Fabrication and structural analysis of polyrotaxane fibers and films

Abstract

Polyrotaxane (PR), a typical example of topological supramolecular architecture, consists of multiple cyclic molecules threaded onto a linear polymer backbone and capped with bulky end-groups. The PR system of polyethylene glycol and α-cyclodextrin (α-CD) has been extensively studied for its facile synthesis, unique molecular structure, and possible applications for various smart materials. We have previously demonstrated the fabrication of PR-based fibers without chemical cross-links by wet spinning of PR solution. In this paper, we investigate the crystal structure of α-CDs in PR fibers and the effect of drawing on it. The α-CDs in PR fiber are found to form hexagonal channel-type structure. The drawing process promotes formation of the packing arrangement of α-CDs in the c-axis because of the sliding of α-CD molecules along the polymer backbone. In addition, we demonstrate the preparation of an elastomeric PR film having similar network structure to the fibers and ethylene glycol oligomer as plasticizer.

Optimization of Anisotropic Crystalline Structure of Molecular Necklace-like Polyrotaxane for Tough Piezoelectric Elastomer

“…9 Because a single α-CD molecule contains a large number of dipole moments (18 hydroxyl groups from six glucose units), it has been suggested that PRX-based materials could serve as piezoelectric polymers with a high number of dipole moments. 10,11 Recently, we had confirmed that a partially cross-linked PRX elastomer exhibited good piezoelectric properties and high mechanical toughness because of its partially crystallized α-CD units and partially cross-linked mobile α-CD units. 12 The hexagonally packed crystalline structures found in the noncross-linked α-CD bundle, which were attributable to the strong hydrogen bonding between the α-CD molecules, were responsible for the elastomer's piezoelectric properties.…”

“…Polyrotaxane (PRX), which is composed of α-cyclodextrin (α-CD) molecules and poly­(ethylene glycol) (PEG), is a type of supermolecule in which the ring-shaped host molecules (α-CDs) are penetrated by the linear guest molecules (PEG) . Because a single α-CD molecule contains a large number of dipole moments (18 hydroxyl groups from six glucose units), it has been suggested that PRX-based materials could serve as piezoelectric polymers with a high number of dipole moments. , …”

“…The hexagonally packed crystalline structures found in the non-cross-linked α-CD bundle, which were attributable to the strong hydrogen bonding between the α-CD molecules, were responsible for the elastomer’s piezoelectric properties. On the other hand, the partially cross-linked α-CD molecules were responsible for its desirable mechanical properties because of the well-known “slide-ring” effect. , In general, the piezoelectric properties of a material are dependent on the size of its crystalline structure, as the number of aligned dipole moments within the crystalline structure has a determining effect on the piezoelectric performance. , Therefore, it could be presumed that the limited piezoelectric performance of the PRX elastomer would improve after the anisotropic alignment of its crystalline structure.…”

Structure and dynamics of polyrotaxane-based sliding graft copolymers with alkyl side chains

“…5a) formed by hydrogen bonding between a-CDs. [27][28][29][30] On the other hand, all the WAXS proles of the SGC samples (Fig. 4b(ii)-(vi)) commonly showed broad humps around q ¼ 1.4 ÅÀ1 instead of the sharp crystalline peaks observed in PR; these humps, or the so-called "amorphous halo", correspond to the average structural correlation distances.…”

Synthesis of polyrotaxane–glycine conjugates with various degrees of substitution via conjugation with Boc- or Z-glycine and subsequent deprotection

“…[5][6][7] A PR consisting of poly(ethylene glycol) (PEG) as an axis and a-cyclodextrins as ring components is one of the most examined and used types of supramolecules, and has been used to create new materials such as conceptual 'slide-ring materials', [1][2][3] promising medical devices 4 and textiles with improved properties. [8][9][10][11] More recently, much attention has been focused on the synthesis, characterization and use of various PR derivatives, in which different types of functional groups were incorporated onto CD moieties to obtain a wide range of properties. [12][13][14][15][16][17][18] For example, the introduction of various functional groups on the PR resulted in solubility of the obtained derivatives in water and a wide variety of solvents, [12][13][14] in contrast to the limited solubility of the unmodified PR.…”