Interaction between Fluorocarbon End-Capped Poly(ethylene oxide) and Cyclodextrins

Abstract

Well-defined fluorocarbon end-capped poly(ethylene oxide) (PEO), known as F-HEUR, were synthesized by varying both fluorocarbon end groups and PEO chain length. Their solution properties were studied and compared with those of hydrogenated carbon end-capped PEO. Variation of the end-capped functional group from -C 6 F 13 to -C 8 F 17 gave rise to a significant shift in the solution rheological properties. The interaction between different cyclodextrins and these fluorocarbon derivatives of PEO was systematically examined by rheological, dynamic light scattering (DLS), isothermal titration calorimetric (ITC), and 19 F NMR techniques. The viscosity of F-HEUR solution was drastically reduced in the presence of methylated β-cyclodextrin (m-βCD) due to the disruption of intermolecular hydrophobic associations, but not observed for Rand γ-cyclodextrins. The destruction of F-HEUR network structure in the presence of m-βCD was reflected by the large reduction in the plateau modulus (G N 0 ). The activation energies (E a ) determined from zero-shear viscosity decreased with m-βCD concentration until a molar ratio of 2; thereafter it remained constant. At high m-βCD concentration, subtle difference was observed for the complexes produced by -C 6 F 13 and -C 8 F 17 hydrophobic moieties. The inclusion complex formation between m-βCD and different fluorocarbon groups derived from ITC thermograms revealed a stoichiometry of 1:1 for C 6 F 13 but 1:1 and 2:1 inclusion complexes for C 8 F 17 at different m-βCD concentrations. DLS results showed a different mechanism for C 6 F 13 and C 8 F 17 fluorocarbon hydrophobes, which were in agreement with the results deduced from activation energies and 19 F NMR spectra. A mathematic model was adopted to describe the relationship between G N 0 and m-βCD concentration.

Temperature-controlled poly(propylene) glycol hydrophobicity on the formation of inclusion complexes with modified cyclodextrins. A DSC and ITC study

“…However, the DH1 IC experimental value is attributable to the light of the large heat (4.2 kJ mol À1 ) required for the dehydration of the PO unit compared to the value 36 of 1.2 kJ mol À1 necessary to desolvate the CH 2 group. Large negative enthalpy and entropy accompanied the formation of supramolecular inclusion complexes namely, methylated-b-CD + copolymers (based on fluorinated chains and EO units) 37 and a-cyclodextrin + azo cellulose. 13 In these cases, the van der Waals interactions as well as the loose of the degree of freedom of motion and translational entropy of the macromolecule were invoked.…”

Interaction between Hydrophobically Modified 2-Hydroxyethyl Cellulose and Sodium Dodecyl Sulfate Studied by Viscometry and Two-Dimensional NOE NMR Spectroscopy

“…Therefore, the activation energy of transient network formation E m could be deduced from the slope of a plot on ln(η 0 /T) versus T −1 . In this work, the zero-shear viscosity of 1 wt % bmHEC solution with/without SDS added and 1 wt % HEC exhibits quite a good Arrhenius dependence on temperature 7,11,12,34 (Figure 6a). As a result, the activation energies for the hydrophobe disentanglement in 1 wt % bmHEC (bs =0.09) solution and 1 wt % bmHEC (bs =0.017) are 32.74 and 30.69 kJ/mol, respectively, comparable to other associative polymers, 7,11,12 whereas that of 1 wt % unmodified HEC solution is 29.96 kJ/mol.…”

“…2 Consequently, the viscosity of the surfactant−polymer complex solution becomes even lower than that of pure HM polymer at the same polymer concentration. 2,7,11,12 Namely, added surfactants could either increase or decrease the viscosity of the HM polymer solution, dependent on the interaction between surfactant molecules and HM polymers. Currently, the effect of added surfactants to the rheological behavior of the surfactant-HM polymer complex system still attracts much research attention.…”

Nonionic fluorosurfactant as an ideal candidate for one-step modification of gold nanorods

“…In comparison with the GNRs@CTAB at the same concentration, we nd that the GNRs@FSN can dramatically decrease the toxicity of the gold nanorods (the cell viabilities remain above 90% aer the addition of the GNRs@FSN up to 124 mg mL À1 ), which could be attributed to the good biocompatibility of FSN as novel coating material for gold nanorods. 53,54 Cellular uptake…”