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Isotactic Poly(propylene oxide): A Photodegradable Polymer with Strain Hardening Properties
Journal of the American Chemical Society ( IF 14.4 ) Pub Date : 2020-03-30 , DOI: 10.1021/jacs.0c01768
Bryce M. Lipinski 1 , Lilliana S. Morris 1 , Meredith N. Silberstein 2 , Geoffrey W. Coates 1
Affiliation  

Leakage and accumulation of highly stable commercial plastics has led to substantial contamination of the environment. Highly isotactic poly(propylene oxide) (iPPO) was investigated as a potential high-strength thermoplastic with greater susceptibility toward degradation under ambient conditions. Various stereoregular forms of iPPO including enantiopure, enantioenriched, racemic, and stereoblock were synthesized with a single catalyst architecture in the presence of chain transfer agents. These materials were found to possess the same approximate ultimate tensile strength (UTS) via uniaxial tensile elongation analysis (∼75 MPa). A serrated tensile response corresponding to stress oscillations was observed in all forms of iPPO. An investigation on strain rate dependence showed that an increase in strain rate results in the decay and disappearance of the serrated response. Further evaluation of iPPO revealed its dramatic strain hardening afforded an UTS comparable to that of nylon-6,6. Exposing iPPO to UVA light (365 nm) resulted in photolytic degradation. Following 30 days of continuous exposure at 250 μW cm-2, the Mn decreased from 93 kDa to 21 kDa, while samples not exposed to UVA light remained unchanged. Through selective stabilization with antioxidant additives, we believe iPPO could be a suitable replacement for nylon-6,6 in environmentally susceptible applications.

中文翻译:

全同立构聚(环氧丙烷):一种具有应变硬化特性的光降解聚合物

高度稳定的商业塑料的泄漏和积累已导致对环境的严重污染。高全同立构聚(环氧丙烷)(iPPO)被研究为一种潜在的高强度热塑性塑料,在环境条件下具有更大的降解敏感性。在链转移剂的存在下,使用单一催化剂结构合成了各种有规立构形式的 iPPO,包括对映体纯、对映体富集、外消旋和立体嵌段。通过单轴拉伸伸长率分析(~75 MPa)发现这些材料具有相同的近似极限拉伸强度(UTS)。在所有形式的 iPPO 中都观察到了对应于应力振荡的锯齿状拉伸响应。应变率相关性的研究表明,应变率的增加会导致锯齿状响应的衰减和消失。对 iPPO 的进一步评估表明,其显着的应变硬化提供了与尼龙 6,6 相当的 UTS。将 iPPO 暴露于 UVA 光 (365 nm) 会导致光解降解。在 250 μW cm-2 连续暴露 30 天后,Mn 从 93 kDa 降至 21 kDa,而未暴露于 UVA 光的样品保持不变。通过使用抗氧化添加剂进行选择性稳定,我们相信 iPPO 可以在环境敏感的应用中成为尼龙 6,6 的合适替代品。将 iPPO 暴露于 UVA 光 (365 nm) 会导致光解降解。在 250 μW cm-2 下连续暴露 30 天后,Mn 从 93 kDa 降至 21 kDa,而未暴露于 UVA 光的样品保持不变。通过使用抗氧化添加剂进行选择性稳定,我们相信 iPPO 可以在环境敏感的应用中成为尼龙 6,6 的合适替代品。将 iPPO 暴露于 UVA 光 (365 nm) 会导致光解降解。在 250 μW cm-2 下连续暴露 30 天后,Mn 从 93 kDa 降至 21 kDa,而未暴露于 UVA 光的样品保持不变。通过使用抗氧化添加剂进行选择性稳定,我们相信 iPPO 可以在环境敏感的应用中成为尼龙 6,6 的合适替代品。
更新日期:2020-03-30
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