Crystallizability of Free and Tethered Chains in Nanometer‐Sized Droplets

Abstract

AbstractConfining polymers to nanometric sizes often interferes with the characteristic length scales of structure formation and thus significantly alters crystallization or nucleation behavior at the nanoscale. To investigate such effects in nanometric samples, past studies relied either on heavily constraining environments like block copolymer mesophases or on deposited droplets that exhibit significant variation in size, thus requiring extensive analysis to assign size classes. This studypresents a novel method to create nanometer‐sized polymer droplets of narrow volume distribution and to study their dynamic and thermodynamic behavior using the change in orientational polarization. A combination of gold‐nanoparticle deposition with a grafting‐to reaction and a nanostructured electrode setup enabled the measurement of poly‐ε‐caprolactone (PCL) droplets consisting of ten chains on average for a relatively small molecular weight. Distinct crystallization and melting signatures in spin‐cast droplets demonstrate the sensitivity of this approach. In contrast, the grafted aggregates exhibit no signs of crystallization, which is attributed to considerable constraints in this configuration, like limited chain motion or too wide chain spacing. Nevertheless, the presented setup is capable of studying ensembles of individualized (macro‐) molecules.