Dabco 33 lv

Tissue slices were treated as previously described by Carasatorre et al.³⁸ . Anti-DIG-POD (1:800) (ROCHE) diluted in TSA was added and the slices were incubated overnight at 4 °C, washed in TBS and TTBS and developed with Tyramide signal amplification-Cy3 (TSA-Cy3; 1:75) detection kit (Perkin-Elmer) in darkness and incubated for 60 min, washed in TBS and TTBS, contrasting with DAPI (1:400 in TBS) (ROCHE), and mounted with medium 1,4-Diazabicyclo[2.2.2]octane (DABCO 33-LV; Sigma-Aldrich).

All reagents used in the present research were used as received. Castor oil (chemically pure) with hydroxyl and acid values of 162 and 2 mg KOH/g, respectively, was purchased from Sigma Aldrich (St. Louis, MO, USA). Poly(trimethylene ether) glycol (PO₃G, Velvetol 1000, Mn = 1046 g/mol) was kindly supplied by Allessa GmbH (Frankfurt, Germany). Gelling catalysts (DBTDL) and blowing catalysts (DABCO 33LV) were purchased from Sigma Aldrich, USA. TDI was used as HRs in PU synthesis and was also supplied by Sigma Aldrich. Niax L-580 silicon oil surfactant was kindly provided by Momentive Performance Materials (Waterford, NY, USA). Distilled water was used as an environmentally friendly blowing agent. Details of the raw materials used in the study are summarized in Table 1.

A commercial USA softwood kraft lignin was used as lignin source for RPU foam preparation. The lignin sample was oven-dried at 105 °C for 24 h before it was used for the preparation of RPU foams. Commercial polyester polyol (R-23-015) and pMDI (A-23-015) were purchased from NCFI Polyurethanes (Mount Airy, NC, USA). Based on the specification provided by NCFI Polyurethanes, the polyol R-23-015 contains tertiary amine catalyst (<1%) and a physical blowing agent containing 1,1,1,3,3-Pentafluoropropane (<3%) and 1,1,1,3,3-Pentafluorobutane (<10%). The total amount of blowing agents in polyol R-23-015 measured by a gravimetric method in our laboratory was 9%. For lignin-based RPU foams, Dabco^® 33-LV (33 wt. % solution of triethylenediamine in dipropylene glycol, Sigma Aldrich, St. Louis, MO, USA) was used as a catalyst. 1,1,1,3,3-Pentafluorobutane (Fisher Scientific, Hampton, NH, USA) was used as a physical blowing agent for the preparation of lignin-based RPU foams. Other chemicals were purchased from Sigma-Aldrich as analytical grade and used as received.