Nanoparticle (NP) assemblies exhibit collective optical, electronic, and magnetic properties that enable applications in sensing, catalysis, energy conversion, and optoelectronics. However, achieving independent control over structural integrity and surface functionality within such assemblies remains a significant challenge in NP self-assembly. Here, we report a modular post-functionalization strategy that decouples structural locking from surface reprogramming in colloidal molecules (CMs). AB_n symmetry CMs assembled from complementary polymer-grafted Au NPs were selected as representative models and reinforced using multivalent N-heterocyclic carbene (NHC)-containing block copolymers. The NHC anchoring segments form robust C–Au bonds, converting initially noncovalent interparticle junctions into covalently bridged connections without perturbing predefined geometries. This multivalent locking reduces interparticle spacing, enhances plasmonic coupling, and significantly improves chemical, ionic, thermal, and mechanical stability, preserving three-dimensional architectures in the dry state. Importantly, separation of anchoring and functional polymer blocks enables independent introduction of amphiphilic and light-responsive surface properties, allowing solvent-dependent plasmonic modulation and reversible light-triggered hierarchical assembly while maintaining discrete CM geometry.

Nanoparticles self-assembly plays a pivotal role in designing new functional structural materials. The manipulation of interactions among nanoparticle building blocks is crucial for achieving assemblies with desired structures and properties. In this work, we assemble binary inorganic nanoparticles into alternating copolymer-like nanostructures by independently regulating hydrogen bonding and electrostatic interactions. The block copolymers grafted on nanoparticles feature oppositely charged groups, where electrostatic attraction drives the linear assembly of nanoparticles into alternate chain configurations. The hydrogen bonding interaction originates from the direct introduction of polyethylene glycol into the systems, serving as hydrogen bond acceptors with the grafted polymer and facilitating the side-by-side assembly of the chain structures. These two forces were observed to compete with each other during the assembly process, and could be precisely controlled by adjusting the quantities of acetic acid and polyethylene glycol, thus regulating the nanoparticle assembly behavior. This work provides a practical framework for the design of muti-force interactions in hierarchical colloid nanomaterials.