Preparation And Properties Of Nanocrystalline Cellulose Modified Fluorinated Polyacrylate Surfactant-free Emulsion

Recently,the development of environment-friendly fluorinated polyacrylate containing short fluorocarbon chains has a profound significance for the improvement of fluoropolymer.Core-shell nanomaterials modified fluorinated polyacrylate surfactant-free emulsion not only can improve the dispersion of nanomaterials,but also enrich the amount of fluorocarbon chains in the shell which is good for the migration of fluorocarbon chains and enhancing the water-oil repellency of film.Nanocrystalline cellulose(NCC)is widely used for preparating nanocomposite due to the high modulus of elasticity,nontoxic,extremely abundant resources,and so on.So the research of core-shell structure nanocrystalline cellulose modified fluorinated polyacrylate surfactant-free emulsion has a great theoretical significance and application prospect.Core-shell structure nanocrystalline cellulose modified fluorinated polyacrylate surfactant-free emulsion was prepared using modified nanocrystalline cellulose as stabilizer and chain transfer agent via RAFT-mediated surfactant-free emulsion polymerization in this investigation.Their properties were also investigated.The main results obtained are as follows.Poly(acrylic acid)macro-RAFT agent was prepared via RAFT polymerization using S-Benzyl-S’-trimethoxysilylpropyltrithiocarbonate(BTPT)as chain transfer agent.The structure of PAA-BTPT was characterized by FT-IR,~1H-NMR and GPC.RAFT polymerization of AA exhibited the first order kinetic feature and controlled/living polymerization characteristics.The molecular weight increased linearly with increasing the polymerization temperature and the molar ratio of AA to BTPT and V501 to BTPT.PAA-g-NCC was prepared by grafting nanocrystalline cellulose with PAA-BTPT and characterized by FT-IR,~1H-NMR,TEM,DLS,TGA and XRD.PAA-g-NCC has the pH responsive and water redispersion properties.The particle size gradually increased and the particle size distribution gradually became narrow with the increase of pH value.PAA-b-PHFBA-g-NCC was synthesized by the RAFT polymerization of HFBA in the aqueous phase using PAA-g-NCC as chain transfer agent.The results showed the monomer conversion increased,and average particle size decreased firstly and increased afterword with increasing the molar ratio of AA to BTPT and the pH value.The results showed a high conversion rate and a narrow particle size distribution when the polymerization time was 6 h,the mass ratio of V501 to PAA-g-CNC was 4:50,the pH value was 9.38,PAA-g-NCC was10 wt%and the molar ratio of AA to BTPT was 80.Nanocrystalline cellulose modified fluorinated polyacrylate surfactant-free emulsion was synthesized by the RAFT polymerization of HFBA/BA/MMA in the aqueous phase using PAA-b-PHFBA-g-NCC as stabilizer and chain transfer agent via RAFT-mediated surfactant-free emulsion polymerization.The obtained latex showed a high conversion rate and good stability and the latex film presented an excellent performance when the stirring speed was 210 r/min,the amount of APS,PAA-b-PHFBA-g-NCC and HFBA was respectively 1.0 wt%,6wt%and 10 wt%,the pH value was 10.55,the molar ratio of AA to BTPT was 80and the mass ratio of BA to MMA was 6:4.The results of TEM and DLS showed the latex particle had a marked core-shell structure and narrow particle size distribution.The surfactant-free emulsion was used for fabric finishing.The contact angle of fabric increased with increasing the amount of HFBA.The fabric showed an excellent water-oil repellency when PAA-b-PHFBA-g-NCC was 6 wt%and HFBA was 10 wt%.