(206f) Preparation and Low Fouling Property of Amphiphilic Fluorinated Block Copolymers (PEGMA-co-MMA)-b-PC6SMA

ABSTRACT

Compared with
traditional
biocide-based marine antifouling paints, novel environmentally benign antifouling coatings are designed
mainly on surface physico-chemical and bulk materials properties. In particular, advances
in nanotechnology and
polymer science, and the development
of novel surface designs 'bioinspired' by nature, are
expected to have a significant
impact on the development of a new generation of environmentally friendly
marine coatings. Therefore, understanding the
correlation between the structure and the properties of the surface of a
material and the tuning of appropriate chemical-physical properties at a
molecular level may contribute to the development of novel materials for anti-biofouling application.

Among the
many environmentally benign coatings, currently in vogue are amphiphilic nanostructured
coatings, which incorporate some of the benefits of both hydrophobic and
hydrophilic functionalities. Such coatings are designed to create a dynamic
surface with local variations in surface chemistry, topography and mechanical
properties, i.e., a surface with a compositional, topological, and
morphological complexity. In general, the heterogeneous surfaces are created
through thermodynamically driven phase segregation, for example, of mutually
incompatible block copolymers, followed by cross-linking in situ.

Amphiphilic polymer
coatings design may be based on blends of immiscible polymers or contrasting
chemistries of block copolymers, which would readily lead to the formation of
dynamic surfaces through phase segregation, driven by the chemical
incompatibility of the different components. As we all know, fluorinated
polymers imbue typical characteristics such
as low surface energy, high chemical and thermal resistance and distinct
self-assembly behavior. While hydrophilic poly(ethylene
glycol) (PEG), which possesses a low polymer¨Cwater interfacial energy,
demonstrates excellent resistance to protein adsorption and cell adhesion.
Furthermore, poly(ethylene glycol) (PEG) can
potentially  possess other
desirable properties such as water
affinity, low toxicity, high biocompatibility. Thus, in our study, the [N-methyl-perfluorohexane-1-sulfonamide]ethyl
methacrylate (C₆SMA) possessing excellent fluoropolymer
properties was selected as hydrophobic, fluorinated component, and Poly(ethylene glycol) methyl ether methacrylate (PEGMA) was chosen as hydrophilic component.
Therefore the amphiphilic fluorinated block
copolymers P(PEGMA-co-MMA)-b-PC₆SMA
prepared herein present an opportunity for combining the favorable
properties of the fluorinated blocks with those of the P(PEGMA) blocks.

In our study,
a series of amphiphilic fluorinated block copolymers P(PEGMA-co-MMA)-b-PC₆SMA consisting of hydrophilic poly(ethylene glycol) methyl ether methacrylate (PEGMA) and
hydrophobic fluorinated [N-methyl-perfluorohexane-1-sulfonamide] ethyl methacrylate (C₆SMA) components were successfully prepared by controlled reversible
addition fragmentation chain transfer (RAFT) polymerization in solution. The copolymer was characterized by FT-IR,
nuclear magnetic resonance proton spectrum (¹H NMR) and gel
permeation chromatography (GPC). When the mass content of PEGMA was less than
40%, static contact angle, ¦È, with water and n-hexadecane
pointed to the simultaneous hydrophobic and lipophobic
character of the films. Dynamic contact angle measurements demonstrated that copolymer film surface underwent
reconstruction after contact with water owing to its amphiphilic
nature. Consistent
with the enrichment of the outer film surface of fluorinated segments, X-ray photoelectron spectroscopy (XPS) measurements
proved that a remarkable difference of chemical composition existed between bulk and
surface. The atomic force microscopy (AFM) images
(tapping mode) revealed distinct microphase
segregation structure of nanostructured films. Moreover, our study explored protein
adsorption characteristics of the amphiphilic fluorinated copolymer surface through experiments with bovine serum albumin (BSA). Fluorescence
microscopy analysis using BSA labelled with fluorescein isothiocyanate
(BSA¨CFITC) was performed on the amphiphilic copolymer surface to establish the polymer's protein adsorption resistance. The
results proved that amphiphilic fluorinated block copolymer material had an excellent protein adsorption resistance.

Scheme 1. Synthesis of amphiphilic fluorinated
diblock copolymer