## 2 Materials and Methods
### Synthesis and Characterization of MeO-PEG-PBA  
To a solution of PBAPin (0.5 mmol) and DMAP (0.75 mmol) in anhydrous CHCl\({}_{3}\) (4 mL) under nitrogen atmosphere, a DCC solution in the same solvent (0.75 mmol, 1 mL) was slowly added dropwise. After 1.5 h, a solution of MeO-PEG\({}_{2000}\) in CHCl\({}_{3}\) (0.25 mmoles, 1 mL) was added dropwise, and stirring was continued under nitrogen atmosphere at room temperature for 24 h. The dicyclohexylurea formed was filtered off by 0.45 \(\upmu\)m PTFE syringe filter, and the clear yellowish solution was dropped into an excess of cold EtOEt under stirring. The formed solid was isolated by centrifugation (ALC PK120 centrifuge, 1129 rcf, 10 min, r.t.), redissolved in CHCl\({}_{3}\), and re-precipitated in EtOEt one more time. After the removal of organic solvents by evaporation under reduced pressure, an off-white, waxy solid (yield 89%) was obtained.  
_Protocol of aprotection of pinacol boronic ester with TFA_: solid MeO-PEG\({}_{2000}\)-PBAPin was dissolved in CH\({}_{2}\)Cl\({}_{2}\) at a concentration of 64 mg/mL and added with 630 \(\upmu\)L of TFA. After 4 to 24 h stirring, the mixture was poured into an excess of cold EtOEt, and the obtained solid was recovered by centrifugation. The yield was 85% of the initial weight.  
_Protocol of aprotection of pinacol boronic ester with NaIO\({}_{4}\)_: MeO-PEG\({}_{2000}\)-PBAPin was dissolved in a mixture H\({}_{2}\)O/THF 1:4 at a concentration of 240 mg/mL and added to NaIO\({}_{4}\) (1.2 eq). The solution turned immediately pink, transiently, and reverted to pale yellow after few minutes. After 80 min, HCl 1 M (1.2 eq) was added, and the mixture was left to stir for other 20 min. After this time, the mixture was diluted with DCM and dried with NaSO\({}_{4}\). The clear organic solution was separated by filtration and concentrated down to a final volume of about 1 mL. The concentrated mixture was then dropped in an excess (40 mL) of cold diethyl ether for precipitation of the polymers. The solid was separated by centrifugation and washed with the same solvent 4 times. Then, the residual solvent was removed from the isolated product by evaporation under reduced pressure.  
_Protocol of aprotection of pinacol boronic ester with acidic resin_: MeO-PEG\({}_{2000}\)-PBAPin was dissolved in a mixture THF/H\({}_{2}\)O 10:1 at a concentration of 50 mg/mL. The same weight amount of DOWEX 50 WX8 was then added, and the mixture was left to stir at room temperature for 24 h. The solution was then isolated by centrifugation (3000 rpm, 10 min), and the resin was washed with 2 mL di of THF. The collected supernatants were treated with anhydrous MgSO\({}_{4}\), filtered, concentrated down to 1 mL under reduced pressure, and added to 40 mL of Et\({}_{2}\)O. The solid formed was collected by centrifugation and washed two times with 40 mL of the same solvent. The white solid was dried under gentle nitrogen flux. Yield 84% of the initial weight. \({}^{1}\)H NMR (400 MHz, DMSO-\(d_{6}\)) & 7.05 (m, 2H), 6.69 (m, 2H), 4.50 (m, 2H), 4.12 (m, 2H), 3.68 (m, 2H), 3.51 (s, 230H), and 3.24 (s, 3H). ATR FT-IR (cm\({}^{-1}\)) 3471, 2884, 2860, 2741, 2696, 2166, 1964, 1736, 1615, 1519, 1456, 1360, 1340, 1279, 1240, 1145, 1103, 1060, 956, 946, 841, and 656.