The Study Of Catalytic System For Azide-Alkyne Click Polymerization

The development of simple and efficient polymerization reactions is of vital significance for the preparation of functional materials.In the field of polymer synthesis,azide-alkyne click polymerization has become one of the most important methods for the synthesis of nitrogen-containing polymers.Particularly,Cu?I?-catalyzed azide-alkyne click polymerization and Ru?II?-catalyzed azide-alkyne click polymerization have become the powerful tools for the fabrication of 1,4-and 1,5-regioregular polytriazoles?PTAs?,respectively.In the past decade,polymer scientists have developed a variety of copper catalysts,which have greatly facilitated the extensive applications of click polymerization.However,the efficiency of these catalytic systems still needs to be improved.Furthermore,polymerization methods for the synthesis of 1,5-regioregular PTAs are quite limited.Therefore,it is meaningful to develop a simple and efficient catalyst for azide-alkyne click polymerization.In this thesis,we focus on the study of catalytic system of azide-alkyne click polymerization,and 1,4-/1,5-regioregular PTAs with various topological structures and advanced properties were also synthesized.The detailed contents are described as follows.Firstly,we synthetized a[Cu(Im¹²)₂][CuBr₂]?Cu-Im?complex,and systematically optimized the polymerization conditions under the catalysis of this efficient Cu-Im.After optimization,a novel Cu-Im catalyzed azide-alkyne click polymerization was established.The polymerization of diazides and diynes proceeded smoothly under mild conditions.1,4-regioregular PTAs with high molecular weights?M_w up to 32000,polydispersity index was 2.61?were obtained in high yields?up to 94%?.The resulting polymers possess abundant aromatic rings and nitrogen heterocycles in their main chains,which endow them with high refractive indices.Moreover,by introducing the fluorescent fluorene moiety into polymer backbone,the yielded polymer has the potential application in highly sensitive detection of explosive.Secondly,a copper-based ionic liquid?Cu-IL?was synthesized and after the optimization of polymerization conditions,we developed an efficient Cu-IL catalyzed azide-alkyne click polymerization.Diazides and diynes were polymerized with Cu-IL as catalyst.1,4-regioregular PTAs with high molecular weights?M_w up to 56100,polydispersity index was 2.53?were obtained quantitatively.More importantly,the water-soluble ionic polytriazole could be easily prepared and applied in explosive detection and Fe³⁺ion recognition.It was found that the limits of explosive detection and Fe³⁺ion recognition were5.10×10^-7 and 5.61×10^-8 M,respectively.Moreover,due to its low biological toxicity,the ionic polytriazole can also selectively label lysosomes in cells.Next,utilizing the Cu-IL catalyzed azide-alkyne click polymerization,a poly?dithienylethene?conjugated polymer was synthesized.Besides,its photochromism,aggregation-enhanced emission?AEE?,fluorescence switch properties,applications in anti-fake and rewrite materials were explored.It should be noted that owing to containing both aggregation-induced emission?AIE?active tetraphenylethene?TPE?and photochromic dithienylethene?DTE?units in its structure,the fluorescence of resultant polymer could be dual regulated,that is,the fluorescence can be regulated not only by the aggregated states of polymer but also under UV and visible light irradiations.Finally,we successfully developed an efficient phosphazene base-mediated click polymerization.Aromatic diazides and aromatic diynes could be polymerized in the presence of phosphazene base t-BuP₄,generating PTAs with high molecular weights in high yields.The click polymerization can proceed in regioselective fashion and solely 1,5-regioregular PTAs were obtained.In addition,1,4-disubstituted PTA was facilely prepared via the powerful Cu?PPh₃?₃Br-catalyzed azide-alkyne click polymerization.The differences in photophysical behaviors,thermal stability,refractive indices and electrochemical properties between 1,4-/1,5-regioregular ones were further investigated.These contrastive results not only illustrate the structure-property relationship of PTAs but also provide guidance for the design of triazole-based functional materials.