Block 4 -- Solid State Forms Flashcards
What are the types of mixtures?
1) Physical
2) Dispersion
What is a mixture?
pure material mixed into a polymer
What are the types of solid-state forms?
1) Mixtures
2) Pure forms
What are the types of pure solid-state forms?
1) Crystalline
2) Amorphous
What are the types of crystalline solids?
1) Crystalline polymorphs
2) Solvate polymorphs
3) Co-crystal polymorphs
4) Salt polymorphs
What are characteristics of a crystalline solid?
1) long-range 3D order
2) unit cell
3) specific melting point
4) all molecules have same conformation(s)
What is polymorphism?
The ability of a substance to exist in 2 or more crystalline phases that differ in arrangement and/or conformation of the molecules in the lattice.
What initiates crystallization?
1) temperature
2) anti-solvent
3) evaporation
Describe the nucleation theories:
1) Classical:
- - monomers cluster
2) Two-step:
- - monomers cluster, then rearrange
Describe the transitions present in crystallization:
1st transition: Crystallization or supercooled liquid.
– discontinuous
2nd transition: rubber to glass
– amorphous cannot be more stable than crystal
What are the 3 temperatures represented on a crystallization transition diagram?
Tm: melting T
Tg: T at which transition from liquid to glass occurs
Tk: T at which supercooled & defective crystal intersect
How do polymorphs differ in chemical properties?
1) solubility
2) stability
3) F
4) processability
How do desolvation & dehydration affect structure of crystalline solvate?
1) New crystalline form
2) Transition to amorphous state
3) Desolvated solvate
Why would a co-crystal be used?
To increase solubility and stability
What are the pseudopolymorphs?
Solvates
Co-crystals
Salts
