Czifrák Katalin, Lakatos Csilla, Szabó Gabriella, Vadkerti Bence, Daróczi Lajos, Zsuga Miklós, Kéki Sándor
Department of Applied Chemistry, University of Debrecen, Egyetem tér 1, H-4032 Debrecen, Hungary.
Doctoral School of Chemistry, University of Debrecen, Egyetem tér 1, H-4032 Debrecen, Hungary.
Polymers (Basel). 2023 Jul 3;15(13):2937. doi: 10.3390/polym15132937.
In this work, the preparation and systematic investigation of cross-linked polyurethane-epoxy (PU-EP) polymer systems are reported. The PU-EP polymers were prepared using a reaction of isocyanate (NCO)-terminated PU-prepolymer with diglycidyl ether of bisphenol A (DGEBA)-amine cooligomer. The oligomerization of DGEBA was carried out by adding furfurylamine (FA) or ethanolamine (EA), resulting in DGEBA-amine cooligomers. For the synthesis of NCO-terminated PU-prepolymer, poly(ε-caprolactone)diol (PCD) (M = 2 kg/mol) and 1,6-hexamethylene diisocyanate (HDI) were used. The cross-linking was achieved by adding DGEBA-amine cooligomer to PU-prepolymer, in which the obtained urethane bonds, due to the presence of free hydroxil groups in the activated DGEBA, served as netpoints. During cross-linking, ethanolamine provides an additional free hydroxyl group for the formation of a new urethane bond, while furfurylamine can serve as a thermoreversible coupling element (e.g., Diels-Alder adduct). The PU-EP networks were characterized using attenuated total reflectance Fourier-transform infrared spectroscopy (ATR-FTIR), differential scanning calorimetry (DSC), dynamical mechanical analysis (DMA) and scanning electron microscopy (SEM). The DMA curves of some PU-EPs (depending on the compositions and the synthetic method) revealed a plateau-like region above the melting temperature (T) of PCD, confirming the presence of a cross-linked structure. This property resulted in a shape memory (SM) behavior for these samples, which can be fine-tuned in the presence of furfurylamine through the formation of additional thermoreversible bonds (e.g., Diels-Alder adduct).
本文报道了交联聚氨酯-环氧（PU-EP）聚合物体系的制备及系统研究。PU-EP聚合物通过异氰酸酯（NCO）封端的PU预聚物与双酚A二缩水甘油醚（DGEBA）-胺低聚物反应制备。DGEBA的低聚反应通过添加糠胺（FA）或乙醇胺（EA）进行，得到DGEBA-胺低聚物。对于NCO封端的PU预聚物的合成，使用了聚（ε-己内酯）二醇（PCD）（M = 2 kg/mol）和1,6-六亚甲基二异氰酸酯（HDI）。通过将DGEBA-胺低聚物添加到PU预聚物中来实现交联，由于活化的DGEBA中存在游离羟基，所形成的聚氨酯键作为交联点。在交联过程中，乙醇胺为形成新的聚氨酯键提供额外的游离羟基，而糠胺可作为热可逆偶联元素（如狄尔斯-阿尔德加合物）。使用衰减全反射傅里叶变换红外光谱（ATR-FTIR）、差示扫描量热法（DSC）、动态力学分析（DMA）和扫描电子显微镜（SEM）对PU-EP网络进行了表征。一些PU-EP的DMA曲线（取决于组成和合成方法）在PCD的熔点（T）以上显示出类似平台的区域，证实了交联结构的存在。这种特性导致这些样品具有形状记忆（SM）行为，在糠胺存在下，通过形成额外的热可逆键（如狄尔斯-阿尔德加合物）可对其进行微调。
