Berlin 2005 – wissenschaftliches Programm

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CPP: Chemische Physik und Polymerphysik

CPP 33: Novel materials I

CPP 33.3: Vortrag

Mittwoch, 9. März 2005, 10:15–10:30, TU C230

Polymer Controlled Mineralization — •Ingo Lieberwirth, Laurent Herschke, Rafael Munoz-Espi, and Gerhard Wegner — Max-Planck Institute for Polymer Research, Ackermannweg 10, 55028 Mainz, Germany

Due to their specific sizedependent optical and electrical properties and their large surface anorganic particles such as metallcolloids, -oxides and -phosphates are of special interest. These powders normally have a non-uniform morphology, a broad grain size distribution and may even consist of several phases. Suitable polymeric additives can control their properties by meshing with the nucleation process and the subsequent crystal growth, comparable to processes in biomineralization.

In order to examine the complex mechanisms of polymer controlled crystallization from aqueous solution zincite (ZnO) and hopeite (Zn₃(PO₄)₂) have been selected as model systems. Amphipolar diblock- copolymers (DBCP) and functionalized latices were used as admixtures to control the crystallization process.

Crystallization of zincite from aqueous medium without any additional polymer results in elongated hexagonal prismatic crystals, having a broad grain size distribution covering a range from 1 to 5 µ m. Addition of PEO-b-PMAA during the crystallization results in a marked decrease in crystal size as well as in a narrowed grain size distribution ( 0.4 to 1.4 µ m). The same effect is observed when replacing the DBCP by the latices. Moreover, it is found that latices are incorporated into the crystal building a No-dqswiss cheeseNo-dq morphology without destroying the single-crystalline character of the zincite crystallites.