Self-assembled monolayers and titanium dioxide: From surface patterning to potential applications

Abstract

SummaryThe ability to control the properties of self-assembled monolayers (SAMs) attached to solid surfaces and the rare photocatalytic properties of titanium dioxide provide a rationale for the study of systems comprising both. Such systems can be realized in the form of SAMs grown on TiO2 or, in a complementary manner, as TiO2 grown on SAMs. Accordingly, the current status of knowledge regarding SAMs on TiO2 is described. Photocatalytic phenomena that are of specific relevance to SAMs, such as remote degradation, and cases where SAMs were used to study photocatalytic phenomena, are discussed as well. Mastering of micro-patterning is a key issue en route to a successful assimilation of a variety of titanium dioxide based devices. Accordingly, particular attention is given to the description of a variety of methods and techniques aimed at utilizing the photocatalytic properties of titanium dioxide for patterning. Reports on a variety of applications are discussed. These examples, representing the areas of photovoltaics, microelectronics, microelectromechanics, photocatalysis, corrosion prevention and even biomedicine should be regarded as appetizers paving the way for further studies to be performed.

Fluorophosphonate-functionalised titanium via a pre-adsorbed alkane phosphonic acid: a novel dual action surface finish for bone regenerative applications

“…The bonds formed between TiO 2 and APAs are robust and covalent in nature and include mono-, bi-and tri-dentate phosphonate units as self-assembled monolayers. These metal-OP bonds are superior in stability to those formed between metal and OSi when using silanes [12,13]. The application of an APA to enhance Ti surface wettability of a dental implant device (SurfLink®) has recently shown promise as a successful APA-functionalised surface [14].…”

Influence of alkylphosphonic acid grafting on the electronic and magnetic properties of La2/3Sr1/3MnO3 surfaces

“…Another application of SAMs is the surface modification of materials [3] to tune, for example, electrodes work functions and thus carriers injection/extraction in organic devices [4] such as organic field effect transistors and organic light-emitting diodes or solar cells. In many cases [5,6,7], phosphonic acids have been used to functionalize the extensively used transparent metal oxide electrodes in organic devices.…”

Crafting positive/negative patterns and nanopillars of polymer brushes by photocatalytic lithography

“…18 According to the mechanism depicted in Figure 2a, the pillars would arise from the zones where the particles actually touch the substrate, efficiently screening the underlying initiator molecules from the etching action of ROS, while the "carpet" would originate from inter-particle spaces. …”

“…Moreover, compared to conventional UV-lithography, it does not require powerful (and potentially dangerous) light sources. 18 We reported, in a recent paper 20 , the first successful application of both direct and remote photocatalytic lithography as an innovative, easy and versatile technique for micro-patterning of polymer brushes. The obtained results prompted us to undergo a systematic exploration of the opportunities offered by such technique for the micropatterning of functional, stimuli-responsive polymer brushes.…”

“…[13][14][15] This is the suggested working principle of photocatalytic lithography, which can be performed both in a "direct" and a "remote" fashion. [16][17][18] In direct photocatalytic lithography, as the name suggests, the pattern is obtained directly on the surface of titanium dioxide by irradiation with UV light through a photomask. If the titania surface is covered with an organic monolayer, selective degradation of the latter will be obtained in the UV-exposed zones.…”