【作者】 刘志强；

【导师】 魏浩；

【作者基本信息】 哈尔滨工程大学 ， 材料科学与工程， 2022， 硕士

【摘要】 通过效仿自然界中生物体的自愈合行为,研究人员开发了一系列功能性的自修复材料,该类材料在受到损伤时可对材料中的微裂纹进行自我修复,是一种前景广阔的智能材料。自修复材料的设计主要从两方面切入,一是在聚合物内部掺杂装有修复剂的微容器,二是在聚合物体系中接入动态键,对于后者,基于四重氢键体系的UPy(2-ureido-4[1H]-pyrimidinone)体系得到了广泛的应用与关注。聚氨酯(PU)是一类用途广泛的材料,具有优异的稳定性、回弹性和机械性能。但在加工和使用过程中,聚氨酯材料容易从内部产生微裂纹,这些裂纹不易察觉,微裂纹的产生会损害材料的机械性能和使用寿命。针对这一问题,本文开展了关于制备常温自修复聚氨酯的研究,将UPy四重氢键体系制备成扩链剂,以侧链的形式引入到聚氨酯体系中,分别制备出不同物理交联和不同化学交联的双交联自修复聚氨酯。基于此,本文的研究内容如下:首先,以6-甲基异胞嘧啶和六亚甲基二异氰酸酯(HDI)为原料合成UPy-NCO,再以UPy-NCO和六亚甲基二异氰酸酯(AMPD)为原料合成UPy扩链剂,并优化合成方案,找出最佳溶剂质量分数,调控UPy扩链剂、1,4丁二醇(BDO)和交联剂(三乙醇胺)的比例,制备一系列双交联聚氨酯(PU-UPy),进一步通过控制物理交联程度,制备出UPy扩链剂比例分别为0%、25%、50%和75%的自修复聚氨酯。实验结果发现随UPy侧链含量增加,材料的热稳定性变化不大,玻璃化转变温度升高,链段移动能力略有降低;硬度和抗拉强度均大幅提升,含量最高时大于未加入溶剂的纯聚氨酯;弹性恢复能力增强,且循环性能测试时的恢复更快。其次,通过控制化学交联程度,制备出交联剂比例分别为0%、10%、20%和30%的自修复聚氨酯。实验结果发现,随着交联剂比例的增加,材料的热稳定性增加,玻璃化转变温度升高,链段移动变得困难;损耗因子峰值下降,但在室温时仍具有较好的阻尼性能;硬度和抗拉强度均大幅提升;弹性恢复能力更强,但循环性能的恢复能力减弱。此外,发现交联剂比例变化在10%和20%之间时,可能出现作为交联剂的硬段发生集中并分散在软段中的情况。最后,对所有两种交联比例聚氨酯进行自修复实验,开展自修复温度及修复后力学性能进行研究。实验结果表明,延长修复时间使氢键解离和链段运动有充分的时间,而升高温度使氢键的解离重组能力与链段的移动能力更强,二者均提高材料的修复效率。随着UPy侧链含量的提高,材料的修复效率先略微减小再提升,在40℃下修复24小时后,PU70-10的自修复效率达到73%。随着交联剂含量的提高,材料的修复效率逐渐降低,但在40℃下修复24小时后,PU50-30的自修复效率仍达到48%。更多还原

【Abstract】 By mimicking the self-healing behavior of organisms in nature,researchers have developed a series of functional self-healing materials.The self-healing materials,as one of the promising smart materials,have the ability of repairing the damage.The design of self-healing materials is mainly started from two aspects: one is to doping microcontainers containing repair agents inside the polymer,and the other is to connect dynamic bonds in the polymer system.For the latter,UPy(2-ureido-4[1H]-pyrimidinone)system based on quadruple-hydrogen bonds has been widely applied to the field of self-healing.Polyurethane(PU)is a kind of versatile material with excellent stability,resilience and mechanical properties.However,in the practice applications,polyurethane materials are easy to appear inside micro-cracks.These cracks are hard to detect and reduce the mechanical properties and service life of the material.To solve this problem,this paper is focus on the preparation of room temperature self-healing polyurethane.The UPy system was prepared as the chain extender and was introduced into the polyurethane system in the form of side chain.The double cross-linking self-healing polyurethane elastomers with physical cross-linking and different chemical cross-linking were prepared,respectively.Therefore,the research content of this paper is as follows:Firstly,UPy-NCO was synthesized by 6-Methylisocytosine and hmethylene diisocyanate(HDI).Then UPy chain extender was synthesized by UPy-NCO and amino-methyl-propanediol(AMPD).The synthesis process was optimized and the best mass fraction of the solvent was confirmed.The proportion of UPy chain extender,1,4 butanediol(BDO)and crosslinking agent(triethanolamine)was controllable to prepare a series of double crosslinking polyurethane elastomers(PU-UPy).By adjusting the degree of physical crosslinking,self-healing polyurethane elastomers with UPy chain extender proportions of0%、 25%、 50% and 75% were prepared,respectively.The results showed that with the increase of UPy side chain content,the thermal stability of the material has little change,the glass transition temperature increases,and the chain segment mobility decreases slightly.The hardness and tensile strength were greatly improved as the inceasing of UPy content.When the content of UPy was the highest,the hardness and the tensile strength were greater than that of pure polyurethane without solvent.Elastic recovery was enhanced and the recovery was faster and faster as the increase of UPy content based on the results of cyclic performance tests.Secondly,by controlling the degree of chemical crosslinking,self-healing polyurethane elastomers with crosslinking agent ratio of 0% 、 10% 、 20% and 30% were prepared,respectively.The experimental results showed that with the increase of the proportion of crosslinking agent,the thermal stability of the material increased,the glass transition temperature increased,and the movement of chain segment became difficult.Though the peak of loss factor decreased as the increasing of the UPy content,the damping performance at room temperature still kept excellent.The hardness and the tensile strength were greatly improved as the inceasing of UPy content.Elastic recovery became stronger and the cyclic recovery became weaker as the inceasing of UPy content.In addition,it was found that when the proportion of crosslinker was between 10% and 20%,the hard segment as crosslinker might be concentrated and dispersed in the soft segment.Finally,self-healing experiments for two kinds of crosslinked proportional polyurethane elastomers were carried out.The self-healing temperature and the mechanical properties of polyurethane elastomers after repairing were investigated,respectively.The experimental results showed that when the repair time was prolonged,the dissociation of hydrogen bond and the movement of chain segment had sufficient time to repair the damage,resulting that the repair efficiency went up.When the temperature was rised,the dissociation and recombination ability of hydrogen bond and the movement ability of chain segment were improved,resulting that the repair efficiency went up,too.With the increasing of UPy side chain content,the repair efficiency of PU70-10 decreased slightly at first and then improved.After repairing for 24 hours at 40 ℃,the self-repair efficiency of PU70-10 reached 73%.With the increasing of crosslinker content,the repair efficiency of PU50-30 decreased gradually and the self-repair efficiency of PU50-30 still reached 48% after repairing for 24 hours at 40 ℃.更多还原