Physics and Chemistry of Hybrid
Organic-Inorganic Materials
Lecture 14: Polymerizing inorganic
monomers dissolved in organic
polymers
Key concepts
• Reasons for making an inorganic filled organic polymer hybrid:
improve strength, abrasion resistance, modulus, hardness,
inflammability,
• Metal oxide inorganic particles can be made by sol-gel, flame
synthesis
• Organic phase: organic polymers
• Inorganic particles increase viscosity
• Particle aggregation ruins hybrid effects
• smaller the particle, the greater the strength and modulus of
the hybrid
• the higher the particle concentration, the greater the strength
and modulus of the hybrid
Making Hybrid Materials: Class 1B
(in situ particle growth)
Ideally, no Solvent except for monomer(s)
No solvent with low tg organic polymers or in polymer
melts (< 100 °C) or if monomer will is soluble in
polymer.
Otherwise solvent may be used to mix before casting.
Preparation by dissolving inorganic monomer in solid
organic polymer then polymerizing to form particles
Solid Organic
Polymer
Inorganic Monomer
(liquid) & catalyst
•Polymerization by:
Monomer must be soluble in polymer
1) hydrolysis & condensation
of M(OR)n
Water diffuses into
Organic Polymer Inorganic
membrane from air
Monomer
2) Reduction of metal
compound. H2 or polymer
Monomer polymerizes & forms particles
itself as reducing agent
3) sulfidation of cations (H2S)
4) photochemical or thermal
decomposition
Preparation by mixing inorganic monomer with liquid
organic polymer & hydrolysis & condensation
Liquid Organic
Polymer
Inorganic Monomer (liquid)
& catalyst
Physical mixing
Very few liquid polymers,
save some elastomers like
polydimethylsiloxane and
low molecular weight
polybutadiene or
polyisoprene
Organic Polymer Inorganic
Monomer
1) Water diffuses in from outside
2) Monomer polymerizes
3) Particles phase separate
Silica-PMS materials are looked at later in lecture
Preparation by mixing inorganic monomer with solid
organic polymer and allowing particles to form
Solid Organic
Polymer
Organic
Polymer in
solvent
Inorganic
Monomer (liquid)
Dissolve
Physical mixing
Solvent must be removed
before polymerization
Water for hydrolysis and
condensation would be
diffused into dry film from
air.
Organic Polymer
Inorganic Monomer
in solvent
Evaporate solvent
Organic Polymer
Inorganic Monomer
Monomer polymerizes & forms particles
Spherical particles
Silica-Nafion materialsmade
this way are looked at later in
lecture
Polymers used
• Elastomers: silicone, polybutadiene,
polyisoprene
• Thermoplastics: polyurethanes,
polycarbonates, polyvinylalcohol,
polyacrylates, polysulfones, polyethylene
oxide (PEO), polypropylene oxide (PPO)
• Thermosets: epoxies
• Polyionomers: Nafion
Review of polymerizations
1) hydrolysis & condensation of M(OR)nor
RSi(OR’)3
2) Reduction of metal compound
3) sulfidation of cations
4) photochemical or thermal decomposition
Hydrolysis & condensation of M(OR)n: the
monomers
Silicon: Si(OR)4 or R’Si(OR)3
Aluminum: Al(OR)3 or AlCl3 6H2O
Transition metals: Mz(OR)n or MzCln hH2O
z = oxidation number for metal
n = number of alkoxide or halide in monomer
h = number of coordinating waters
Hydrolysis & condensation of Si(OR)4
Catalyzed by acids (HCl,HNO3) or bases (NH3 aq, NaOH) or fluoride.
Particles from hydrolysis & condensation of
Si(OR)4
• Typically leads to amorphous spherical particles (not quartz)
• Can template particles with ordered mesopores with
surfactants
• Stober synthesis from TEOS with NH3 and water gives
monodisperse particles
• Emulsion polymerization (water in oil) gives monodisperse
particles
• Other preps give polydisperse particles
Hydrolysis & condensation of RSi(OR)3
Particles from hydrolysis & condensation of
RSi(OR)3
• Typically leads to amorphous spherical particles
• Not as easy to prepare particles as with silica
• Can template particles with ordered mesopores with
surfactants
• Stober synthesis from TEOS with NH3 and water
affords polydisperse particles
• Emulsion polymerization (two step) gives
monodisperse particles
Hydrolysis & Condensation of Mz(OR)n to
form MOn/2
Hydrolysis: formation of monomeric MOH species
Condensation: formation of “oxo” (neutral) M-O-M
higher charge & higher pH
More reactive, but too high shuts
down condensation
Hydrolysis & Condensation of Mz(OR)n
to form MOn/2
Olation: formation of “oxo” (neutral) M-O-M
olation >> oxolation
Particles from hydrolysis & condensation of
M(OR)n
• Particles may be amorphous or crystalline
• Some amorphous particles will crystallize with time.
• Stober synthesis from TEOS with NH3 and water does not work
• Emulsion polymerization (water in oil) gives monodisperse particles
• Many more molecular clusters are available through olation chemistry
Reduction of metals
Metal and Semiconducting Sulfides
in situ Silica-Nafion Nanocomposite
Solid Nafion
Nafion in
Ethanol
Si(OEt)4 (liquid)
Dissolve
Physical mixing
Nafion & TEOS
in ethanol
Evaporate solvent
NafionTM
Nafion & TEOS
Silica particles form in membrane
Spherical particles
in situ Silica-Nafion Nanocomposite
Class 1A
Class 1B
5 weight percent ex situ silica in Nafion
In situ Silica particles
Polymerization of Si(OEt)4 in Hydrogels
0-60 wt% SiO2
Journal of Non-Crystalline Solids 379 (2013) 12–20
In situ filled Silica in polydimethylsiloxanes
Solid Organic
Polymer
Inorganic Monomer
(liquid) & catalyst
Organic Polymer Inorganic
Monomer
Spherical particles
Journal of Polymer Science Part B: Polymer Physics, 2003, 41, 16
In situ filled Silica in polydimethylsiloxanes
•Highly transparent
•Does not require mechanical blending
Journal of Polymer Science Part B: Polymer Physics, 2003, 41, 16
In situ filled Silica in polydimethylsiloxanes
Journal of Polymer Science Part B: Polymer Physics, 2003, 41, 16
Silver particles made in situ
polydimethylsiloxanes
Reverse templating with percolating organic gel
Reverse templating with inorganic monomer in
colloidal crystal
Templating with
triblock copolymer
is formally a
Class 1B material
Polymer is template. After removal, silica remains
Summary: In situ formation of
inorganic phases in polymers
• Method for mixing at nanoscale without
mechanical blending required-less chance for
aggregation and segregation to occur (steric
stabilization)
• Raises modulus and strength of materials
• In situ polymerization of inorganics selectively in
blocks of block copolymers-first step to
biomimetic mineralization.