聚雙電性水凝膠成功的以熱聚合方法合成。聚雙電性水凝膠是由隨機散布的陽離子與陰離子重複基團所組成。離子性側鏈的物理交聯給予水凝膠自我癒療和強壯的機械性質。在本研究中，以N,N’-methylenebis(acrylamide) (Bis-Am)做為化學交聯劑增強水凝膠的機械性質。摻入擁有羥基的2-hydroxyethyl methacrylate (HEMA)提高水凝膠的含水量。引入非離子的重複單元改變了超分子結構且顯著的影響製成的水膠。
結果顯示由Bis-Am交聯的水凝膠展現強健的機械性質但同時失去了含水量。由此推論化學交聯劑可以緊密地抓住高分子網絡使水凝膠堅固但提供較少的空間給水貯存。相對於Bis-Am，HEMA確實幫助吸收更多水卻也導致水凝膠軟弱因為無法加入離子對的交聯系統。藉由加入這些試劑，楊氏模量可以從0.4增強到2.4 MPa含水量由62%提升至73%。離子性基團在適當的莫爾比可以展現良好的自我癒合效能。加入過多的非離子劑阻擾了離子側鏈的重新鍵結導致自我癒合的失敗。本研究中開發了一個簡單的方法來調變雙電性水膠的性質。

The polyampholyte (PA) hydrogels were successfully synthesized by thermal-polymerization method. Polyampholytes are composed of randomly dispersed cationic and anionic repeating groups. The physical cross-linking of ionic side-chains gives the hydrogels self-healing and strong mechanical properties. In this study, N,N’-methylenebis(acrylamide) (Bis-Am) is served as chemical cross-linker to enhance the mechanical property of hydrogels. 2-hydroxyethyl methacrylate (HEMA) containing hydroxyl group is incorporated to improve water content. Introducing of non-ionic units changes supramolecular construction and significantly affects the properties of the fabricated gels.
The results showed the hydrogels cross-linked with Bis-Am exhibiting strong mechanical property but losing water content simultaneously. The results suggest that chemical cross-linker hold the polymer network more tightly and made the hydrogel rigid but offered less space for water storage. In contrast to Bis-Am, HEMA indeed helped to absorb more water but caused the hydrogels weak due to incapability of joining ion-pair cross-linking system. By introducing such agents, the Young’s modulus was promoted from 0.4 to 2.4 MPa and the water content was boosted from 62% to 73%. With proper molar ratio of ionic groups, the PA hydrogels showed great self-healing performance. Adding of excess non-ionic agents interrupted the re-forming of ionic side chains led to fail in self-healing. In this study, a simple approach to adjust the properties of PA hydrogels was developed.

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