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Direct arylation polymerization (DArP) has emerged as an environmentally friendly, atom efficient method of synthesizing a variety of conjugated polymers. Here, we report a one-pot approach consist...

Side chain engineering has been used widely to expand the functionality and enhance the solubility of conjugated polymers, promoting their utility in various applications. Herein, we report the synthesis of an adenine-functionalized, thiophene-based alternating copolymer via direct arylation polymerization. This nucleobase-modified, alkyl thiophene-based alternating copolymer was accessed by copolymerization of a Boc-protected, adenine functionalized thiophene monomer 9-(6-(2,5-dibromothiophen-3-yl)hexyl)-9H-purine-6-amine (TAd), with 3,3′,3′′,4′-tetrahexyl-2,2′:5′,2′′-terthiophene, (tT4h). Quantitative post-polymerization deprotection of Boc groups results in the adenine bearing alternating copolymer (TAd-tT4h), which is soluble in common organic solvents due to steric hindrance-induced flexibility of the tT4h comonomer, allowing structure–property relationships to be established. In comparison to the unfunctionalized analogue, interchain hydrogen bonding through the adenine functionality enhances the packing of the copolymer, resulting in a ∼70 °C increase in the glass transition temperature. Furthermore, the improved solubility of the copolymer and capacity for strong metal ion binding by the nucleobase leads to dramatic fluorescence quenching (>90%) upon addition of Cu2+ ions, which is also reflected in a high Stern–Volmer constant of 1.28 × 104 M−1. The fluorescence emission is recovered almost completely after washing the copolymer solution with EDTA-disodium salt aqueous solution. These findings demonstrate the viability of synthesizing soluble, fully conjugated copolymers with nucleobase functionality via direct arylation polymerization, as well as the influence of the hydrogen bonding nucleobase on thermal, optical, and metal-ion sensing properties.

Fundamental properties of conjugated copolymers are sensitively linked to their constitution and features of their repeat unit design that govern assembly and organization across multiple length scales, ultimately impacting device performance. Herein we report the efficient synthesis and characterization, and optical, electrochemical and transport properties of complementary pairs of nucleobase-functionalized, fully conjugated copolymers based on benzo[1,2-b:4,5-b′]-dithiophene (BDT) and 3-hexylthiophene (3hT), which is a quintessential low bandgap polymer. Stille cross-coupling polymerizations enable access to high molecular weight, alternating copolymers of modest dispersity containing pendant adenine or thymine groups in each repeating unit, which provide the capacity to direct molecular assembly. Variations in nucleobase type and design of alkyl side chains on BDT units give rise to a strongly red-shifted absorbance onset for the copolymers containing thymine and adenine functionality in comparison to solution and dried films. Higher hole mobilities were also observed and attributed to the tendency of the nucleobase inclusion to heighten organization. The influence of the nucleobases on the organization is further revealed when thermal pre-treatment is used during film formation: modest heating before casting the non-functionalized BDT-3hT copolymers leads to increases in the mobility, optical absorbance and fluorescence, while copolymers with adenine or thymine pendant groups do not show analogous improvements, suggesting that the nucleobases have promoted nanoscale organization, which is consistent with assessments of hydrogen bonding interactions. Given the structure-directing ability of nucleobases through hydrogen bonding, π-stacking, and complementary base pairing, these novel materials engender myriad opportunities to examine how specific molecular-level interactions that cue self-assembly affect optoelectronic properties and device-level performance.

In this work, a facile and scalable method to produce cellulose based flexible electrodes is introduced. Composite paper electrodes from recycled paper pulp and graphene oxide (GO) were fabricated by solvent casting at room temperature. Electrical conductivity and surface chemistry of the nanocomposite samples were tuned by chemical reduction of GO. Contact angle measurements showed a change in water droplet angle from 0° to 89° depending on the GO content and degree of reduction. Electrical measurements depicted high electrical conductivity with an ideal Ohmic behavior for the composite paper electrodes. Sheet resistance of the sample containing 4 wt% of reduced GO (rGO) was 1.649 × 103 Ω/□ which is 5 orders of magnitude higher than paper pulp. The obtained sheet resistance for the sample with 16 wt% rGO was remarkably high for cellulose based conductive electrode compared with previously reported data. Moreover, the sample containing only 0.5 wt% of rGO showed 40% higher modulus than the neat recycled paper in tension. The resultant nanocomposite can be introduced as a highly conductive and low cost flexible electrode.

In the present work we report a facile method for fabrication of glucose oxidase immobilized on the partially reduced graphene–gold nanocomposite (PRGO–AuNPs/GOx) as a novel biosensor for determination of glucose concentration. Scanning electron microscopy (SEM) and transmission electron microscopy (TEM) were used to study the morphology of PRGO and PRGO–AuNPs. Also, fast Fourier transformation infrared spectroscopy (FTIR) and UV–Vis spectroscopy were used to confirm formation of graphene and graphene–gold composite. Then, the electrochemical behavior of PRGO–AuNPs/GOx modified electrode was studied by cyclic voltammetry (CV). Our electrochemical studies, especially chronoamperometry (CA), showed that the PRGO–AuNPs/GOx modified electrode has excellent electrocatalytic activity towards the glucose. The limit of detection and sensitivity towards glucose were estimated as 0.06 μM and 15.04 mA mM− 1, respectively.

Various approaches have been employed to disperse graphene in polymers. We introduce a new method which takes advantage of the amphiphilic nature of graphene oxide (GO). This feature results in the spontaneous self-assembly of monolayers at the oil–water interface. Thermodynamically favorable adsorption of GO sheets on the liquid droplets serves as the first step in the fabrication of well-dispersed composites. It eliminates the need for sonication and further compounding, which can destroy the structure of the graphene layers. Another equally important consideration is how to vaporize the liquid medium to preserve appropriate dispersion in the dried masterbatch. Microwave radiation is employed to vaporize the liquids and also to partially reduce GO while keeping it well-dispersed in the polymer. As a challenging matrix, the dispersion of GO in natural rubber is studied here. XRD and SEM results confirm appropriate dispersion of the particles. Improvements in the modulus and ultimate strength were observed without any significant reduction in elongation at break.