Abstract
Insulating polymers have received little attention in electronic applications. Here, we synthesize a photoresponsive, amphiphilic block copolymer (PEO-b-PVBO) and further control the chain growth of the block segment (PVBO) to obtain different degrees of polymerization (DPs). The benzylidene oxazolone moiety in PEO-b-PVBO facilitated chain-conformational changes due to photoisomerization under visible/ultraviolet (UV) light illumination. Intercalation of the photoresponsive but electrically insulating PEO-b-PVBO into graphene sheets enabled electrical monitoring of the conformational change of the block copolymer at the molecular level. The current change at the microampere level was proportional to the DP of PVBO, demonstrating that the PEO-b-PVBO-intercalated graphene nanohybrid (PGNH) can be used in UV sensors. Additionally, discrete signals at the nanoampere level were separated from the first derivative of the time-dependent current using the fast Fourier transform (FFT). Analysis of the harmonic frequencies using the FFT revealed that the PGNH afforded sawtooth-type current flow mediated by Coulomb blockade oscillation.
Highlights
Insulating polymers have received little attention in electronic applications
The aldehyde group of PEO-b-PVBA was converted to benzylidene oxazolone (BO) by reacting with hippuric acid in the presence of sodium acetate, yielding the poly[(ethylene oxide)-b-poly[(3vinylbenzylideneoxazolone)] (PEO-b-PVBO) block copolymer
UV illumination led to an increase in the resistance of the PVBO-intercalated graphene nanohybrid (PGNH) electrode, indicating that the chain-conformational change of PEO-b-PVBO by Z‒E photoisomerization had a negative effect on current flow through the electrode
Summary
Insulating polymers have received little attention in electronic applications. Here, we synthesize a photoresponsive, amphiphilic block copolymer (PEO-b-PVBO) and further control the chain growth of the block segment (PVBO) to obtain different degrees of polymerization (DPs). These calculated data confirmed that photoisomerization triggered by the different light sources can induce significant changes in the chemical and electronic properties of PEO-b-PVBO, as well as its geometrical structure. PEO-b-PVBO was successfully intercalated into the confined space between graphene sheets by physical exfoliation of graphite in an aqueous medium.
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