Recent advances in molecular programming of liquid crystal elastomers with additive manufacturing for 4D printing

Abstract

Liquid crystal elastomers (LCEs) are crosslinked polymers within which liquid crystal molecules are linked with elastomeric polymer chains. Various anisotropic materials properties of LCEs can be created through an orientational...

Additive Manufacturing of Liquid Crystal Elastomer Actuators Based on Knitting Technology

“…Among existing methods to fabricate LCE actuators, [12][13][14][15][16][17][18][19][20][21][22][23] additive manufacturing has shown great advantages in controllability on alignment and shaping, and imparts LCE actuators with complex deformability. [24][25][26] For example, direct ink writing (DIW) aligns the LC mesogens while shaping through shearing force and precisely controls the local alignment by adjusting the printing parameters. [20][21][22][23] However, when the fabrication is completed and the chemical network is fixed, it is difficult to reshape and recycle LCE actuators.…”

A dive into the bath: embedded 3D bioprinting of freeform in vitro models

“…The possibility of using support baths not only during the bioprinting process but as a continuous medium 35 with modulable properties over time 106 (4D bioprinting) or the controlled release of growth factors 107 or genetic material 108 is another alternative that is certainly worth to be explored. The same applies to the use of sacrificial inks with programmable dissolution rates.…”

Toward Monodomain Nematic Liquid Crystal Elastomers of Arbitrary Thickness through PET-RAFT Polymerization

“…Since the original work of Kupfer and Finkelmann, other methods have been developed to align LCEs, often replicating alignment methods applied to low molecular weight liquid crystals. Such methods include the application of electric/magnetic fields to the system to induce the desired alignment. , While field alignment presents the advantage of no sample thickness limitations, its limitations include possible breakdown of samples, limited availability of appropriate field sources, and, in the case of electric fields, the possible alignment achievable being limited by the dielectric anisotropy of the sample. ,,, A relatively recent development in LCE production is the use of additive manufacturing techniques (such as 3D printing). − These techniques present exciting opportunities for the future of LCEs, as samples with complex structures and shapes can be produced in a cost-effective manner. However, additive manufacturing too can have drawbacks depending on the method employed, including slow print speeds, low resolution, and moderate alignment quality …”