A SANS investigation of silk-stabilized aqueous poly(3-hexylthiophene): phenyl-C61-butyric acid methyl ester nanoparticle dispersions

Regenerated silk fibroin (RSF) protein comprising both hydrophilic and hydrophobic chain segments offer great potential for interfacial interaction and stabilization of organic nanoparticles (NPs) in aqueous medium. In this work, aqueous dispersion of poly(3-hexylthiophene):phenyl-C61-butyric acid methyl ester (P3HT:PCBM) NPs of 1:1 weight ratio were prepared using RSF as surfactant for the first time via the mini-emulsion method. The size, morphology, internal structure, interface and hierarchical organization of RSF-stabilized P3HT:PCBM NPs was investigated using UV–visible spectroscopy, contrast-variation small-angle neutron scattering (CV-SANS) and ultra-small-angle neutron scattering (CV-USANS). The P3HT:PCBM NPs were established to be stabilized in the matrix of RSF colloidal microparticles in water. Unlike the commonly used surfactant sodium dodecyl sulfate which produces core–shell (PCBM–P3HT) NPs, the RSF molecules generated P3HT:PCBM NPs with internal structure that resemble phase-separated solvent-cast films. The as-prepared dispersion has good film-forming ability and has been demonstrated for fabrication of composite films comprising graphene oxide. [Display omitted] •Aqueous dispersion of P3HT:PCBM (1:1) nanoparticles have been prepared using silk as surfactant via mini-emulsion method.•The CV-SANS study reveals the overall structure as P3HT:PCBM NPs (with de-mixed domains) dispersed in silk microspheres.•The dispersion has good film-forming ability and can be fabricated into composite films with graphene materials.•The developed system has potential for photovoltaic applications.