SUPPORTING INFORMATION 3D Printing of Photocurable Cellulose Nanocrystal Composite for Fabrication of Complex Architectures via Stereolithography Napolabel B. Palaganas 1,3, Joey Dacula Mangadlao 1,2, Al Christopher C. de Leon 1, Jerome O. Palaganas 1,3, Katrina D. Pangilinan 1, Yan Jie Lee 1, Rigoberto C. Advincula 1* 1 Department of Macromolecular Science and Engineering, 2 Department of Radiology, Case Western Reserve University, Cleveland, Ohio 44106, United States 3 School of Graduate Studies, Mapua Institute of Technology, Intramuros, Manila, Metro Manila 1002, Philippines *Email: rca41@case.edu Phone: +1 216-368-4566 S-1
Figure S1. Images of (a) abaca plant which resembles banana and normally cultivated in tropical regions, (b) abaca fibers extracted from the leaf sheaths, and abaca fiber products such as (c) cordage, (d) garment, (e) furniture while recent developments have led to the discovery of highly crystalline nanocellulose from (f) the hierarchical structure of a plant fiber, which is capable of imparting reinforcement to various composites. References: (a-b) Courtesy of Philippine Rural Development Project, Regional Project Coordination Office V InfoACE Unit (PRDP RPCO V InfoACE Unit) and the Department of Agriculture Regional Agriculture and Fisheries Information Section V (DA RAFIS V) (c) Abaca Philippines, http://www.abacaphilippines.com/abaca.php?go=products&show= cordage, accessed: August, 2016. (d) Abaca Philippines, http://www.abacaphilippines.com/abaca.php?go=products&show= garments, accessed: August, 2016. (e) Holloways, https://www.holloways.co.uk/news/garden-room/sofas-a-buyers-guide, accessed: December, 2016. (f) 2015 Rojas J, Bedoya M, Ciro Y. Published in Organic Chemistry under CC BY 3.0 license. Available from: http://dx.doi.org/10.5772/61334 S-2
Figure S2. Chemical structure of (a) PEGDA, (b) RO16, (c) TEMPO, (d) LAP, and (e) Cellulose S-3
Figure S3. (a) AFM image of singulated CNC, (b) height profile of a line along the width of CNC, and (c) height profile of a line along the length of CNC. S-4
Figure S4. 3D printing defects in dogbone (top) and butterfly (bottom) specimens include (a) inconsistent curing, (b) delamination (or peeling off), and (c) bulging (or swelling) through unintended additional volume. Primary problem (not shown) includes also but not limited to failure to form any structure at all. S-5
Figure S5. (a) Full FT-IR spectra of pure CNC and 3D-printed PEGDA hydrogel with varying CNC loading (0, 0.3, 0.5, 0.9, and 1.2 wt % CNC), (b) Increase in absorption intensities at around 3450 cm -1 (H-bonded O H stretching vibration) and 2870 cm -1 ( C H stretching vibration) for given CNC loadings, and (c) the trend curve of the absorption intensities of C H and O H bands as a function of CNC loading in wt %. S-6
Equation S1. Beer-Lambert Law A = εlc = mc (1) where A is the absorbance, ε (proportionality constant between absorbance and concentration) represents the extinction coefficient (or the molar absorptivity), l (path length) gives the thickness of the sample, and c indicates the concentration of the analyte of the sample. The product of ε and l, when taken as a single quantity, may be interpreted as the slope (m) of the calibration line. S-7
Fabrication Technique Conventional Method (Casting) 23 3D Printing (SLA)* Resin Composition Pure PEGDA PEGDA-CNC Pure PEGDA PEGDA-CNC (unfilled) (1.4 wt % CNC) (unfilled) (0.3 wt % CNC) a) Tensile Strength 65 kpa 375 kpa 0.6 ± 0.2 MPa 1.2 ± 0.3 MPa b) Elongation 296 ± 18% 659 ± 24% 2 ± 1% 5 ± 1.5% c) Tensile Modulus 7.5 kpa 31 kpa 26 ±1 MPa 28 ± 1 MPa d) Fracture Energy 0.21 ± 0.01 kj m -3 4.78 ± 0.22 kj m -3 8 ± 5 GJ m -3 35 ± 20 GJ m -3 Table S1. Comparison of mechanical properties between casting as the conventional method and 3D printing via SLA. Data obtained from Yang et al. 23 using the conventional method and from this study* via 3D printing. S-8
Figure S6. (a) Stress-Strain curves for PEGDA with varying CNC Loading, (b) toughness comparison between unfilled PEGDA and PEGDA filled with 0.3 wt % CNC, and (c) elastic and plastic regions of the curve for PEGDA filled with 0.3 wt % CNC. S-9
Equation S2. Direct Relationship between Curing Depth and Radiation Wavelength C d d Q 1 ln E E c (2a) where C d measures the curing depth, d is the mean particle size, Ø is the volume fraction of the particle in suspension, E represents the actual exposure energy hitting the surface of the resin, while E c measures the critical energy required for the transition of the resin from the liquid phase to solid phase; and then equation (2b) gives an expression for Q Q = ( n n o ) 2 ( d λ )2 (2b) where n o is the refractive index of the polymeric solution, n quantifies the difference between the refractive index of the particle and that of the polymeric material, and λ represents the radiation wavelength. Substituting equation (2b) in (2a) gives the direct relationship between the curing depth (C d ) and the square of the radiation wavelength (λ) as shown in equation (2c). C d = ( n o n )2 1 dθ λ2 ln E E c (2c) S-10
Figure S7. (a) Thermogravimetric mass loss and (b) derivative mass of a sample of pure CNC and pure LAP heated at a constant rate of 5 ⁰C min -1 with 14.3% and 17.2% mass residues at 1,000 ⁰C, respectively. The boiling point of lithium (Li) contained in LAP is around 1,342 ⁰C. S-11
Figure S8. Contact angle measurement for PEGDA nanocomposite hydrogel with varying CNC loading (0, 0.3, 0.5, 0.9, and 1.2 wt %). S-12