Dynamic-covalent chemistry has enabled the facile synthesis of a new generation of degradable materials, but controlling the rate at which these materials degrade remains elusive. Using segmented hyperbranched polymers (SHPs) as model branched architectures, we demonstrate that SHPs containing imine cross-links degrade under acidic conditions into well-defined linear chains at rates controllable via modification of the imine N-substituent. Imine-cross-linked SHPs were synthesized in a one-pot protocol by reversible addition–fragmentation chain transfer (RAFT) copolymerization of novel divinyl compounds containing dynamic-covalent oxime, semicarbazone, and acyl hydrazone moieties. The extent of SHP branching could be controlled through the relative stoichiometric ratios of cross-linker and chain transfer agent (CTA), and studies of the polymerization kinetics confirmed the growth of polydisperse branched species at high monomer conversions. When subjected to aqueous acidic conditions, the polydisperse branched architecture degraded into well-defined polymers, a process that was accelerated under more strongly acidic conditions and by incorporating less hydrolytically stable imine cross-links. Finally, we found that the rate of SHP degradation could be tuned with an unprecedented level of control by cross-linking the polymers with different proportions of multiple imines.

中文翻译：

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利用亚胺多样性来调节超支化聚合物的降解

动态共价化学使得能够容易地合成新一代可降解材料，但是控制这些材料降解的速率仍然是遥不可及的。使用分段的超支化聚合物（SHPs）作为模型分支体系结构，我们证明了含有亚胺交联键的SHP在酸性条件下降解为定义明确的线性链，其速率可通过修​​饰亚胺N来控制-取代基。通过一锅操作规程，通过可逆的加成-断裂链转移（RAFT）共聚新的含有动态共价肟，半卡巴zone和酰基部分的二乙烯基化合物，来合成亚胺交联的SHP。SHP支链的程度可以通过交联剂和链转移剂（CTA）的相对化学计量比来控制，聚合动力学的研究证实了高单体转化率下多分散支链物种的生长。当在酸性水溶液条件下时，多分散支链结构降解为定义明确的聚合物，该过程在更强的酸性条件下并通过引入水解稳定性较低的亚胺交联而加速。最后，