New Polymerization Based on Carbon Dioxide and Alkyne

Author:Song Bo

Supervisor:tang ben zhong


Degree Year:2019





The continuous increase of carbon dioxide(CO2)in the atmosphere has caused serious environmental problems.As an abundant,inexpensive,non-toxic and renewable C1 resource,CO2 has been widely used in the organic chemistry.Using CO2 to prepare polymeric materials has attracted more attention because of widespread needs.However,due to its low reactivity,only a few polymerizations based on CO2 have been developed.The copolymerization of CO2 and epoxide monomers was widely studied in the past few years,but the polymerization of CO2 and alkyne monomers was rarely reported.Compared to vinyl monomers,alkyne monomers are another kind of important monomers with more abundant chemical properties.Polymers based on alkynes generally contain unsaturated carbon-carbon(heteroatom)bonds and thus have specific optoelectronic properties.Therefore,our aim in this dissertation is to develop new polymerizations based on CO2 and alkyne monomers toward a series of functional polymers.In chapter 2,we established a new polymerization of CO2,diynes,and alkyl dihalides under atmospheric pressure.The polymerization was catalyzed by a bifunctional catalyst,silver tungstate,and the poly(alkynoate)s with high molecular weights can be obtained in high yields under mild conditions.The resultant poly(alkynoate)s can be post-modified with benzylamine in 100%grafting ratio.In addition,we also prepared telechelic polymers via this polymerization which can be used as macromonomers to generate poly(alkynoate)s with much higher molecular weights.Thanks to the functional group tolerance,the tetraphenylethene(TPE),silole,and tetraphenylpyrazine(TPP)moieties can be introduced into the polymer main chains to make them feature the aggregation-induced emission(AIE)characteristics,and high absolute quantum yields up to 61%in the film state could be recorded.In addition,their containing ester linkages endow the polymers degradable property under basic conditions.In chapter 3,the fourth monomers amines were introduced to the polymerization we established in chapter 2.Thus a simple and efficient"one-pot,two-step,four-component"tandem polymerization based on CO2 was developed.After the polymerization of CO2,diynes,and alkyl dihalides,amines were directly added without separation and purification of the intermediate,and finally the regio-and stereoregular poly(aminoacrylate)s were obtained.We can also use different monomer combinations to prepare poly(aminoacrylate)s with diverse main chains and tunable thermal properties.The TPE groups can be introduced into the polymer main chains to make them AIE active.Thanks to the intense luminescence and the nitrogen-rich structures,the poly(aminoacrylate)s we obtained can be applied to the sensitive detection of explosives.In chapter 4,we prepared hyperbranched poly(alkynoate)s through multifunctional alkyne monomers and CO2 under mild conditions.It can be seen by NMR and FT-IR analysis that there are a large number of unreacted terminal alkyne groups on the periphery of the polymers.By analyzing the NMR spectra,we can calculate the degree of branching of the polymers,which is 0.61.Notably,this value is larger than the traditional hyperbranched polymers.Due to their highly reactive alkynoate and terminal ethynyl groups,hyperbranched poly(alkynoate)s can undergo precise multi-step post-polymerization modifications(PPMs)with nearly 100%conversion in every step to generate structure-and sequence-controlled hyperbranched polymers.In Chapter 5,benzamidine can be introduced to achieve precise,fast and visible degradation of linear,hyperbranched and cross-linked poly(alkynoate)s toward the well-defined functional imidazolidones.We used in-situ FT-IR to study the kinetics of the degradation reaction,and found that the temperature significantly affects the degradation rate.In addition,the concentration of Bu3P imparts a great influence on the degradation rate,while the concentration of benzamidine does not affect the degradation rate.What’s more,the visible degradation was realized by monitoring the change in fluorescence intensity of the reaction system.Using the efficient and fast degradation reactions,we achieved clear pattern at macro and micro dimension.Due to the unique imidazolidone structures,the degradation products can be used for the specific detection and adsorption of gold ions.In Chapter 6,we developed an"one-pot,three-component"polymerization of CO2,bis(propargylic alcohol)s and aryl dihalides toward 5CC-based polymers.The in situ FT-IR and density functional theory calculation unveiled the reaction mechanism,both indicating that this polymerization is highly efficient under mild conditions and there are synergistic reaction effects among CO2,bis(propargylic alcohol)s and aryl dihalides.Moreover,the5CC-based polymers could be postfunctionalized by amines via catalyst-free regioselective ring opening reaction with unity grafting ratio.Thanks to its excellent functional group tolerance,the TPE and binaphthyl units could be facilely incorporated to endow the resultant polymers with unique AIE and chiral properties,respectively.Hyperbranched polymers could also be generated from CO2 via versatile monomer combinations in high conversion rates and the porous polymers with high BET surface area could be constructed.In Chapter 7,we developed a multicomponent tandem polymerization of CO2,diynes,and alkyl dihalides.The polymerization can be carried out under atmospheric pressure,and the poly(alkenyl ester)s with high molecular weights can be obtained in high yields.The polymerization has good functional group tolerance,so the TPE moiety can be introduced into into the polymer main chains to make them show aggregation-enhanced emission(AEE)property.In the last chapter,as another inexpensive,abundant,non-toxic and renewable resource,O2 was used as a vital monomer to develop a new alkyne-based polymerization under mild reaction conditions.Difunctionalized diynes could react with O2 in the presence of Pd(OAc)2/ZnCl2 in DMAc and C10F18 under atmospheric oxygen.Soluble poly(tetrasubstituted furan)s with high molecular weights were obtained in high yields.The ratio of isomeric repeating units of polymers can be identified by analyzing the components of model reaction products.Moreover,P1(6)could function as a fluorescent sensor for explosive detection with superamplification quenching effect.P2-P5 with conjugated structures also possess large two-photon absorption cross-sections up to 1570 GM,showing great potential as two-photon absorption materials applied in optoelectronic and biologic fields.In summary,we developed a series of new and efficient polymerizations of CO2/O2 and alkyne monomers.They can proceed under atmospheric pressure,catalyzed by cheap and commercially available catalysts,and diverse functional polymers were prepared through flexible design of monomers,opening up new ways for the chemical utilization of CO2 and O2.