【作者】 周黎鹏；

【导师】 刘俊秋；

【作者基本信息】 吉林大学 ， 高分子化学与物理， 2013， 博士

【摘要】 凝胶是一类“软物质”，它是具有三维空间结构的聚合物交联网络，能够将溶剂分子固定在这种网络结构中，有着非常独特的物理化学性质。尤其是刺激响应性凝胶作为一种能够对外界的刺激，如：pH、温度、光、化合物、电磁场等在体积上（收缩溶胀）、相态上（溶胶-凝胶）、理化性质（颜色等）等方面发生做出响应变化的智能型材料，在最近几十年受到了有越来越多的关注，被广泛应用于可控的药物运输与释放、可控的催化、分离纯化、传感检测、组织工程、药物载体、液晶显示等领域。但在如何设计新型的刺激响应性凝胶，尤其是设计多重刺激响应和具有新的功能方面，仍然有许多工作需要开展。动态共价键作为一种共价键，但同时又具有超分子相互作用的可逆性，随着超分子化学的发展，最近十多年里又被重新审视，焕发了新的生机，被和超分子相互作用一起应用于构建刺激响应性材料。本论文就利用苯甲酰亚胺键这种具有pH响应能力的动态共价键设计构建了刺激响应性凝胶，并得到了以下研究结果：1）pH和光双重响应准聚轮烷水凝胶：设计了THPP-(PEG2000-BA)4聚合物，此聚合物能够和α-环糊精形成准聚轮烷水凝胶。由于苯甲醛能够和胺类化合物形成苯甲酰亚胺键动态共价键，可以通过pH的变化，对此聚合物进行封端与解封端，进而调节准聚轮烷水凝胶的形成与解散。此外，借助于光敏性的竞争性客体分子Azo-C1-N+，可以对水凝胶进行光调控实现凝胶-溶胶间相互转换。在二者的共同作用下，制备了能够对pH和光刺激双重响应但响应方式又不同的准聚轮烷水凝胶。2）分散碳纳米管的准聚轮烷水凝胶：卟啉作为一种共轭环能够通过π-π堆积相互作用，和碳纳米管形成J-聚集复合物，来分散碳纳米管。我们设计的THPP-(PEG2000-BA)4聚合物，其具有一个卟啉核，通过其对碳纳米管分散的研究，发现它具有很好地分散碳纳米管能力。同时，在分散碳纳米管之后，其仍然能够形成准聚轮烷水凝胶，成凝胶能力得到明显提高。另外，分散碳纳米管的准聚轮烷水凝胶仍然具有pH和光刺激双重响应能力。3）具有pH响应能力的自修复凝胶：设计了两种都修饰有氨基和苯甲醛但含量不同的聚合物P(AM25-co-EAM1-co-BA1)和P(AM50-co-EAM1-co-BA1)，分别研究了它们的成凝胶能力、pH敏感性，并进行了pH刺激下的凝胶-溶胶转换实验。研究显示P(AM50-co-EAM1-co-BA1)展现了非常好的自修复功能。更多还原

【Abstract】 Gel，as a kind of "soft matter", is a three-dimensional polymeric crosslinked network, whichabsorbs and retains large amounts of solvents. The gel has very unique physical and chemicalproperties. Gels have pervaded our everyday life in a variety of forms. Scientists have used thegel for tissue engineering, separation and purification, drug delivery, sensor and detection,chemical convertors, catalysis, etc..With the development of smart materials, the gel chemistry is more tending to the "smart"direction. A variety of smart gels, which is capable to responding to external stimuli, aredesigned and studied. These stimuli can be pH, temperature, light, chemicals, electromagnetic ormechanical field, strain, and so on, which can be single, duple, or mutiple. The response may beon the volume (contraction or swelling), also be on state (sol or gel), or physical properties (color,etc.) and so on. Such materials are usually more controllable and easy to be adjusted, so they areeasier to meet the needs of different situations, and are more attractive.After the recent thirty years of research, there has been a great development ofsupramolecular chemistry, but in some cases, the feature of "weak" of the supramolecularinteractions limits its application. The last ten years, some chemists fixated back to covalentbonds, and found that part of covalent bonds are similar to supramolecular interactions, whichwas ignored before. They are the dynamic covalent bonds, which are also thermodynamicallyreversible. But the essence of dynamic covalent bond is covalent bond, more stable than thesupramolecular interactions. Herein, we use the benzoic imine bond, one of dynamic covalentbonds, to build stimuli-responsive gels.1. Dual stimuli-responsive pseudopolyrotaxane hydrogelsThe medium of hydrogels is water, and the majority of the organisms are present in theaqueous medium, therefore, hydrogels generally have a better biocompatibility, and have verybroad applications as biomedical materials. There is a hydrogel which is formed byα-cyclodextrin and polyethylene glycol (PEG) chains. The PEG chain is an axis threadingα-cyclodextrin. The supramolecular inclusion complex, defined as pseudopolyrotaxane, can formhydrogel when the concentration is enough. Many chemists focused on the formation and structure of this hydrogel. A number of bio-pharmaceutical applications have been carried on.However, the stimulus of this hydrogel is primarily the thermal, mechanical, optical. All of thesestimulus is single-stimulus. The design of dual stimuli-responsive pseudopolyrotaxane hydrogelsis necessary.Herein, we designed the polymer of THPP-(PEG2000-BA)4, a four-branched molecule whichhas a core of porphyrin and is end-decorated with benzaldehyde. It can form physicalpseudopolyrotaxane hydrogels in the presence of α-cyclodextrins. Since benzaldehyde can reactwith amine to form a pH-responsive Schiff-base which possesses a dynamic covalent nature, theformation of gels can be modulated by pH. By means of a strongly competitive photoresponsiveguest,1-[p-(phenylazo)benzyl]-bromide (Azo-C1-N+), this hydrogel can be regulated to achievegel-sol transitions by alternation of visible and UV irradiation. Reversible cycles of sol-to-geland gel-to-sol transitions were achieved by means of the synergy of pH-adjustment andUV-visible irradiation. A dual stimuli-responsive pseudopolyrotaxane hydrogels was prepared.2. A pseudopolyrotaxane hydrogels dispersing carbon nanotubeCarbon nanotube is a very attractive nanomaterial, which has a unique structure, mechanicaland electrical properties, including in high electronic and thermal conductivities, greatmechanical strength, and huge specific surface are. There are a wide range of applications in thephysics, materials and many other fields. However, bundled aggregates due to stronginter-tubular van der Waals interactions cause the poor solubility in many conventional solvents,which acts as an obstacle to both the purification and handling of the SWNTs. This seriouslylimits its application. Therefore, all the scientists are meeting and have to solve the problem howto improve its solubility.Conjugated porphyrin macrocycle is capable of forming a J-aggregate composite withcarbon nanotubes through π-π stacking interaction, and can be used to disperse carbon nanotubes.Considering that the polymer of THPP-(PEG2000-BA)4which we previously designed has aporphyrin core, we studied its ability of dispersing carbon nanotubes. Indeed, it is found thatcarbon nanotubes can be dispersed. Meanwhile, after the dispersing carbon nanotubes, it is stillcapable of forming a pseudopolyrotaxane hydrogel. In addition, the pseudopolyrotaxanehydrogel dispersing carbon nanotubes still is dual (pH-and photo-) stimuli-response.3. A pH-responsive self-healing gelSelf-healing is a fascinating property of living creatures, A living body can automaticallyrepair damage by activating the self-healing process and, thus, restore certain destroyedfunctions.Scientists have been simulating this process in the past decade and designed a variety of self-healing materials. They hope that it can improve the safe and prolong the life of thematerials through self-repairing process.Herein, we designed two polymer P(AM25-co-BocEAM1-co-BA1) and P(AM50-co-BocEAM1-co-BA1), which are both modified with amine and benzaldehyde, but with differentcontents. We investigated their ability to gel. We found that the former is capable of forming agel in the DMSO solvent, while the latter not. This is because benzaldehyde can react with amineto form a pH-responsive benzoic imine bond, which plays a role in cross-linking. The differencein the contents of amine and benzaldehyde results in the difference in the degree of cross-linking,further affects the ability to gel. But they are both pH-sensitive. They can maintain the gel orsolution state under weak acidic conditions, both formed the gel under alkaline condition, andboth converted into a sol under strong acid condition. We carried out the sol-gel conversionexperiments by pH-adjusting. In addition, we also found the gel by the latter under alkalinecondition has a good self-healing capability.更多还原