3D Printable Hybrid Gel Made of Polymer Surface-Modified Cellulose Nanofibrils Prepared by Surface-Initiated Controlled Radical Polymerization (SI-SET-LRP) and Upconversion Luminescent Nanoparticles

• Published in: ACS applied materials & interfaces Vol. 15; no. 4; pp. 5687 - 5700
• Main Authors: Jiang, Xuehe, Mietner, J. Benedikt, Harder, Constantin, Komban, Rajesh, Chen, Shouzheng, Strelow, Christian, Sazama, Uta, Fröba, Michael, Gimmler, Christoph, Müller-Buschbaum, Peter, Roth, Stephan V., Navarro, Julien R. G.
• Format: Journal Article
• Language: English
• Published: United States American Chemical Society 01.02.2023
• Subjects: cellulose; cellulose nanofibers; crosslinking; Fourier transform infrared spectroscopy; Functional Nanostructured Materials (including low-D carbon); gels; hydrophilicity; hydrophobicity; ligands; luminescence; luminescent assay; nanoparticles; oleic acid; polymerization; polymers; rheology; small-angle X-ray scattering; thermogravimetry; viscoelasticity; X-ray diffraction; cellulose nanofibrils (CNFs); single electron transfer living radical polymerization (SET-LRP); upconversion nanoparticles (UCNPs); cellulose-based hybrid material; 3D gel printing
• DOI: 10.1021/acsami.2c20775
• ISSN: 1944-8244; 1944-8252

A cellulose nanofibril-based hybrid gel material was developed by grafting the polymerized stearyl acrylate (PSA) and upconversion nanoparticles (UCNPs) onto cellulose nanofibrils (CNFs) via Cu0-mediated radical polymerization (SET-LRP) to create a highly cross-linked CNF system. A two-step strategy was exploited to surface-exchange the ligand of the UCNPs from a hydrophobic ligand (oleic acid) to a hydrophilic small-molecule ligand (2-acrylamido-2-methyl-1-propanesulfonic acid, AMPS) and therefore be suitable for SET-LRP. The characteristics and properties of the hybrid material (UCNP-PSA-CNF) were monitored by Fourier transform infrared (FTIR) spectroscopy, thermogravimetric analysis (TGA), rheology, X-ray diffraction (XRD), and microscopic analysis. Those characterization techniques prove the efficient modification of the CNF, with the presence of 1.8% UCNPs. The luminescence measurement was carried out using a homebuilt confocal microscope with a 980 nm laser source. The nanostructure of UCNPs and their incorporated CNF species were measured by small-angle X-ray scattering (SAXS). In addition, this CNF-based hybrid gel has decisive rheological properties, such as good viscoelasticity (loss tangent was below 0.35 for the UCNP-PSA-CNF gel, while the PSA-CNF gel reached the highest value of 0.42), shear-thinning behavior, and shape retention, and was successfully applied to three-dimensional (3D) gel printing throughout various 3D print models.