| 摘要: | 常用於分散劑以及具生物相容性質的醫療用黏著劑中的聚丙烯酸 (PAA) 可以在水中與其他水溶性高分子（例如：聚乙烯醇、聚乙烯吡咯烷酮等）形成氫鍵沉澱物。根據質子受體聚合物的類型，沉澱物可以形成不同種類的材料，包括奈米的聚集體、締合聚合物的濃縮液、水凝膠、彈性體和高分子的複合物。在這項研究中，研究了聚合物分子量對氫鍵沉澱物的力學性質影響。發現一般來說，隨著高分子複合物的水含量降低，但其機械強度隨著質子供體或受體的分子量增加而增加。其中，水凝膠和彈性體都表現出固體般的行為(G′>G”），並且由於氫鍵的可再生而具有自我修復的能力。然而，水凝膠具有較低的機械強度而使用振盪測試做量測；彈性體具有較高的機械強度，所以採用拉伸測試做測量。與具有小分子量的PAA 相似，單寧 (TA)具有多個氫鍵，用於與質子受體形成網絡結構（水凝膠）。然而，高分子複合物的機械強度對單寧的摩爾分率很敏感。作為交聯劑，TA可產生比 PAA更強的聚合物複合物，且分子量較小。由於TA的平面結構，TA與聚合物（PEO或PVP）之間的沉澱結果取決於聚合物結構，以及氫鍵的強度。;Polyacrylic acid (PAA) used for dispersants and biocompatible matrices in medical glue can form hydrogen-bonded precipitates with other water-soluble polymers (e.g., poly(ethylene oxide), polyvinylpyrrolidone, …etc.) readily in water. Dependent on the type of proton acceptor polymers, the precipitates can be developed into different kinds of materials, including nanosized aggregates, concentrated solutions of associated polymers, hydrogels, elastomers, and polymeric composites. In this work, the effect of the polymer molecular weight on the mechanical properties of the hydrogen-bonded precipitates is studied. It is found that in general, the water content of the polymer complex decreases but its mechanical strength grows, as the molecular weight of donor or acceptor is increased. Both hydrogel and elastomer exhibit the solid-like behavior (G’>G”) and possess the self-healing ability owing to the regeneration of hydrogen bonding. However, hydrogels have lower mechanical strength characterized by the oscillatory test, while elastomers have higher mechanical strength characterized by the tensile test. Similar to PAA with small molecular weight, tannin (TA) has multiple hydrogen-bonding sites for developing a network structure (hydrogel) with proton acceptor. However, the mechanical strength of the polymer complex is sensitive to the mole fraction of tannin. As a crosslinker, TA yields a stronger polymer complex than PAA with a small molecular weight. Because of the planar configuration of TA, the outcomes of the precipitation between TA and polymers (PEO or PVP) depend on the polymer structure, in addition to the strength of hydrogen bonding. |
