Neutron Spin Echo Investigations on the Segmental Dynamics of Polymers in Melts, Networks and Solutions

Abstract

Neutron spin echo (NSE) spectroscopy, an advanced high-resolution quasi-elastic neutron scattering technique, provides the unique opportunity to investigate long-range relaxation processes of macromolecules simultaneously in space and time on nano-scales. In particular, information on the single-chain behavior is not restricted to dilute solutions, but may also be obtained from concentrated solutions and melts, if labelling by proton deuterium exchange is used. Thus, this method facilitates a direct microscopic study of molecular models developed to explain the macroscopic dynamic properties of polymers, e.g. transport and viscoelastic phenomena.This article gives a short outline of the method and reviews the relevant experimental results obtained from polymer melts and networks and from dilute and semi-dilute solutions of chain molecules with different architectures since the first successful NSE work on polymers was published in 1978. The experimental observations are compared with the predictions of the related microscopic models and other theoretical approaches, which are briefly introduced and adapted accordingly.

Starlike dendrimers in solutions: Structural properties and internal dynamics

“…In this paper we report our results on the dynamic behavior of poly͑-caprolactone͒ dendrimers in dilute solutions measured with NSE spectroscopy. The experiment is sensitive to the internal dynamics and we observe similar dynamic behavior as found by Richter and co-workers [42][43][44] for highfunctionality star polymers. Shape fluctuations are not a relevant relaxation mechanism for the starlike dendrimers.…”

“…The experimental results on the dynamics of dendrimers reported so far reflect the compact shape that means the colloid-like character of dendrimers rather than their loose, polymeric nature. Previous studies by Richter and co-workers [42][43][44] on highfunctionality star polymers, another class of highly branched, compact polymers, with NSE spectroscopy revealed a different dynamic behavior. On large length scales NSE spectroscopy resolves c.m.…”

Structure and dynamics of poly(vinyl alcohol) gels in mixtures of dimethyl sulfoxide and water

“…The PVA-borax sol was a solution, and the Zimm model 48 or a bead-spring model with hydrodynamic interactions is known to describe well the polymer motions in solutions. 49 Structure and dynamics of poly(vinyl alcohol) gels T Kanaya et al PVA-borax sol and the gel in Figures 16a and b, respectively. The data points fall on the theoretically calculated master curve, which suggests that the Zimm scaling works well for the sol and even for the gel.…”

High-throughput chromatin motion tracking in living yeast reveals the flexibility of the fiber throughout the genome

“…Crowding is expected to screen out hydrodynamic effects, which otherwise induce long-range interactions in between chromosome segments (Doi and Edwards 1988), so that nearest-neighbor elastic interactions between consecutive chromosome segments dominate their local dynamics. This approximation, which leads to the ''Rouse'' regime (Rouse 1953), has been extensively documented for concentrated solutions of synthetic polymers (see, e.g., Ewen and Richter 1997) and was recently validated in vivo for the bacterial chromosome (Weber et al 2010).…”