Multifunctional Glues

The Department of Functional Polymers, Empa is part of the CTI project "Structured multifunctional polymers for electronic packaging (SMACK)". Among Empa, the research institutes NTB (Buchs) and CSEM (Alpnach), the Swiss companies APM Technica AG (Heerbrugg), Fisba Optik AG (St. Gallen), Baumer Electric AG (Frauenfeld), Unisensor AG (Attikon), UCP Group (Ruggell) and the Nano-Cluster-Bodensee (St. Gallen) are involved. The aim of the project is to develop new multifunctional adhesives for optical applications. An outstanding feature of the developed adhesives is a high refractive index. By a clever choice of organic groups, a very high refractive index of the adhesives was achieved.

Figure: refractive indices of the high refractive adhesives and a commercial optical adhesive as a function of wavelength

For optical applications a high level of transparency of the adhesive is an essential material property. Also production requirements from the industry and the bonded material itself define further properties of the adhesive. Thus good processing can only be achieved if the adhesive is liquid, cures at low temperatures and is compatible with the other used materials. It has to be stable and the built device has to function under the influence of temperature, bacterial infestation, humidity, excessive UV exposure, cleaning agents, mechanical stress and much more over years.

Figure: cured high refractive index adhesive layer between two glass plates as a demonstration of transparency.


Schneider R., Lüthi S., Albrecht K., Brülisauer M., Bernard A., Geiger T.
Transparent silicone calcium fluoride nanocomposite with improved thermal conductivity
Macromolecular Materials and Engineering (2014)

NTB (Buchs) (
CSEM (Alpnach) (
APM Technica AG (Heerbrugg) (
Fisba Optik AG (St. Gallen) (
Baumer Electric AG (Frauenfeld) (
Unisensor AG (Attikon) (
UCP Group (Ruggell) (
Nano-Cluster Bodensee (St. Gallen) (

KTI-Nr. 12682.1 PFNM-NM „SMACK: Strukturierte  multifunktionale Polymere für Electronic Packaging“