Needlelike and spherical polyelectrolyte complex nanoparticles of poly(L-lysine)

2019-09-11 23:03:05

PLL nanoparticles MS PMA PEC

责任者: Muller, M.;Reihs, T.;Ouyang, W. 单位: Leibniz Inst. of Poly. Res. Dresden, D-01069 Dresden, Germany 来源出处: Langmuir,2005,21(1):465-469 摘要: We report on the bulk and surface properties of dispersions consisting of nonstoichiometric polyelectrolyte complex (PEC) nanoparticles. PEC nanoparticles were prepared by mixing poly(L-lysine) (PLL) or poly(diallyldimethylammonium chloride) (PDADMAC) with poly(maleic acid-co-a-methylstyrene) (PMA-MS) or polyCmaleic acid-co-propylene) (PMA-P). The monomolar mixing ratio was n-/n+ = 0.6, and the concentration ranged from 1 to 6 mmol/L. Subsequent centrifugation enabled the separation of the excess polycation, resulting in a stable coacervate phase further used in the experiments. The bulk phase parameters turbidity and hydrodynamic radius (R h) of the PEC nanoparticles showed a linear dependence on the total polymer content independently of the mixed polyelectrolytes. This can be interpreted by the increased collision 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, were obtained by atomic force microscopy (AFM). The combinations of PLL/PMA-MS and PDADMAC/PMA-MS revealed more or less hemispherical particle shapes, whereas that of PLL/PMA-P revealed an elongated needlelike particle shape. Circular dichroism and attenuated total reflection Fourier transform infrared (ATR-FTIR) measurements proved the α-helical conformation for the PEC PLL/PMA-P and the random coil conformation for the PEC PLL/PMA-MS. We conclude that stiff a-helical PLL induces anisotropic elongated PEC nanoparticles, whereas randomly coiled PLL forms Isotropie spherical PEC nanoparticles. 关键词: Copolymers;Polyelectrolytes;Surface properties;Anisotropy;Complexation;Concentration (process);Precipitation (chemical);Atomic force microscopy;Fourier transform infrared spectroscopy;Probability;Complex particles;Colloid stability