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Authors
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Müller, M. ; Reihs, T. ; Ouyanf, W.
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Title
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Needlelike and Spherical Polyelectrolyte Complex Nanoparticles of Poly(L-lysine) and Copolymers of Maleic Acid
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Date
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03.01.2005
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Number
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12632
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Abstract
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We report on the bulk and surface properties of dispersions consisting of nonstoichiometric polyelectrolytecomplex (PEC) nanoparticles. PEC nanoparticles were prepared by mixing poly(<FONT SIZE="-1">L</FONT>-lysine) (PLL) or poly(diallyldimethylammonium chloride) (PDADMAC) with poly(maleic acid-<I>co</I>-<IMG SRC="/images/gifchars/alpha.gif" BORDER=0>-methylstyrene) (PMA-MS)or poly(maleic acid-<I>co</I>-propylene) (PMA-P). The monomolar mixing ratio was <I>n</I>-/<I>n</I>+ = 0.6, and theconcentration ranged from 1 to 6 mmol/L. Subsequent centrifugation enabled the separation of the excesspolycation, resulting in a stable coacervate phase further used in the experiments. The bulk phase parametersturbidity and hydrodynamic radius (<I>R</I><SUB>h</SUB>) of the PEC nanoparticles showed a linear dependence on the totalpolymer content independently of the mixed polyelectrolytes. This can be interpreted by the increasedcollision probability of the polyelectrolyte chains when the overlap concentration is approached or exceeded.Different morphologies of the cationic PEC nanoparticles, which were solution-cast onto Si supports, wereobtained by atomic force microscopy (AFM). The combinations of PLL/PMA-MS and PDADMAC/PMA-MSrevealed more or less hemispherical particle shapes, whereas that of PLL/PMA-P revealed an elongatedneedlelike particle shape. Circular dichroism and attenuated total reflection Fourier transform infrared(ATR-FTIR) measurements proved the <IMG SRC="/images/gifchars/alpha.gif" BORDER=0>-helical conformation for the PEC PLL/PMA-P and the randomcoil conformation for the PEC PLL/PMA-MS. We conclude that stiff <IMG SRC="/images/gifchars/alpha.gif" BORDER=0>-helical PLL induces anisotropicelongated PEC nanoparticles, whereas randomly coiled PLL forms isotropic spherical PEC nanoparticles.
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Publisher
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Langmuir
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Wikidata
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Citation
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Langmuir 21 (2005) 465-469
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DOI
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https://doi.org/10.1021/la0483257
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Tags
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