Materials and Methods PEG (MW 2000, PEG2K), sodium hydride (NaH), 4- dimethylaminopyridine (DMAP), triethylamine (TEA), L-cysteine hydrochloride, and 5, 5′- dithiobis-(2-nitrobenzoic acid)(DTNB) were purchased from Alfa Aesar. Acryloyl chloride was purchased from TCI Chemical. 4Arm-PEG-SH (MW 10,000) was purchased from Jen Kem Technology. Ethyl 2-(hydroxymethyl) acrylate (EHMA) was purchased from Jiachen ...