Tondi Gianluca
Forest Product Technology & Timber Construction Department, Salzburg University of Applied Sciences, Marktstraße 136a, 5431 Kuchl, Austria.
Polymers (Basel). 2017 Jun 13;9(6):223. doi: 10.3390/polym9060223.
In recent years, the interest for bio-sources is rising exponentially and tannins extracts are one of the most interesting, easily-available, phenolic building blocks. The condensed tannins or proanthocyanidins are already known for their polymerization chemistry, which is the basis for several natural-based materials (e.g., adhesives, foams). In the present work we aim to observe the behavior of the extract of Acacia Mimosa (Acacia mearnsii) when reacted with several possible co-monomers at different relative amount, pH and temperature conditions. The more insoluble copolymers obtained with formaldehyde, hexamine, glyoxal, maleic anhydride, furfural and furfuryl alcohol were analyzed through solid state C NMR (Nuclear magnetic resonance) and FT-IR (Fourier Transform-Infrared) spectroscopy. The C NMR afforded the opportunity to detect: (i) aromatic substitutions and consequent poly-condensations for the majority of the hardeners studied; (ii) acylation for the maleic anhydride and also some; (iii) Diels⁻Alder arrangements for the furanic co-monomers; the FT-IR spectroscopy suggested that the formaldehyde and hexamine copolymers present a higher cross-linking degree.
近年来，对生物源的兴趣呈指数级增长，单宁提取物是最具吸引力、易于获取的酚类结构单元之一。缩合单宁或原花青素因其聚合化学而闻名，这是几种天然材料（如粘合剂、泡沫）的基础。在本工作中，我们旨在观察金合欢（黑荆树）提取物在与几种可能的共聚单体以不同相对量、pH值和温度条件下反应时的行为。通过固态碳核磁共振（NMR）和傅里叶变换红外（FT-IR）光谱对用甲醛、六亚甲基四胺、乙二醛、马来酸酐、糠醛和糠醇得到的更难溶的共聚物进行了分析。碳核磁共振提供了检测以下情况的机会：（i）对于所研究的大多数固化剂，检测到芳族取代以及随之而来的缩聚反应；（ii）检测到马来酸酐的酰化反应，以及一些其他情况；（iii）检测到呋喃类共聚单体的狄尔斯-阿尔德排列；傅里叶变换红外光谱表明甲醛和六亚甲基四胺共聚物具有更高的交联度。
