Effects of linker flexibility on phase behavior and structure of linked colloidal gels

Colloidal nanocrystal gels can be assembled using a difunctional “linker” molecule to mediate bonding between nanocrystals. The conditions for gelation and the structure of gel are controlled macroscopically by linker concentration microscopically linker’s molecular characteristics. Here, we demonstrate toy model colloid–linker mixture that flexibility plays key role in determining both phase behavior mixture. We fix length systematically vary its bending stiffness span flexible, semiflexible, rigid regimes. At fixed concentration, flexible-linker rigid-linker mixtures separate at low colloid volume fractions, agreement with predictions first-order thermodynamic perturbation theory, but semiflexible-linker do not. correlate attribute this qualitatively different undesirable “loop” linking motifs predicted more prevalent linkers end-to-end distances commensurate locations chemical sites on colloids. Linker also influences spacing linked colloids, suggesting strategies design desired behavior, structure, and, extension, structure-dependent properties.