{
    "protocol": "To synthesize hydrophilic polymers with functional groups, employ a photoinduced strategy involving the coupling of photolysis, photopolymerization, and transesterification. First, use photolysis to generate dissociable ionic groups which enhance the swelling ability of the substrate. This swelling allows nutrient solutions containing polymerizable components to be absorbed into the irradiated region. Next, utilize photopolymerization to convert these polymerizable components into polymers. Finally, perform transesterification to incorporate the newly formed polymers into the original polymer network structure. This method enables spatial control, dose-dependency, and modulation of the size, composition, and mechanical properties of the synthesized structures.To fabricate seeds, mix HBA (80 mol%) and NBA (20 mol%). Add HDDA (crosslinker, 1 wt%) and I-819 (photoinitiator, 1 wt%) to obtain the precursor. Coat the precursor solution on Teflon substrates and cure under blue light (intensity: 0.6 mW cm^-2) for 20 min. Immerse the obtained substrate in ethanol, changing the solution every 8 hours (3 times) to remove unreacted specimens. Dry to afford seed-20%. For light-induced growth, immerse seed-20% in a nutrient solution containing HBA (96 wt%), HDDA (1 wt%), I-819 (1 wt%), and BZSA (2 wt%) for 12 hours to obtain swollen samples. Subject swollen samples to UV light (intensity: 10 mW cm^-2) with a suitable photomask for growth."
}