Intrinsically flexible electronic materials for smart device applications

Abstract

COMMUNICATIONA novel method to fabricate chemically linked conducting polymer-biopolymer composites that are intrinsically flexible and conducting for functional electrode applications is presented. Polypyrrole was synthesized in situ during the cellulose regeneration process using 1-butyl-3-methylimidazolium chloride ionic liquid as a solvent medium. The obtained polypyrrole-cellulose composite was chemically blended and showed flexible polymer properties while retaining the electronic properties of a conducting polymer. Addition of an ionic liquid such as trihexyl(tetradecyl)phosphonium bis(trifluoromethylsulfonyl)imide, enhanced the flexibility of the composite. A functional application of these materials in electrochemically controlled release of a model drug has been demonstrated. This strategy opens up a new design for a wide spectrum of materials for smart electronic device applications wherein the functionality of doping and dedoping of conducting polymers is retained and their processability issue is addressed by exploiting an ionic liquid route.

Durable Flexible Supercapacitors Utilizing the Multifunctional Role of Ionic Liquids

“…[22] TheE DLS had al arge EW (2.1 V) and the area under the rectangular shape of the CV wasl arger compared to the ES. [4] As PPy was bound throughh ydrogen bonding to the cellulosem atrix, the conductivityw as low [11] compared to a PPy backboneg rafted onto fabric or cellulose. [23] Therefore, the integrated area under the CV of the ES and the EW (1.6 V) was lower compared to the EDLS( 2.1 V) and the HS (2.2 V).…”

“…TheP Py-Cell-IL showedc auliflower-like PPy structures integrated homogenously within the cellulose matrix (Figure 3c)a sp reviously reported. [11] After 15 000 cycles,a nd even after several times of washingw ith methanol, it was impossible to completely removet he [C 2 mim] [NTf 2 ]e lectrolyte.H owever, after al ong cycling period PPy structures slightly piercingo ut from the cellulose matrixc an be observed (Figure 3d). This may be attributed to the breaking of hydrogen bonds between PPy and Cell competing with the electrochemical reaction occurring on the PPy backbone.M oreover, the volume change [34] occurring during the redox mechanism [35] of conductingp olymers is also expectedt oi nfluence the PPy backbone to move outwards to the surface of the cellulose matrix.…”

“…Recently,w ed emonstrated the fabrication of an ew class of electroactive materials that are inherently homogeneous and flexible while retaining the smart functionality of the CPs using ionic liquids (ILs). [11] Our flexible CP-biopolymer-ionic liquid composites [11] constitute more durable electrodes;i onic liquids are safe replacements for organic-solvent/aqueous-basede lectrolytes as they impartl onger cycle life,a re inflammable,c ould be incorporated into biopolymer membranes (such as cellulose) to provide solid-state electrolytes with no leakage issues and possess lower internal resistance.O nt he other hand, ILs have been identified as safe electrolytec andidates for electrochemical devicea pplications due to their excellent properties including good ionic conductivity,w ide electrochemical window (EW), inflammable nature,a nd negligible vapor pressure. [12] Flexible energy de-As imple scalable approach to designf lexible,u ltrathin,a nd safe supercapacitors to power up the next-generation of portable electronics and implantable biomedical devices is reported.…”

“…Theg eneralp reparation of CP-biopolymer-ionic liquid composite was carried out using the procedure reported earlier. [11] Polypyrrole (PPy) was used as the CP,c ellulose( Cell) as the biopolymer, andt rihexyl(tetradecyl)phosphonium bis[(trifluoromethyl)sulfonyl] amide ([P 6,6,6,14 ][NTf 2 ]; IL) as the ionic liquid plasticizer to form PPy-Cell-IL composite films.T he cellulose-regeneration process using ionic liquids was exploited to make these materials. [16] Due to in situ preparationo fP Py with hydrogen bonding to cellulose in the solution state using 1-butyl-3-methylimidazolium chloride ([C 4 mim]Cl) ionic liquid as the solvent, the PPy-Cell-IL composite films preparedb yt his methodw ere inherently homogeneous and flexible.G raphite was added to improve the conductivityt of orm the PPy-Cell-IL-graphite composite film.…”

“…This IL plasticizer was also chosen to be biocompatible as reportede arlier. [11,18] Given the hydrophobic natureo ft he individual components,t he resulting polymer composites were hydrophobic by nature.T he average thickness of these composite films when dried was roughly 50 mm. Thef abricationo fasymmetrical supercapacitor was carried out by punch-cutting1cm 2 size sheets of the composite films described above,s andwiched with a1 .5 cm 2 paper separator dip coated with 1-ethyl-3-methylimidazolium bis[(trifluoromethyl)sulfonyl]amide( [C 2 mim][NTf 2 ]) IL as shown in Figure 1.…”