Physics and Chemistry of Hybrid Organic-Inorganic Materials
Download
1 / 42

Key points on how to characterize the structure of a hybrid material - PowerPoint PPT Presentation


  • 98 Views
  • Uploaded on

Physics and Chemistry of Hybrid Organic-Inorganic Materials Lecture 2: Characterizing the structure of Hybrids. Key points on how to characterize the structure of a hybrid material. appearance of the material solubility in organic solvents and water Amorphous versus crystalline materials

loader
I am the owner, or an agent authorized to act on behalf of the owner, of the copyrighted work described.
capcha
Download Presentation

PowerPoint Slideshow about ' Key points on how to characterize the structure of a hybrid material ' - eben


An Image/Link below is provided (as is) to download presentation

Download Policy: Content on the Website is provided to you AS IS for your information and personal use and may not be sold / licensed / shared on other websites without getting consent from its author.While downloading, if for some reason you are not able to download a presentation, the publisher may have deleted the file from their server.


- - - - - - - - - - - - - - - - - - - - - - - - - - E N D - - - - - - - - - - - - - - - - - - - - - - - - - -
Presentation Transcript

Physics and Chemistry of Hybrid Organic-Inorganic MaterialsLecture 2: Characterizing the structure of Hybrids


Key points on how to characterize the structure of a hybrid material
Key points on how to characterize the structure of a hybrid material

  • appearance of the material

  • solubility in organic solvents and water

  • Amorphous versus crystalline materials

    • X-ray diffraction, calorimetry, dilatometry, SEM, TEM and AFM

  • Composition: Elemental analysis, x-ray techniques

  • Molecular level structure: X-ray (if crystalline), NMR, infrared or Raman spectroscopies.

  • Morphology: TEM, SEM, AFM, confocal fluorescence microscopy, optical microscopy

  • Fractal structures: small angle scattering (neutron or X-ray)

  • If soluble, molecular weight (Gel Permeation Chromatography, Vapor Phase Osmometry, Dynamic light scattering)


Hybrid materials
Hybrid Materials material

Synthesis & Processing

Materials Science is a key field in studying hybrids

Properties

Structure

Function, Application,

Performance


First step in characterizing a hybrid
First step in characterizing a hybrid: material

  • Use your senses (take pictures to document)

    • What color? Does it fluoresce

    • Transparent or opaque?

    • Homogeneous in appearance?

    • Solid or liquid

    • Tacky or sticky or brittle or tough

  • Mass – compare with theoretical yield




Second try and dissolve the hybrid in different solvents
Second, try and dissolve the hybrid in different solvents material

  • 50 milligrams of material in glass vial with 20 mL of: water, ethanol, benzene, methylene chloride, tetrahydrofuran, acetonitrile, hexane, acetone, diethyl ether, dimethyl sulfoxide, N-methyl pyrrolidone (NMP)

  • Leave samples in solvents at room temp overnight. Look for swelling if not dissolved.

  • Next, try boiling polymer in solvent for 4 hours.

  • If it doesn’t dissolve its probably cross-linked or really crystalline


Types of Polymers & solubility material

soluble

insoluble

If swelling of polymer in solvent is observed: low low of crosslinking

No swelling, then highly crosslinked.


Structural characterization of soluble polymers
Structural Characterization of soluble polymers material

  • 1H & 13C & 29Si Nuclear Magnetic Resonance and infrared spectroscopy

  • Molecular weight by gel permeation chromatography, dynamic light scattering, viscosity or vapor phase osomometry

  • Composition by combustion analyses

  • X-ray diffraction on film or powder

  • Viscosity of dilute solutions- shape of polymer


Nuclear magnetic resonance nmr spectroscopy
Nuclear Magnetic Resonance (NMR) Spectroscopy material

  • Probably the most powerful and general technique for structural characterization

  • Uses radio frequency photon absorption to change nuclear spin states in 1H, 13C and 29Si atoms in molecules or materials

  • Most commonly used with samples in solution

  • Can also be used with insoluble solids

  • Signal chemical shift and coupling are used to determine structures.


Structure determination of organic compounds using NMR: material

Types of protons & carbons present

Numbers of protons on each carbon

Number of protons on adjacent carbons

Stereochemistry of adjacent protons

Some longer distance information

Dissolve sample

in deuterated solvent

Place solution in

glass NMR tube

Run experiment

Work-up data


Solution nuclear magnetic resonance spectroscopy

Epoxide Open material

Epoxide Closed

A)

B)

C)

Epoxide Open

Epoxide

Closed

Solution Nuclear Magnetic Resonance spectroscopy

  • Key tool in indentifying soluble polymers or figuring out their structure.

  • 1H, 13C and 29Si nuclei have spins of 1/2

13C NMR


Solid state nmr
Solid state NMR material

Excellent tool for characterizing insoluble hybrids

Best with 13C and 29Si, not so good with 1H

β

γ

H3C

α

C=

C=O

H2C=

200 180 160 140 120 100 80 60 40 20 ppm

β

α

γ

200 180 160 140 120 100 80 60 40 20 ppm

Broader peaks than solution. More sample is required.


Infrared spectroscopy
Infrared Spectroscopy material

  • Structural information based on bond vibrational absorptions in the infrared wavelengths.

  • Harder to determine structure than with NMR

  • Excellent for corroborating other characterization techniques.



1790-1720 material

very strong

no

yes

1610 –1590,

1600 – 1580 and

1510 - 1490

1610-1590,

1600-1580 and

1510-1490

All numbers have the meaning of wave numbers

and are given in cm-1

3500 - 3200

840 - 820

3500 - 3200

1680 - 1630

strong

1450 -1410

sharp

strong

1450 - 1410

sharp

1550 - 1530

1100 - 1000

Polyvinyl

acetate,

PVC-copolymers

Modif.

Epoxies

Polycarbon-

ates

Phenol

derivatives,

Epoxies

Cellophan,

Alkylcellulose,

PVA, PEO

Polyamides,

amines

Alkylsilicone,

aliphatic hy

drocarbons,

Polytetra

fluorethylene

Thiokol

Acrylics,

Polyester

Cellulose

ester

Polyurethane

Alkyd-,

Polyesters,

Cellulose ether,

PVC(plasticized)

Polystyrenes,

Arylsilicones,

Aryl-alkyl Silicone Copolymers

PAN, PVC,

Polyvinylidene

chloride

POM

Nitrocellulose

cellophane

Identification of organic polymers using Infrared spectroscopy


Molecular weight determinations
Molecular Weight determinations material

  • Only on soluble polymers

  • Different methods:

    • Gel permeation chromatography (MN, MW)

    • Dynamic Light scattering (MN, MW)

    • Viscosity (MV)

    • Vapor phase osmometry (MN)


Composition what elements are present and in what percent
Composition: What elements are present and in what percent material

  • Organics are analyzed by combustion analysis

  • Inorganics may be analyzed by

    • emission or absorption spectroscopies

    • X-ray fluorescence

    • Elemental dispersive spectroscopy

  • The amount of inorganic in a hybrid can be determined gravimetrically by burning away all of the organic.


Amorphous versus crystalline
Amorphous versus crystalline material

  • Amorphous – kinetic, no long range order, no time for crystals to grow from solution or liquid.

    How can you tell if a material is amorphous?

  • Crytsalline: thermdynamic structures made with reversiblity to remove defects and correct growth. Long range order.

    How can you tell if a material is crystalline?


Crystalline materials
Crystalline materials material

  • Long range order: Bragg diffraction of electromagnetic radiation (or electron beams in TEM) by crystalline lattice into sharp peaks.

  • Solid structures with geometric shapes, straight lines and flat surfaces, and vertices.

  • Optical affects like bifringence

  • Direct visuallization of crystal at molecular level with AFM or STEM.

  • Melting point (not always though)


AFM of polyethylene crystallite material

microcrystals

Inorganic crystals

XRD from semicrystalline

polymer film

Rutile titania crystals in amorphous TiO2

Micrograph of polymer crystalline spherulites


Xrd wide angle
XRD (wide angle) material

  • Single crystal or microcrystalline powder (crystals with atomic or molecular scale order)


Xrd of crystalline material
XRD of crystalline material material

2 theta plot

BCC iron


Amorphous materials
Amorphous materials material

  • No long range order: diffuse peaks may be present, due to average heavy atom distances.

  • No crystalline geometries, glass like fractures (conchoidal)

  • Aggregate spherical particles common

  • Negative evidence for crystal at molecular level with AFM or STEM.

  • No Melting point


X-ray powder diffraction from polybenzylsilsesquioxane material “LADDER” Polymer

4.2 A

3.1 A

Mostly amorphous material.

Small sharp peaks are due to contaminant from preparation

Not a ladder polymer!!!!!!!!!


Xrd amorphous material
XRD amorphous material material

Al2O3 thin films prepared by spray pyrolysis

J. Phys.: Condens. Matter 13 No 50 (17 December 2001) L955-L959


Amorphous materials xrd
Amorphous materials: XRD material

amorphous

amorphous

crystalline


Xrd of organic polymers
XRD of organic polymers material

amorphous

semi-crystalline

crystalline


Conchoidal fractures in amorphous materials
Conchoidal Fractures in amorphous materials material

Crystals break along miller planes

Unless microcrystalline


If crystals are small compared to impact conchoidal fracture can occur
If crystals are small compared to impact, conchoidal fracture can occur

In metal

In sandstone 3 meters tall)


Or third structural characterization of insoluble polymers
Or third, Structural Characterization of insoluble polymers fracture can occur

• Harder to characterize

• Does it burn (many inorganics do not)

  • Solid state 1H & 13C & 29Si Nuclear Magnetic Resonance and infrared spectroscopy

    • X-ray diffraction on film or powder

  • Composition by

    • combustion analyses if organic

    • X-ray fluorescence if inorganic


Electron microscopy
Electron Microscopy fracture can occur

  • Scanning electron microscopy (reflection)

  • Transmission electron microscopy (through sample)

TEM of surfactant templated silsesquioxane

TEM of amorphous hybrid

SEM of amorphous hybrid

SEM of surfactant templated

hybrid


Surface area measurements
Surface area measurements fracture can occur

  • Gas sorption porosimetry at the boiling point of the analysis gas (nitrogen).

  • Meassuring cell pressure after adsorption of gas in small doses on an evacuated sample of known mass generates a gas sorption isotherm.

  • Then you determine surface area, pore size, pore volume, pore size distribution from isotherm using mathematical models.


Morphological characterization of polymers
Morphological Characterization of polymers fracture can occur

  • If opaque or transluscent, SEM and optical microscopy (bifringence)-crystalline or amorphous & more.

  • Fracture polymer and look at fracture surfaces

  • Look for phase separation (like immiscible block copolymers)

  • Look for long range order

  • Look for pores


Morphology of hybrids
Morphology of hybrids fracture can occur

TEM, SEM and AFM are good tools for evaluating morphology

solid (1) phase of particles with pores. Other phase is gas.

One continuous phase (light); One planar dispersed phase (black)

Long range order, no particulate structure.

Two phases


Differential scanning calorimetry
Differential Scanning Calorimetry fracture can occur

Glass transition temperatures, melting points and reactions


Not every polymer needs all of these analyses but structure is the most basic and important
Not every polymer needs all of these analyses, but structure is the most basic and important

  • Known (described in literature) polymers need less structural characterization. Often just IR and Mw from GPC.

  • New polymers need complete structural characterization: NMR, IR, Combustion analysis, GPC, solubility, glass transition temp and/or melting point.


Summation
Summation is the most basic and important

  • Characterization is key step in any science with hybrid materials

  • NMR, XRD, IR are central tools for characterization

  • Composition – including fraction inorganic to organic is also needed.

  • Determination if the material is ordered or not

  • Microscopic evaluation of morphology aids in identifying phase separated systems.


Literature procedure: is the most basic and important

See how experimentals are written in good papers. Use them as model


Template for lab notebook: is the most basic and important


Template for research labnotebook: is the most basic and important


ad