Ball-milling Promoted Chemical Bonding between Cellulose and Plastics - Ball Milling Towards Green Synthesis: Applications, Projects, Challenges - page 205

Figure 9.1 Molecular structures of malto- (a) and cello-oligosaccharides (b).
Reprinted from ref. 3 with permission of Elsevier.
(F, C) ¼ ( þ 451, 381) 5 or ( þ 321, 211) 6 determined experimentally, but still
agree well with other calculation results with (F, C) ¼ ( þ 441, þ 2.91). 6 For
cello-oligosaccharides the relatively flat ribbon conformations obtained from
experiments may reflect some interactions between the chains because such
conformations are somewhat similar to that of crystalline cellulose.
Conformational flexibilities of the oligosaccharides are evaluated on the
basis of the root-mean-square displacement (RMSD) per atom in each solute.
Notably, for cello-oligosaccharides their standard deviations of the RMSDs
are steady over the degree of polymerization (DP) of 2-6, while that for
malto-oligosaccharides increases with DP, in particular when greater than 3.
This indicates that malto-oligosaccharides fluctuate more with the DP, while
cello-oligosaccharides keep rigidity. Distribution maps of the dihedral angle
pair (F, C) also reveal a difference in flexibility at the glycosidic linkages
between both types of oligosaccharides. The angle pair distributes more
widely in malto- than in cello-oligosaccharides, with an elliptical and a round
shape, respectively, which is consistent with the results from the RMSDs.
Every pair in malto- or cello-oligosaccharides has a maximal occupancy at a
single point that does not differ among DPs, except for malto-hexamer
(DP ¼ 6) with plural maximal occupancies at another point in addition to it.