New Azide-Alkyne Click Polymerization

The establishment of efficient polymerizations can greatly promote the exploitation of new functional polymers,which is of critical significance to the development of polymer science.Nowadays,azide-alkyne click polymerization?AACP?has been developed into a powerful tool for the preparation of functional polymers with diverse topological structures.However,compared with the famous and popular Cu?I?-catalyzed azide-alkyne click polymerization?CuAACP?,other AACPs are rarely reported,especially AACPs with1,5-regioselectivity.Therefore,the establishment of new AACP can not only provide a new tool for the preparation of functional polymers,but also benefit to the further development of click polymerization.In this dissertation,we focus on the exploitation of new AACPs with1,4-or 1,5-regioselectivity.Using these effective AACPs,we prepared various 1,4-and1,5-regioregular polytriazoles with linear and hyperbranched structures,and investigated their structure-property relationship.First,we established a 1,4-regioselective Ru?II?-catalyzed azide-alkyne click polymerization?RuAACP?by altering the ligands on Ru?II?complex and using RuH₂?CO??PPh₃?₃ as catalyst.Soluble and thermally stable 1,4-and 1,5-regioregular polytriazoles with high molecular weights and regioregularities were obtained in high yields by the RuH₂?CO??PPh₃?₃-/Cp*Ru?PPh₃?₂Cl-catalyzed AACPs,respectively.And we then systematically studied the relationships between the regiostructures of these polytriazoles and their thermal,photophysical,and optical properties.With Cp₂Ni/Xantphos as catalyst system,we developed an efficient 1,5-regioselective Ni?II?-catalyzed azide-alkyne click polymerization?NiAACP?.The NiAACP was carried out at room temperature,and soluble polytriazoles with high molecular weights?M_w up to 67900g/mol?and high 1,5-regioregularities(F_1,5 up to 100%)were obtained in high yields?up to96.7%?after 0.5 h.All the prepared polytriazoles are thermally stable.It was found that the refractive indices of these polytriazoles are related to the contents of aromatic rings in their structures.By introducing chiral binaphthyl moieties and aggregation-induced emission?AIE?active tetraphenylethylene?TPE?moieties into the polymer chains,we prepared polytriazoles with chirality and AIE features,indicating that the NiAACP are promising polymerization technique in the construction of functional polymers.Using the efficient NiAACP,we successfully prepared a series of hyperbranched polytriazoles with good solubility,high molecular weights?M_w up to 34200 g/mol?,and high1,5-regioregularites(F_1,5 up to 100%)through an A₂+B_n?n=3 or 4?comonomer strategy.The obtained polytriazoles show high thermal stability with the temperature at 5%weight loss higher than 382 ^oC.In addition,thanks to the good functional tolerance of NiAACP,binaphthyl and TPE moieties were successfully incorporated into the polymer chains to endow the polytriazoles with chirality and AIE features.We also prepared 1,5-regioregular hyperbranched polytriazoles through a metal-free method without risk of metal residue.With NMe₄OH as catalyst,the click polymerizations of aromatic diazides and aromatic triynes or tetrayne were carried out at room temperature,furnishing hyperbranched polytriazoles with M_w as high as 35100 g/mol after 1 h.It is noteworthy that all the 1,5-regioregularites of the obtained polytriazoles are 100%.Meanwhile,the obtained triphenylamine-containing polytriazole exhibit solvatochromism due to the cooperative effects of triphenylamine?donor?and triazole ring?acceptor?.In addition to the development of new AACPs,we also established a CuAAC-mediated multicomponent polymerization based on azide,alkyne,and trifluoroacetic anhydride.Under the catalysis of CuI,diazides,diynes,and trifluoroacetic anhydride were polymerized at room temperature in the presence of triethylamine,producing poly?3-trifluoromethyl substituted-1,2,4-triazinone?s with good solubility.The obtained polymers containing trifluoromethyl groups and 1,2,4-triazinones are envisioned to find broad applications in the biomaterial field.