Understanding the molecular origin of shear thinning in associative polymers through quantification of bond dissociation under shear

Transient network theory is the state of the art for understanding the mechanical response of associative networks. However, the predictions of the models are difficult to verify in the absence of direct observations of the bond states. This manuscript introduces a method to quantitatively measure force-induced bond dissociation in associative networks through the design of an opto-mechanically coupled model polymer system and a rheo-fluorescence set-up. The findings show that shear thinning in the model associative polymers cannot be explained by classical theories, and likely involves alternative modes as suggested by newer models.