Seminar

 In this talk, I will discuss the interactions between colloidal particles adsorbed at an interface and their spontaneous self-assembly. We synthesize poly(N-isopropyl acrylamide) (PNIPAM) microgel particles with varying stiffness and investigate their behaviour through droplet drying experiments. Due to their amphiphilic nature, PNIPAM microgels migrate to the air-water interface, and interparticle interactions govern the resulting self-assembled structures. Our experiments show a transition from ordered clusters to a two-dimensional foam, and then to loosely ordered triangular lattices as particle concentration increases. These structures were observed during the drying of sessile droplets containing soft, deformable PNIPAM microgels. In addition, stiffer PNIPAM microgels form chain-like clusters, which evolve into a two-dimensional percolated gel-like network with increasing microgel concentration. To further understand these self-assembled structures, we are currently performing molecular dynamics (MD) simulations to model colloidal self-assembly driven by short-range capillary attractions and long-range repulsive interactions between particles.