Constructing Click Functionalization Platform For Cellulose Fibers Via In Situ Polymerization Of 3-ethynylaniline

Modification of cellulose by click chemistry is a quick,efficient and popular way to realize the multi-functionalization of cellulose.And it is the crucial step to introduce the click reaction module for the functionalization of cellulose by click chemistry.As the most effective click reaction modules in the “click chemistry” family,alkynyl group and azide group are usually introduced into cellulose to achieve the click functionalization of cellulose.In this study,alkynylated cellulose fibers were prepared via in situ chemical oxidization polymerization of 3-ethynylaniline with or without adding aniline,and their click reactivity were explored.In this study,the polymerizability of 3-ethynylaniline was preliminary studied.It was found that its polymerization was a very slow process,and the acid concentration and reaction temperature were the main factors influencing the polymerization: higher acid concentration(>1.5 mol/L)or higher temperature(>25 ?)would lead to the oxidation of alkynyl group.So the polymerization of 3-ethynylaniline should maintain lower acid concentration and lower temperature.Poly(3-ethynylaniline)was deposited on cellulose fibers via in situ polymerization for the preparation of alkynylated cellulose fibers.Optical microscopy,SEM,FTIR and XPS analysis confirmed the successful deposition of poly(3-ethynylaniline)on cellulose fibers.The effects of monomer concentration,mole ratio of ammonium persulfate to 3-ethynylaniline,hydrochloric acid concentration and reaction time on deposition of polymers,fiber loss and alkynyl group intensity were investigated.The results showed that the suitable preparation conditions were as follows: 1.5%(wt%)3-ethynylaniline,mole ratio of ammonium persulfate to 3-ethynylaniline 4:1,1.0 mo/L hydrochloric acid,the reaction temperature 5 ?,and the reaction time 48 h.The mole ratio of 3-ethynylaniline to aniline was investigated during copolymerization process,and suitable copolymerization mole ratio of 3-ethynylaniline to aniline was 4:1.Then,alkynylated cellulose fibers were prepared via in situ copolymerization of 3-ethynylaniline and aniline.The effects of reaction time,monomer concentration,reaction temperature and acid concentration on the deposition of copolymers and alkynyl group intensity were investigated.It was found that the blending of aniline with 3-ethynylaniline significantly shortened the preparation cycle of alkynylated cellulose fibers.The suitable preparation conditions were as follows: 0.10 mol/L monomer concentration,0.6 mol/L hydrochloric acid concentration,mole ratio of 3-ethynylaniline to aniline 4:1,mole ratio of ammonium persulfate to monomer 2:1,temperature 5?,and reaction time 6 h.FTIR and SEM analysis confirmed the successful deposition of poly(3-ethynylaniline-aniline)on cellulose fibers.Click reactivity of these above two kinds of alkynylated cellulose fibers were evaluated by Cu(I)catalyzed alkyne-azide 1,3-dipolar cycloaddition reaction(CuAAC).The FTIR and XPS results confirmed that the prepared alkynylated cellulose fibers via in situ polymerization were clickable.The study not only provided a new strategy for preparation of alkynylated cellulose fibers,but also constructed a new,efficient and generic reaction platform for the click functionalization of cellulose fibers.