Printability and mechanical performance of biomedical PDMS-PEEK composites developed for material extrusion

Polydimethylsiloxane (PDMS) materials are widely adopted in the manufacture of facial prostheses, lab-on-chip devices and scaffolds for soft-tissue engineering applications; however, their processing by additive manufacturing (AM) has proved challenging. Liquid silicone rubbers (LSRs) favoured high shape fidelity when cast, but low viscosity surface tension often prevent self-support, post-extrusion. Poly(ether) ether ketone (PEEK) particle reinforcement through interfacial bonding proven to enhance key properties PDMS, expanding end-use functionality. Still, impact such particles on printability LSR-PDMS is not explored. In this study, first time, solvent-free biocompatible PDMS-PEEK composites (up 30 wt% PEEK) were successfully characterised material extrusion (ME) printing. Rheological analysis confirmed shear-thinning all under applied load (within tolerances printer) dominant storage moduli at rest (i.e. prints can self-support), considered highly desirable ME-based Attained rheological datasets used guide initial studies, which revealed finer track with rising fractional content PEEK, comparable print speed displacement values. Composites higher PEEK demonstrated significant increases Shore A hardness stiffness (in compression) bulk form. Last least, enhanced (thanks reinforcement) geometrical autonomy further expanded freedom whereby infill density could be controlled order increase range mechanical performance, previously unachievable conventional casting fabrication. Fundamentally, lead bespoke spatially graded multi-material structures that replicate heterogenous soft human tissues other advanced applications.