Self-Diffusion of Polystyrene Solutions in Porous Acrylate-Based Monoliths Studied by ¹H PFG NMR

Abstract

The pulsed field gradient (PFG) nuclear magnetic resonance (NMR) method has been used to study the molecular self-diffusion of polystyrene (PS) solutions in porous acrylate-based monoliths. It was found that the characteristic concentration and molar mass dependencies of the PS self-diffusion in the solution (describable by the Zimm and Doi−Edwards models) remain unchanged in case that the self-diffusion occurred in this porous material. However, the self-diffusion coefficients of the PS were reduced in the monoliths by a constant factor, which is independent of the molar mass and the concentration. This constant factor represents the tortuosity of the porous monoliths and agrees with the reduction of the initial turnover frequency found in the ring-closing metathesis reaction of diethyl diallyl malonate catalyzed in these monoliths.

Quantitative Studies of Block Copolymers and Their Containing Homopolymer Components by Diffusion Ordered Spectroscopy

“…The clear crossover of the characteristic exponent of −0.5 to higher negative values of the exponents of the molar mass dependence of PS was also verified in refs. . Whereas Beckert et al demonstrated pulsed field gradient measurements in semidilute solutions of PS in deuterated benzene, Zettl et al measured diffusion coefficients with fluorescence correlation spectroscopy of PS in toluene solutions.…”

“…. Whereas Beckert et al demonstrated pulsed field gradient measurements in semidilute solutions of PS in deuterated benzene, Zettl et al measured diffusion coefficients with fluorescence correlation spectroscopy of PS in toluene solutions. Beckert et al showed the molar mass dependences of PS at different concentrations in deuterated benzene and also obtained different slopes for molar masses below and above 30 000 g mol −1 .…”

‘Pseudo-halide’ Derivatives of Grubbs- and Schrock-Type Catalysts for Olefin Metathesis

“…74 Monolithic and silica-based supports were also fabricated via grafting of two polymerizable monomers with carboxylate-containing ligands, exo,exo-7-oxa-2-norbornene-5,6-dicarboxylic anhydride and 7-oxa-2-norbornene-5-carboxylic acid. 20 ROMP-based monolithic supports were synthesized through grafting of either of these two monomers directly with the living ROMP-based termini of the synthesized supports.…”

Catalysts Immobilized on Organic Polymeric Monolithic Supports: From Molecular Heterogeneous Catalysis to Biocatalysis

“…Self-diffusion could be correlated to the reptation of polymer chains by using the Zimm model and the Doi-Edwards model. [83] The other characterization methods for monolithic materials have been described boundlessly, but the basic methods are listed only briefly. The most important tools used for the evaluation of porosity are inverse size-exclusion chromatography (ISEC), mercury intrusion, and Brunauer-EmmettTeller gas adsorption studies.…”