Materials for 3D printing; from model to green reality
Lightweight, renewable origin, mild processing and easy recyclability make thermoplastics the circular building materials of choice. However, additive manufacturing (AM), better known as 3D printing, lags the mass application of thermoplastics. After heating in the melt, particles or filaments fuse together first in 2D and then in 3D, creating unprecedented geometric freedom. Despite a scientific understanding of fusion, industrial and scientific consortium experts still face inferior mechanical properties of fused welds in practice. One example is premature mechanical failure in patient-specific and biodegradable medical devices based on Corbion's polylactides and more technical constructions based on Mitsubischi's poly(ethylene terephthalate), PET. The cause lies in conflicting low rates of polymer diffusion and entanglement, and too high a rate of crystallization to compensate for insufficient entanglement.
Previously, we eliminated the conflicting time scales via interfacial co-crystallization where alternating deposition of two opposite stereospecific polymers occurs. Stereocomplexation is commercially limited to poly(lactide) which despite enhanced interfaces further demonstrates its intrinsic brittleness at product scale. To promote mass application of thermoplastic AM industries, the research question was formulated as follows. Based on the fundamentals underlying interfacial stereocrystallization, what are the ultimate and scalable material formulations that ensure high performance of AM thermoplastic products while promoting circularity and the principles of green chemistry?