Transcript Powerpoint - Loy Research Group

Physics and Chemistry of Hybrid
Organic-Inorganic Materials
Lecture 5: Naturally occurring
hybrids
Biological hybrids: key points
• Hybrids made by plants or animals
• Strong composites from very weak components
– Wet protein and carbohydrates are very soft
– calcium carbonate is also weak and soft
• Multiple phases, hierarchical structures
Hybrid Organic-Inorganic materials are
common in nature: composites
Animals
Nacre
Organic phase is biopolymers
Plants
Argonite (CaCO3) plates as inorganic
with protein (polyamide) as organic
Teeth, spines in echinderms
Mussel shells, sponges, diatoms and
corals are utilize hybrid organic-inorganic
materials
phytolith
Carbohydrates are the template and
organic phase
What is a hierarchical structure?
In materials, a structure with different structures at different length
scales: like in tendons (above)
The Building Plan
Fabrication Conditions in Living Organisms
only few elements: C, H, O, N, P, S, Ca, Si, Mg
mild pH
ambient pressure and temperature
Calcite Crystals Extracted from the Prismatic Layer of Pinna Nobilis Shells
www.cutgana.it/acquario/specie
Marin et al., J. Biol. Chem., 2005, 40, 33895
The Building Plan
Fabrication Conditions in Living Organisms
only few elements: C, H, O, N, P, S, Ca, Si, Mg
mild pH
ambient pressure and temperature
Interaction of an Organic and
an Inorganic Component
Incorporation of biopolymers 
increased fracture resistence
aspartate residue
in peptide bond
&
Hierarchical Design – Morhpology
Control on Several Levels
chitin network
Nudelman et al.,
Faraday Discuss.
2007, 136, 9
Colloidal silica in diatoms: Hierarchical structure
pH ≈ 5
Silica walls are build up from ca. 5nm particles to give ca. 40nm
diameter particles that are organized within the frustule.
Silica (SiO2) & protein
radiolaria
diatoms
Proteins act as templates for building silica architectures
Bio-Hybrids based on CaCO3: Nacre
Argonite (CaCO3) plates as inorganic phase
with protein (polyamide) as organic phase
Mother-of-pearl
Opalescence from light
diffraction in nacre
(argonite blocks height
≈ λ light)
Fracture strength is
3000 times higher
than its mineral
constituent CaCO3.
The hierarchical structure of nacre
The shell itself
Growth rings
(mesolayers)
Inner surface of
shell (mother or
pearl)
Macromolecular
Phase
morphology
Long range
order:
stacked
crystals
Barthelat F Phil. Trans. R. Soc. A 2007;365:2907-2919
argonite
crystal
structure
Lobster exoskelton
CaCO3
& Carbohydrate &
protein
Teeth: Enamel, dentin,
& cementum
Apatite – hydrated CaPO4
Protein– collagen & others
The layered, rod structure of hydroxyapatite (a calcium
phopshate) in dental enamel. Very tough for a ceramic.
Hierarchical structure of alligator gar, a primitive fish, scales. Ganoine is mostly mineral, like
enamel, with tougher bone beneath.
Regular Fish Scales
Enamel and collagen
Fish scale puncture resistance
fish scales are better than polycarbonate.
note how they give, and then reload. This is just one scale.
Apatite – hydrated CaPO4
Protein– collagen
200 MPa yield strength
Bones
30 MPaM0.5 toughness
The Building Plan
Fabrication Conditions in Living Organisms
only few elements: C, H, O, N, P, S, Ca, Si, Mg
mild pH
ambient pressure and temperature
Interaction of an Organic and
an Inorganic Component
&
Hierarchical Design – Morhpology
Control on Several Levels
structural optimization from the atomic
to the macroscopic scale
Bone
Peterlik et al., Nat. Mat., 2006
Gupta et al., PNAS, 2006
Fratzl et al., Progr. Mat.
Science, 2007
Echinoderm spine
CaCO3
Protein templating
Phytoliths
SiO2 silica
2-3% silicon by weight
Horsetail, banana leaves
Silica in Sponges
hierarchical structures
Templated
by proteins
Euplectella sp.
 7 hierarchical
levels
Stress-deflection responses of synthetic silica rod and sponge
spicule in flexuretesting. (Courtesy of M. Sarikaya and G.
Mayer.)
conch shell
Almost no protein
3 hierarchical levels of layers
made from layers of calcite.
Chiton Teeth
the tips of the teeth are hard magnetite
(Fe3O4) with a tough fibrous calcite interior
Metal in Spider Fangs
carbohydrate fibers in a
protein matrix
with zinc and
magnesium ions
Politi, Y., Priewasser, M., Pippel, E., Zaslansky, P., Hartmann, J., Siegel, S., Li, C., Barth, F. G. and Fratzl, P.
(2012), A Spider's Fang: How to Design an Injection Needle Using Chitin-Based Composite Material. Adv.
Funct. Mater., 22: 2519–2528
Biomaterial: Toucan Beak
(a) Toucan beak; (b) external shell made of keratin scales.
Cellular materials: (a) synthetic aluminium foam; (b) foam
found in the inside of toucan beak.(Courtesy of M. S. Schneider
andK. S. Vecchio.)
Bio Hybrid Organic-Inorganic Materials
Sophisticated, highly evolved hybrids
-nominally weak, but bio-accessible minerals (eg. CaCO3)
-hydrophilic, water plasticized biopolymers (eg. protein)
-Integrated at nano-length scales
-Phase separation templating of hierarchical structures
-All water based chemistry!! The ultimate green
chemistry
Optimized to give non-additive property (synergistic effects)
Models for many research programs in hybrid materials