Anomalous dewetting dynamics in active entangled polymer films: flexible chains

Spin-coated polymer films store molecular recoiling stress in kinetically trapped chain conformations, providing an extra driving force for dewetting beyond capillarity. I develop an analytical framework connecting this preparation-induced nonequilibrium stress, continuum viscoelastic thin-film hydrodynamics, and the activity-enhanced elasticity of active entangled polymer melts containing flexible chains. Activity generates grip forces at entanglement junctions, enhancing the elastic plateau by (1 + α)-where α is the activity parameter, growing linearly with chain length and Péclet number-and opening a fast grip-force relaxation channel on the timescale τ_g ∼ L, far shorter than the reptation time τ_d ∼ L³. The molecular recoiling stress decays biexponentially: the fast grip channel releases on τ_g, while the slow channel relaxes on the segmental timescale τ_eff ≪ τ_d, set by conformational rearrangements within the spin-cast film rather than by whole-chain reptation. Dewetting hole growth in all three rim-geometry regimes obeys R^p = K_pΦ^act(t) with the same integrated active stress function Φ^act; the early-stage small-hole regime gives exponent n ≈ 1, consistent with polystyrene film experiments. Four unambiguous activity signatures emerge: a biexponential decay in sequential hole nucleation velocities with a kink at t_inc ∼ τ_g and slow slope measuring τ_eff; a reversed morphological fingerprint in which both rim height and rim width are suppressed-because activity raises both the hole growth driving stress and the restoring modulus by the same factor (1 + α); a double maximum in the rim-width time trace above a universal activity threshold α > e² ≈ 7.4, with the first peak W_max,1 = [(1 + α)τ_g/τ_d]^2/3 < 1 and the second peak recovering the passive value exactly for all α via the algebraic identity (1 - f)(1 + α) = 1; and a shift in slip length from b_pass ∼ L³ to b_act ∼ L², reducing the rim width by a factor L^2/3.