The entanglement concept in polymer rheology

Hyperbranched polymers: a promising new class of materials

http://nathan.instras.com/documentDB/paper-137.pdf

Functional dendrimers, hyperbranched and star polymers

In the last 12 years the field of hyperbranched polymers has been well established with a large variety of synthetic approaches and fundamental studies on structure and properties of these unique materials. However, new developments involving hyperbranched materials appeared recently, for example, different synthetic strategies, new reaction mechanisms, formation of more complex architectures, a deeper understanding of the branched structure and their kinetic development, and intensive studies on the material properties and possible applications. This demonstrates the high versatility and the possibilities that are still involved in hyperbranched polymers and render it one of the most active fields in polymer science with a very promising future. © 2000 John Wiley & Sons, Inc. J Polym Sci A: Polym Chem 38: 2505–2525, 2000

https://onlinelibrary.wiley.com/doi/pdf/10.1002/1099-0518%2820000715%2938%3A14%3C2505%3A%3AAID-POLA10%3E3.0.CO%3B2-8

New developments in hyperbranched polymers

The field of microrheology is concerned with how materials store and dissipate mechanical energy as a function of length scale. Recent developments in the theory and instrumentation of the microrheology of complex fluids are reviewed. Equal emphasis is given to the physical phenomena probed, advances in instrumentation, and specific experimental systems in which this field has already had an impact. The inversion of the compliance data, measurement of sample heterogeneity, high frequency viscoelasticity, effects of shear flow, single molecule experiments, surface viscoelasticity and time evolution studies are considered. The techniques highlighted include particle tracking microrheology, diffusing wave spectroscopy, laser tracking, magnetic tweezers and atomic force microscopy. Specific examples of complex fluid systems are chosen from the fields of polymers, colloids and biological assemblies.

https://iopscience.iop.org/article/10.1088/0034-4885/68/3/R04/pdf

Microrheology of complex fluids

A survey of the phase behavior of blends of hydroxyphenyl- and acetoxyphenyl-terminated hyperbranched polyesters with linear polymers such as polycarbonate, polyesters, and polyamides was carried out For comparison, blends of poly(acetoxystyrene) (PAS) and poly(vinylphenol) (PVPh) and pairwise combinations of these and the two hyperbranched polyesters were studied The hydroxyterminated hyperbranched polyester blend miscibility was identical to that of poly(vinylphenol); this suggests that strong interactions due to hydrogen bonding, more so than chain architecture, dominate the blend miscibility The acetoxy-terminated hyperbranched polyester showed less miscibility than those hydroxy-terminated polymers due to the absence of strong interactions but still more miscibility than the linear PAS None of the blends of linear PVPh or PAS with hyperbranched polymer was viscible However, homogeneous blends of PAS with PVPh and of the two hyperbranched polyesters were observed In addition, a blend of linear Bisphenol A polycarbonate (PC) with an all-aromatic hyperbranched polyester resulted in increased tensile and compressive moduli and decreased strain-to-break and toughness compared to those of PC

Novel blends of hyperbranched polyesters and linear polymers

This high‐resolution solid‐state NMR work explores the usefulness of carbon–carbon nuclear spin diffusion to probe the miscibility of polymer blends. Experiments involving one‐ and two‐dimensional NMR spectra, applied to blends of poly(ethylene terephthalate) (PET) and bisphenol‐A polycarbonate (BPAPC), show that spin exchange occurs between carbon‐13 nuclei located in monomer units that belong to the two different homopolymers. Carbon spin diffusion, which strongly depends on the internuclear distance, is explored as a possible probe for specific interactions between polar groups of the two polymers. Our results clearly show that the PET/BPAPC blends studied are homogeneously mixed at distances of 4.5 to 6 A.

Use of carbon–carbon nuclear spin diffusion for the study of the miscibility of polymer blends

Disclosed is an optical compensator for liquid crystal displays comprising a first polymeric layer having an out-of-plane birefringence not more negative than −0.005 and a second polymeric layer having an out-of-plane birefringence more negative than −0.005. The invention also provides an LC display and a process for making such compensators.

Dennis J. Massa

Papers

Novel blends of hyperbranched polyesters and linear polymers

Use of carbon–carbon nuclear spin diffusion for the study of the miscibility of polymer blends

Multilayer optical compensator, liquid crystal display, and process

Blend miscibility of bisphenol A polycarbonate and poly(ethylene terephthalate) as studied by solid-state high-resolution carbon-13 NMR spectroscopy

Dynamic Viscoelastic Properties of Polystyrene in High-Viscosity Solvents. Extrapolation to Infinite Dilution and High-Frequency Behavior