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The thinning of a cylinder of a polymer solution in a volatile solvent is argued to be controlled by solvent diffusion through a dense polymer layer at the cylinder surface. This naturally leads to the exponential time dependence of cylinder radius that is observed in experiments using a fast camera, such as capillary breakup extensional rheometry (CaBER). The relaxation time is controlled by the thickness of the dense (and often glassy) polymer layer and the diffusion coefficient of solvent through that layer. If correct, this means that while CaBER is very useful for understanding fiber spinning, the relaxation time does not yield a measure of the extensional viscosity of polymer solutions in volatile solvents. 

Intervals of shear flow stretch polymer chains and form flow-induced precursors, which accelerate crystallization and transform the crystalline morphology from isotropic spherulites to anisotropic structures. The flow-induced crystallization of two commercial samples of isotactic polypropylene with nearly identical molecular weight distributions, differing in concentrations of catalyst residue particles, was investigated using dynamic rheology and ex situ Synchrotron X-ray scattering. Upon the application of flow, the sample with higher particle concentration crystallized at faster rates relative to the sample with lower levels of heterogenous impurities. The nucleation ability of these particles was particularly pronounced at lower levels of deformation, while flow effects became prominent as larger deformations were applied. For sufficiently strong flows ((γ ) ̇≤145 s-1), a lower critical shear stress (~0.096 MPa) was observed for the formation of shish-kebab structures in the sample with higher concentrations of particles. In this work, we have also identified the formation of shish-kebab structures in the presence of weak flow ((γ ) ̇ ≤ 0.3 s-1) when sheared for long durations of time. For equivalent levels of specific work within both flow regimes, the morphologies of these anisotropic structures were found to be characteristically distinct from one another. The long period and degree of crystallinity were also found to increase with shear stress above the stress level needed for the formation of shish-kebab structures. 

Literature viscosity data are reviewed in both entangled solutions and semidilute unentangled solutions, with several examples of using de Gennes’ thermal blob to rationalize observations for flexible polymers dissolved in intermediate quality solvents. Some puzzling literature data in θ-solvents are also nicely understood with two parameter scaling upon reanalysis (where the correlation length and the tube diameter concentration dependences differ). However, some literature data seem to not be understood with this simple scheme, suggesting that our understanding of neutral polymer solution viscosity is incomplete. Lastly, combinations of experiments are suggested to better examine the concept of the thermal blob. 

Maximizing ion conduction in single-ion-conducting ionomers is essential for their application in energy-related technologies such as Li-ion batteries. Understanding the anion chemical composition impacts on ion conduction offers new perspectives to maximize ion transport, since the current approach of lowering T g has apparently reached a limit (lowest T g ∼ 190 K, highest conductivity ∼10 −5 –10 −4 S cm −1 ). Here, a series of random ionomers are synthesized by copolymerizing poly(ethylene glycol)methacrylate with either sulfonylimide lithium methacrylate (MTLi) or sulfonate lithium methacrylate (MSLi) using reversible addition–fragmentation chain transfer (RAFT) polymerization. Li-Ion conduction and self-diffusion coefficients ( D Li + ) of the ionomers are characterized with dielectric relaxation spectroscopy (DRS) and pulsed-field-gradient (PFG) NMR diffusometry, respectively. Increasing ion content decreases the Li-ion conductivity and D Li + , as expected from the increased T g . Moreover, a considerably lower ionic conductivity and D Li + are observed for MSLi compared to MTLi at constant ion content and T g / T . As revealed from X-ray scattering, strong ion aggregation in MSLi results in much lower conductivity and D Li + compared with less aggregated MTLi based on the more delocalized sulfonylimide anion. These results emphasize the detrimental and molecularly specific role of ion aggregation in Li-ion conductivity, and highlight the necessity for minimizing ion aggregation via the rational choice of anion chemical composition.