Figure 1. Process during surface modification.

A) The process: A substrate, covered with a functional polymer layer, is mounted on the print bed. On top of this layer, a thermoplastic layer is printed first, followed by additional layers. A coupling reaction is initiated on contacting the melt with the functional polymer.

B) Example of a reaction: A carbonyl derivate 1 is converted to an acyl cation 3. Contact with an aromatic system of poly styrene results in chemical coupling by electrophil aromatic substitution, 4. After rinsing with water, the bottom side of the printed part exhibits a high density of carboxylic acids, which characterises the surface properties. The printed part surface is very hydrophilic and polar. XPS measurements show a high oxygen content.

The printed parts with taylored functional surface may be used in research labs as model systems. The approach can be applied when parts with defined geometry and defined robust and tailored surface functionalisation are required on-demand, e.g. in life science research.