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ORMOCER®s: Nanoscaled Hybrid Materials

ORMOCER®s are hybrid polymer materials synthesized by the sol-gel process. This process starts by building up an inorganic network through controlled hydrolysis and condensation of organically modified Si alkoxides on the nanoscale. Co-condensation with other metal alkoxides (Ti, Zr, Al alkoxides) is also possible

In a subsequent step the polymerizable groups, which are fixed to the inorganic network, react with each other in a thermal or UV-initiated process. In this two-stage process an inorganic-organic copolymer is synthesized on the nanoscale. In addition it is possible to use organically modified Si alkoxides, which do not enter into any organic polymerization reaction and thereby contribute to an organic functionalization of the inorganic network.

Link: https://www.ormocere.de/en.html

Figure: Schematic representation of hybrid polymers (ORMOCER®s).
(=> please click to enlarge)

 

 

Schematic representation of hybrid polymers (ORMOCER®s)

 

Some examples of the use of inorganic and hybrid sol-gel materials are shown below.

Interference filter

TiO2 layers are manufactured via a sol-gel process, which enables single layer thicknesses up to 300 nm. The material shows very good adhesion to all substrates investigated (glass, metals, Si). The layers are of excellent optical quality and the TiO2 particles have a size of 20 nm. The process is industrially applied for the manufacture of interference filters.

Figure: Photograph of interference filter (inset: SEM of cross-sectional view).

 

 

Photograph of interference filter (inset: SEM of cross-sectional view)

Optical Scattering Layers

Using silica nanoparticles light scattering layers can be prepared by Sol-Gel Processing. When thin film solar cells are deposited on such substrates, the light pathway of incident radiation is prolonged in the absorber resulting in improved cell efficiency. Light extraction from LEDs is another possible application of these visual scattering materials.

Figure: Cross-sectional view of a, a-Si / µc - Si solar cell deposited on a nanoscale optical scattering layer.

 

 

Cross-sectional view of a, a-Si / µc - Si solar cell deposited on a nanoscale optical scattering layer

Multifunctional nanoparticles

Monodisperse hybrid and inorganic nanoparticles (NPs) can be synthesized by sol-gel technology. The structure, size, and composition of these NPs can easily be controlled to tailor their chemical and physical properties. Luminescent hybrid NPs with mean diameters in the range of 60 – 900 nm can be synthesized by modified Stoeber process and labelled with organic conventional dyes. They exhibit significant resistance to photobleaching and dye leakage. Luminescent inorganic NPs with mean diameters in the range of 5 – 800 nm can also be obtained by sol-gel technology. The well-controlled preparation of luminescent inorganic NPs of core-shell structure based on biocompatible materials is feasible.

Subsequent to the NP fabrication reactive functionalities are introduced to the surface of nanoparticles by conventional functionalization methods such as silanization, ligand exchange or NP surface coating. Spacer length and type of chemical functionality are systematically adapted to the intended application. The NP surface coverage with chemical functionalities is then analyzed qualitatively and quantitatively. Surface modified NPs are covalently attached to various matrix or coating materials to tailor their chemical and physical properties. With respect to the application of NPs in biological and medical diagnostics, they are covalently attached to biological moieties, such as antibodies, peptides or nucleobases by means of standard bioconjugation methods. The functionality of the bound biomolecules is verified by subsequent biological tests.

Link: https://www.isc.fraunhofer.de/en.html

Figure: Nanoparticles (top) and luminescent dispersions of functionalized nanoparticles (bottom).

 

 

Figure: Nanoparticles (top) and luminescent dispersions of functionalized nanoparticles (bottom

Encapsulation materials

Spray drying of nanoscale silica dispersions yield porous particles and hollow spheres. After infiltration with e.g. antibiotics they may be used for the controlled release of active pharmaceutical ingredients

 

Figure: Spray-dried silica nanocapsules

 

 

Spray-dried silica nanocapsules


Barrier Coatings

Barrier layers for flexible packaging and technical applications are used daily and are indispensable for food industry, pharmaceuticals, and cosmetics or in technical applications.
The Fraunhofer Institute for Silicate Research ISC offers its customers a wide range of barrier materials based on ORMOCER®s of high technical barrier films up to ultra-barrier films as well as the expertise to preparation and processing methods from a single source.
Together with our customers and partners we develop customized barrier concepts and optimize materials. In addition, we advise and assist our project partners to industrial implementation.
In collaboration new ideas arise that we support with our know-how and the overall competences of the Fraunhofer ISC and the recourse to the other institutes of the Fraunhofer Gesellschaft, in particular the Fraunhofer Alliance POLO®, by support and transferring into new products.

Figure: Barrier films for packaging sensitive products.

 

 

Barrier films for packaging sensitive products

Scratch- and Abrasion-Resistant Coatings

In hybrid polymers organic and inorganic domains coexist on the nanoscale. ORMOCER®s with such features were developed that provide scratch- and abrasion-resistant coatings on different polymers and metals

 

Figure: Polymer substrate partially protected by a scratch-resistant ORMOCER® coating (left side).

 

 

Polymer substrate partially protected by a scratch-resistant ORMOCER® coating (left side)

Anti-adhesive Coatings

When functional groups are incorporated into ORMOCER®s the wetting behavior on the resulting surface can be tailored. In this way hydrophobic/oleophobic properties are realized on various substrates. Using fluorinated silanes results in anti-adhesive films that are both water- and oil-repellant: Since the adhesion of contaminations is reduced the hybrid polymer surfaces show an improved cleanability.

Specific ORMOCER®s diminish wetting and adhesion of spraying paints, Graffiti either do not adhere or are easily removed.

Figure: Hydrophobic ORMOCER® film (left) and uncoated substrate (right).

 

 

Hydrophobic ORMOCER® film (left) and uncoated substrate (right)

 

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