02211naa a2200229 a 450000100080000000500110000800800410001910000190006024501300007926000090020952015300021865000230174865300180177165300230178965300180181265300220183070000180185270000190187070000240188970000170191377300510193021095952019-11-18       2019    bl uuuu     u00u1 u    #d1 aBREGADO, J. L.  aAmorphous paracrystalline structures from native crystalline celluloseba molecular dynamics protocol.h[electronic resource]  c2019  aCellulose amorphization is a suitable process that allows greater accessibility of cellulolytic enzymes to glycosidic bonds of cellulose, thus improving the yield of bioethanol obtained from lignocellulosic biomass. In a theoretical framework, we demonstrated the amorphization process of two cellulose allomorphs (Ia, Ib) using a new Molecular Dynamics (MD) protocol at high temperatures. At 700 K, in the high-temperature molten phase, these allomorphs showed the formation of structures with quite amorphous-shell and slightly paracrystalline-core (Am-Par structures) when the degree of polymerization is increased. Applying different characterization methods, we confirmed that Am-Par structures were similar at 700 K, as well as over a temperature ranging from 680 K to 380 K. This confirmation was based on low density of intra-chain hydrogen bonds (HBs), the absence of bands in the region of 3330 e3470 cm1 corresponding to such HBs in the simulated IR, low values of the lateral order index calculated from IR, Q4 and Q6 values close to zero, loss of long-range ordering observed in radial distribution functions, total destruction of crystal unit cell corroborated by X-ray diffraction, and similarity between probability density distribution of dihedral angle j with that computed for completely amorphous cellulose. Nonetheless, as revealed by X-ray diffraction results, this protocol seems to provide more crystalline structures starting from cellulose microfibrils having a polymerization degree higher than 10.  aMolecular dynamics  aAmorphization  aCHARMM force field  aCrystallinity  aThermal treatment1 aSECCHI, A. R.1 aTAVARES, F. W.1 aRODRIGUES, D. de S.1 aGAMBETTA, R.  tFluid Phase Equilibriagv. 491, p.56-76, 2019.