【作者】 陈承响；

【导师】 卜伟锋；

【作者基本信息】 兰州大学 ， 化学·无机化学， 2020， 硕士

【摘要】 带有双硫键的环状分子具有快速,可逆和可调动态共价键交换平衡。因此,它们展现出化学、热、光等外在刺激响应性。端基含硫辛酸酯的ABA三嵌段共聚物在基础油中通过双硫键交换反应形成动态网络结构,其凝胶性质可以通过温度、pH值或通过封端所得游离硫醇来调节。这些动态聚合物网络可广泛用于制作减震缓冲材料、抗冲击防护材料、自修复材料、韧性材料等。但是,此类聚合物动态材料在摩擦学领域却鲜有应用。针对这一问题,本硕士学位论文合成了一系列遥爪型聚合物,并研究了其在基础油中的凝胶性能。具体从以下三个部分进行讨论:第一部分,我们合成了一系列端基为硫辛酸酯的ABA三嵌段共聚物TMAn-b-PSMA2m-b-TMAn(2m=10,20,40,80;n=2)。其中末端 A 嵌段包含有侧链 1,2-二硫杂环戊烷,而B嵌段则是油溶性PSMA。将其溶解在PAO10基础油中形成动态共价网络结构,并形成自支撑油凝胶。该类基于动态硫硫键的油凝胶具有较好的粘弹性以及较高的屈服应力,同时在高剪切力破坏结构后具有较快的恢复性。根据流变学测试可知,保持A嵌段长度不变,随着B嵌段增加,凝胶强度增强后趋于稳定。根据SAXS和WAXS研究可知,凝胶虽然是无序结构,但WAXS测试信号峰对应是十八烷基链缠绕所导致的。第二部分,为了研究硫辛酸酯嵌段长度对油凝胶形成和性能的影响,我们进一步利用聚合后合成方法制备了端基为硫辛酸酯的遥爪型聚合物TMAn-b-PSMA2m-b-TMAn(2m=24,70;n=8)。这两例遥爪型聚合物可在基础油中形成具有网络状结构的动态油凝胶。通过对该聚合物进行制备和表征后,我们发现更长的A嵌段,更多的硫硫键基团,会导致更多的动态交联,进而形成网络状结构,从而包裹基础油形成凝胶。从观察可知,该类基于动态硫硫键的凝胶具有较好的粘弹性以及较高的屈服应力,同时在高剪切力破坏结构后具有较快的恢复性。第三部分,我们合成了端基含嘧啶酮的ABA三嵌段共聚物Upyn-b-PSMA2m-b-Upyn(2m=24;n=4),研究了其在基础油中形成的凝胶性能,发现嘧啶酮嵌段可与其自身在基础油中形成四级氢键。通过对比发现嘧啶酮的油不溶性以及强四级氢键作用有促进凝胶形成的作用。该类基于四级氢键的凝胶具有较好的粘弹性以及较高的屈服应力,同时在高剪切力破坏结构后具有较快的恢复性。更多还原

【Abstract】 As cyclic disulfides have the properties of fast,reversible,and tunable disulfide exchange equilibria,with the capacity for responding to chemical,thermal and photochemical stimuli.We envisioned that ABA triblock copolymers where the terminal A blocks contain pendant 1,2-dithiolanes and the B block is a flexible oil-soluble PSMA would provide a class of structurally dynamic networks whose properties could be modulated by temperature or pH or by capping of the resultant free thiols.The dynamic polymersare widely applied for manufacturing of shock-absorbing cushioning materials,impact-resistant protective materials,self-healing materials,ductile materials,etc.However,such polymer dynamic materials are rarely applied in the field of tribology.In response to this problem,this master’s degree thesis synthesized a series of telechelic polymers and studied their gel properties in base oils.The discussion will be conducted in the following three parts:In the first part,a series of ABA triblock copolymers TMAn-b-PSMA2m-b-TMAn(2m=10,20,40,80;n=2)have been synthesized,of which terminal A contains side chain 1,2-dithiolane,while the block B is oil-soluble PSMA,which forms dynamic covalent network structure and self-supporting oil gel by dissolving in PAO10 base oil.This type of dynamic sulfur-sulfur bond-based oil gel good viscoelasticity and higher yield stress,and it recovers faster after the structure is destroyed by high shear strength.Rheological test suggests that while keeping the length of block A still,with acceleration of block B,after enhance of strength of the gel,it tends to maintain still.According to SAXS and WAXS tests,though disordered structure,the WAXS test showed that signal peak corresponds to the octadecyl chain entanglement.It is thus concluded that this series of teleclaw polymers with lipoic acid end groups form oleogel in the base oil,and has good viscoelasticity,and the cyclic disulfide bond provides excellent lubrication performance.In the second part,different synthetic methods are used to study the the dynamic oil gel with a dynamic network structure formed in base oil of telechelic polymer TMAn-b-PSMA2m-b-TMAn(2m=24,70;n=8),which keeps the length of the block B remains still and changes the length of the block A.After preparation and characterization of the polymer,we found that polymers with longer block A lengths,and more sulfur-sulfur bond groups will be formed which further generate more dynamic cross-linking,and interlace to network structures.The structure will wrap the base oil and form gels.It can be seen from the observations that this type of dynamic sulfur-sulfur bond-based gel has better viscoelasticity and higher yield strength.and it has faster recovery efficiency after the structure is destroyed by high shear force.In the third part,ABA triblock copolymer Upyn-b-PSMA2m-b-Upyn(2m=24;n=4)containing pyrimidinone at the end group is synthesized,and studies on gel performance formed in the base oil.It is found that the block can form a quaternary hydrogen bond with self reaction in the base oil.By comparison,it is found that the insolubility of pyrimidone and its strong hydrogen bonding effect promotes formation of gel This type of quaternary-hydrogen-bond-based gel generates better viscoelasticity and higher yield strength,at the same time,it has faster recovery performance after the structure is destroyed by high shear force.更多还原