Versatile Hybrid Polymers as Matrices for Nanoparticle Preparation
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1007-S12-08
Versatile Hybrid Polymers as Matrices for Nanoparticle Preparation Claudia Feldgitscher, Sorin Ivanovici, and Guido Kickelbick Institute of Materials Chemistry, Vienna University of Technology, Getreidemarkt 9/165, Vienna, A1060, Austria ABSTRACT Hybrid inorganic-organic polymers were prepared applying poly(ethylene oxide) (PEO) crosslinked polysiloxanes as a matrix for the precipitation of metal or metal oxide nanoparticles. Polysiloxanes as flexible and hydrophobic polymer backbones were crosslinked with end-group functionalized PEO by using Pt-catalyzed hydrosilation reactions. Systematic variation of the chain length of the different components resulted in tunable matrices with adjustable hydrophilic regions. The chemical nature of the polysiloxane backbone and the thermal stability of the crosslinked polymer system facilitated nanoparticle preparation through different mechanisms. The crosslinked hybrid polymers were infiltrated with solutions of lanthanide salts, cobalt carbonyl or HAuCl4 allowing the application of three different chemical methods (hydrolysis, thermal decomposition, reduction) for nanoparticle preparation. FT-IR, SEM and TEM analyses were used to characterize the insoluble hybrid systems. INTRODUCTION Water-in-oil microemulsions are widely used in the controlled formation of inorganic nanoparticles [1]. The concept of applying hydrophilic cavities that allow the formation of inorganic nanoparticles in a hydrophobic environment can also be transferred to a gel-like crosslinked polymer system. For this approach, hydrophobic polymers are used as the matrix in combination with hydrophilic polymer segments creating a hydrophilic cavity. Polysiloxanes as primarily hydrophobic polymers are found in a wide range of applications, owing to their high flexibility, thermal stability, possibility for chemical modification and high elasticity at low temperatures [2,3]. Therefore they represent an ideal class of polymers for hydrophobic environments. Poly(ethylene oxides) (PEO) possess the ability to complex metal ions and are therefore used in a variety of applications, such as solid state ion electrolytes [4]. Microphase-separation in systems consisting of both components leads to materials that contain cavities that are size limiting for chemical reactions inside and therefore ideal for the formation of nanoparticles [5], which are preserved inside the matrix and protected from agglomeration and environmental influences. Several model nanoparticle systems were used to prove the concept of particle formation in poly(ethylene oxide)-polysiloxane matrices. The systems were selected based on two criteria: (i) type of chemical reaction leading to the particles, and (ii) properties of the nanoparticles. Lanthanide based nanoparticles are particularly interesting because of their potential use in biomedical stains, optical fibers and lighting devices [7]. Magnetic cobalt particles were used as second model systems because they can be easily prepared by thermal decomposition [8]. The reduction of no
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