Niu Xun, Zhu Hui, Mhatre Sameer, Bi Ran, Ye Yuhang, Rojas Orlando J
Bioproducts Institute, Department of Chemical and Biological Engineering, University of British Columbia, 2360 East Mall, Vancouver, BC V6T 1Z3, Canada.
Material Science Engineering, University of Pennsylvania, Philadelphia, Pennsylvania 19104-6243, United States.
ACS Nano. 2024 Jul 25. doi: 10.1021/acsnano.4c04011.
The significance of synthetic foams as insulative materials stems from their mechanical and water resistance as well as their cost-effectiveness. Broadly, the design of building envelopes should also consider fire and mold resistance and the impacts on the environment (end of life and compostability). This study addresses these issues considering the ever-increasing demand for sustainable sources to develop highly porous insulative materials. We introduce a versatile strategy based on wet-foam laying of cellulosic fibers that leads to hierarchical structures whose performance is tailored by the surface incorporation of betulin (BT), a bioactive molecule extracted from tree bark, combined with poly(dimethylsiloxane) (PDMS) after installation of urethane linkages. As such, we introduce an eco-friendly alternative to traditional polyurethane foams with competitive mechanical and thermal insulation performance. The modification of the fiber foams at low BT loading simultaneously endows superhydrophobicity (water contact angle >150°), fire retardancy (self-extinguish within 10 s), microbial resistance, and durability (no degradation in soil conditions after 3 months). BT plays a critical role as an antimicrobial and hydrophobic agent that synergizes with PDMS to achieve fire resistance. The life cycle assessment of the BT-modified foams reveals a significant reduction in greenhouse gas emission and human toxicity compared with rigid polyurethane foams by 96 and 92%, respectively. Overall, the valorization of the bark-derived BT is demonstrated by considering the scalability and cost-effectiveness of solid foams designed to substitute petroleum-derived counterparts.
合成泡沫作为绝缘材料的重要性源于其机械性能、防水性能以及成本效益。一般来说，建筑围护结构的设计还应考虑防火、防霉以及对环境的影响（使用寿命结束时的情况和可堆肥性）。考虑到对可持续资源以开发高度多孔绝缘材料的需求不断增加，本研究探讨了这些问题。我们介绍了一种基于纤维素纤维湿泡沫铺设的通用策略，该策略可形成分级结构，其性能通过在安装聚氨酯键后，将从树皮中提取的生物活性分子桦木醇（BT）与聚二甲基硅氧烷（PDMS）进行表面结合来进行调整。因此，我们引入了一种环保型替代传统聚氨酯泡沫的材料，其具有具有竞争力的机械和隔热性能。在低BT负载下对纤维泡沫进行改性，可同时赋予其超疏水性（水接触角>150°）、阻燃性（10秒内自熄）、抗微生物性和耐久性（3个月内在土壤条件下无降解）。BT作为一种抗菌和疏水剂发挥着关键作用，它与PDMS协同作用以实现防火性能。与硬质聚氨酯泡沫相比，BT改性泡沫的生命周期评估显示温室气体排放量和人体毒性分别显著降低了96%和92%。总体而言，通过考虑设计用于替代石油衍生同类产品的固体泡沫的可扩展性和成本效益，证明了树皮衍生的BT的价值。
