| As an important solid surface characteristic, the wettability has a significantimpact on a variety of activities in everyday life, industrial and agricultural production.Due to many important applications of controlled wettability surfaces onstimulus-response devices, self-cleanness, discrete liquid droplet manipulators ortunable optical lenses and so on, to construct easily-prepared new materials with highgrafting density, stable contact with the subtrate,controllable structure and surfaceroughness, reversible switching between superhydrophilicity and superhydrophobicityhas been attracting interests of the material scientists.There have been many ways to be used for control of surface wettability, such assurface morphology manipulation, organic polymer layer coating and surfacechemical composition control and so on. Among them surface grafting teclinique hasmuch more attracted researcher's interests for the covalently immobilized chemicalbond between the polymer layer and solid surface. Surface-initiated radicalpolymerization (SIRP) can form highly oriented and high grafting density polymerfilms with controllable molecular weight and molecular weight distribution.Functional poly (ionic liquids) are the first choices to achieve reversiblewettability due to their structural characteristics which can be easily introduced ontomaterial surface via SIRP, and the reversible wettability of the surface can be achievedby simple counteranion exchange.In this work, different poly (ionic liquids) brushes have been successfullygrafted onto different material surface via surface initiated radical polymerization, andthen reversible wettability is achieved by choosing proper counter anions.At first a novel functional ion liquid monomer [allyltriphenylphosphoniumhexafluoro-phosphate] (ATPP-PF6) was synthesized, Then using newly-preparedATPP-PF6 as a monomer, with 2-bromoisobutyryl bromide and3-aminopropyltriethoxysilane as the surface initiator, 2, 2, 6, 6-tetramethylpiperidine1-oxyl (TEMPO) as the radical initiator, cyclohexanone as the solvent, well-definedpoly[allyltriphenylphosphonium hexafluorophosphate] brushes with tunablewettability using surface-initiated nitroxide-mediated radical polymerization (NMP) are grafted onto the silicon surface.Using [1-(4-vinylbenzyl)-3-butyl imidazolium hexafluorophosphate (VBIm-PF6)synthesized according to reference method as a monomer, with 2-bromoisobutyrylbromide and 3-aminopropyltrimethoxysilane as the surface initiator, SmCl3 as thecatalyst, lactic acid as the ligand, AIBN as the radical initiator, DMF as the solvent,well-defined PVBIm-PF6 brushes with tunable wettability by a reverse surfaceinitiated atom transfer radical polymerization(RATRP) are grafted onto the coppersurface.Using VBIm-PF6 as a monomer, with 2-bromoisobutyryl bromide and3-aminopropyltriethoxysilane as the surface initiator, 2, 2, 6, 6-tetramethylpiperidine1-oxyl (TEMPO) as the radical initiator, xylene as the solvent, well-definedPVBIm-PF6 brushes with tunable wettability by using surface-initiatednitroxide-mediated radical polymerization (NMP) are grafted onto the siliconsubstrate.X-ray photoelectron spectroscopy, contact angle measurements, ellipsometry,atomic force microscopy and gel permeation chromatography, nuclear magneticresonance (1H and 13C NMR) spectra are employed to characterized praparedmonomers and polymer filoms respectively. The results have indicated that polymerbrushes growth from the surfaces are a controlled process with a"living"characteristic. Furthermore, the surfaces of poly(ionic liquids) brushes with tunablewettability, reversible switching between hydrophilicity and hydrophobicity can beeasily achieved by exchanging their counteranions. |
