Grafting PMMA From Nano-microcrystalline Cellulose By ARGET ATRP

Cellulose is one of most abundant,non-toxic and renewable natural polymeric materials on the earth.Nano-microcrystalline cellulose(CNC)can be made by the methods of mechanics,chemistries,and biologics.As a kind of environmental-friendly biomacromolecular material,CNC has the feature of low cost,low dentisy and can be easily prepared.With relatively high aspect ratio,perfect crystal structure,good thermal stability,excellent mechanical properties,high specific surface area,and small size,Rod-like CNC is easy to be modified by chemical approach,so it can be widely used,involving new field of vary disciplines penetrating into each other.However,there are a large amount of hydrophilic hydroxyl in each glucose monomer unit of CNC,which makes it cannot be dissolved in polymer or hydrophobic solvent,therefore its application will be limited.On the CNC chain,new polymers groups grafted by ARGET(activators regenernated by electron transfer)ATRP(atom transfer radical polymerization)was introduced and applications scopes would be expanded.This modified method not only can reduce the number of hydroxyl groups on the surface of CNC,which make it have a better dispensability in hydrophobic system,but also can introduce the new functional groups with special function under the condition of remaining the original properties,the application field of CNC is widely enlarged consequently.The Stable suspensions of CNC were prepared by hydrolyzing cellulose microcrystalline(MCC)at 45 ? using 64 % acid.The structures and properties of the products were characterized and investigated through several analytical techniques such as FIIR,TEM,TG and XRD.The results showed that the yields were typical of rod-like nano-structure material,belonging to the cellulosic substances.The length of CNC was 100~300 nm,diameter was about 10~20 nm.The crystallinity of CNC was 88.71 %,and the thermal decomposition temperature of CNC was 334.12 ? with good thermal stability.Based on the activated mechanism of O-alkylation,instead of hydrogen atom in the hydroxyl groups of CNC by opening the loop of glycidyl methacrylate(GMA),active carbon carbon double bonds on the surface of CNC was introduced,which laid a foundation for further research.The structures and properties of activated NCC were characterized and investigated by the FTIR,XRD,TG,13C-NMR.The results indicated that after CNC being activated,the carbon-carbon double bonds had successfully grafted to the surface of CNC,The crystallinity of CNC was 84.28 %,and activated CNC had higher maximum thermal decomposition temperature than CNC.The growth of poly methyl methacrylate(PMMA)was self-propagation on the surface of CNC using the method of ARGET ATRP,and thus modified nano-crystalline cellulose was obtained.The effects of the experimental parameters on the graft yield and graft efficiency were investigated.It was showed that the grafting yield was 22.88 % and grafting efficiency was 24.11 % when the optimun molar ratio of CNC-GMA:MMA:EBi B:Cu Br2:PMDETA:As Ac was 50:100:1:0.1:1:1.The reaction temperature and time were 30 ? and 5h,respectively.The molecular weight and the distribution of PMMA were measured by GPC,The results appeared that the molecular weight of PMMA was 9569 and the molecular weight distribution of PMMA was narrow(Mw/ Mn= 1.11),The test results proved that the PMMA could be grafted onto the surface of CNC,and the grafted CNC had the basic cellulose structure,and the CNC of dispersion state was improved,and the thermal stability of the grafted CNC were better than CNC,and the crystalline of the grafted CNC was 82.22 %.