Diphenyl phosphate dpp

Polyethylene glycol (PEG) with number average molecular weights (Mn) of 6 kg/mol, 10 kg/mol and 14 kg/mol, 1,4-diazabicyclo[2.2.2]octane (DABCO) and hexamethylene diisocyanate (HDI) were purchased from Sigma Aldrich (St. Louis, MO, USA). PEG was dried by azeotropic distillation with toluene before use. Diphenyl phosphate (DPP) was obtained from Tokyo Chemical Industry (Oxford, UK). ɛ-caprolactone (CL) monomer was obtained from Acros Organics (Geel, Belgium) and was purified by drying over CaH₂ (Merck, Darmstadt, Germany) and distillation under vacuum before use. Tetrahydrofuran (THF, from Merck, Germany) was dried over molecular sieves before use. Dichloromethane, methanol and diethyl ether were obtained from VWR Chemicals (Amsterdam, The Netherlands) and used as received. Deuterated chloroform (CDCl₃) was purchased from Sigma Aldrich (USA).

Cellulose acetate (CA, M_n,GPC = 84.5 × 10³ g mol⁻¹, polydispersity index PDI = 3.00) with the degree of substitution (DS) of 2.4 was supplied from Nippon Paper Industries Co., Ltd. (Tokyo, Japan). Diphenyl phosphate (DPP), δ-valerolactone (VL), 2-amino-4-hydroxy-6-methylpyrimidine, and hexamethylene diisocyanate (HDI) were purchased from Tokyo Chemical Industry Co., Ltd. (Tokyo, Japan). N,N-Dimethylformamide (DMF) was purchased from Kanto Chemical Co., Inc. (Tokyo, Japan).