2014 AIChE Annual Meeting, Paper ID: 361967

Programmed Design and Synthesis of Fluorinated

Gradient Copolymer for Photo-Reversibly Switchable

Hydrophobic Surface

Yin-Ning Zhou, Zheng-Hong Luo*
Department of Chemical Engineering, School of Chemistry and Chemical Engineering, Shanghai Jiao Tong University, Shanghai 200240, China
*Correspondence to: Professor Z.H. Luo; E-mail: luozh@sjtu.edu.cn

Abstract:

Functional surfaces and surface coatings as a key area of concern in almost all industrial fields have attracted increasing attentions in the past few years, which include easy-cleaning and/or self-cleaning properties, switchability properties responding to external stimuli, and long-term stability.1,2 Among them, smart surfaces or smart coatings with tunable wettability
induced by external environment are interesting3,4 and have applications in separators,5 chemical
valves,6 sensors,7 microfluidic devices,8 and so on.
In addition, the microstructure control of monomers along the polymer chain has revitalized and become an intriguing topic in polymer chemistry because sequence regulation has a vital impact on the spatial placement of functionality, polymer morphology and properties.9 The recent development of reversible-deactivation radical polymerization (RDRP) techniques provides an effective platform for the realization of the precision polymerization with gradient composition.10-15
In this work, a novel photo-controlled smart surface was fabricated by gradient copolymer
with fluoroalkyl and spiropyran side chains. The polymeric product is poly(2,2,3,3,4,4,4-heptafluorobutyl methacrylate-grad-2-(2-bromoisobutyryloxy)ethyl methacrylate-graft-[1'-(2-methacryloxyethyl)-3',3'-dimethyl-6-nitrospiro-(2H-1-benzopyran-2,2'-i ndoline)]) (abbreviated as poly(HFBMA-grad-BIEM-graft-SPMA)) and was synthesized via atom transfer radical polymerization (ATRP) with programmed design feeding strategy for main chain gradient structure and graft-from method for side chains.

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2014 AIChE Annual Meeting, Paper ID: 361967

Focusing on the strategy of new product development in the perspective of chemical product engineering, the product characterizations, switching mechanism analysis and performance evaluation were carried out for confirming the manufacture of new product, and followed by an aging test for ensuring the product application. The results show that the product enables surfaces with reversibly switchable wettability (Figure 1) and excellent stability (Figure 2) with eight irradiation cycles.

Thanks to the surface engineering technique (decorated with functional film and surface roughening), etched silicon surface possesses a fairly large variation range of WCA (28.1°) on smart surface fabricated by copolymer involving Sp moieties, and achieves the transformation between hydrophilicity and hydrophobicity based on blank sample. The synthetic strategy and developed smart surface offer a promising application in coating with controllable wettability in moisture resistant field, and also offers a new technique for the manipulation of liquids.

Figure 1. Photo-reversibly switchable hydrophobic surface fabricated by fluorinated gradient coplymer

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2014 AIChE Annual Meeting, Paper ID: 361967

Figure 2. Reversible photoresponsive wettability of flat glass slide, flat silicon and etched silicon substrates modified by fluorinated gradient copolymer

Keywords: Chemical product engineering, Model-based ATRP, Gradient copolymer, Photo-reversibly switchable hydrophobic surface

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2014 AIChE Annual Meeting, Paper ID: 361967

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