Facile Approach to Grafting of Poly(2-oxazoline) Brushes on Macroscopic Surfaces and Applications Thereof

Abstract

This study reports on a facile and versatile approach for modification of macroscopic surface via grafting of multifunctional poly(2-oxazoline) molecules in brush-like conformation. For this purpose, carboxyl-terminated poly(2-isopropyl-2-oxazoline) molecules have been synthesized by ring-opening cationic polymerization and subsequently grafted on underlined substrates by exploiting the "grafting to" approach. A systematic variation in thickness of the grafted poly (2-isopropyl-2-oxazoline) brushes has been demonstrated. Polymer-modified surfaces have been characterized by means of a number of analytical tools including ellipsometry, X-ray photoelectron spectroscopy, ultraviolate spectroscopy, attenuated total reflection infrared spectroscopy and atomic force microscopy. Interestingly, poly(2-isopropyl-2-oxazoline) molecules have been found to retain their physical properties even after grafting on macroscopic surfaces. Finally, fabricated polymer brushes have been used as platform for stabilization of inorganic nanoparticles on macroscopic surfaces.

Temperature-Dependent Adsorption and Adsorption Hysteresis of a Thermoresponsive Diblock Copolymer

“…17 The formation and loss of hydrogen bonds due to temperature variations in poly(2-isopropyl-2-oxazoline) brush layers prepared by the grafting-to method has been observed by ATR-FTIR, which was detected as a temperature-reversible upward shift of the adsorption band of the amide groups. 12 Another interesting feature is that the PIPOZ chains adopt mostly trans conformations above T c , which facilitates interchain dipolar interactions between amide groups and possibly promotes partial organization of the chains. 17,19 The conformational change decreases the steric repulsion between the polymer chains and new favorable interactions may occur since the new conformation is reminiscent of the conformation of the chain in the crystal, and this is likely to facilitate increased polymer adsorption and further dehydration of the adsorbed layer.…”

Design Strategies for Functionalized Poly(2-oxazoline)s and Derived Materials

“…Only films with a grafting density of pMeOx of 0.33 (highest density with a surface potential close to zero) were able to inhibit the adhesion of bacteria. Stamm, Agrawal and co-workers synthesized p(ester) n PrOx-block-p i PrOX block copolymers that were grafted (after alkaline deprotection of the carboxylic acids of the first block) onto poly(glycidyl methacrylate)-coated silicon wafers [115]. The chemical reaction between the carboxylic acid groups and the epoxy units of the poly(glycidyl methacrylate) layer provided chemical attachment of the poly(2-oxazoline)s on the silicon wafers in brush-like conformation.…”

“…Characterization of these films was carried out by ellipsometry. Carboxyl-functionalized block copoly(2-oxazoline)s were synthesized by Agrawal, Stamm and co-workers after alkaline cleavage of the carboxylic acid protection groups of p( n Pr-ester)Ox 4 -block-p i PrOx 100 [115]. These copoly(2-oxazoline)s were subsequently grafted onto poly(glycidyl methacrylate) spincoated on a silicon substrate.…”

Probing carbonyl–water hydrogen-bond interactions in thin polyoxazoline brushes

“…[5][6][7] In the past years, another class of temperature-responsive polymers has been used to fabricate biocompatible switchable surfaces, namely, poly(2-alkyl-2-oxazoline)s (POx). 8,9 POx were first synthesized in the 1960s, [10][11][12][13] but their potential use in surface modification has been explored only recently. 14 The thermoresponsive behavior of POx and PNIPAAm involves changes in polymer-polymer and polymer-water interactions around the polymers' lower critical solution temperatures (LCST).…”

“…The previously mentioned studies address POx in solution. Only a few publications exist about the switching behavior of thin POx films, 8,9 and these involve only noncyclic poly(2-oxazoline)s like PiPrOx. In the present study, in situ infrared spectroscopic ellipsometry (IRSE) was applied to characterize the thermoresponsive behavior of POx brush films consisting of either PcPrOx or a statistical copolymer containing 75% cPrOx and 25% MeOx.…”