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Smart Materials: New Ways to Microstructured Particles of Environmental Concern

 
: Kümmel, R.; Weiß, C.; Bertling, J.

White, T. ; Materials Research Society -MRS-:
Advances in Environmental Materials. Vol.2: Environmentally Preferred Materials
Singapur: MRS, 2001
ISBN: 981-04-4992-7
S.175-187
International Conference on Materials for Advanced Technologies (ICMAT) <1, 2001, Singapur>
Englisch
Konferenzbeitrag
Fraunhofer UMSICHT Oberhausen ()
Mikropartikel; Populationsbilanz; überkritische Fluide; Verkapselung; Fällung; micro-sized particles; population; supercritical fluid (SCF); precipitation; encapsulation balance

Abstract
In material sciences, one of the most promising strategies to approach eco-efficiency is the combination of micronisation and functionalisation, i.e. the synthesis of materials that provide several integrated functions on as little area as possible. During the past decade, the better understanding of the operating modes of biological systems has caused an increasing tendency to prepare micro-sized particles with high functionalities, large surface-to-volume ratios, and multiple application potentials. Numerous methods are available to produce microstructured solid particles and to assist the preparation procedures by theoretical considerations. Physical and chemical processes can be used to encapsulate liquid or solid materials by various synthetic or natural polymeric shells. Sparingly soluble metal oxides are appropriate coating materials for functional filling agents, pigments, and powdery ceramic precursors. Amphiphilic polymers can be used to combine different substances with virtually incompatible structural properties based on a thermodynamically promoted self-structurization. The precipitation of inorganic or organic solids from solutions by means of supercritical fluids proves to be an effective tool to prepare nano- or micro-sized composite particles.
For the production of microspheres, the scale-up problem can be simplified by mathematical models that include population balances and describe multicomponent mass transfers as well as nucleation and crystal growth phenomena. The models consider varying solubilities, cross diffusivities and relevant transport phenomena for the transfer of mass and energy.

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