Cellulose molecule (=1, 4βdglucan)
Side view
Hydrophobic site
Top view
6
4
OH
OH
5 O
HO
O
2
O
HO
O
1
3
OH
OH
n/2
Hydrophilic site
Hydrophobic site
Surface properties of cellulose films depend on the tilted angle of
anhydroglucose planes when the glucan chains are uniaxially aligned.
Hydrophobicity
Hydrophilicity
Figure 6.1
116
Bacterial Cellulose
patterned. nanostructures,. which. also. opens. pathways. toward. preparation. of. potentially. versatile. organic–inorganic. as. well. as. organic–organic.
order-patterned.composites.with.less.energy.consumption.
What is NOC?
Prior. to. NOC,. one. needs. to. know. the. characteristic. feature. of. a. cellulose.
molecule. (Figure 6.1):. cellulose. has. an. extended. structure. with. a. 2 1 . screw.
axis.composed.of.β-1,4.glucosidic.linkages. between.anhydroglucose.units..
Thus.it.would.be.natural.to.accept.the.dimer.called.“cellobiose”.as.a.repeating. unit.. The. three. kinds. of. OH. groups. within. an. anhydroglucose. unit.
exhibit.different.polarities,.which.contribute.to.formation.of.various.kinds.
of.inter-.and.intramolecular.hydrogen.bonds,.including.secondary.OH.at.the.
C2,.. secondary.OH.at.the.C3,.and.primary.OH.at.the.C6.position..In.addition,.
all. the. OH. groups. are. bonded. to. a. glucopyranose. ring. equatorially.. This.
causes.the.appearance.of.a.hydrophilic.site.parallel.to.the.ring.plane..In contrast,.the.CH.groups.are.bonded.to.a.glucopyranose.ring.axially,.causing.a.
hydro. phobic.site.perpendicular.to.the.ring,.as.shown.in.the.upper.image.of.
Figure 6.1..These.effects.lead.to.the.formation.of.hydrogen.bonds.parallel.to.
the.glucopyranose.ring,.and.to.van.der.Waals.interactions.perpendicular.to.
the.ring.
Figure 6.1
The.site-specific,.amphiphilic.nature.of.cellulose.chemical.structure.leading.to.unique.surface.
properties.of.cellulose.films,.depending.on.the.tilted.angle.of.the.anhydroglucose.planes.when.
the.glucan.chains.are.uniaxially.aligned.