[science] BM科学家发现新型聚合物Two New Self-Healing Polymers Disco...

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IBM科学家发现新型聚合物
http://digi.163.com/14/0516/19/9SD2JOQS00162OUT.html
摘要：IBM Almaden研究中心的研究人员在《科学》期刊上发表论文，描述了一种新发现的工业聚合物，这种聚合物被认为有望彻底改变交通运输、航空航天和微电子等各个领域。新聚合物的发现源自于一次意外，IBM 的化学家Jeannette M. Garcia整天搅拌和加热化学物质，旨在寻找出一种更强硬更容易回收的塑料。 IBM科学家发现新型聚合物

她根据一个简单配方在烧杯中混合三种化合物，但不知怎么回事她错过了一步， 忘记了一种化合物。等她返回时烧杯充满了一种白色的硬塑料，它甚至冻结了搅拌器。Garcia博士徒劳的研磨神秘的材料，最后只能拿来铁锤砸碎烧杯释放材 料。一次实验室错误却意外发现了一种异常强硬而轻盈，能表现出自我愈合属性的新材料，它很容易改造，可用于制造可回收的产品。

Recyclable, Strong Thermosets and Organogels via Paraformaldehyde Condensation with Diamines
http://www.sciencemag.org/content/344/6185/732

Abstract:
Nitrogen-based thermoset polymers have many industrial applications (for example, in composites), but are difficult to recycle or rework. We report a simple one-pot, low-temperature polycondensation between paraformaldehyde and 4,4ʹ-oxydianiline (ODA) that forms hemiaminal dynamic covalent networks (HDCNs), which can further cyclize at high temperatures, producing poly(hexahydrotriazine)s (PHTs). Both materials are strong thermosetting polymers, and the PHTs exhibited very high Young’s moduli (up to ~14.0 gigapascals and up to 20 gigapascals when reinforced with surface-treated carbon nanotubes), excellent solvent resistance, and resistance to environmental stress cracking. However, both HDCNs and PHTs could be digested at low pH (<2) to recover the bisaniline monomers. By simply using different diamine monomers, the HDCN- and PHT-forming reactions afford extremely versatile materials platforms. For example, when poly(ethylene glycol) (PEG) diamine monomers were used to form HDCNs, elastic organogels formed that exhibited self-healing properties.

EDITOR'S SUMMARY
Recyclable Thermoset Polymers
The high mechanical strength and durability of thermoset polymers are exploited in applications such as composite materials, where they form the matrix surrounding carbon fibers. The thermally driven polymerization reaction is usually irreversible, so it is difficult to recycle the constituent monomers and to remove and repair portions of a composite part. García et al. (p. 732; see the Perspective by Long) now describe a family of polymers formed by condensation of paraformaldehyde with bisanilines that could form hard thermoset polymers or, when more oxygenated, produce self-healing gels. Strong acid digestion allowed recovery of the bisaniline monomers.