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Blend homogeneous films of chitosan and water-soluble methoxy poly(ethylene glycol)-b-poly(e-caprolactone) (MPEG-b-PCL) diblock copolymer with different blend ratios were prepared by aqueous solution blending method. The water-soluble MPEG-b-PCL was synthesized using MPEG with molecular weight of 5000 g/mol and stannous octoate as the initiating system. The molecular weight of MPEG-b-PCL obtained from 1 H-NMR was 5800 g/mol. FTIR spectra of the blend films showed that there were intermolecular bonds between chitosan and MPEG-b-PCL. Thermal properties of the blend films strongly depended on the blend ratios. Scanning electron micrographs indicated that the blend films were homogeneous films. However, roughness of the blend films increased whereas transparency and moisture uptake decreased upon increasing the MPEG-b-PCL blend ratios.

Herein we report the synthesis, and optical and electrochemical properties of a rhodamine-appended polyterthiophene network thin film which demonstrates ion selective potentiometric, chromic and fluorescent responses. The rhodamine-appended terthiophene monomer (RhoT) was electropolymerized and deposited on an ITO electrode. Ion selective potentiometric studies have shown that the potentials of the conducting polymer films decreased upon adding Hg 2+ because interactions of Hg 2+ with the rhodamine-appended conducting polymer film may increase charge carrier transport properties on a conjugated polymer through rhodamine-bound Hg 2+ , reduce the doping states by interfering with ions through ion-ion interactions, and perturb the p-extended conjugated polymer through p-p interactions. Moreover, the lower detection limit of the ultrathin film sensor toward Hg 2+ (0.10 mM) was less than that obtained from RhoT (1.34 mM), and the response time was less than 30 seconds.Reusability was evaluated by repeating dipping and rinsing cycles in aqueous Hg 2+ and EDTA solutions. This approach may provide an easily measurable and inherently sensitive method for Hg 2+ ion detection in environmental and biological applications.