Shear rheology and scaling of semiflexible polymers: Effect of polymer-solvent interactions in the semidilute regime

摘要

Semiflexible polymers and their assemblies are important in biology as cross-linked networks of semiflexible polymers form a major structural component of tissue and living cells. This research used shear rheology to demonstrate the tuning from worm-like to rod-like conformation in semiflexible polymers by polymer-solvent interactions. The conformation was assessed by the persistence lengthl(p), and its influence, in the semidilute regime, was assessed by the scaling of zero-shear viscosity eta(o)with concentrationcand molecular weightM over bar . The polymers were poly n-butyl and poly n-octyl isocyanate (PBIC and POIC, respectively). PBIC exhibited the largestl(p)in chlorinated solvents, and the solutions obeyed the scaling law eta o proportional to c3.0M over bar 6.6. However, when PBIC was dissolved in benzene thel(p)was greatly reduced and the scaling law now was eta o proportional to M over bar 4.2, consistent with a worm-like conformation. On the other hand, POIC dissolved in chlorinated and benzenic solvents exhibited a worm-like conformation and the scaling was eta o proportional to c2.5M over bar 3.5. These results were contrasted with those of hydroxypropyl cellulose (HPC) aqueous solutions, which exhibit worm-like conformation, the solutions obeyed the scaling eta(o) proportional to c(2.5). Finally, the shear viscosity of the polyisocyanates and HPC obeyed the Saito scaling, valid for anisotropic particles in solution.