regenerative Medicine Cluster, Advanced Medical and Dental Institute (AMDI) Universiti Sains Malaysia, Penang (Malaysia).
authors.forename: Y L
authors.initials: YL
authors.lastname: Khung
authors.affiliation: Regenerative Medicine Cluster, Advanced Medical and Dental Institute (AMDI) Universiti Sains Malaysia, Penang (Malaysia).
authors.forename: S H
authors.initials: SH
authors.lastname: Ngalim
authors.affiliation: University of Milan-Bicocca, Department of Materials Science Via R. Cozzi 55, I-20125 Milan (Italy).
authors.forename: A
authors.initials: A
authors.lastname: Scaccabarozi
authors.affiliation: University of Milan-Bicocca, Department of Materials Science Via R. Cozzi 55, I-20125 Milan (Italy).
authors.forename: D
authors.initials: D
authors.lastname: Narducci