Conference Program - LOPE-C 2011
Conference Program - LOPE-C 2011
Conference Program - LOPE-C 2011
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SCIENTIFIC CONF. | THURSDAY-JUNE 30, <strong>2011</strong><br />
Track 4<br />
Novel Inks and Processes (04:30 pm - 06:00 pm) | LOCATION HARMONIE D / LEVEL C2<br />
05:00 pm Plasma Functionalized Carbon Nanotubes for use in Functional Inks<br />
Mr Neil Graddage,<br />
Swansea University, PhD Student, United Kingdom<br />
The rapid development of printed electronics provides a continuous demand for novel materials and functionalities for inks. One material which has been the subject of<br />
much research interest in recent years is carbon nanotubes (CNTs). The dispersion of CNTs is not trivial due to particle aggregation. One method for improving the<br />
solubility of CNTs is to bond molecules to the surface of the material, a process known as functionalisation. Selection of appropriate molecules decreases nanotube<br />
agglomeration and allows improved bonding with the resin and dispersants. This is normally achived by acid processing, however this is known to adversely affect the<br />
electrical and mechanical properties.<br />
In this work a proprietary plasma processing technique (Haydale Ltd.) has been investigated. Functionalisation is achived by introducing defects to the surface of the CNTs<br />
to facilitate bonding without causing the severe structural damage typically seen after conventional acid processing. Carboxyl, Hydroxyl or amine group molecules are then<br />
bonded to the defects via atmospheric exposure.<br />
Suitable base inks were developed using functionalised and non functionalised CNTs. A full factorial experiment was performed varying the agitation energy, CNT<br />
concentration and the type of functionality applied. Fluid properties of the inks were characterised by studying the rheology and surface tension. The inks were coated onto<br />
a PET substrate. The conductivity and transmission properties of the printed layer were studied and average agglomerate size was investigated.<br />
The deagglomeration as a result of the plasma functionalisation provided a 60% improvement in sample homogeneity with a 43% reduction in agglomerate size compared<br />
to non-functionalized samples. Despite the introduction of defects to the nanotubes there was still a 7% improvement in the sheet resistivity.<br />
The use of plasma processing as a method for the functionalisation of CNTs for use in conductive inks allows for reduced processing time and improved electrical<br />
performance.<br />
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