Post-funcionalización de polianilina con grupos precursores de la función vinilsulfona

Resumen de la comunicación presentada en la XXXI Reunión Bienal de la RSEQ, Toledo, 9-14 septiembre 2007En este trabajo se describe la obtención de polianilina modificada con grupos precursores de la función vinilsulfónica, bien conocida por su reactividad específica a fibras celulósicas (algodón, lino...) y proteicas (lana, seda...). Las cadenas modificadas se obtuvieron mediante un procedimiento de post-funcionalización mediante la reacción de acoplamiento con sales de diazonio, que ha demostrado ser una ruta útil y versátil de incorporación de grupos funcionales en polímeros conductores.Generalitat Valenciana (proyecto GV06-106) Ministerio de Educación y Ciencia (proyecto MAT2004-01479

Compact polyelectrolyte hydrogels of gelatin and chondroitin sulfate as ion's mobile media in sustainable all-solid state electrochemical devices

The creation of flexible and high strength hydrogel materials from natural polymers aslow cost and safe solid electrolytes is an area of intense research nowadays. We presenta novel approach for the preparation of gelatin and chondroitin sulfate hydrogelscomplexes by using a simple centrifugation process. The innovative dual-bio-gelnetworkis able to swell and shrink upon environmental changes on the pH and NaClconcentration. The solid bio-gels sandwiched between two macroporous carbonelectrodes materials are assembled in symmetric cells and their electrochemicalproperties are evaluated by cyclic voltammetry, galvanostatic, and impedancespectroscopy. The cells exhibit areal capacitance values by up to 2.74 mF/cm2 (3.1 F/g)and a low resistance value of 12 Ohm.cm2 for graphene electrode materials. Theseproperties are the consequence of the successful infiltration of the solid gel inside theporous structure of the carbon electrode that boosts the charge transfer at thebiopolymer/carbon electrode interphase. The results obtained may provide additionalinspiration in the emerging field of bioelectronics, where biocompatible and poweredsystems are of the utmost importance.Fil: Gonzalez, Jimena Soledad. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Mar del Plata. Instituto de Investigaciones en Ciencia y Tecnología de Materiales. Universidad Nacional de Mar del Plata. Facultad de Ingeniería. Instituto de Investigaciones en Ciencia y Tecnología de Materiales; Argentina. Consejo Superior de Investigaciones Científicas; EspañaFil: Burlaka, Arsen. Consejo Superior de Investigaciones Científicas; EspañaFil: Paz, José. Consejo Superior de Investigaciones Científicas; EspañaFil: Salavagione, Horacio. Consejo Superior de Investigaciones Científicas; EspañaFil: Carretero González, Javier. Consejo Superior de Investigaciones Científicas; EspañaFil: Hernández, Rebeca. Consejo Superior de Investigaciones Científicas; Españ

Graphene and polyethylene. A strong combination towards multifunctional nanocomposites

The key to the preparation of polymer nanocomposites with new or improved properties resides in the homogeneous dispersion of the filler and in the efficient load transfer between components through strong filler/polymer interfacial interactions. This paper reports on the preparation of a series of nanocomposites of graphene and a polyolefin using different experimental approaches, with the final goal of obtaining multifunctional materials. A high-density polyethylene (HDPE) is employed as the matrix, while unmodified and chemically modified graphene fillers are used. By selecting the correct combination as well as the adequate preparation process, the nanocomposites display optimized thermal and mechanical properties, while also conferring good gas barrier properties and significant levels of electrical conductivity

Advanced synthesis of conductive polyaniline using laccase as biocatalyst

18 p.-7 fig.-1 tab.Polyaniline is a conductive polymer with distinctive optical and electrical properties. Its enzymatic synthesis is an environmentally friendly alternative to the use of harsh oxidants and extremely acidic conditions. 7D5L, a high-redox potential laccase developed in our lab, is the biocatalyst of choice for the synthesis of green polyaniline (emeraldine salt) due to its superior ability to oxidize aniline and kinetic stability at the required polymerization conditions (pH 3 and presence of anionic surfactants) as compared with other fungal laccases.Doses as low as 7.6 nM of 7D5L catalyze the polymerization of 15 mM aniline (in 24 h, room temperature, 7% yield) in the presence of different anionic surfactants used as doping templates to provide linear and water-soluble polymers. Aniline polymerization was monitored by the increase of the polaron absorption band at 800 nm (typical for emeraldine salt). Best polymerization results were obtained with 5 mM sodium dodecylbenzenesulfonate (SDBS) as template. At fixed conditions (15 mM aniline and 5mM SDBS), polymerization rates obtained with 7D5L were 2.5-fold the rates obtained with commercial Trametes villosa laccase. Moreover, polyaniline yield was notably boosted to 75% by rising 7D5L amount to 0.15 μM, obtaining 1g of green polyaniline in 1L-reaction volume. The green polymer obtained with the selected system (7D5L/SDBS) holds excellent electrochemical and electro-conductive properties displayed in water-dispersible nanofibers,which is advantageous for the nanomaterial to be readily cast into uniform films for different applications.This work was funded by INDOX (KBBE-2013-7-613549) European project and NOESIS (BIO2014-56388-R) Spanish national project.Peer reviewe

Identification of high performance solvents for the sustainable processing of graphene

Nanomaterials have many advanced applications, from bio-medicine to flexible electronics to energy storage, and the broad interest in graphene-based materials and devices means that high annual tonnages will be required to meet this demand. However, manufacturing at the required scale remains unfeasible until economic and environmental obstacles are resolved. Liquid exfoliation of graphite is the preferred scalable method to prepare large quantities of good quality graphene, but only low concentrations are achieved and the solvents habitually employed are toxic. Furthermore, good dispersions of nanomaterials in organic solvents are crucial for the synthesis of many types of nanocomposites. To address the performance and safety issues of solvent use, a bespoke approach to solvent selection was developed and the renewable solvent Cyrene was identified as having excellent properties. Graphene dispersions in Cyrene were found to be an order of magnitude more concentrated than those achieved in N-methylpyrrolidinone (NMP). Key attributes to this success are optimum solvent polarity, and importantly a high viscosity. We report the role of viscosity as crucial for the creation of larger and less defective graphene flakes. These findings can equally be applied to the dispersion of other layered bi-dimensional materials, where alternative solvent options could be used as drop-in replacements for established processes without disruption or the need to use specialized equipment. Thus, the discovery of a benign yet high performance graphene processing solvent enhances the efficiency, sustainability and commercial potential of this ever-growing field, particularly in the area of bulk material processing for large volume applications

Phase shift of amplitude-modulated optical signals in graphene oxide water dispersions due to thermal lens focal length oscillation

We analyze the phase shift induced in an amplitude-modulated laser beam propagating through a water dispersion of graphene oxide sheets in a fiber-to-fiber U-bench. This phase shift arises from the thermally induced nonlinear refraction in the sample. The system exhibits strong optical limiting performance for weak continuous-wave signals. A theoretical model including beam propagation and thermal lens focal length oscillation reproduces the experimental findings

Synthesis and characterisation of controllably functionalised polyaniline nanofibres

A novel method for functionalising solution based polyaniline (PAni) nanofibres is reported whereby the degree of side-chain attachment can be controllably altered. The covalent attachment of functional side-groups to the surface of PAni nanostructures is achieved by post-polymerisation reflux in the presence of a nucleophile and the functionalised nanomaterial can be purified by simple centrifugation. The technique is therefore easily scalable. We demonstrate that control over the extent of side-chain attachment can be achieved simply by altering the amount of nucleophile added during reflux. We provide evidence that covalently attached carboxlate side-chains influence the doping mechanism of polyaniline and can be used to introduce self-doping behaviour. Acid functionalised nanofibres remain redox active and retain their optical switching capabilities in response to changes in the local chemical environment, thus making them suitable for adaptive sensing applications

Injectable hybrid hydrogels physically crosslinked based on carrageenan and green graphene for tissue repair

Financiado para publicación en acceso aberto: Universidade da Coruña/CISUG[Abstract] Injectable and biocompatible novel hybrid hydrogels based on physically crosslinked natural biopolymers and green graphene for potential use in tissue engineering are reported. Kappa and iota carrageenan, locust bean gum and gelatin are used as biopolymeric matrix. The effect of green graphene content on the swelling behavior, mechanical properties and biocompatibility of the hybrid hydrogels is investigated. The hybrid hydrogels present a porous network with three-dimensionally interconnected microstructures, with lower pore size than that of the hydrogel without graphene. The addition of graphene into the biopolymeric network improves the stability and the mechanical properties of the hydrogels in phosphate buffer saline solution at 37 °C without noticeable change in the injectability. The mechanical properties of the hybrid hydrogels were enhanced by varying the dosage of graphene between 0.025 and 0.075 w/v%. In this range, the hybrid hydrogels preserve their integrity during mechanical test and recover the initial shape after removing the applied stress. Meanwhile, hybrid hydrogels with graphene content of up to 0.05 w/v% exhibit good biocompatibility for 3T3-L1 fibroblasts; the cells proliferate inside the gel structure and show higher spreading after 48 h. These injectable hybrid hydrogels with graphene have promising future as materials for tissue repair.Xunta de Galicia; ED431C 2019/17Instituto de Salud Carlos III; CD21/00042Chile. CORFO; 22CVID-20683