Diverse two-dimensional arrays of PNIPAM beads formed by spin-coating

Two-dimensional arrays of thermosensitive poly(N-isopropylacrylamide) colloids were formed by spin-coating. The addition of the surfactant sodium dodecylsulfate to bead suspensions led to the formation of a variety of ordered arrays. A mechanism explaining the final shape and bead density of the arrays is proposed, taking into account the interplay between the different interactions presented in the process, including depletion, capillary and electrostatic forces.