Oxidation Degradable Aliphatic Polycarbonates with Pendent Phenylboronic Ester

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• 作者：Fang-Yi Qiu ; Mei Zhang ; Fu-Sheng DuZi-Chen Li
• 刊名：Macromolecules
• 出版年：2017
• 出版时间：January 10, 2017
• 年：2017
• 卷：50
• 期：1
• 页码：23-34
• 全文大小：738K
• ISSN：1520-5835

文摘

Functional polyesters and poly(carbonate)s (PCs) with controlled and on-demand degradation properties have great advantages for biomedical and pharmaceutical applications. Herein, we report a new kind of aliphatic PC that possesses the feature of oxidation promoted degradation. Two six-membered cyclic carbonates (C1 and C2) containing phenylboronic ester group have been synthesized from serinol (1) and 2-aminomethyl-2-methylpropane-1,3-diol (2), respectively. Both monomers could undergo well-controlled ring-opening polymerization (ROP) catalyzed by an organic base, but the 5,5-disubstituted C2 has the character of equilibrium ROP and a much slower rate than the monosubstituted C1. The copolymerization of C1 or C2 with trimethylene carbonate and its derivative leads to a series of copolymers. Two series of amphiphilic block copolymers (BPC1s and BPC2s) have been prepared from C1 and C2 using poly(ethylene glycol) as the macroinitiator. They are able to form nanoparticles with the diameters less than 150 nm. The H₂O₂-triggered decomposition of C1, C2, and their corresponding noncyclic model compounds was studied by ¹H NMR, showing the consecutive process of oxidation, 1,6-elimination, release of CO₂, and intramolecular isomerization or cyclization. The degradation of the block copolymer nanoparticles, investigated by ¹H NMR, GPC, laser light scattering (LLS), and Nile Red fluorescence, can also be accelerated drastically by H₂O₂ following the similar mechanism but is affected by steric hindrance of the polymer chain and heterogeneous microenvironment inside the nanoparticles. The results of ¹H NMR and LLS reveal that the nanoparticles of BPC1 and BPC2 exhibited different degradation profiles, with a slightly faster degradation rate for BPC2. Of particular interest, BPC2 nanoparticle is sensitive to as low as 0.02 mM H₂O₂.