N n dimethylformamide (dmf)

Hydrochloric acid (36%) and N,N-Dimethylformamide (DMF) were purchased from Chempur (Piekary Śląskie, Poland). Zinc nitrate hexahydrate (Zn(NO₃)₂·6H₂O) and Terephthalic acid (C₆H₄(COOH)₂) were provided by Sigma Aldrich (MERCK, Darmstadt, Germany).

The extraction experiments in N,N-dimethylformamide (DMF) solvent (Chempur, Piekary Śląskie, Poland) were conducted to evaluate the crosslinking level (gel fraction). Three samples of each studied foam (approx. 200 mg) were prepared, weighted (m₀), and immersed in DMF for 24 h. Afterwards, the samples were taken out from the DMF and washed twice by immersing the sample in acetone (Chempur, Piekary Śląskie, Poland) for 5 min. Excess solvent was blotted on cellulose sheets. The samples were dried at 25 °C under vacuum until the constant weight was achieved. The weight of the dry samples (m) was determined, and the gel fraction was calculated as the ratio between the dry mass of the sample after extraction (m) and the dry mass of the sample before extraction (m₀).

Kraft lignin (Sigma-Aldrich, Poznań, Poland); sodium lignosulfonate (TCI, Tokyo, Japan); tetrahydrofuran (THF, Sigma-Aldrich, ≥99.0%); hydrochloric acid (HCl, solution 37%, Honeywell, Warsaw, Poland); acetic acid (Chempur, Piekary Śląskie, Poland, ≥99.5%); N,N-dimethylformamide (DMF, Chempur, ≥99.8%); ethyl acetate (Chempur, ≥99.5%); ethanol (Chempur, ≥96.0%); acetone (Chempur, ≥99.0%); zinc chloride (ZnCl₂, Sigma-Aldrich, ≥97.0%); potassium carbonate (K₂CO₃, Sigma-Aldrich, ≥99.0%); phenol (Chempur, ≥98.0%); nitrogen (5.2, Air Products, Warszawa, Poland); commercial activated carbon WG-12 (Gryfskand, Gryfino, Poland).

Hydrochloric acid (36%) and N,N-dimethylformamide were purchased from Chempur (Poland). Zinc nitrate hexahydrate (Zn(NO₃)₂·6H₂O) and terephthalic acid (C₆H₄(COOH)₂) were bought from Sigma Aldrich.

The monomer, L-lactide (LA) (Huizhou Foryou Medical Devices Co., Ltd., Huizhou, China), was purified by means of recrystallization from anhydrous ethyl acetate and then dried in a vacuum oven at room temperature until a constant weight was reached.
Zinc (II) acetylacetonate monohydrate (Avantor Performance Materials Poland S.A., Gliwice, Poland), Pd/C palladium catalyst (Merck Sp. z o.o., Warszawa, Poland), N,N dimethylformamide (99.8%) (Chempur, Piekary Slaskie, Poland), ethyl chloroformate (97%), (Alfa Aesar, Heysham, Lancashire, United Kingdom), potassium hydroxide (99.8%) (Merck Sp. z o.o., Warszawa, Poland), L-phenylalanine, 4-pyridine carboxaldehyde, methanol anhydrous (99.8%), benzene anhydrous (99.8%), chloro-form anhydrous (99%), tetrahydrofuran anhydrous (99.9%), 2,2-Bis(hydroxymethyl) propionic acid (bis-MPA) (98%), and benzyl bromide (98%) were purchased from Merck Sp. z o.o., Warszawa, Poland. All these chemicals were used as received.

D-glucose, tetramethylenediamine, hexamethylenediamine, iodoethane, 1-iodopropane, 1-iodododecane were purchased from Sigma-Aldrich. Hexanal was obtained from Fluka. Octanal, decanal, dodecanal, sodium borohydride and sodium cyanoborohydride were purchased from Merck. Sodium hydroxide, potassium hydroxide, hydrochloric acid, acetic acid, methanol, 2-propanol, N,N-dimethylformamide and diethyl ether were obtained from Chempur. Nitromethane was purchased from POCH. All reagents and solvents were used as obtained without further purification.