时间尺度依赖的结构-属性关系在动态 imine-benzoxazine 网络中
John J Peyrefitte1, Levi J Hamernik1, Elaina M Booker1
1School of Polymer Science and Engineering, The University of Southern Mississippi, 118 College Dr. #5050, Hattiesburg, Mississippi 39406, United States.
Macromolecules
|March 2, 2026
概括
这项研究探讨了称为玻璃体的动态聚合物网络,重点关注它们的结构如何影响材料特性. 研究人员发现,改变聚合物骨干和交叉链密度显著影响放松时间和激活能量,突出了调整这些动态材料的复杂性.
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
- 类风病学 类风病学 类风病学
背景情况:
- 动态聚合物网络,或玻璃体,具有可变的交叉链接,可以通过债券交换重新安排网络,受热和应变的影响.
- 玻璃体的线性粘弹性取决于局部细分运动和动态交换机制的动力学.
- 具有高玻璃过渡温度的含伊米因的佐 (iBOX) 网络,模仿结构热,但具有动态能力.
研究的目的:
- 为了研究含有 imine 的佐素 (iBOX) 玻璃体网络的线性粘度弹性.
- 了解聚合物结构,包括骨干结构 (PPO,PEO,PE) 和交叉链之间的分子量,如何影响粘弹性反应.
- 阐明结构变异对放松动态和明显激活能量的影响.
主要方法:
- 通过用二功能的氨基胺对化功能化佐素进行凝聚,合成九种iBOX单体.
- 电离环开放聚合,以创建具有多种骨干结构和分子重量的iBOX玻璃聚合物网络.
- 时间-温度叠加 (TTS) 应用于小振幅振荡剪切 (SAOS) 和应力放松数据.
主要成果:
- 对于短期和长期动态的不同温度依赖,需要单独的转移因子.
- 短期和长期动态都表现出阿雷尼乌斯温度依赖性,产生不同的明显激活能量 (Ea).
- 结构变化导致不同时间尺度的Ea发生了不均的变化,这表明交换动力学的复杂调整.
结论:
- iBOX玻璃制剂的粘弹性行为受到聚合物结构的显著影响.
- 观察到具有明显温度依赖和激活能量的单独的放松过程.
- 在动态聚合物网络中调整交换动力学是复杂的,需要仔细考虑结构变化.
更多相关视频
10:52Line Shape Analysis of Dynamic NMR Spectra for Characterizing Coordination Sphere Rearrangements at a Chiral Rhenium Polyhydride Complex
Published on: July 27, 2022
3.4K
14:44Structure and Coordination Determination of Peptide-metal Complexes Using 1D and 2D 1H NMR
Published on: December 16, 2013
10.1K
相关概念视频
01:23Aldehydes and Ketones with Amines: Imine Formation Mechanism
8.7K
Imine formation involves the addition of carbonyl compounds to a primary amine. It begins with the generation of carbinolamine through a series of steps involving an initial nucleophilic attack and then several proton transfer reactions. The second part includes the elimination of water, as a leaving group, to give the imine.
Imines are formed under mildly acidic conditions. A pH of 4.5 is ideal for the reaction.
If the pH is low or the solution is too acidic, the reaction slows down in the...
Imines are formed under mildly acidic conditions. A pH of 4.5 is ideal for the reaction.
If the pH is low or the solution is too acidic, the reaction slows down in the...
8.7K
01:19Structure of Amines
3.4K
The hybridized nitrogen atom in amines possesses a lone pair of electrons and is bound to three substituents with a bond angle of around 108°, which is less than the tetrahedral angle of 109.5°. However, the C–N–H bond angle is slightly larger at 112°, with a carbon–nitrogen bond length of 147 pm. This carbon–nitrogen bond length of of amines is longer than the carbon–oxygen bond of alcohols (143 pm) but shorter than alkanes’ carbon–carbon bond (154 pm). These aspects are...
3.4K
01:18Structure of Benzene: Molecular Orbital Model
13.2K
According to the molecular orbital (MO) model, benzene has a planar structure with a regular hexagon of six sp2 hybridized carbons. As shown in Figure 1, each carbon is bonded to three other atoms with C–C–C and H–C–C bond angles of 120°. The C–H bond length is 109 pm, and the C–C bond length is 139 pm which is midway between the single bond length of sp3 hybridized carbons (154 pm) and sp2 hybridized carbons (133 pm).
13.2K
01:07Structure of Benzene: Kekulé Model
12.7K
In 1865, August Kekule suggested the structure of benzene according to the structural theory of organic chemistry based on the three assertions—formula of benzene is C6H6, all the hydrogens of benzene are equivalent, and each carbon must have four bonds due to its tetravalency.
He proposed that benzene has a cyclic structure of six carbon atoms attached to one hydrogen atom each, with three alternating pi bonds.
He proposed that benzene has a cyclic structure of six carbon atoms attached to one hydrogen atom each, with three alternating pi bonds.
12.7K
01:25Basicity of Heterocyclic Aromatic Amines
7.1K
Heterocyclic amines, where the N atom is a part of an alicyclic system, are similar in basicity to alkylamines. Interestingly, the heterocyclic amine having a nitrogen atom as part of an aromatic ring has much less basicity than its corresponding alicyclic counterpart. For this reason, as presented in Figure 1, piperidine (pKb = 2.8) is significantly more basic than pyridine (pKb = 8.8).
7.1K
02:34Structural Isomerism
22.0K
Isomerism in Complexes
Isomers are different chemical species that have the same chemical formula. Structural isomerism of coordination compounds can be divided into two subcategories, the linkage isomers and coordination-sphere isomers.
Linkage isomers occur when the coordination compound contains a ligand that can bind to the transition metal center through two different atoms. For example, the CN− ligand can bind through the carbon atom or through the nitrogen atom. Similarly, SCN− can...
Isomers are different chemical species that have the same chemical formula. Structural isomerism of coordination compounds can be divided into two subcategories, the linkage isomers and coordination-sphere isomers.
Linkage isomers occur when the coordination compound contains a ligand that can bind to the transition metal center through two different atoms. For example, the CN− ligand can bind through the carbon atom or through the nitrogen atom. Similarly, SCN− can...
22.0K