A detailed spectroscopic anal. performed on aq. solns. of uncharged Star-Polymers, having a porphyrin core and four poly(ethylene glycol) methoxy terminated arms, at different mol. wt. values, by Elastic and Quasi-Elastic Light scattering and Fourier Transform IR absorption (FT-IR) has been reported. The aim of the present work is essentially to characterize the structural and dynamical properties of the studied samples by applying different spectroscopic techniques which permit to investigate different features of an unique problem.In particular from the light scattering measurements we showed that the species having higher mol. wt. (3600 and 8500 Da), have a very low scattered intensity compatible with the presence of the mols. in the monomer form. At the lowest investigated mol. wt. (2100 Da) mols. aggregate to form large supramol. structures. This tendency to aggregate was confirmed by FT-IR measurements performed in the same water solns. at low frequency (200-700) cm-1. Also the high frequency region, in the OH stretching vibrational range, (2800-3800) cm-1, has been investigated vs. the mol. mass of the star-polymer. From the comparison of the IR spectra in the case of star-polymers aq. solns. with the absorbance spectrum of bulk water, we showed a destructuring effect for the collective' band centered at about 3200 cm-1, which is related to the OH stretching of tightly bonded water mols. (tetrahedral water)
Aggregation effects in aqueous solutions of Star-polymers by spectroscopic investigations
Micali N;Villari V;Mineo P;Vitalini D;
2003
Abstract
A detailed spectroscopic anal. performed on aq. solns. of uncharged Star-Polymers, having a porphyrin core and four poly(ethylene glycol) methoxy terminated arms, at different mol. wt. values, by Elastic and Quasi-Elastic Light scattering and Fourier Transform IR absorption (FT-IR) has been reported. The aim of the present work is essentially to characterize the structural and dynamical properties of the studied samples by applying different spectroscopic techniques which permit to investigate different features of an unique problem.In particular from the light scattering measurements we showed that the species having higher mol. wt. (3600 and 8500 Da), have a very low scattered intensity compatible with the presence of the mols. in the monomer form. At the lowest investigated mol. wt. (2100 Da) mols. aggregate to form large supramol. structures. This tendency to aggregate was confirmed by FT-IR measurements performed in the same water solns. at low frequency (200-700) cm-1. Also the high frequency region, in the OH stretching vibrational range, (2800-3800) cm-1, has been investigated vs. the mol. mass of the star-polymer. From the comparison of the IR spectra in the case of star-polymers aq. solns. with the absorbance spectrum of bulk water, we showed a destructuring effect for the collective' band centered at about 3200 cm-1, which is related to the OH stretching of tightly bonded water mols. (tetrahedral water)I documenti in IRIS sono protetti da copyright e tutti i diritti sono riservati, salvo diversa indicazione.
