| 摘要: | 交聯(Cross-link)是一種利用共價鍵將聚合物鏈相互連結的反應，藉由交聯反應，能 夠形成三維立體網狀結構，此反應在日常生活中無處不在，例如:生物學中蛋白質之間的 生物偶聯作用、高透氧水凝膠隱形眼鏡、硫化橡膠輪胎等等。化學共價交聯鍵結雖然具 有穩定的機械性質及熱性能，但是此鍵結一旦形成便難以被打斷，使得輪胎等化學交聯 產品受到外部破壞以致裂紋產生，損壞的產品不但無法繼續使用，同時也無法被回收， 不僅僅造成材料上的浪費，更是對地球環境的一大破壞。因此，若能製備出一種具有可 逆鍵結的交聯劑，便可以利用可逆鍵結的特性，製備出具有自修復、可回收等功能的三 維結構聚合物材料。在此研究中，使用了芳香族雙硫鍵及氫供體/受體作為交聯劑中的可 逆鍵結，其優秀的自癒合能力及可回收能力，皆歸因於雙硫鍵的低鍵能，當材料結構中 其餘鍵結完全斷裂前，雙硫鍵會先行斷裂，但由於其特殊的鍵結交換能力，最終將會重 新鍵結成雙硫鍵，而此過程甚至不需要給與外部刺激就可以實現，因此在眾多可逆鍵結 中，雙硫鍵結構是具有潛力的材料候選人之一。 本研究中合成出三種芳香族雙硫鍵交聯 劑，並將其命名為 Bis[4-(methacrylyl-2-methyl-isocyanato-isophorone)phenyl] disulfide (MIS) 、 Bis[4-(acrylyl-2-methyl-isocyanato-isophorone)phenyl] disulfide (AIS) 及 Bis[4- (methacrylyl-2-methylamide-isocyanato-isophorone) benzyl amide] disulfide (MUS)。其中， MIS 側基為甲基丙烯酸酯， AIS 側基為丙烯酸酯， MUS 側基為甲基丙烯醯胺， 選用了疏 水性的丙烯酸丁酯(Butyl acrylate, BA)作為反應單體，與這三種雙硫鍵交聯劑以及商業用 交聯劑聚乙二醇二甲基丙烯酸酯（ Polyethylene glycol dimethacrylate）進行反應，成功合 成了四種彈性體，分別命名為 MIS-BA、 AIS-BA、 MUS-BA 和 PEGDMA-BA。此外，還 製備了以丙烯酸丁酯為單體的聚合物 Poly Butyl acrylate (PBA)，以便與交聯劑製備的熱 固性材料進行性質比較。 通過核磁共振光譜儀(NMR)對 MIS、 AIS 和 MUS 的分子結構 進行了鑑定。 使用衰減全反射式傅立葉轉換紅外線光譜儀(ATR-FTIR)和 X 射線光電子 能譜儀(XPS)分析了彈性體表面的元素組成。 此外，利用熱重量分析儀(TGA)比較了 MUS、 AIS 和 MUS 交聯劑之間的熱穩定性，並通過差示掃描量熱分析儀(DSC)和動態熱II 機械分析儀(DMA)鑑定並比較了 MIS-BA、 AIS-BA、 MUS-BA、 PEGDMA-BA 和 PBA 之 間的熱性質差異。 在彈性體的動態鍵結性能鑑定中，我們利用光學顯微鏡(OM)觀察室溫 下彈性體表面劃痕的癒合情形，並使用萬能拉力機檢測彈性體的機械性質和斷裂後的癒 合性能，最終透過核磁共振光譜儀(NMR)鑑定了彈性體在二硫蘇糖醇(DTT)溶液中的還 原情形。;Cross-linking is a process that utilizes covalent bonding to link together polymer chains, resulting in the formation of a three-dimensional network structure. The reaction occurs ubiquitously in daily life, including biological coupling between proteins in biology, high oxygen permeability hydrogel contact lenses, and vulcanized rubber tires. Although chemical covalent crosslinking bonds offer stable mechanical and thermal properties, they exhibit low flexibility and are challenging to break once formed. As a result, products such as tires that undergo external damage may develop cracks, rendering them unusable and non-recyclable. To address this issue, the use of cross-linkers with reversible bonding presents a promising approach that can generate a three-dimensional structured polymer material with self-healing and recyclable properties. The study employed aromatic disulfide bonds along with hydrogen donors/acceptors as reversible bonds in the cross-linker, which exhibit excellent self-healing and recycling capabilities due to their low bonding energy. Among the various reversible bonds, the disulfide bond structure shows great potential. In this study, three aromatic disulfide cross-linkers were synthesized and named as Bis[4-(methacrylyl-2-methyl-isocyanatoisophorone)phenyl] disulfide (MIS), Bis[4-(acrylyl-2-methyl-isocyanato-isophorone)phenyl] disulfide (AIS), and Bis[4-(methacrylyl-2-methylamide-isocyanato-isophorone)benzyl amide] disulfide (MUS). The MIS side group is methacrylate, the AIS side group is acrylate, and the MUS side group is methacrylamide. A hydrophobic monomer, Butyl Acrylate (BA), was chosen as the reactive monomer. It was reacted with the three disulfide cross-linkers and a commercial cross-linker, Polyethylene Glycol Dimethacrylate (PEGDMA), resulting in the synthesis of four elastomers named MIS-BA, AIS-BA, MUS-BA, and PEGDMA-BA. Additionally, a polymer, Poly Butyl Acrylate (PBA), was prepared using BA as the monomer for property comparison with the crosslinked thermosetting materials.The molecular structures of MIS, AIS, and MUS were identified using Nuclear Magnetic Resonance spectroscopy (NMR). The elementalIV composition of the elastomer surfaces was analyzed using Attenuated Total Reflection Fouriertransform infrared spectroscopy (ATR-FTIR) and X-ray photoelectron spectroscopy (XPS). The thermal stability of MUS, AIS, and MUS cross-linkers was compared using Thermogravimetric analysis (TGA). Differential scanning calorimetry (DSC) and Dynamic mechanical analysis (DMA) were employed to identify and compare the thermal properties of MIS-BA, AIS-BA, MUS-BA, PEGDMA-BA, and PBA. In the evaluation of the dynamic bonding performance of the elastomers, Optical Microscopy (OM) was used to observe the healing of surface scratches at room temperature. Mechanical properties and post-fracture healing performance were assessed using a Universal Testing machine. Finally, the reduction of the elastomers in Dithiothreitol (DTT) solution was identified using Nuclear Magnetic Resonance spectroscopy (NMR) spectroscopy. |
