Biofouling, which is the undesirable growth of marine organisms on artificial surfaces including ship hulls, aquaculture cages, and pipelines, may cause serious problems for mariners, such as excessive consumption of fuel, initiation of corrosion, increased frequency of dry-docking and the introduction of invasive species. So the creation of effective antibiofouling surfaces is a very challenging task. Ionic liquids have not only unique chemical properties but interesting physical and biological properties as well. Poly(ionic liquid)s act as a new class of functional polymer materials with unique properties combining those of molecular ionic liquids and specific properties of polymers, such as film formation and processibility. However, the biological properties of poly(ionic liquid)s have not yet been reported so far.

The surface/interface research group at the State Key Laboratory of Solid Lubrication, Lanzhou Institute of Chemical Physics (LICP), Chinese Academy of Sciences (CAS), has grated poly(ionic liquid) brushes onto substrates surfaces very efficiently via the surface initiated ring opening metathesis polymerization from catecholic initiator.

The poly(ionic liquid) brushes showed very good stability in aqueous solution and provided significantly good anti-microbial function in comparison with conventional anti-bacterial ammonium based polymer brushes. The evaluation of anti-bacterial and anti-biofouling properties of poly(ionic liquid) brushes show that poly(ionic liquid) brushes can obviously resist adhesion of Chlorella spores and the counter-anions have a key impact on the anti-microbial property. The poly(ionic liquid) coated TiO2 nanomaterials have excellent anti-bacterial properties compared to pristine TiO2 nanoparticles against both E. coli and S. aureus.

The eco-friendly poly(ionic liquid)–TiO2 nanomaterials can be applied to various anti-microbial applications ranging from light activated systems to the dark sterilization approach.

The work has received support from National Natural Science Foundation of China, the Key Research Program of the CAS. The findings have been published in J. Mater. Chem.(J. Mater. Chem., 2012, 22, 13123).

Moreover, the surface/interface research group has prepared the ionic liquid-based anti-fouling coatings. The experimental results in the East China Sea, Yellow Sea and South China Sea show that ionic liquid-based anti-fouling coatings have excellent anti-fouling effect. Three patents about the anti-fouling coatings have been applied.( Patent application serial number: 201110369543.7, 201110369516.X, 201110425357.0 )

 Grafting poly(ionic liquid) brushes for anti-bacterial and anti-biofouling via surface initiated ring opening metathesis polymerization. (Image by ZHOU Feng et al.)

 The experimental results of ionic liquid-based anti-fouling coatings after 3 months' immersion in seawater (April 2012-July 2012, South China Sea, Shenzhen). (Image by ZHOU Feng et al.)