Surface engineering through responsive polymer brushes

Introduction:

Polymer brushes refer to an assembly of polymer chains, which are tethered by one end to a surface. Because, tethering of the chains in close proximity to each other, forces the chains to stretch away from the surface to avoid overlap. There are several types of polymer brushes with molecular structures sensitive to environmental changes, such as pH, electric field, chemical species, and temperature.

Research:

The aim of this project is to design smart polymer architectures that are covalently attached to a substrate via the ``grafted to`` method. The advantage of this method is that very smooth and well-defined interfaces can be achieved. Stimuli responsive polymer brushes have the possibility to tune the surface properties ``on`` and ``off``. We will work with temperature and pH sensitive brushes that can respond to a sudden change with aforementioned external triggers. Especially, water soluble temperature responsive polymer, poly(N-isopropylacrylamide) (PNIPAM) and pH sensitive poly(acrylic acid) (PAA) are the main subjects of this assignment. PNIPAM, for instance, exhibits a lower critical solution temperature (LCST) and undergoes a reversible phase transition at this critical temperature (32 °C). PNIPAM is in the stretched form (``on state``) at T < 32 ° while it goes to coiled formation (``off state``) at T > 32 °C. Creating such thermoresponsive brushes enables us to control surface properties, which can switch between on and off. The goal of the project is to create well-defined smart brush films to be used in biosensor applications and in membrane technology, as they will simultaneously have responsive and antifouling properties.

Dr. Namik Akkilic n.akkilic@utwente.nl

Dr. Wiebe de Vos w.m.devos@utwente.nl