Biomaterials Surface: Physics (wk. 3)

Description

incomplete
Christine Luk
Flashcards by Christine Luk, updated more than 1 year ago
Christine Luk
Created by Christine Luk about 7 years ago
87
0

Resource summary

Question Answer
Biomaterials Surface - Physics Key concepts 1. bonding 2. surface tension/ adhesion & cohesion 3. hydrophobicity
ionic bond (metal + nonmetal) High BP, high MP solid - insulator e- molten/aqueous - conductor e- HARD, BRITTLE
Covalent bonding (nonmetal + nonmetal) s, l, g at room Temp s, l, g, poor conductor low MP, low BP Soft, brittle, cleaves non electrolyte
Metallic bonding delocalized electrons/bonds good e- and thermal conductor opaque relatively ductile contain 1 to 3 electrons outer shell
Van der Waals Bond weak attractive/repulsive force betw molecules partial dipoles occur to some extent in all materials, important for polymers
Polymers - important bonds covalent + van der waals covalent: STRONG - carbon back bone, strong, rupture only in extreme conditions. key for thermosetting van der waals: WEAK allow sliding, rupture. Key for thermoplastics thermoplastics: head breaks van deer Waal forces thermosetting: 3D network of covalent bonds, don't break easily
Amorphous Solid random supercooled liquids nio long range periodicity e.g., glass (SiO2 cooled rapidly to prevent crystallization
Crystalline solids >90% of solids ares crystalline more stable, minimized intermolecular energy regular arrangements
Surface properties influencing protein and cell adhesion (3) surface hydrophobicity (proteins like) surface roughness (cells like) surface charge (determined by peptide sequence)
Cohesive force attraction betw SAME molecules
Adhesive force attraction betw DIFFERENT molecules adhesive tape: sticks two different things together.
Surface tension (T or gamma) tendency of molecules on the surface of a liquid to go into the liquid
Surface tension formula
Capillary action adhesion to walls > cohesion liquid upward force raising liquid forms miniscus T holds surface intact height dependent on T
Capillary action: Force Upward formula
high surface tension (T) materials metals carbides oxides (strong bonds, metallic & covalent bonds)
low surface tension (T) materials polymers, organics (van der waals bonded)
Work of Cohesion Surface tension is a measure of degree of cohesion
Work of Adhesion Work required to separate a unit area of interface between to phases
Protein resistance by work of adhesion W12 = 0 higher work adhesion of water, water will be harder to displace by protein, protein resistance is good
(a) >90 = non wetting = hydrophobic (b) <90, partial = hydrophillic >150 is superhydrophobic/ ultraphobic
Cassie's equation
Wenzel equation
use wenzel's equation cos(pheta)* = rcos(pheta) pheta*= arccos(rcos(pheta))
Show full summary Hide full summary

Similar

Biomaterials - Introduction (wk. 1)
Christine Luk
Cell-Biomaterial Surface Interaction (wk. 6)
Christine Luk
Biomaterials Surface Chemistry (wk. 4)
Christine Luk
OCR Chemistry - Atoms, Bonds and Groups (Definitions)
GwynsM
Rates of Reaction
Evie Papanicola
American West - Key Dates
Rachel I-J
The Norman Conquest 1066-1087
adam.melling
Maths GCSE - What to revise!
sallen
iGCSE Biology Questions
Pranali Amlani
The Weimar Republic, 1919-1929
shann.w
Networks
B Ilo