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Nematic Ordered Cellulose Templates
width. of. 500. nm. with. splayed. microfibrils. 7–8. nm. apart. (see. Figure  6.11A.
and.6.11B).(Kondo.et.al..2002).
The. amphiphilic. molecular. tracks. on. NOC. allow. close. contact. with. the.
glucan. chains. of. microfibrils. as. they. are. being. secreted. and. crystallized..
Thus,.in.theory,.this.interaction.is.predicted.to.alter.the.self-assembly.of.glucan.chains.into.the.crystalline.microfibril.(Benziman.et.al..1980;.Haigler.et.al..
1980,.1982;.Tokoh.et.al..1998;.Yamamoto.et.al..1996)..In.fact,.alteration.of.the.
aggregation.of.cellulose.microfibrils.on.NOC.was.demonstrated.as.described.
earlier..Such.interactions.with.the.substrate.alter.production.of.the.cellulose.
ribbon. and. also. the. motion. of. the. bacterium,. and. provide. support. for. the.
epitaxial.nature.of.cellulose.deposition.on.NOC..Thus.nanoscale.interactions.
induce.microscale.structural.changes..Such.interactions.could.be.used.on.a.
larger.scale.to.selectively.modify.biopolymers.for.many.applications.
Critical Factors
The.adhesion.for.epitaxial.growth.of.microfibril.deposition.requires.several.
different. critical. factors. relating. to. molecular. “order”. of. the. substrate.. This.
order. is. represented. by. three. factors:. molecular. chain. orientation,. specific.
polymer.chain.conformation,.and.O6.rotational.position.with.respect.to.O5.
and.C4.in.a.β-glucan.chain..The.importance.of.molecular.chain.orientation.is.
supported.by.the.observation.that.unstretched.NOC.does.not.cause.epitaxial.
deposition..As.already.described,.we.believe.the.C6.hydroxymethyl.conformation.of.NOC.is.also.of.importance..Its.role.is.like.an.anchor.for.molecular.
tracks.to.direct.the.epitaxial.deposition.of.cellulose.nanofibers..The.conformation. of. C6. OH. groups. is. believed. to. contribute. to. the. crystalline. forms,.
depending. on. either. gt. (cellulose. II). or. tg. (native. cellulose).. When. an. NOC.
with. the. gg. hydroxymethyl. conformation. is. crystallized,. it. is. converted. to.
ordered.films.containing.cellulose.II.crystalline.forms.with.gt.hydroxymethyl.
conformation.(Togawa.and.Kondo.2007)..When.Gluconacetobacter.is.incubated.
on.the.crystallized.NOC,.there.is.no.adhesion.of.the.secreted.microbial.cellulose.nanofibers..The.crystallized.films.do.not.exhibit.the.molecular.track.
effect.to.direct.bacterial.movements.any.longer..The.same.lack.of.adhesion.
is.observed.with.substrates.prepared.from.native.crystalline.cellulose.I.from.
Valonia. (data. not. shown).. In. the. crystalline. samples,. the. specific. polymer.
chain.conformation.is.changed,.and.the.rotational.conformation.at.C6.is.gt.in.
crystallized.NOC.and.tg.in.Valonia.cellulose..Considering.this,.we.conclude.
that.the.role.of.primary.OH.groups.at.the.C6.position.is.greater.than.those.of.
OH.groups.at.the.C(2).and.C(3).positions..In.addition,.it.is.also.noted.that.not.
only.the.OH.tracks.but.also.the.hydrophobic.tracks.are.supposed.to.appear.
on.the.NOC.surface,.and.thus.the.amphiphilic.molecular.tracks.are.critical.for.
regulating.the.epitaxial.deposition.of.the.. cellulose nanofibers.
Ordered. noncrystalline. cellulose. (NOC). and. related. blends. have. been.
proven. to. work. very. well. as. templates.. Surfaces. of. nematic. ordered. chitin.
also.show.the.adhesive.effect,.but.in.an.unusual.fashion.