Multiresponsive behavior of functional poly(p-phenylene vinylene)s in water

The multiresponsive behavior of functionalized water-soluble conjugated polymers (CPs) is presented with potential applications for sensors. In this study, we investigated the aqueous solubility behavior of water-soluble CPs with high photoluminescence and with a particular focus on their pH and temperature responsiveness. For this purpose, two poly(phenylene vinylene)s (PPVs)-namely 2,5-substituted PPVs bearing both carboxylic acid and methoxyoligoethylene glycol units-were investigated, with different amount of carboxylic acid units. Changes in the pH and temperature of polymer solutions led to a response in the fluorescence intensity in a pH range from 3 to 10 and for temperatures ranging from 10 to 85 degrees C. Additionally, it is demonstrated that the polymer with the largest number of carboxylic acid groups displays upper critical solution temperature (UCST)-like thermoresponsive behavior in the presence of a divalent ion like Ca2+. The sensing capability of these water-soluble PPVs could be utilized to design smart materials with multiresponsive behavior in biomedicine and soft materials

Spontaneous stacking of electrospun conjugated polymer composite nanofibers producing highly porous fiber mats

We produced novel composite nanofibers based on poly(6,6′-((2-methyl-5-((E)-4-((E)-prop-1-en-1-yl)styryl)-1,4-phenylene)bis(oxy))dihexanoic acid)/poly(lactic acid) (PDMP/PLA), using electrospinning technique. The composite nanofibers have a diameter in the range of 50–150 nm and present a novel morphology consisting of spontaneously stacked nanofibers creating a “wall-like” structure that then collectively form a “honeycomb” structure. As low as 0.5–1 wt% of the photoluminescent PDMP was able to produce this type of morphology. The pore size depends on the amount of PDMP incorporated in the nanofibers. The highly fluorescent and porous nanofibers mats provide good biosensing substrates. We provide evidence that the composite nanofibers can be used to construct a simple oligonucleotide (ODN) sensor, where capture probe ODNs (capODN) were covalently grafted onto the carboxylic acid functionalities of the composite nanofibers and the reporting ODN carries a reporting chromophore dye. The results indicate potential of such nanofiber mats as biosensor