ε caprolactone

1,4-butanediol (BD), ε-caprolactone (CL), dimethyl succinate (DMS) and titanium tetraisopropoxide (TTP)—as the catalyst—were purchased from Aldrich and were used as received.

ε-Caprolactone (2-Oxepanone, CL, 97%, Aldrich, Poznan, Poland), zirconium(IV) acetylacetonate (tetrakis(2,4-pentanedionato)zirconium(IV), Zr(acac)₄, 97%, Aldrich, Poznan, Poland), poly(ethylene glycol) 200 (PEG 200, M_n = 200 g/mol, pure, Fluka, Warsaw, Poland), poly(ethylene glycol) 600 (PEG 600, M_n = 600 g/mol, pure, Fluka, Warsaw, Poland), poly(ethylene glycol) 1000 (PEG 1000, M_n = 1000 g/mol, pure, Sigma-Aldrich, Poznan, Poland), poly(ethylene glycol) 1500 (PEG 1500, M_n = 1500 g/mol, pure, Sigma, Poznan, Poland), poly(ethylene glycol) 2000, (PEG 2000, M_n = 2000 g/mol, pure, TCI, Zwijndrecht, Belgium), dichloromethane (DCM, CH₂Cl₂, ≥99.8%, POCh, Gliwice, Poland), hydrochloric acid (HCl, ChemPur, Piekary Slaskie, Poland), Dulbecco’s Modified Eagle Medium (DMEM, Thermo Fisher Scientific, Warsaw, Poland), 5-fluorouracil (5-fluoropyrimidine-2,4-[1H,3H]-dione, 5-FU, 99%, Sigma-Aldrich, Poznan, Poland), phosphate-buffered saline (PBS, pH = 7.40 ± 0.05, ChemPur, Piekary Slaskie, Poland), phosphate-buffered saline for cell cultures (PBS, GIBCO, Dublin, Ireland), acetonitrile (ACN, HPLC grade min. 99.9%, POCH, Gliwice, Poland) and trifluoroacetic acid (TFA, 99%, Sigma-Aldrich, Poznan, Poland). Prior to use, PEGs compounds were heated in a vacuum for 2 h at 80 °C to remove residual water. Other reagents were used as received.

DXO was synthesized through Bayer-Villiger oxidation according to the literature, then purified by recrystallization from the dry ether, and two subsequent distillations under reduced pressure [32 (link),33 (link)]. ε-Caprolactone (CL) from Aldrich (Shanghai, China) was dried over calcium hydride (CaH₂) and distilled under reduced pressure prior to use. Ethylene glycol (EG) and benzyl alcohol (BnOH) from Sinopharm (Shanghai, China) were dried over sodium with protective nitrogen atmosphere and distilled under reduced pressure prior to use. Tetrahydrofuran (THF) and toluene (TOL) from Sinopharm (Shanghai, China) were freshly distilled from sodium/benzophenone and stored under an argon atmosphere. DBU, TBD, t-BuP₄ from Aldrich (Shanghai, China) were used as received, and other reagents from Sinopharm (Shanghai, China) were also used as received.

Methyl methacrylate (MMA, 99%; Aldrich), 2-hydroxyethyl methacrylate (HEMA, 99%; Aldrich) and styrene (St, 99%, Aldrich) were passed through a basic alumina column to remove the inhibitor. 4-hydroxymethyl styrene (HMS) was synthesized from 4-vinylbenzyl chloride (90%; Acros Organics) as reported and then vacuum distilled [33 ]. ε-Caprolactone (CL, 97%; Aldrich) was distilled under vacuum over CaH₂. Ethyl α-bromophenylacetate (EBPA, 97%; Alfa Aesar), phosphazene base (P₂-t-Bu, ~2.0 M in THF; Aldrich) and perylene (>98.0% (GC); TCI) was used as received. Toluene (99.5%; Aldrich) was distilled over sodium and benzophenone as indicator and stored in molecular sieves under nitrogen atmosphere. Methanol (Technical) and n-hexane (≥95.0% (GC); Merck) were used to precipitate polymers.

Methanol (MeOH), dichloromethane
(DCM), chloroform, and isopropyl alcohol were obtained from Fisher
Scientific (Pittsburgh, USA). Pentaerythritol, ε-caprolactone,
methacrylic anhydride (MAAn), 2,4,6-trimethylbenzoyl phosphine oxide/2-hydroxy-2-methylpropiophenone
blend (photoinitiator), tin(II) 2-ethylhexanoate, β-carotene,
triethylamine (TEA), and hydrochloric acid (HCl) were obtained from
Sigma-Aldrich (Poole, UK). Hypermer B246 (the surfactant) was provided
as a gift by Croda. PCL pellets were purchased from Capa 6500 and
used as they were received (Perstorp Holding AB, Sweden).