Degradable polymers are under intense development for sustainability and healthcare. Evidence has accumulated that the chemical reaction that decomposes a polymer an also grow a crack. Even under a small load, the crack speed can be orders of magnitude higher than the overall rate of degradation, leading to premature failure. Here, we demonstrate that a crack slows down markedly in a composite of two degradable materials. In a homogeneous degradable material, the stress concentrates at the crack tip, so that a relatively small applied stretch induces a high stress and a high rate of reaction. The fracture behavior of a composite that consists of two degradable materials, a stiff material for the fibers and a compliant material for the matrix, with strong adhesion between both, is different: The soft matrix blunts the crack and distributes the stresses at the crack tip over a long length of the fibers. The same rate of reaction requires a larger applied stretch. This stress de-concentration retards crack growth in the composite. We demonstrate this concept using a composite made of stiff polydimethylsiloxane (PDMS) fibers in a soft PDMS matrix. In the presence of water molecules in the environment, siloxane bonds in the PDMS hydrolyze, causing hydrolytic crack growth. We show that a hydrolytic crack grows much more slowly in a PDMS composite than in homogeneous PDMS, and may even arrest in the composite. It is hoped that this concept will contribute to the development of degradable materials that resist premature failure.

可降解聚合物正在大力发展可持续性和医疗保健。已经积累的证据表明，分解聚合物的化学反应也会产生裂缝。即使在小载荷下，裂纹速度也可能比整体退化速度高几个数量级，从而导致过早失效。在这里，我们证明了在两种可降解材料的复合材料中裂纹明显减慢。在均质可降解材料中，应力集中在裂纹尖端，因此相对较小的拉伸会引起高应力和高反应速率。由两种可降解材料（一种用于纤维的刚性材料和一种用于基体的柔顺材料）组成的复合材料的断裂行为是不同的：软基体使裂纹变钝，并将裂纹尖端的应力分布在纤维的很长一段上。相同的反应速率需要更大的应用拉伸。这种应力分散会阻碍复合材料中的裂纹扩展。我们使用由硬质聚二甲基硅氧烷 (PDMS) 纤维在软质 PDMS 基质中制成的复合材料证明了这一概念。在环境中存在水分子的情况下，PDMS 中的硅氧烷键会水解，导致水解裂纹扩展。我们表明，水解裂纹在 PDMS 复合材料中的生长比在均质 PDMS 中慢得多，甚至可能在复合材料中停滞。希望这个概念将有助于开发可抵抗过早失效的可降解材料。这种应力分散会阻碍复合材料中的裂纹扩展。我们使用由硬质聚二甲基硅氧烷 (PDMS) 纤维在软质 PDMS 基质中制成的复合材料证明了这一概念。在环境中存在水分子的情况下，PDMS 中的硅氧烷键会水解，导致水解裂纹扩展。我们表明，水解裂纹在 PDMS 复合材料中的生长比在均质 PDMS 中慢得多，甚至可能在复合材料中停滞。希望这个概念将有助于开发可抵抗过早失效的可降解材料。这种应力分散会阻碍复合材料中的裂纹扩展。我们使用由硬质聚二甲基硅氧烷 (PDMS) 纤维在软质 PDMS 基质中制成的复合材料证明了这一概念。在环境中存在水分子的情况下，PDMS 中的硅氧烷键会水解，导致水解裂纹扩展。我们表明，水解裂纹在 PDMS 复合材料中的生长比在均质 PDMS 中慢得多，甚至可能在复合材料中停滞。希望这个概念将有助于开发可抵抗过早失效的可降解材料。引起水解裂纹扩展。我们表明，水解裂纹在 PDMS 复合材料中的生长比在均质 PDMS 中慢得多，甚至可能在复合材料中停滞。希望这个概念将有助于开发可抵抗过早失效的可降解材料。引起水解裂纹扩展。我们表明，水解裂纹在 PDMS 复合材料中的生长比在均质 PDMS 中慢得多，甚至可能在复合材料中停滞。希望这个概念将有助于开发可抵抗过早失效的可降解材料。