通过热分析,通过对基于基改性聚树脂的模型网络中复古基-老化反应的证据
Daniela Ionita1, Mariana Cristea1, Constantin Gaina1
1"Petru Poni" Institute of Macromolecular Chemistry, Aleea Grigore Ghica 41A, 700487 Iasi, Romania.
Polymers
|October 14, 2023
概括
这项研究研究了原基改性聚树脂. 热分析证实了迪尔斯-阿尔德 (DA) adduct cleavage,但复杂的降解阻止了清晰的反DA反应观察.
科学领域:
- 聚合物化学 聚合物化学
- 材料科学 材料科学 材料科学
- 有机化学 有机化学
背景情况:
- 高性能聚合物利用稳定的迪尔斯-阿尔德 (DA) adducts 提供热稳定性.
- 对于高级聚合物应用来说,炭烯-马莱胺添加物是有前途的.
- 关于这些系统中的反复-迪尔斯-阿尔德 (rDA) 反应存在不一致的数据.
研究的目的:
- 为了研究烯基改性聚树脂中的反复-迪尔斯-阿尔德 (rDA) 反应.
- 为了澄清聚基矩阵中马莱胺-二烯添加物的热行为.
- 为了确定rDA反应在热应力下是否可观察.
主要方法:
- 热重力测量分析 (TGA)
- 高分辨率TGA (HiRes TGA) 是一个
- 多维TGA (MTGA) 是一个多维的TGA.
- 不同扫描热量计 (DSC)
- 调制DSC (模块化DSC) 是指模块化DSC (模块化DSC) 是指模块化DSC.
主要成果:
- TGA证实了安特拉-马莱胺DA adduct 的裂变.
- DSC表示聚合物系统中存在甲烯.
- 在高温下观察到maleimide同聚合和-ene反应.
- 由于复杂的,相互关联的降解过程,rDA反应无法清晰地辨认.
结论:
- 虽然发生了DA adduct cleavage,但rDA反应被竞争的热降解途径掩盖了.
- 随后的冷却和加热循环显示出由于不可逆转的副作用反应而改变的热过渡.
- 先进的热分析技术提高了数据分辨率,但无法完全解决复杂的降解.
相关概念视频
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The Diels–Alder reaction is one of the robust methods for synthesizing unsaturated six-membered rings. The reaction involves a concerted cyclic movement of six π electrons: four π electrons from the diene and two π electrons from the dienophile.
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01:31Diels–Alder vs Retro-Diels–Alder Reaction: Thermodynamic Factors
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The Diels–Alder reaction is thermally reversible, meaning that the reaction reverts to the starting diene and dienophile under suitable temperatures. The forward reaction gives a cyclohexene derivative and is favored at low to medium temperatures. The reverse process, also called retro-Diels–Alder reaction, is a ring-opening process favored at high temperatures.
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Characteristics of the diene
Conformation
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01:17Thermal Electrocyclic Reactions: Stereochemistry
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Selection Rules: Thermal Activation
Conjugated systems containing an even number of π-electron pairs undergo a conrotatory ring closure. For example, thermal electrocyclization of (2E,4E)-2,4-hexadiene, a conjugated diene containing two π-electron pairs, gives trans-3,4-dimethylcyclobutene.
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