248
Bacterial Cellulose
a)
b)
100 nm
1 μm
Figure 12.5
FEG-SEM.micrographs.of.BNC.(a).and.BNC.blends.obtained.(b).by.using.FeC13.
In addition,.for.a.fixed.PPy.concentration,.the.electrical.conductivity.value.
for.the.BNC/PPy·APS.blend.was.1.7.×.10 −5 .S/cm,.10 4 -fold.lower.than.those.for.
the.BNC/PPy·FeCl 3 .blend.(0.2.S/cm)..This.behavior.is.probably.attributed.to.
the.higher.doping.degree.of.PPy·FeCl 3 .particles.and/or.the.interaction.level.
between.BNC.and.PPy·FeCl 3 .(Muller.et.al..2011b).
Conductive.BNC/polyaniline.blends.have.also.been.synthesized.through.
in. situ. oxidative. polymerization. of. aniline. onto. BNC. by. using. APS. as. an.
oxidizing.agent.and.different.protonic.acids.(Hu.et.al..2011;.Lee.et.al..2012;.
Marins. et al.. 2011).. Hu. et. al.. (2011). studied. the. influence. of. the. reaction.
time. and. different. types. of. protonic. acids. on. the. electrical. conductivity. of.
BNC/PAni. blends.. As. expected,. the. amount. of. polyaniline. deposited. on.
the.BNC.nanofibers.and.electrical.conductivity.values.of.BNC/PAni.blends.
increased.with.the.reaction.time,.reaching.a.maximum.value.of.5.×.10 −2 .S/cm.
at. 90. min,. thus. demonstrating. that. the. nanofibrils. worked. as. a. good. template. for. the. polymerization.. The. electrical. conductivities. were. also. shown.
to. be. affected. by. the. protonic. acid.. BNC/hydrochloric. acid-doped. polyaniline. blends. (BNC/PAni·HCl). displayed. significantly. higher. conductivity.
than. blends. composed. of. BNC/PAni·dodecylbenzene. sulfonic. acid. (DBSA),.
BNC/PAni·p-toluene. sulfonic. acid. (PTSA),. BNC/PAni·sulfuric. acid. (H 2 SO 4 ),.
BNC/PAni·phosphoric.acid.(H 3 PO 4 ),.and.BNCPAni·sulfamic.acid.(NH 2 SO 3 H)..
According. to. Hu. et. al.. (2011),. this. behavior. is. attributed. to. the. fact. that.
PAni·HCl.probably.has.a.higher.doping.degree.than.the.others.
Conductive. BNC/PAni·DBSA. blends. prepared. through. in. situ. polymerization. of. aniline. by. using. DBSA. and. ammonium. persulfate. were. also.
reported. by. Marins. et. al.. (2011).. The. morphology,. crystalinity. degree,. and.
. electrical.conductivity.are.affected.by.the.DBSA.concentration..The.optimum.
DBSA/aniline.molar.ratio.to.produce.BNC/PAni.with.electrical.conductivity.
quite.similar.to.that.found.by.Hu.et.al..(2011).was.1.5.
Lee.et.al..(2012).obtained.BNC/PAni.blends.through.direct.in.situ.polymerization. of. aniline. on. BNC. fibers. by. using. HCl. solution. containing. ammonium. persulfate. and. PTSA.. Electrical. conductivity. values. of. BNC/PAni.