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Authors
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Müller, M. ; Keßler, B. ; Richter, S.
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Title
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Preparation of Monomodal Polyelectrolyte Complex Nanoparticles of PDADMAC/Poly(Maleic Acid-alt-a-methylstyrene) by Consecutive Centrifugation
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Date
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22.07.2005
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Number
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13287
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Abstract
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We report on the refinement of anionic and cationic nanoparticles of nonstoichometric polyelectrolytecomplexes (PEC) by consecutive centrifugation, which was studied by dynamic light scattering (DLS),atomic force microscopy (AFM), colloid titration and infrared spectroscopy (IR). PEC dispersions wereprepared by mixing poly(diallyldimethylammonium chloride) (PDADMAC) and sodium poly(maleic acid-<I>alt</I>-<IMG SRC="/images/gifchars/alpha.gif" BORDER=0>-methylstyrene) (PMA-MS) at the monomolar mixing ratio of <I>n</I>-/<I>n</I>+ = 1.50 (anionic PEC) and 0.66(cationic PEC), respectively, and the polymer concentration of <I>c</I><SUB>POL</SUB> = 0.002 M. The particle size (<I>R</I><SUB>h</SUB>),titrable charge amount, and IR spectra were determined for both dispersions in the original state, afterthe first centrifugation and after the second centrifugation. Freshly prepared PEC dispersions containedtwo different particle sizes: around 10-25 nm (small particles) and around 100 nm (large particles).Consecutive centrifugation of freshly prepared PEC dispersions resulted in the separation of highly chargedexcess polyelectrolyte (PEL) and small PEC particles from a low charged coacervate phase of the desiredlarger PEC particles. After the second centrifugation, the coacervate phase of both dispersions PEC-1.50and PEC-0.66 consisted of monomodal particles sizing around 100 nm. These results were supported byAFM measurements on the respective dispersions deposited on glass plates. PEC-1.50 particles tendedto adopt slightly smaller sizes (<IMG SRC="/images/entities/ap.gif">90 nm) in comparison to PEC-0<br />.66 ones (<IMG SRC="/images/entities/ap.gif">110 nm). No significant influenceof the PDADMAC molecular weight on the particle size was found. IR spectroscopy showed changes in theenvironment of the carboxylate groups of PMA-MS by consecutive centrifugation. The centrifuged PEC-1.50 dispersions showed remarkable long-term stability over more than a year. The high macroscopicstability of the studied PEC dispersions is presumably due to repulsive electrostatic interparticle interactionsand attractive hydrophobic intraparticle interaction. The introduced monomodal PEC particles might beprojected as latex analogues or as nanocarriers for drugs and proteins.
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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) 7044-7051
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DOI
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https://doi.org/10.1021/la050716d
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