Electrically-Conductive Polyketone Nanocomposites Based on Reduced Graphene Oxide

In this work, we investigated the functionalization of polyketone 30 (PK30) with glycyl-glycine (Gly-Gly) via the Paal-Knorr reaction with the aim of homogenously dispersing two types of reduced graphene oxide (rGO, i.e., lrGO and hrGO, the former characterized by a lower degree of reduction in comparison to the latter) by non-covalent interactions. The functional PK30-Gly-Gly polymer was effective in preparing composites with homogeneously distributed rGO characterized by an effective percolation threshold at 5 wt. %. All the composites showed a typical semiconductive behavior and stable electrical response after several heating/cooling cycles from 30 to 115 °C. Composites made by hrGO displayed the same resistive behaviour even if flanked by a considerable improvement on conductivity, in agreement with the more reduced rGO content. Interestingly, no permanent percolative network was shown by the composite with 4 wt. % of lrGO at temperatures higher than 45 °C. This material can be used as an ON-OFF temperature sensor and could find interesting applications as sensing material in soft robotics applications

Immobilization of rhodamine 6G in calcium alginate microcapsules based on aromatic–aromatic interactions with poly(sodium 4-styrenesulfonate)

Artículo de publicación ISIImmobilization of rhodamine 6G in calcium alginate microcapsules was achieved using the polyanion bearing negatively charged aromatic groups poly(sodium 4-styrenesulfonate) as complexing agent. The immobilization of the dye by this method finds its basis on the stabilization of the dye/polymer complex by short-range aromatic–aromatic interactions, which are resistant to the cleaving effect of highly concentrated electrolytes. On the contrary, direct immobilization of the dye in the microcapsules resulted unsuccessful due to its high diffusion coefficient in the aqueous medium, and complexation with poly(sodium vinylsulfonate) did not improve the immobilization, since the corresponding complex is based on long-range electrostatic interactions, which are easily cleaved under the high ionic strength conditions of the microcapsule formation reaction. Thus, the present investigation represents a proof of concept on the use of aromatic–aromatic interactions between polyelectrolytes bearing charged aromatic rings and their aromatic counterions as a tool to achieve improved functionalities. The release of the rhodamine 6G/poly(sodium 4-styrenesulfonate) complex from the microcapsules has been investigated as a function of pH and temperature. Coating the microcapsules with chitosan allowed minimizing the release of the dye from the microcapsules.FONDECYT (Grants Nos. 1090341, 1120514, and 11121481) and Innova-CORFO (Grant No. 07-CN-13-PPT- 256