TY - JOUR
T1 - Anisotropic hygro-expansion in hydrogel fibers owing to uniting 3D electrowriting and supramolecular polymer assembly
AU - Wu, Dan Jing
AU - Vonk, Niels H.
AU - Lamers, Brigitte A.G.
AU - Castilho, Miguel
AU - Malda, Jos
AU - Hoefnagels, Johan P.M.
AU - Dankers, Patricia Y.W.
PY - 2020/12/5
Y1 - 2020/12/5
N2 - Melt electrowriting (MEW) is mostly applied to print complex three-dimensional (3D) structures using traditional, relatively hydrophobic polymers, such as polycaprolactone. Here, we 3D printed a supramolecular hydrophilic polymer into a solid micrometer-sized fiber structure, solely held together via non-covalent interactions. Interestingly, the solid fibers showed anisotropic swelling in a humid environment as demonstrated by the longitudinal and transverse surface strain determined using a novel global digital height correlation algorithm. This anisotropy in swelling is proposed to originate from a shear-induced orientation of crystals packed into lamellae as shown with small-angle x-ray scattering measurements. The MEW fibers were dried after swelling to study structural differences. Remarkably, no differences in nano-structural conformation in the micrometer-sized fibers was observed after swelling and subsequent drying. In conclusion, a free-standing supramolecular polymer-based hydrogel scaffold, displaying anisotropic hygro-expansion, is shown to be produced using MEW. This unique combination of 3D printing, via a top-down approach, and supramolecular polymer chemistry, via a bottom-up approach, provides new ways to introduce anisotropy and hierarchy in aqueous supramolecular systems. This will open the door towards even more complex hierarchical structures with unprecedented properties.
AB - Melt electrowriting (MEW) is mostly applied to print complex three-dimensional (3D) structures using traditional, relatively hydrophobic polymers, such as polycaprolactone. Here, we 3D printed a supramolecular hydrophilic polymer into a solid micrometer-sized fiber structure, solely held together via non-covalent interactions. Interestingly, the solid fibers showed anisotropic swelling in a humid environment as demonstrated by the longitudinal and transverse surface strain determined using a novel global digital height correlation algorithm. This anisotropy in swelling is proposed to originate from a shear-induced orientation of crystals packed into lamellae as shown with small-angle x-ray scattering measurements. The MEW fibers were dried after swelling to study structural differences. Remarkably, no differences in nano-structural conformation in the micrometer-sized fibers was observed after swelling and subsequent drying. In conclusion, a free-standing supramolecular polymer-based hydrogel scaffold, displaying anisotropic hygro-expansion, is shown to be produced using MEW. This unique combination of 3D printing, via a top-down approach, and supramolecular polymer chemistry, via a bottom-up approach, provides new ways to introduce anisotropy and hierarchy in aqueous supramolecular systems. This will open the door towards even more complex hierarchical structures with unprecedented properties.
KW - Additive manufacturing
KW - Hydrogel
KW - Hygro-expansion
KW - Melt electrowriting
KW - Supramolecular polymer
UR - http://www.scopus.com/inward/record.url?scp=85094155671&partnerID=8YFLogxK
U2 - 10.1016/j.eurpolymj.2020.110099
DO - 10.1016/j.eurpolymj.2020.110099
M3 - Article
AN - SCOPUS:85094155671
VL - 141
JO - European Polymer Journal
JF - European Polymer Journal
SN - 0014-3057
M1 - 110099
ER -