246
Bacterial Cellulose
the.relevance.of.the.cellulose’s.abundance,.its.well-established.industrial.use,.
environmental.friendliness,.mechanical.flexibility,.high.surface.area,.and.low.
cost,.matched.by.the.interesting.electrical,.optical,.magnetic,.chemical.conductivity,.and.efficient.electroactive.behavior.of.the.ICPs..The.cellulose-based.
conducting.polymer.composites.are.thus.typically.flexible.conductive.paper.
materials,.which.can.be.molded.into.different.shapes..Further,.given.recent.
advances.in.the.production.of.nanofibers.from.cellulosic.substrates.(mostly.
from.vegetable.origin).the.properties.of.the.ICPs.could.be.enhanced,.not.only.
by. mechanically. reinforcing. their. brittle. polymeric. structure,. but. also. by.
increasing.the.surface.area.for.coating.(Chen.et.al..2010;.Johnston.et.al..2006;.
Kelly.et.al..2007;.Richardson.et.al..2006).
In. recent. work,. PPy. has. been. coated. onto. high. surface. area. Cladophora
algae.cellulose.(Mihranyan.et.al..2008)..This.type.of.cellulose.displays.distinct.properties.in.comparison.to.plant.cellulose.(Mihranyan.and.Stromme.
2004),.properties.perhaps.only.rivaled.with.BNC..In.previous.chapters,.the.
unique.properties.of.this.biopolymer.have.already.been.addressed..In.this.
view,.conductive.blends.composed.of.BNC.fibers.coated.with.either.polypyrrole.or.polyaniline.emerge.as.new.promising.conducting.polymer.templates.
The.first.and.recent.(2007–2010).reports.concerning.the.production.of.conductive.BNC.dealt.with.the.use.of.carbon.nanotubes.(Chen.et.al..2010;.Yan.
et.al..2008;.Yoon.et.al..2006).and.also.silver.nanoparticles.(Barud.et.al..2008;.
Maneerung.et.al..2008;.Maria.et.al..2009).for.additional.antimicrobial.properties..This.year.(2011),.four.independent.reports.focusing.on.the.preparation.of.
electrically.conducting.blends.of.BNC.as.the.polymer.matrix,.and.ICPs.as.the.
conductive.filler.were.published.(Hu.et.al..2011;.Lee.et.al..2012;.Marins.et.al..
2011;.Muller.et.al..2011a)..Muller.et.al..(2011b).synthesized.polypyrrole-coated.
BNC. through. in. situ. oxidative. polymerization. of. pyrrole. in. aqueous. solution. by. using. iron. III. hydrochloride. (FeCl 3 ·6H 2 O). as. an. oxidizing. agent..
Figure 12.4. summarizes. the. effects. of. the. reaction. time. on. the. PPy·FeCl 3 .
. content.and.electrical.conductivities.of.BNC/PPy·FeCl 3 .blends.
The. amount. of. pyrrole. deposited. on. the. BNC. surface. and. the. electrical.
conductivity. of. BNC/PPy·FeCl 3 . increases. with. the. reaction. time.. The. electrical. conductivity. reaches. a. maximum. and. constant. value. of. 3.1. S/cm. at.
90.min.reaction.time,.while.weight.increase.tends.to.plateau.after.150.min..
Comparative.study.of.Fourier.transform.infrared.attenuated.total.reflectance.
mode.(FTIR-ATR).spectra.of.polypyrrole.powder,.BNC.and.BNC/PPy·FeCl 3 .
blends.provides.direct.support.that.the.delocalized.π-electrons.of.the.polypyrrole. backbone. are. affected. by. the. presence. of. BNC,. indicating. the. formation. of. chemical. bonds. probably. originated. from. chemical. interactions.
of. PPy·FeCl 3 . and. BNC. chains.. The. field. emission. gun. scanning. electron.
micrographs. (FEG-SEMs). (Figure 12.5a). showed. that. BNC. is. formed. by. a.
three-dimensional.(3D).network.structure.with.fiber.diameters.of.30–100.nm..
The.BNC/PPy·FeCl 3 .blend.micrograph.(Figure 12.5b).showed.that.PPy·FeCl 3 .
particle. agglomerates. with. a. mean. size. diameter. of. 35. mm. are. entangled.
within. BNC. fibers,. forming. a. uniform. and. continuous. coating. nanolayer,.
Bacterial Cellulose
the.relevance.of.the.cellulose’s.abundance,.its.well-established.industrial.use,.
environmental.friendliness,.mechanical.flexibility,.high.surface.area,.and.low.
cost,.matched.by.the.interesting.electrical,.optical,.magnetic,.chemical.conductivity,.and.efficient.electroactive.behavior.of.the.ICPs..The.cellulose-based.
conducting.polymer.composites.are.thus.typically.flexible.conductive.paper.
materials,.which.can.be.molded.into.different.shapes..Further,.given.recent.
advances.in.the.production.of.nanofibers.from.cellulosic.substrates.(mostly.
from.vegetable.origin).the.properties.of.the.ICPs.could.be.enhanced,.not.only.
by. mechanically. reinforcing. their. brittle. polymeric. structure,. but. also. by.
increasing.the.surface.area.for.coating.(Chen.et.al..2010;.Johnston.et.al..2006;.
Kelly.et.al..2007;.Richardson.et.al..2006).
In. recent. work,. PPy. has. been. coated. onto. high. surface. area. Cladophora
algae.cellulose.(Mihranyan.et.al..2008)..This.type.of.cellulose.displays.distinct.properties.in.comparison.to.plant.cellulose.(Mihranyan.and.Stromme.
2004),.properties.perhaps.only.rivaled.with.BNC..In.previous.chapters,.the.
unique.properties.of.this.biopolymer.have.already.been.addressed..In.this.
view,.conductive.blends.composed.of.BNC.fibers.coated.with.either.polypyrrole.or.polyaniline.emerge.as.new.promising.conducting.polymer.templates.
The.first.and.recent.(2007–2010).reports.concerning.the.production.of.conductive.BNC.dealt.with.the.use.of.carbon.nanotubes.(Chen.et.al..2010;.Yan.
et.al..2008;.Yoon.et.al..2006).and.also.silver.nanoparticles.(Barud.et.al..2008;.
Maneerung.et.al..2008;.Maria.et.al..2009).for.additional.antimicrobial.properties..This.year.(2011),.four.independent.reports.focusing.on.the.preparation.of.
electrically.conducting.blends.of.BNC.as.the.polymer.matrix,.and.ICPs.as.the.
conductive.filler.were.published.(Hu.et.al..2011;.Lee.et.al..2012;.Marins.et.al..
2011;.Muller.et.al..2011a)..Muller.et.al..(2011b).synthesized.polypyrrole-coated.
BNC. through. in. situ. oxidative. polymerization. of. pyrrole. in. aqueous. solution. by. using. iron. III. hydrochloride. (FeCl 3 ·6H 2 O). as. an. oxidizing. agent..
Figure 12.4. summarizes. the. effects. of. the. reaction. time. on. the. PPy·FeCl 3 .
. content.and.electrical.conductivities.of.BNC/PPy·FeCl 3 .blends.
The. amount. of. pyrrole. deposited. on. the. BNC. surface. and. the. electrical.
conductivity. of. BNC/PPy·FeCl 3 . increases. with. the. reaction. time.. The. electrical. conductivity. reaches. a. maximum. and. constant. value. of. 3.1. S/cm. at.
90.min.reaction.time,.while.weight.increase.tends.to.plateau.after.150.min..
Comparative.study.of.Fourier.transform.infrared.attenuated.total.reflectance.
mode.(FTIR-ATR).spectra.of.polypyrrole.powder,.BNC.and.BNC/PPy·FeCl 3 .
blends.provides.direct.support.that.the.delocalized.π-electrons.of.the.polypyrrole. backbone. are. affected. by. the. presence. of. BNC,. indicating. the. formation. of. chemical. bonds. probably. originated. from. chemical. interactions.
of. PPy·FeCl 3 . and. BNC. chains.. The. field. emission. gun. scanning. electron.
micrographs. (FEG-SEMs). (Figure 12.5a). showed. that. BNC. is. formed. by. a.
three-dimensional.(3D).network.structure.with.fiber.diameters.of.30–100.nm..
The.BNC/PPy·FeCl 3 .blend.micrograph.(Figure 12.5b).showed.that.PPy·FeCl 3 .
particle. agglomerates. with. a. mean. size. diameter. of. 35. mm. are. entangled.
within. BNC. fibers,. forming. a. uniform. and. continuous. coating. nanolayer,.