Lecture 6 Hybrid POSS
Class 1B: inorganic phase is made insitu in organic continuous phase.
in situ means “in place”
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
Preparation by mixing inorganic monomer with liquid
organic polymer & hydrolysis & condensation
Preparation by mixing inorganic monomer with solid
organic polymer and allowing particles to form
Monomer polymerizes &
forms particles
Silica-Nafion materials
made this way are looked
at later in lecture
Polymers used in class 1B systems
• 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
Hydrolysis
OR
RO Si OR
OR
OH
RO Si OR
OR
H2O
ROH
Condensation
OR
RO Si OH
OR
Water from
Condensation
Hydrolyzes
Additional SiOR
Net Reaction
OR
RO Si OR
OR
OR
RO Si OR
OR
RO
HO Si OR
RO
H2O
2 H2O
OR RO
RO Si O Si OR
HOH
OR RO
OH
RO Si OR
OR
ROH
O O
Si
O
O
n
SiO2
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
M = Al, B, Ti, Zr, Cr, Fe…..
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
Class 1B: in situ Silica-Nafion Nanocomposite
Class 1B: in situ Silica-Nafion Nanocomposite
5 weight percent ex situ silica in Nafion
In situ Silica particles
In situ filled Silica in polydimethylsiloxanes
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
Templating with
triblock copolymer
is formally a
Class 1B material
Polymer is template. After removal, silica remains
Class 1B: 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.