Kinetic Study:Photoinduced Controlled/Living Radical Polymerization Catalyzed By 0D/1D Cadmium Selenide

Phtotoinduced Controlled/living radical polymerization is one of the fastest growing polymerization methods and has received a lot of attention.And it is widely used that photoinduced atom transfer radical polymerization(photo ATRP)and photoinduced charge/energy transfer reversible addition-fragmentaton chain transfer polymerization(PET-RAFT),performing the design and preparation of macromolecular polymers with various morphologies and molecular weights.The improvement of photocatalyst will be conducive to the development of photoinduced Controlled/living radical polymerization.Among many photocatalysts,semiconductor catalysts are more suitable for the promotion of photoinduced polymerization.And the development of quantum dots has attracted much attention due to the huge specific surface area,adjustable conduction band gap and simple preparation process and so on,which promote its rapid development.At present,people have prepared various semiconductor quantum dots.Cadmium selenide quantum dots(CdSe QDs)have been the primary photocatalytst to drive organic polymerization resulted from its absorb the light energy in the visible light region,abundant reserves,and the simple of thermal injection method.However,the relationship between quantum size effect and Controlled/living radical polymerzation still exist much work to explore.Now,the research are still aimed the visible light region,and the use of infrared light(NIR)is still a big challenge.And nanotechnology offers a new strategy.That is to change the morphology of semiconductors to obtain new properties,comparing with the change of particle size.One-dimensional cadmium selenide nanorods(CdSe NRs)have been prepared,and it has been proved that there are domain ultraviolet absorption peaks in the infrared region,which provides the possibility for NIR driven organic polymerization.In this paper,PET-RAFT polymerization and photoATRP polymerization are catalyze by CdSe with different morphologies,and it is discussed that the influence of quantum size effect on polymerization and the polymerization in full spectrum through kinetic research.Moreover,various influencing factors of polymerization are also studied.The specific work is as follows:1.The influence of CdSe QDs quantum size effect on PET-RAFT polymerizationFirst,based the thermal injection method,CdSe QDs with different sizes(3.8,5.1 and 6.8 nm)are successfully prepared and characterized detaily.Through a series of characterization,the product is proved to be CdSe and the spherical morphology is observed with the change of particle size.Meanwhile,based the optical characterization of CdSe QDs,it is carried out that the red shift of the ultraviolet absorption peak and the excitation peak with the change of particle size.Subsequently,the PET-RAFT polymerization is catalyzed by CdSe QDs with different size.Through kinetic studies,it is found that the increase of QDs size make an improvement of the light energy absorption capacity and the charge transfer rate,promoting the progress of polymerization.And the quantum size effect has an impact on the polymerization.With the increased of the size,the result of polymerization is becoming better.What’s more,through the kinetic study of other elements,it will promote the polymerization that the increase of the co-catalyst TEA during a certain value,the wavelengh and the solvent polarity.Finally,the light controllability,versatility and chain end activity are studied.2.The influence of CdSe QDs quantum size effect on photoATRP polymerizationFirst,the ppm of CuBr2 in the reaction system is discussed.It was found that with the increase of Cu content to 700 ppm,the controllability and the conversion of polymerization is better.Then,photoATRP is carried out by different sizes CdSe QDs as photocatalyst.Through kinetic research,it is found that the best catalytic is RedCdSe QDs(R QDs).Meanwhile,the quantum size has an effect on the polymerization,which the increase of particle size is beneficial to the polymerization.Moreover,the Kinetic studies of different elements show that the reaction system with complex composition will perform under coordination of various factors.Finally,the light controllability,versatility and chain end activity are also studied.3.Full-spectrum polymerization of PET-RAFT catalyzed by CdSe NRsFirst,based the thermal injection method with changing the ligand,different aspect radio CdSe NRs(1.6,2.1,3.3 and 4.1)are successfully prepared.According to the systematic characterization,it is proved that the product is CdSe with rod-like structure,and absorption peak is appeared after 600 nm,include the range of infrared light.Then,PET-RAFT polymerization is carried out by CdSe NRs as photocatalyst during full spectrum.Through the kinetic study,it is found that PET-RAFT polymerization during full spectrum is realized by the transformation of CdSe morphology,and the increase of the aspect ratio is benefical to the polymerzation.What’s more,the CdSe NRs with aspect ratio of 4.1 exhibits excellent catalytic activity under wavelengths of 740 and 800 nm.4.Full-spectrum polymerization of photoATRP catalyzed by CdSe NRsFirst,the CuBr2 content of the reaction system is explored.When it is 400 ppm,the polymerization result is the best.Using CdSe NRs with different aspect ratios as photocatalyst,the full spectrum photoATRP polymerization is successfully realized.Under λ=740 and 800 nm light,photoATRP catalyzed CdSe NRs with aspect ratios of 3.3 and 4.1 show a surprised polymerization rate.Finally,the controllability,versatility and chain end activity were also studied.In summary,this article proves that the quantum size effect of CdSe QDs has a positive effect on photoinduced controlled/living radical polymerization,that is,the larger the size of the quantum dots,the more conducive to the polymerization,and a detailed kinetic study has been carried out,which will provide a reference for future work;through a simple method of changing the morphology,CdSe NRs can catalyze photoinduced controlled/living radical polymerization under full spectrum light,providing a new idea for the design of wide-wavelength photoinduced organic polymerization.