Rheological and chemical analysis of reverse gelation in a covalently crosslinked Diels-Alder polymer network.
Rheological and chemical analysis of reverse gelation in a covalently crosslinked Diels-Alder polymer network.
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DOI：
10.1021/ma801863d
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发表时间：
2008-12-09
期刊：
影响因子：
5.5
通讯作者：
Bowman, Christopher N.
中科院分区：
文献类型：
--
作者：
Adzima, Brian J.;Aguirre, H. Alan;Kloxin, Christopher J.;Scott, Timothy F.;Bowman, Christopher N.
采用Diels-Alder反应合成了一种包含动态和可逆交联的网络聚合物。傅里叶变换红外光谱（FTIR）被用来表征反应速率和热力学平衡在很宽的温度范围内。呋喃和马来酰亚胺的平衡转化率从85°C下的74%变化到155°C下的24%，表明通过逆Diels-桤木反应的显著解聚。通过流变仪使用Winter-Chambon标准测定的凝胶点温度为92°C，对应于71%的凝胶点转化率，与Flory-Stockmayer方程一致。的标度指数的复杂的模量，粘度，和平台模量，在凝胶点附近，进行了测定，并与实验和理论文献值进行比较。此外，由于Diels-桤木和逆Diels-桤木反应的交联的动态重排，该材料表现出低频弛豫。
A network polymer, incorporating dynamic and reversible crosslinks, was synthesized using the Diels-Alder reaction. Fourier transform infrared (FTIR) spectroscopy was used to characterize the reaction rate and thermodynamic equilibrium over a broad temperature range. Equilibrium conversion of the furan and maleimide varied from 74% at 85°C to 24% at 155°C, demonstrating significant depolymerization via the retro-Diels-Alder reaction. The gel point temperature, as determined by rheometry using the Winter-Chambon criterion, was 92°C, corresponding to a gel-point conversion of 71%, consistent with the Flory-Stockmayer equation. The scaling exponents for the complex moduli, viscosity, and plateau modulus, in the vicinity of the gel-point, were determined and compared with experimental and theoretical literature values. Further, the material exhibited a low frequency relaxation owing to dynamic rearrangement of crosslinks by the Diels-Alder and retro-Diels-Alder reactions.
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