Interface-engineered graphene oxide/polyaniline hybrids via seed-initiated polymerization: morphology control and magnetoresistance enhancement.

Seed-initiated polymerization was developed to prepare graphene oxide and polyaniline composites (GO/PANI) with a regular morphology. Pre-functionalization of GO with p-phenylenediamine (PDA) was employed to tailor the interface and seed uniform aniline polymerization across the GO surface, replicating and deepening the substrate's wrinkled texture. Excess aniline, however, drives PANI agglomeration. Magnetoresistance (MR) measurements reveal a monotonic increase in MR to 1.4% at 3 T with an aniline amount of up to 360 µL for the GO-PDA/PANI-4 sample, whereas surplus aniline (480 µL) disrupts the interface between PANI and GO, and reduces MR to 0.8%. These findings underscore the pivotal role of an intact organic-inorganic interface in governing magnetotransport and offer a new design principle for tuning organic MR effects.