Two types of polymeric self-assemblies will be discussed. The first one comprises complexes of polyelectrolytes with opposite charges. As is well known the complexes with the anion/cation ratio close to unity turn hydrophobic and ppt. from aq. solns. We have managed to prep. anionic diblock copolymers with short poly(ethyleneoxide), PEO, blocks, as well as polycations grafted with relatively short PEO chains. Using these polymers it has been possible to obtain colloidally stable amphiphilic complex particles. An interesting finding is that the complex particles are typically very monodisperse, and clearly tend to form particles with a certain optimal size regardless of the molar mass of the polymers. The complex particles are in a dynamic equil.: chain exchange between the dispersed entities takes place continuously. The kinetics and mechanism of the chain exchange has been studied using fluorescence spectroscopy. Fluorescence labeling of the polymers has also enabled the investigation of the overcharging of the complexes. The other type of polymers to be discussed is star diblock copolymers. Diblock stars with four arms have been prepd., where the inner block is hydrophobic poly(Me methacrylate) and the outer one is poly(acrylic acid). These are polymers with an extremely complicated behavior when dissolved in water. Semidilute solns. tend to gelate, they form fragile gels which break upon shear. In dil. aq. solns., a tendency to aggregate into spherical micelles may be obsd. and upon addn. of salt, wormlike micelles build up. The very delicate balance between electrostatic and hydrophobic interactions in this case has been exptl. studied by changing the relative lengths of the hydrophobic and hydrophilic blocks. In addn., mol. modeling by computer simulations has been initiated and the first results are promising: it seems we can e.g. predict the ionic strength where the worm-like micelles build up. [on SciFinder(R)]
|Julkaisun otsikon käännös||Self-assembling of aqueous polyelectrolytes: Polyelectrolyte complex particles and micellar structures.|
|Otsikko||Unknown host publication|
|Tila||Julkaistu - 2006|
|OKM-julkaisutyyppi||A4 Artikkeli konferenssijulkaisuussa|
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CAPLUS AN 2006:245988(Conference; Meeting Abstract; Computer Optical Disk)
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