Dibutyltin dilaurate dbtdl

Reagent grade hydrogen peroxide 30% and methanol were supplied by Merck (Darmstadt, Germany). Isophrene diisocyanate (IPDI), dimethylol propionic acid (DMPA), n-methyl pyrollidone (NMP), hydroxyethyl methacrylate (HEMA), phtalic anhydride, and dibutyltin dilaurate (DBTDL) were supplied by Sigma Aldrich (Milwaukee, WI, USA). Ethyl methyl ketone (MEK), triethylamine (TEA), formic acid, magnesium sulphate anhydrous, pyridine, and sodium hydroxide were reagent grade, supplied by Classic Chemicals (Shah Alam, Malaysia). The crude jatropha oil was supplied by Biofuel Bionas Sdn Bhd, Kuala Lumpur, Malaysia. It is a non-food grade material and was used as received. All chemicals were used without further purification.

Polypropylene glycol (PPG,
M.W. 2000 kDa), hexamethylene diisocyanate (HDI), triethylene glycol
(TEG), glycerol, CA, trans PCA, FA, chloroform, dimethylformamide
(DMF), phosphate-buffered saline (PBS), Dulbecco’s modified
Eagle’s medium (DMEM), penicillin–streptomycin (P/S),
fetal bovine serum (FBS), and crystal violet (CV) were purchased from
Fisher Scientific (Waltham, Massachusetts, USA) and used as received.
Ethyl-3-(3-(dimethylamino)propyl)carbodiimide (EDC), 4-(N,N-dimethylamino)pyridine (DMAP), and dibutyltin
dilaurate (DBTDL) were purchased from Sigma-Aldrich (St. Louis, Missouri,
USA). Escherichia coli (E. coli, 397E strain), Staphylococcus
aureus (S. aureus,
Wichita strain), and Swiss mouse 3T3 fibroblasts were purchased from
ATCC (Manassas, Virginia, USA), and glutaraldehyde was purchased from
Electron Microscopy Sciences (Hatfield, Pennsylvania, USA). PPG, TEG,
EDC, DMAP, CA, PCA, FA, and glycerol were all dehydrated under a vacuum
overnight to remove trace moisture before use. All solvents were dried
over sieves before use.

WBPUU inks were synthesized with a soft segment (SS) composed by two di-functional polyols, polycaprolactone (PCL) (CAS: 24980-41-4) and poly (ethylene glycol) (PEG) (CAS: 25322-68-3) (Mn = 2000 and 1000 g mol⁻¹, respectively), both provided by Sigma-Aldrich. On the contrary, 2,2-bis(hydroxymethyl) propionic acid (DMPA, 98% purity, CAS: 4767-03-7) and ethylene diamine (EDA, 99% purity, CAS: 107-15-3), which were used as an internal emulsifier and a chain extender, respectively, also provided by Sigma-Aldrich, and isophorone diisocyanate (IPDI, 99.5% purity, CAS: 4098-71-9), supplied from Covestro, were used as components of the hard segment (HS). Dibutyltin dilaurate (DBTDL, CAS: 77-58-7), provided by Sigma-Aldrich, was used as a catalyst. The polyols and the DMPA were dried under a vacuum at 60 °C for 4 h prior to their use. Butanone (supplied by Panreac, CAS: 78-93-3) was used to adjust the viscosity of the prepolymer in an intermediate state as well as to transfer the neutralized DMPA into the reaction medium. The neutralization of the carboxylic groups of DMPA has been carried out by using triethylamine (TEA, 99.5% purity, CAS: 121-44-8), provided by Fluka. Cellulose nanocrystals (CNC) provided by the University of Maine (2018-FPL-CNC-117) were used and CaCl₂ solution (0.1 M, CAS: 10043-52-4) was provided by Sigma-Aldrich.

All chemicals used in this study were purchased from Macklin with AR grade or higher (unless otherwise specified) and used as received. Dibutyltin dilaurate (DBTDL, 95%) was purchased from Sigma-Aldrich. Tetrahydrofuran (THF, 99.9%, superdry) and N,N-dimethylformamide (DMF, 99.9%, superdry) were purchased from J&K Scientific Ltd. Teflon molds of various shapes and depths were manufactured in-house to shape polyurethane.

Before the experimental procedures, all glassware utilized in the synthesis was thoroughly washed with ethanol, rinsed with distilled water, and dried with absorbent paper to eliminate potential impurities. The used reagents for the experimental procedures were dimethyl ketone (C₃H₆O) (99.5%, Meyer^®, Mexico City, Mexico); hydroxy-terminated polydimethylsiloxane (PDMS-OH) (2550–3570 cSt, Sigma Aldrich^®, Milwaukee, WI, USA); tetraethylorthosilicate (TEOS) (98% Sigma Aldrich^®, Wuxi, China); ammonium hydroxide (NH₄OH) (28% J.T.Baker^®, Madrid, Spain); nitric acid (HNO₃) (65–70% J.T.Baker^®, Madrid, Spain); and dibutyltin dilaurate (DBTDL) (95% Sigma Aldrich^®, Milwaukee, WI, USA).

Commercially available POM copolymer (Ultraform^®, BASF, Ludwigshafen, Germany) with melt flow rate (MFR (190/2.16, ISO 1133) 2.6 g/10 min has been used for composite preparation. The average molar mass was determined using the GPC method according to ASTM D5296-05 at a temperature 40 °C with the VE2001 Viscotek GPC system equipped with the RI-VE 3580 Viscotek detector (PL HFIPgel, 605 E901506 and HFIP 603 E910606 columns). Average molar mass has been determined based on the polystyrene standard as: M_n = 8 269, M_w = 78 565 and dispersity M_w/M_n = 8.96. Stoichiometric spherical-shaped hydroxyapatite (HAp) with general chemical formula C₁₀(PO₄)₆(OH)₂ was supplied from nGimat Co. (Atlanta, USA). The diameter of 99% HAp particles was below 100 nm. 1,6-heksamethylenodiisocyanate (HDI), poly(ε-caprolactone) diol (PCL) with average molar mass of 2000 g/mol and dibutyltin dilaurate (DBTDL) were supplied from Sigma Aldrich and used as received. Anhydrous N,N-dimethylformamide (DMF) and ethanol were produced by Avantor (Gliwice, Poland).