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37 Cards in this Set
- Front
- Back
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What is the definition of a macromolecule? |
5-10 kDa oligomer with <50% by weight of the same molecule (have a mass distribution) |
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Name 3 structural uses for polymers |
Casing for electronics clothes Packaging storage Plastic bags |
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Name a functional use for polymers |
Drug delivery |
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What is a thermoplastic? |
A polymer that softens and hardens reversibly on changing the temperature. e.g. polystyrene, PVC |
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Thermoset |
Irreversible A polymer that has undergone crosslinking by chemical covalent bond formation via a cure chemical reaction. e.g. rubber, silicon |
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Elastomers |
An amorphous polymer existing above its glass transition temperature. Rubber and elastomer are the same. useful rubbers have Tg <0degC |
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Glass transition |
The temperature at which an amorphous polymer changes from a glass into a rubber. |
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Volume of solid = |
volume of molecule + volume of space |
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Fractional free volume |
Vf / vol (Vf = volume of free space) |
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What is the structure of Nylon? |
Highly crystalline Intramolecular forces Molecular packing |
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Name 3 examples of highly crystalline polymers |
Nylon Poly(ethene) Poly(propene) |
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What is an amorphous polymer? |
Chains arranged in less ordered state exhibit a glass transition temp Tg |
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What is the effect of hydrogen bonding in highly crystalline polymer? |
Tg and Tm are higher Tm = melting temperature |
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Which is lower , Tm or Tg? |
Tg is always lower than Tm |
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Do all polymers have a Tm? |
All have Tg but not all have Tm |
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How can polymer properties be measured? |
Differential scanning calorimetry (DSC) |
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What is a polymer dissolved in a good solvent? |
A random coil |
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What is the volume and radius of a random coil? |
Hydrodynamic volume Radius of gyration, Rg |
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What is a good solvent for Poly(styrene) |
Toluene Methanol is bad solvent |
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What is intrinsic viscosity? |
A measure of a solutes contribution to the viscosity of a solution |
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How does intrinsic viscosity relate to Mw |
ln Mw against [n] |
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What is GPC? |
Gelpermeation chromatography |
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What is SEC? |
Size exclusion chromatography |
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Number average molecular mass = |
Mo x DP Mo is mass of repeat unit DP is no of repeat units (degree of polymerisation) |
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Number av = molecular mass Mn = ? |
Mn = sum NiMi/sumNi Ni is number fraction Mi is Mass distribution midpoint |
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What is the Wt average ? |
Mw = sumNiMiMi/ MiMi |
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What is the molecular weight distribution = |
Mw/Mn = polydispursity |
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What does isotatic mean? |
All monomers have the same stereochemistry e.g. polypropene |
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What is the name of a polymer with different stereochemistry in monomers |
Syndiotatic Random is atactic or heterotactic |
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Why is PMMA a mixture of stereochemistry? |
Radical addition at sp2 carbon is directed by relative thermodynamics of monomer approach. |
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What can be found out about polymers from 1H NMR? |
Composition of monomer Stereochemistry Molecular weight (Number average) Mn |
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Name an addition polymer and a condensation polymer |
Poly(ethene) Polyamide, polyesters, polyethers |
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How does Mwt change as a function of monomer conversion? |
Highest Mw at 0% conversion Reduced slightly at 100% |
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Anionic polymerisation of styrene graph |
-lnC against Mwt directly proportional |
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Degree of polymerisation |
1/ 1-p p is conversion Carothers equation (extent of reaction) |
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Mn = Mw = |
(1/ 1-P ) x Mo (1+P)/(1-P) |
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What is dispersity? |
1+ p At 50% conversion, P = 0.5 1+0.5 = 1.5 dispersity / 2 |
