The Aggregation of Hydrophobically Modified Polysaccharides

SpectroscopicEllipsometry Ellipsometric Study of the Aggregation ofHydrophobically Modified Polysaccharidesin Solution at the Air / Water Interface UVISEL Michel Stchakovsky -Application Scientist - Thin Film Division Pullulan is a natural， water-soluble polysaccharide used in the production of foods， pharmaceuticals andcosmetics. From the consumer side it is popular as it is of non-animal origin being manufactured fromcorn， and from the technical side it is easily formed into films suitable for use in capsules. In this study， we have compared the physico-chemical properties of two ionic pullulan derivatives (CMP)modified by 10% and 35% Cg chains in aqueous solutions. These derivatives exhibit an associative behav-iour which stems from intra and intermolecular interactions between the hydrophobic C； groups graftedonto the molecules. Characterisation of the CMP polymer solutions The work was performed using a Jobin Yvon UVISEL Visible Spectroscopic Phase Modulated Ellipsome-ter. To make meaningful measurements of ellipsometric spectra requires the ultimate sensitivity for the tech-nique as the contrast in refractive index between the solvent and polymer molecules is extremely weak.The measurements described here were made at an incident angle close to 53° (which is the Brewsterangle for the system under consideration)， across the spectral range 250-800 nm. Moreover， such transparent ultrathin layered systems generate a A angle near 0 [180]. When com-pared to conventional ellipsometers， the phase modulated ellipsometer configuration is unique inthat it allows the highest sensitivity and precision of the A angle across the full [0°， 360°] range， evenwhen A is close to 0°. Explore the future HORIBAGROUP SpectroscopicElipsometry The figure shows three spectra of the ellipsometric angles W and ▲showing how the signals changewithin 10 minutes after perturbation of the air/liquid interface. The effect can be observed on themolecules modified by 10% C； chains only. Change in surface properties measured 3 timesduring a 10 minute interval for 10% modified. Stable surface for 35% modified measured3 times. -360.000 -340.000 -320.000 -300.000 -280.000 A() -260.000 -240.000 -220.000 -200.000 -180.000 Conclusion This interpretation has been supported by both surface tension measurement for the liquid phase and fluorescence spec-troscopy for bulk behaviour. From this study there is clear evidence that increasing the substitution rate from 10% to 35% induces a reinforcement ofthe hydrophobic interactions and thus the formation of more compact and stable aggregates which can complex hydro-phobic compounds. The use of CMP 35% C； could be envisaged in drug formulations where dispersion of a hydrophobicdrug in an aqueous phase is required. The authors would like to thank Veronique Rosilio from Paris-Sud University for her support in this work. USA： Jobin Yvon S.A.S.Jobin Yvon Inc.Z.A. De la Vigne aux Loups3880 Park AvenueJY Germany：+49 (0)894623 17-05， Avenue AragoEdison， NJ 08820-3012JY Italy： +39 0 2 5760 305091380Chilly MazarinToll-Free：1-866-jobinyvonJY Japan： +81 (0)33861 8231Tel： +33 (0) 1 64 54 13 00Tel：+1-732-494-8660JY UK：+44 (0) 20 8204 8142Fax： +33(0) 1 69 74 88 61Fax：+1-732-549-5125JY China： +86 (0) 10 6849 2216Email： tfd-sales@jobinyvon.frEmail： info@jobinyvon.comJY Korea：+82 2 576 8650 France： EMISSION·FLUORESCENCE·FORENSICS· GRATINGSG OEM·OPTICAL SPECTROSCOPY·RAMAN·THIN FILM