Self-organized meso- and hybridic phases of poly(aspartic acid) and poly(glutamic amino acid) with cationic surfactants (C(n)TAB, n=14, 16) and a silica source (TEOS)

 
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Self-organized meso- and hybridic phases of poly(aspartic acid) and poly(glutamic amino acid) with cationic surfactants (C(n)TAB, n=14, 16) and a silica source (TEOS) (EN)

Kodona, E. K. (EN)

Πανεπιστήμιο Ιωαννίνων. Σχολή Θετικών Επιστημών. Τμήμα Χημείας (EL)
Kodona, E. K. (EN)

In this work the self-organized mesophases obtained by the ionic interaction of poly( amino acids) poly(L-aspartic acid (P-L-Asp) and poly(L-glutamic acid) (P-L-Glu) with the cationic surfactants C(14)TAB and C(16)TAB, as well as the mesoporous silicate materials obtained by addition and hydrolysis of tetraethyl orthosilicate ( TEOS) on the hybridic mesophases, are described. The mesophases isolated at pH 6.5-8.5 were examined by X-ray diffraction (XRD) analysis for their structure, thermogravimetry for their thermal stability, scanning electron microscopy for their structural features, and circular dichroism (CD) for the conformation of the polypeptide-C(n)TAB (n = 14, 16) complexes. The mesophases P-L-Asp/C(14)TAB isolated at pH 7.5 and 8.5 showed in XRD a single peak at d = 3.45 nm and d = 3.54 nm, respectively, corresponding to typical hexagonal packing of the micellar aggregates. The mesophases P-L-Asp/C(16)TAB isolated at pH 7.5 showed an XRD peak at d = 3.90 nm, corresponding to a similar hexagonal packing of larger micellar aggregates and also two peaks at d = 3.37 nm and d = 1.69 nm indicating a layered configuration of the micellar sheets. The layered component decreases by the increase of pH from 7.5 to 8.5 or the addition of small amounts (0.5%) of EtOH. The P-L-Glu/C(14)TAB mesophases isolated at pH 7.5 and 8.5 showed a single XRD peak at d = 3.60 nm, while the P-L-Glu/C(16)TAB system showed also a single XRD peak at d = 4.10 nm. The CD spectra showed that the complexes P-L-Asp/ C(14)TAB possess a more random configuration compared to the P-L-Glu/C(14)TAB, which have the tendency to form alpha- and 3(10)-helices. The mesoporous silicate materials obtained from the systems P-L-Asp/C(16)TAB/ TEOS and P-L-Glu/C(16)TAB/ TEOS showed a single XRD peak corresponding to hexagonal pore arrangement typical in MCM-41 materials. The nitrogen adsorption-desorption isotherms of the silicate mesostructures indicate that they possess high surface areas in the range 500-800 m(2) g(-1) for the P-L-Asp/ C(n)TAB/TEOS and 1000-1070 m(2) g(-1) for the P-L-Glu/C(n)TAB/ TEOS and ordered or semi-ordered porosity depending on the hybridic system used for isolating the corresponding mesophases. (EN)

sodium dextran sulfate (EN)


Chemistry of Materials (EN)

English

2007


American Chemical Society (EN)



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