Preparation and Characterization of Organic/Inorganic Polymer Nanocomposites
Advancing the chemical engineering fundamentals
Polymer Science & Engineering - I (T2-12a)
Keywords: reactive nanoparticles, miniemulsion, polymercomposite
The combination of polymers with inorganic materials is a research field of steadily growing interest and importance. Especially, the synergism of polymeric properties such as elasticity and chemical resistance with organic ones like hardness, stability, electrical conductivity and other properties offer a vast potential concerning new materials and applications.
The preparation of polymer composites does not always lead to the desired synergetic effects. Due to the complementary properties of the components often phase separation occurs, giving rise to unsatisfactory material properties. This problem can be solved by linking organic and inorganic part covalently. Typical coupling agents for this purpose are substituted alkyl trialkoxysilanes and tetraalkoxysilanes.
Different styrene and acrylate based org./inorg. polymer composites incorporating magnesium hydroxide were successfully synthesized using 3-(methacryloxy)propyl-trimethoxysilane (MPTMS) as coupling agent and MgCl2 as inorganic precursor [1,2]. The polymer composites were prepared by free radical emulsion polymerization.
Another interesting field of research is devoted to the encapsulation of inorganic particles by polymers, the so called core-shell particles.
The main focus of our study are the preparation of functionalized hybrids[3,4]. Therefore, inorganic cores were produced, varying from silica cores to Al2O3 - , ZrO2 - and TiO2 -cores with polymerizable functionalities. Those cores have been copolymerized in miniemulsion using sodium dodecyl sulphate as surfactant and potassium peroxo disulphate as initiator with styrene or other monomers as matrix and glycidyl methacrylate, styrene sulfonic acid (SSA) and aminoethyl methacrylate hydrochloride and other as comonomers. This leads to functionalized emulsion products. The comonomer concentration was varied to achieve different polymer compositions and thus different rates of functional groups at the surface. The received emulsions were investigated with respect to thermal stability, rate of functionalization at the surface and particle size distribution, using a dynamic light scattering machine, equipped with a cross correlation system which enables the investigation of emulsions in reaction-state concentration.
The sol-gel-process is a powerful method for preparing polymer/silica organic-inorganic hybrids, in which a nanometer-size silica component is dispersed in a polymer matrix. This process can be be carried out also in the polmer melt. The steady-shear rheological behaviour show that the polymer composites are viscoelastic solids. We discuss the role and functional mechanism of the silane coupling agent. At high inorganic content storage and loss compliance become nearly independent from frequency due to extensive cross-linking.
[1] O. Pankow and G. Schmidt-Naake, Macromol. Mater. Eng. 2004, 289, 990
[2] O. Pankow and G. Schmidt-Naake, Macromol. Mater. Eng. 2006, 291, 1348
[3] M. Valencia, W. Dempwolf, F. Günzler, O. Knöpfelmacher,G. Schmidt-Naake,
Macromolecules, 2006, in press
[4] O. Töpfer, G. Schmidt-Naake, Macromol. Chem. Phys. 2006, submitted
See the full pdf manuscript of the abstract.
Presented Tuesday 18, 11:20 to 11:40, in session Polymer Science & Engineering - I (T2-12a).
