{
    "protocol": "PUA is synthesized from polyurethane by introducing double bonds of acrylates into the molecular chain terminal. Oligomers are then utilized to initiate a double-crosslinking reaction using photoinitiators.To synthesize hydrophilic polymers with functional groups, select diisocyanates (such as TDI, IPDI, MDI, HMDI, or HDI) as urethane segments and use chain extenders like polyethylene glycol (PEG) or polytetrahydrofuran (PTMEG). Employ hydroxyethyl acrylate (HEA) as the end-capper to introduce unsaturated bonds. For enhanced functionality and mechanical properties, consider incorporating trimethylolpropane diallyl ether (TMPDE) or pentaerythritol triacrylate (PETA) as end-capping reagents. For a greener approach, utilize non-isocyanate polyurethane (NIPU) synthesis through transurethanization polycondensation involving cyclic carbonate and diamine, or explore renewable resources such as vegetable oils as raw materials."
}