Abstract Multi-walled carbon nanotubes (MWCNTs) have an ordered geometric structure, large specific surface area, prominent electrical conductivity, and unique mechanical properties. They are nontoxic and can be used in biomedicine. Physical and surface chemical characteristics of MWCNTs should be tuned to that required to improve certain properties and obtain a variety of functional materials. We modified the MWNTs by using the barothermal Diels-Alder reaction with dienophiles, p-benzoquinone, fumaronitrile, and maleimide, to address this issue. The prepared MWCNTs were studied by SEM-EDX, nitrogen adsorption porometry, ATR FTIR, and thermal analysis. Results showed that both separate and conjugated C = C bonds at the edge and outer/inner surface of walls could react with dienophiles. The grafted groups are separated by the temperature on weak (low-temperature) and strong (high-temperature) chemisorbed forms; they are detached at temperatures below and above 350 °C, correspondingly. Thermal analysis shows that up to 5% of the carbon atoms are involved in the [4 + 2] cycloaddition. The high-temperature forms of the grafted groups under extreme heating can be involved in the retro-Diels-Alder reaction that breaks six-membered rings, producing a dienophile.

中文翻译：

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多壁碳纳米管的气压 Diels-Alder 功能化

摘要 多壁碳纳米管（MWCNTs）具有有序的几何结构、大的比表面积、显着的导电性和独特的机械性能。它们是无毒的，可用于生物医学。MWCNTs 的物理和表面化学特性应调整到改善某些性能和获得各种功能材料所需的特性。我们通过使用与亲二烯体、对苯醌、富马腈和马来酰亚胺的气压热 Diels-Alder 反应来修改 MWNT，以解决这个问题。通过SEM-EDX、氮吸附孔隙度法、ATR FTIR和热分析研究了制备的多壁碳纳米管。结果表明，壁的边缘和外/内表面的单独和共轭 C = C 键都可以与亲二烯体发生反应。弱（低温）和强（高温）化学吸附形式的接枝基团通过温度分开；相应地，它们会在低于和高于 350 °C 的温度下分离。热分析表明高达 5% 的碳原子参与 [4 + 2] 环加成。在极端加热下接枝基团的高温形式可参与逆狄尔斯-阿尔德反应，该反应破坏六元环，产生亲二烯体。