Principle of Disentanglement by Intrachain Cross-Linking in the Melt of Soft-Nanoparticles

Abstract

Polymer entanglements confer exceptional properties, but, at certain conditions, pose significant processing challenges. Disentangled polymers are thermodynamically unstable, leading to ambiguities in their dynamics. The soft nanoparticles (SNPs) may be considered a random coil stabilized by intramacromolecular cross-linking. As a model system of inhibited interpenetration, it could be used to illustrate the disentanglement and shed light on the boundary between polymers and colloids. We bring fractionation to SNPs and systematically curated over forty samples. Terminal relaxation time τ spanning nine decades was quantified while molecular mass spanning as narrow as two decades. Based on the analysis, governing equations for τ were established as functions of bulk diameter (D_bulk) and cross-linking strand length (N_c). We identify the parameter space capable of reducing τ 1000 times, defining the limits of disentanglement. Compared to linear polymers of equivalent molecular weights, lightly cross-linked polymeric nanoparticles exhibit significantly faster relaxation and improved processability. At larger D_bulk and N_c, τ shows a greater divergence than the mechanism of entanglements. Such precise fractionated SNPs are essential for achieving these quantitative insights.