Page 90 - IJB-9-3

International Journal of Bioprinting Biocompatible 3D printing photosensitive resin

Figure 1. Schematic diagram of the preparation of NIPUA resin and the 3D printing procedure.

2.2. Synthesis of non-isocyanate polyurethane PTZ (0.05 wt.%) was added as a free radical inhibitor, then
methacrylate rotary evaporation removed the organic solvent to obtain
NIPU was synthesized from PC and IPDA by a ring-opening NIPUMA (yield: 93%).
reaction. Propylene carbonate (30.00 g, 0.29 mol) was added
into a round bottom four-neck flask (250 mL) equipped with 2.3. Polymerization and 3D printing of NIPUA
a mechanical stirring and reflux-condenser. The mixture NIPUA solution including NIPUMA monomer, TEGDA,
was heated to 120°C, followed by dropwise addition of PEGDA, 1 wt.% CQ photoinitiator was stirred at 50°C,
isophorone diamine (27.52 g, 0.16 mol) and stirring for 8–10 400 rpm for 15 min and then printed by LCD printing
h until the 1791 cm carbonyl group peak disappeared. The technology (LD-002H, CREALITY, China, 470 nm).
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product was then cooled down, and dissolved in 100 mL of The printed model structure was further drawn using a
dichloromethane. After vigorous stirring for 1.5 h, 300 mL computer-assisted design (CAD) software. The NIPUA
of n-Hexane was added to extract the product. The white formulation is shown in Table 1. Commercial resin (trans
precipitate was washed with n-Hexane to completely remove and white) was also printed in the same way.
the byproduct of ammonium and unreacted triethylamine. 2.4. Characterization of physical property
The resulting mixture was further dried under vacuum at 2.4.1. FITR characterization
60°C to remove n-Hexane. The transition of functional groups such as carbonyl,
The schematic diagram of the preparation of 3D hydroxyl, and alkene in FTIR characterize the thermal
printing photosensitive resin is shown in Figure 1. ring-opening with polyamines, as well as the acylation. The
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NIPUMA was synthesized from NIPU and MAC by a ring transmission spectra in a region of 500–4000 cm were
acylation reaction. NIPU prepolymer (60.00 g, 0.16 mol) obtained in an infrared spectrometer (Thermo Scientific
and triethylamine (36.65 g, 0.36 mol) were dissolved in Nicolet iS50, USA).
200 mL of anhydrous dichloromethane and cooled to 0°C 2.4.2. NMR characterization
in an ice bath. A solution of acryloyl chloride (38.71 g, The H nuclear magnetic resonance (NMR) spectra were
1
0.37 mol) in 100 mL of anhydrous dichloromethane was determined by a Bruker AV400MHz NMR spectrometer
added dropwise with stirring. This chemical reaction was (Bruker, Karlsruhe, Germany). NIPU and NIPUA were
allowed to warm until its temperature was equivalent to dissolved in dimethylsulfoxide (DMSO) and were injected
room temperature, and the triethylamine hydrochloride into NMR sample tubes (5 mm diameter).
salts were filtered off after 12 h. Then saturated sodium
bicarbonate solution was added to get two phase-separated 2.4.3. UV absorption analysis
mixture. The product at the bottom layer was collected and TU-1901 visible light photometer was used to test the
washed with 400 mL brine and 400 mL distilled water. The ultraviolet (UV) absorption of NIPUMA. NIPUMA

Volume 9 Issue 3 (2023) 82 https://doi.org/10.18063/ijb.684