Bulk glassy dynamics determines the rate at which polymer melts form interfacial layers

We present a simple model capable of predicting the rate at which polymer chains adsorb on flat substrates, based on measurements of bulk molecular mobility. We tested this framework on various commonly used polymers and found that the formation of adsorbed layers is minimally affected, if at all, by surface chemistry. We show that the complex set of molecular rearrangements involved in the adsorption can be modeled as an equilibration kinetics driven by the slow Arrhenius process (SAP), a recently discovered molecular mechanism. We stress that this observation is at odds with the common assumption that equilibration phenomena of polymer melts follow the structural (segmental, α-) relaxation. Our approach goes well beyond the qualitative arguments connecting equilibration kinetics and molecular mobility, and identifies the exact proportionality between the rate at which an interfacial layer forms and that at which molecules spontaneously fluctuate. Importantly, we show that the number of chains adsorbed per unit surface is constant if the timescale of the phenomenon is rescaled to the molecular time of the SAP, a key result in line with the predictions of the Collective Small Displacements (CSD) model.