Conformation of Methylcellulose as a Function of Poly(ethylene glycol) Graft Density

Abstract

Low molecular weight thiol-terminated poly-(ethylene glycol) (PEG) (M ≈ 800) has been grafted onto a high molecular weight methylcellulose (MC, M w ≈ 150000) by a facile thiol−ene click reaction; graft densities varied from 0.7% to 33% (grafts per anhydroglucose unit). Static and dynamic light scattering reveals that the overall radius of the chain increases systematically with graft density, in a manner in excellent agreement with theory. As the contour length remains unchanged, it is apparent that grafting leads to an increase in the persistence length of this semiflexible copolymer, by as much as a factor of 4. These results represent the first experimental verification of the excluded volume theory at low grafting densities, and demonstrate a promising synthetic platform for systematically increasing the persistence length of a model semiflexible, water-soluble polymer.

Evidence for the extended de Gennes regime of a semiflexible polymer in slit confinement

“…2. It would also be interesting to explore the possibilities engendered by confining highly anisotropic biopolymers, such as bottle-brush coated DNA [59], RecA-coated DNA [60], actin [61], or polyethlylene-grafted methylcellulose [62], which will allow one to reach larger values of l p /w than are possible with naked DNA.…”

The Past Ten Years of Carbohydrate Polymers in ACS Macro Letters

“…Transformation of the free hydroxyl groups at the 2, 3, and 6 positions of glucopyranoside to tris­(phenylcarbamate) results in a significant increase in chain stiffness as Kuhn length changed from 4 nm for cyclic amylose to 16–22 nm for cyclic amylose tris­(phenylcarbamate) (Figure ). High molecular weight methylcellulose was also grafted with short poly­(ethylene glycol) chains, as reported by Lodge et al, and while the contour length remained unchanged, the grafting led to an increase in the persistence length by a factor of 4 . Furthermore, the conformation change of linear polysaccharide λ-carrageenan controlled by chloroquine and inorganic cations has been reported by Mezzenga et al…”

“…15 High molecular weight methylcellulose was also grafted with short poly-(ethylene glycol) chains, as reported by Lodge et al, and while the contour length remained unchanged, the grafting led to an increase in the persistence length by a factor of 4. 16 Furthermore, the conformation change of linear polysaccharide λ-carrageenan controlled by chloroquine and inorganic cations has been reported by Mezzenga et al 17 The applications of carbohydrate polymers, especially glycopolymers, have drawn significant attention in the past ten years. These functions can be roughly divided into carbohydrate moieties on the polymer acting as a targeting agent, primarily on account of their ability to bind proteins and/or act as a hydrophilic shell.…”

Chiral and achiral mechanisms of self-limiting assembly of twisted bundles

“…This rather tight diameter regulation might support the interpretation that MC fibers are achiral, or at best, retain a weak chirality that may not propagate to twisted assembly. Going beyond pure MC molecules, Morozova and coworkers [35,58] modified the bending stiffness of the chains via grafting MC with a controlled density of oligomeric PEG side chains. Upon assembly, it was found the fiber diameter increased with MC chain persistence length [35].…”