%0 Journal Article
%T Effect of Polymer Volume Fraction on Fracture Initiation in Soft Gels at Small Length Scales
%J -
%D 2019
%R https://doi.org/10.1021/acsmacrolett.9b00086
%X The influence of polymer volume fraction, £¿v on fracture initiation via puncture is studied in self-assembled triblock copolymer gels. Spherically tipped indenters of radii varying over a wide range were used to characterize puncture at length scales on the same order of magnitude as the elasto-capillary length (¡«¦Ìm) and significantly below the elasto-fracture length (¡«mm) for £¿v = 0.12¨C0.53. Critical energy release rate, Gc for £¿v = 0.12¨C0.30 was found to be in agreement with the predicted scaling from the classical Lake-Thomas model modified for gel fracture via the failure mechanism of chain pull-out and plastic yielding of micelles (Gc ¡« £¿v2.2). Interestingly, we demonstrate that fracture initiation energy, o, from puncture scales as o ¡« £¿v, thus, indicating the role played by different fundamental mechanisms governing fracture initiation in soft gels. Additionally, gels with £¿v = 0.53 show deviation from experimental scalings for Gc and o, likely due to a change in micellar morphology leading to anomalous fracture behavior
%U https://pubs.acs.org/doi/10.1021/acsmacrolett.9b00086