Preparation of Polyrotaxane Fibers. Part II: Tensile Properties of Polyrotaxane Fibers Treated with Two Cross-linking Reagents

Abstract

Polyrotaxane fibers prepared with wet spinning of polyrotaxane consisting of poly(ethylene glycol) and cyclodextrins (CDs) were cross-linked with two different cross-linking reagents, i.e., divinyl sulfone (DVS) and ethylene glycol diglycidyl ether (EGDE), to improve tensile properties of the fibers. By cross-linking with DVS, the values for the tenacity at break and the initial modulus were increased with cross-linking time, while the elongation at break was improved only moderately. On the other hand, drastic improvements in elongation at break were observed after EGDE cross-linking, up to 645% of its original length, although the tenacity at break and the initial modulus showed only slight improvements. After cross-linking, only minor changes in the degree of crystallinity fibers were observed by wide-angle X-ray scattering (WAXS) measurements.Keywords: polyrotaxane fibers, cyclodextrins, cross-linking, tensile measurements -2 - IntroductionIn our previous paper [1] on the functional polyrotaxane fibers, we reported a successful preparation of pure polyrotaxane fibers by wet spinning from polyrotaxane dope solution in various polyrotaxane solvents, i.e., dimethylsulfoxide (DMSO), dimethylacetamide (DMAc) containing lithium chloride (LiCl), and dimethylformamide (DMF) containing LiCl. Electron microscopy observations revealed a smooth and crack-free surface texture of the as-spun polyrotaxane fibers. By tensile measurements, the fibers spun from these three solvent systems showed similar levels of initial modulus and tenacity at break, whose values were relatively lower than those of commercial fibers such as polyesters and rayons. The values for elongation at break, however, were extremely high: up to 388% at 50% RH and 972% at 95% RH. The fiber spun from the DMSO dope solution showed a higher value of the elongation at break than the fibers from DMF/LiCl and DMAc/LiCl. 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60 -3 -The results also imply a successful preparation of novel spandex-like fibers exhibiting high levels of elongation at break and elastomeric properties.Cross-linking treatments of spun fibers are widely used for the preparation of functional fibers and improvements in physical properties of fibers. For example, previous studies showed remarkable improvements in wet and dry mechanical properties of chitosan fibers by cross-linking [7,8]. Poly(vinyl alcohol) fibers cross-linked with boric acid also showed improved strength and Young's modulus [9]. Cross-linking treatments are also applied to the preparation of rayons [10] and ultra-high-molecular weight polyethylene fibers [11] with improved physical properties, as well as finishing of fabrics such as crease-resistant finishing [12]. Recent investigations have utilized novel bio-mimetic cross-linking mechanisms, mediated by the action of enzymes or oxidation ...

Fabrication and structural analysis of polyrotaxane fibers and films

“…PR fibers were prepared by wet spinning according to the methods in the previous reports [40,41]. As a spinning solution, PR was dissolved in 60 • C DMSO at a concentration of 20 wt%, then degassed in an aspirator.…”

“…In addition, we have demonstrated the fabrication of PRbased fibers without chemical cross-links by wet spinning of PR solution [39][40][41]. In conventional synthetic fibers, polymer chains are oriented to a fiber direction and form crystal structure to retain the shape of the fiber.…”

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.…”