2 2 azobisisobutyronitrile aibn

Acyclovir (ACV; MW 225.21 g/mol; solubility in water 1.02 mg/mL [35 (link)]) was purchased from Farmalabor (Canosa di Puglia, Italy); valacyclovir hydrochloride (VACV; MW 360.80 g/mol; solubility in water 174 mg/mL [36 ]) was from Acros Organics (Geel, Belgium); 2,2′-azo-bis(isobutyronitrile) (AIBN), dichlorodimethylsilane, ethylene glycol dimethacrylate (EGDMA), and methacrylic acid (MAA) were from Sigma-Aldrich (Steinheim, Germany); ethanol absolute and NaOH were from VWR (Leuven, Belgium); 2-hydroxyethyl methacrylate (HEMA) was from Merck (Darmstadt, Germany); acetic acid and NaCl were from Scharlau (Sentmenat, Spain); and methanol was from Fisher (Loughborough, UK). Ultrapure water (resistivity ˃18 MΩ·cm) was obtained by reverse osmosis (MilliQ^®, Millipore, Madrid, Spain). Simulated lacrimal fluid (SLF) was prepared with the following composition: 6.78 g/L NaCl, 2.18 g/L NaHCO₃, 1.38 g/L KCl, and 0.084 g/L CaCl₂·2H₂O with pH 7.5. Carbonate buffer pH 7.2 was prepared by mixing buffer solution A (6.2 g/L NaCl, 0.355 g/L KCl, 0.1 g/L NaH₂PO₄·H₂O, and 2.45 g/L NaHCO₃) and buffer solution B (0.115 g/L CaCl₂ and 0.155 g/L MgCl₂·6H₂O).

1H,1H,2H,2H-Perfluorooctyl acrylate (F6, Fluorochem, Hadfield, UK), 3-(trimethoxysilyl)propyl methacrylate (PTMSi, ABCR, Karlsruhe, Germany), N-(3-sulfopropyl)-N-(methacryloyloxyethyl)-N,N-dimethylammonium betaine (MSA, Sigma Aldrich, St. Louis MO, USA), 2-methacryloyloxyethyl phosphorylcholine (MPC, Sigma Aldrich, St. Louis MO, USA), 2,2′-azobis(2-methylpropionamidine) dihydrochloride (V50, Sigma Aldrich, St. Louis MO, USA), hexafluorobenzene (HFB, Fluorochem, Hadfield, UK), α,α,α-trifluorotoluene (TFT, Fluorochem, Hadfield, UK) and 2,2,2-trifluoroethanol (TFE, Sigma Aldrich, St. Louis MO, USA) were used as received. 2,2′-Azobis(isobutyronitrile) (AIBN, Sigma Aldrich, St. Louis MO, USA) was recrystallized from methanol. Toluene was kept over CaH₂ for 4 h and then distilled. Methanol was kept over molecular sieves before use. Tetrahydrofuran (THF) was refluxed and distilled on Na/K.

Hydrogen tetrachloroaurate trihydrate (HAuCl₄·3H₂O) and L-glutathione in the reduced form (GSH) were obtained from Sigma-Aldrich. N-isopropylacrylamide (NIPAAm, Aldrich, St. Louis, MO, USA, 98%) was recrystallized twice in hexane and toluene prior to use. 2,2′-Azobis-(isobutyronitrile) (AIBN, Sigma, St. Louis, MO, USA, 98%) was recrystallized from methanol. 2-mercaptothiazoline (Sigma, 98%), acetonitrile (CH₃CN, 99.5%, Aladdin Industrial Corporation, Shangai, China), and glutaraldehyde (GA, Aladdin, AR, Shangai, China) were used as received. Ultrapure water (Milli-Q, Millipore, Burlington, MA, USA) with a resistivity of 18.2 MΩ was used as the solvent throughout the study. All other reagents and solvents are of analytical grade and can be used directly without further purification.

Methyl methacrylate (MMA), tert-butyl methacrylate (t-BMA), glycidyl methacrylate (GMA), and 2-(dimethylamino)ethyl methacrylate (DMAEMA) are monomers that were purchased from Sigma–Aldrich for chain extender synthesis. Furthermore, 2,2′-azobisisobutyronitrile (AIBN) as an initiator, toluene as a solvent, and hexane as a precipitation solvent after the synthesis of the chain extender, were also obtained from Sigma–Aldrich. The PGA (inherent viscosity 1.3–1.7 dL/g) was supplied by META BIOMED Co. Ltd., Republic of Korea, and the PCL (Mn 80,000 g/mol, Mw/Mn < 2) was obtained from Sigma–Aldrich. A Joncryl^® (ADR-4368), purchased from BASF Co. Ltd., was used to compare the mechanical properties of the blending plastics.

The solvents petroleum ether (40–60 °C), diethyl ether, dichloromethane, ethyl acetate and acetone, and the reagents cyanomethyl dodecyl trithiocarbonate, 4,4′-azobis(4-cyanovaleric acid) (ACVA) and 4-dimethylaminopyridine (DMAP) were purchased from Sigma Aldrich and used as received. N-(3-Dimethylaminopropyl)-N′-ethylcarbodiimide hydrochloride (EDC·HCl) was purchased from Alpha Aesar and used as received. 1,4-Dioxane, and the monomers DEGMA, OEGMA (M_n = 300 g mol^–1), nBA and DMA were purchased from Sigma Aldrich and passed through a column of basic alumina prior to use. NIPAM was purchased from Sigma Aldrich and recrystallized from a toluene–hexane mixture prior to use. 2,2′-Azobisisobutyronitrile (AIBN) was purchased from Sigma Aldrich and recrystallized from methanol prior to use. Dialysis membrane (MWCO = 3.5–5 kDa) was purchased from Spectra/Por. The synthesis of N,N-diethylacrylamide,⁶¹
2-cyano-2-propyl dodecyl trithiocarbonate,⁶²
4-cyano-4-(((ethylthio)carbonothioyl)thio) pentanoic acid⁶³
have been described previously in the literature.

Carminic acid was purchased from Sigma Aldrich and used without any further purification. n-Butyl acrylate (BA) from Sigma Aldrich was purified by freezing and thawing. 2,2′-Azobis-(isobutyronitrile) (AIBN, Sigma Aldrich) was recrystallized twice from methanol.