ABSTRACT
Water-soluble conducting polymers are of interest to enable more versatile processing in aqueous media as well as to facilitate interactions with biomolecules. Here, we report a substituted poly(3,4-ethylenedioxythiophene) derivative (PEDOT-S:H) that is fully water-soluble and self-doped. When electrochemically oxidizing a PEDOT-S:H thin film, the film detaches from the underlying electrode. The oxidation of PEDOT-S:H starts with an initial phase of swelling followed by cracking before it finally disrupts into small flakes and detaches from the electrode. We investigated the detachment mechanism and found that parameters such as the size, charge, and concentration of ions in the electrolyte, the temperature, and also the pH influence the characteristics of detachment. When oxidizing PEDOT-S:H, the positively charged polymer backbone is balanced by anions from the electrolyte solution and also by the sulfonate groups on the side chains (more self-doping). From our experiments, we conclude that detachment of the PEDOT-S:H film upon oxidation occurs in part due to swelling caused by an inflow of solvated anions and associated water and in part due to chain rearrangements within the film, caused by more self-doping. We believe that PEDOT-S:H detachment can be of interest in a number of different applications, including addressed and active control of the release of materials such as biomolecules and cell cultures.
Subject(s)
Electrolytes/chemistry , Water/chemistry , Anions , Bridged Bicyclo Compounds, Heterocyclic/chemistry , Electrochemistry , Electrodes , Hydrogen-Ion Concentration , Materials Testing , Microscopy, Atomic Force , Oxygen/chemistry , Polymers/chemistry , Solubility , Solvents/chemistry , TemperatureABSTRACT
Let it grow: The conjugated polymer poly(3,4-ethylenedioxythiophene) (PEDOT) was synthesized with heparin as the counterion to form a cell culture substrate. The surface of PEDOT:heparin in the neutral state associated biologically active growth factors. Electrochemical inâ situ oxidation of PEDOT during live cell culture decreased the bioavailability of the growth factor and created an exact onset of neural stem cell differentiation.
