Study On The Nitroxide-mediated Radical Polymerization With Tertiary Amine N-oxides

Nitroxide-mediated radical polymerization(NMRP)is highly controllable,which has excellent radical mediation performance.Compared with other method,for example anionic polymerization,it has the characteristics of mild polymerization condition and wide application,and it is widely used in the fields of radical polymerization for preparing complex polymers.However,NMRP also has some problems,such as high polymerization temperature and low polymerization rate,which severely limits the development and application of NMRP.Based on NMRP,a new radical polymerization which mediated by tertiary amine N-oxide is proposed in this paper,and various polymerization systems are investigated.This paper takes tertiary amine N-oxide as main object,and tertiary amine N-oxide-mediated radical polymerization in complex emulsion system was investigated,such as in-situ emulsion polymerization system,tertiary amine N-oxide-mediated radical polymerization in solution system.At the same time,the solvothermal reaction of polyacrylonitrile was studied in tertiary amine N-oxide system and the following conclusions are drawn:(1)A new radical polymerization method mediated by tertiary amine N-oxide is proposed,which is different from normal NMRP(secondary amine N-oxides capture radicals to form stable dormant species)through N-oxygen non-chemical bonds.In the process,N-oxygen non-covalent bonds are semi-stable radicals which is unstable dormant species reacted with radicals,and it can prolong the life of radicals in the polymerization.The key factor of tertiary amine N-oxide-mediated radical polymerization lies in the non-chemical bonds of nitrogen and oxygen.Through the non-chemical bonds of nitrogen and oxygen,the transition state energy barrier of dormant species is weakened and the dormant species can still dissociate into radicals at low temperature.It can be observed that tertiary amine N-oxides can mediate radical polymerization at low temperature.(2)Tertiary amine N-oxides representing interface and radical effects tertiary amine N-oxide can mediate emulsion polymerization in complex emulsion system and radical polymerization in in-situ emulsion dispersion system.From different polymerization systems,the polymerization reactions show "living" controllable characteristics mediated by tertiary amine N-oxide.For example,tertiary amine N-oxide AO1805 represented good radical mediation ability in the emulsion system.In the UV-initiated emulsion polymerization of styrene,the process can be followed at 5?and ultra-high molecular weight PS is obtained.In the complex emulsion copolymerization of St and MMA,block copolymerization can be worked mediated by tertiary amine N-oxide AO1805,and a "living"/controllable of polymerization is proved.In the in-situ emulsion polymerization,AO1805 represents favorable interfacial properties which helps silica well dispersed in the organic phase,and the obtained styrene-butadiene rubber/silica composite shows excellent properties.(3)Radical solution polymerization of acrylonitrile is studied mediated by tertiary amine N-oxide,which shows a well process and the obtained polyacrylonitrile has ultrahigh viscosity-average molecular weight over one million.In the solution polymerization,AO-1805 suggested as solvent and meditator at same time,and it is beneficial to recovery of solvent and to prepare the ultrahigh molecular weight polyacrylonitrile which indicates the quite difference from conventional radical polymerization.In fact,further research needs to be followed for it explaining some key problems.(4)The process of pre-oxidation process of polyacrylonitrile is studied in the solvothermal process with AO1805,and polyacrylonitrile can be cyclized and pre-oxidation in liquid phase at lower temperature.It is a novel solvothermal process in fact.