Brainscape's Knowledge GenomeTM

Browse over 1 million classes created by top students, professors, publishers, and experts.


See full index

Materials Science > Notes > Flashcards

Notes Flashcards

You may prefer our related Brainscape-certified flashcards:
Biology 101 flashcards
1
Q

Material Dispersions

A

Multiple constituent (phase) system in which one phase is contained within a continuous phase.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
2
Q

Short Range Forces

A
  • Electromagnetic by nature
  • Vander Waals forces
  • ions<1nm (nanoscale)
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
3
Q

Long Range Forces

A

Electrical and Magnetic

1nm-10um in size (microscale)

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
4
Q

Gravitational Forces

A

10um-mm) Macroscale

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
5
Q

Colloids

A

A state of subdivision with a dispersed particle (phase) dispersed with at least 1 direction of a dimension (1nm-1um)

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
6
Q

Lyophilic

A
  • Solvent-loving
  • Colloids: behave like a single phase solution, which can contain macro-molecules (polymers and proteins) and association colloids (self assembled structures like micelles)
  • Causes no true interface - solvent particles all around molecules
  • THERMO and KINETICALLY stable
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
7
Q

Lyophobic

A
  • solvent-fearing
  • Colloid particle (discontinuous phase) well defined by interface

THERMODYNAMICALLY stable, not kinetically

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
8
Q

Protected Lyophobic

A

Stabilized with surface chemistry to increase kinetic stability

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
9
Q

Forming Colloid Particles (Top Down)

A

-Breaking down bulk materials

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
10
Q

Comminution

A
  • wet and dry

- Mechanical disintegration

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
11
Q

Forming Colloid Particles (Bottom Up)

A
  • Start with solution or gas mixture with rxn precursors
  • Induced to nucleate through reaction and precipitate or be stabilized to form our desired particles
  • Process
    1) Precursors –> controlled precipitation: supersaturated solution in which particle size grows –> insoluble salt
    2) Chemical rxn that produces particles
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
12
Q

Electrostatic Stabilization

A

Existence of a layer of charge on particle surface surrounded by a diffuse “cloud” of oppositely charged counterions

*Repulsion of these like charges causes stabilization

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
13
Q

Steric Effects

A

Particles coated with stabilizing or capping agent (surfactant or ligand) causes repulsion of neighboring particles

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
14
Q

Ostwald Ripening

A

Inhomogeneous phases leading to precipitation of larger particles, coming from smaller particles, due to energy factors
-Surface atoms desire proper coordination to minimize cohesive energy

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
15
Q

Limiting Ostwald Ripening

A

1) Arrested Precipitation

2) Stabilizing Agent

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
16
Q

6 Prevalent Strategies to Synthesize Colloids

A

1) Controlled Precipitation
2) Reduction of Metal Complexes
3) Sol-gel Process
- Hydrolysis of a metal salt
- Condensation/evaporation to remove the water
4) Emulsion and Dispersion Polymerization (to form colloidal polymer particles)
5) Template Controlled Growth

Ex: Colloidal Semiconductors (Quantum Dots)
-Formed through arrested precipitation

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
17
Q

Three “Rules” of Quantum Confinement

A

1) Motion of electron inside the well increases in energy in 1 dimension
2) Electrons behave like waves - “particle-wave duality”
3) Standing waves will have an amplitude of 0 at the walls

18
Q

Size vs. Energy for Nanoparticles

A

Smaller particles have high energy!

19
Q

Aggregation

A

“small” particles clump together, do NOT fuse into a new particle

*No significant surface reduction

20
Q

Coalescence

A

-2 or more particles fuse together to form a single larger particle

  • Reduced Surface Area
  • Ostwald Ripening takes place
  • Solid particles: Sintering
21
Q

Flocculation

A
  • Chains of particles that aggregate together

- A “flock” of particles

22
Q

Coagulation

A

Compact aggregate, possibly at the bottom of solution

23
Q

Aggregate Reversal Examples

A
  • Dispersion
  • Deflocculation
  • Peptization
24
Q

Creaming

A

Concentration of particles move upward in a dispersion to the surface (based on density)

25
Q

Sedimentation

A
  • Settling of dispersed particles under the action of gravity or a centrifugal field
  • Should be done at constant Temperature
26
Q

RCF

A

Relative Centrifugal Force

27
Q

Ultracentrifuge (particles they are useful for)

A

nanoparticles and lyophilic colloids

28
Q

Sedimentation Coefficient (Units, Definition)

A
  • Seconds

- Sedimentation velocity per unit of centrifugal acceleration

29
Q

Diffusion

A

Tendency to keep things dispersed

30
Q

Surface Energy

A

Atoms on the surface are at a lower energy state

  • They have stronger lateral bonds, causing surface tension
  • Surface energy refers to solids, surface tension refers to liquids
  • Good indicator of wettability by liquids
  • High SE –> more wettable
  • Polymers have low SE, while metal solids and clean glass have high SE
31
Q

Work of Cohesion

A

Work required to pull apart a material by overcoming attraction between atoms

32
Q

γ (lowercase gamma)

A
  • Measure of resistance of a surface to increase its area

- Force operating perpendicular and inward from a surface boundary

33
Q

Contact Angle

A

Angle measured in the liquid that is formed at the junction of the 3 phases

34
Q

Goniometer

A
  • Used to measure the contact angle when a liquid droplet is placed on a solid surface
  • A digital camera will record the contact angle with respect to different droplets
35
Q

Variation in γLV due to what intermolecular forces?

A

Metallic Bonding
Hydrogen Bonding
Polar Molecules “Keesom”
London Dispersion Forces

γLV = Σγforces

As T is increased, γLV is decreased due to less interaction

36
Q

Capillary Effect

A

Rise or fall of liquid in a small diameter tube inserted in liquid

37
Q

Micelle

A

Self-assembled ordered structure

38
Q

CMC

A
  • Critical Micelle Concentration
  • Gibb’s Monolayer is formed, number density of molecules at the surface will increase with concentration until the CMC is hit
39
Q

Surface Excess (Γ)

A

Difference in solute concentration between the bulk and surface

40
Q

Aggregation Number (n)

A
  • Number of molecules to form a micelle

- Influenced by headgroup repulsion and hydrophobic tail attraction

41
Q

Krafft Point

A

Sharp increase in solubility of surfactant

-The longer the hydrophobic taill, the higher the Krafft Point temperature

Materials Science (7 decks)

Brainscape helps you reach your goals faster, through stronger study habits.
© 2024 Bold Learning Solutions. Terms and Conditions