利用動態鍵結開發具有剪切稀化及自癒合特性的奈米複合水凝膠

Abstract

水凝膠是一種發展已久的材料，然而因為機械性能不佳，受到許多限制。有許多提升水凝膠機械性能的方法被發表，如奈米複合水凝膠(NC hydrogel)、雙網絡水凝膠(DN hydrogel)、奈米複合雙網絡水凝膠(ncDN hydrogel)。然而，開發的趨勢轉向具有壓力及破壞響應且能長時間應用的水凝膠。為了因應這個需求，動態鍵結開始被引入水凝膠的系統中。動態鍵結可分為物理性(超分子作用力)及化學性的動態鍵結，不論由何種動態鍵結建構網絡，都能賦予水凝膠自修復的能力以及剪切稀化的性質。使得水凝膠可由針筒注射成形，開闊其應用範疇。 在本研究中，我們在雙網絡水凝膠結構中引入了多種動態鍵結(如:動態共價鍵、氫鍵、靜電作用力及金屬配位鍵)，藉此賦予雙網絡水凝膠剪切稀化以及自我修復的能力。除此之外，在雙網絡水凝膠中摻入官能基團修飾的奈米材料，可透過動態鍵結進一步交聯雙網絡水凝膠中的兩種高分子鏈，以增加水凝膠結構的多樣性。最重要的是，本研究中水凝膠的性質能夠藉由摻入奈米材料的濃度、pH值或是溶液種類等外在因素來調控。 綜合以上所述，在這篇論文裡，我們提供了一種藉由奈米粒子來製備新一代水凝膠的方法，未來可配合特定的應用來調控網絡結構。

Hydrogels have been utilized in different applications. Nevertheless, most of conventional hydrogels presented weak mechanical properties, restricting the development of hydrogels. Recently, several hydrogels possessed great mechanical properties have been demonstrated, such as nanocomposite hydrogels, double network hydrogels, and nanocomposite double network hydrogels. However, researchers start to develop hydrogels with ability to respond to stress and damage, which is a tendency to more durable application. In order to make hydrogels possess self-recovery and self-healing ability, dynamic bonds have been introduced to construct polymer network. Dynamic bonds are either noncovalent by physical interactions (supramolecular interaction) or covalent via dynamic covalent bonds. Hydrogels constructed by dynamic bonds possess self-healing and shear-thinning properties, allowing hydrogels to perform injectability to expand their applications. In this work, we aim to develop versatile DN hydrogels by introducing multiple dynamic bonds to DN hydrogel structures to provide shear-thinning and self-healing ability. The dynamic bonds include dynamic covalent bonds (i.e. imine bonds and boronate ester bonds) and noncovalent bonds (i.e. hydrogen bonds, electrostatic interaction and coordination bonds). Additionally, surface functionalized nanomaterials were used to further crosslink two polymer chain in DN hydrogel by dynamic bonds to increase the complexity of hydrogel structure. Most importantly, the properties of designed hydrogels could be simply modulated by the amounts of nanomaterials, pH value, or even solution. Taken together, we hereby provide a nanomaterial approach to fabricate a new class of DN hydrogels with controllable networks and favorite properties for specific biomedical applications.