The difference between structural unit and repeating unit?

Click For Summary
SUMMARY

The discussion clarifies the distinction between structural units and repeating units in polymer chemistry. Polyethylene terephthalate (PET) has a repeating unit of [-O-CH2-CH2-O-CO-Ph-CO-] but consists of two structural units derived from its inputs. In contrast, polyethylene has a repeating unit of [-CH2-] and a structural unit of [-CH2-CH2-], originating from ethylene. Understanding these definitions is crucial for accurately describing polymer structures.

PREREQUISITES
  • Basic knowledge of polymer chemistry
  • Understanding of structural and repeating units
  • Familiarity with polyethylene terephthalate (PET) and polyethylene
  • Ability to interpret chemical structures and formulas
NEXT STEPS
  • Research the chemical structure of polyethylene terephthalate (PET)
  • Study the synthesis process of polyethylene and its structural units
  • Explore the implications of structural units in polymer properties
  • Learn about other polymers and their repeating and structural units
USEFUL FOR

Chemistry students, polymer scientists, and anyone interested in understanding the fundamentals of polymer structures and their implications in material science.

royzizzle
Messages
48
Reaction score
0

Homework Statement



The difference between structural unit and repeating unit

Homework Equations





The Attempt at a Solution



http://en.wikipedia.org/wiki/Structural_unit

wikipedia gives an example with polyethylene terephthalate but I can't figure it out based on the slight difference
 
Physics news on Phys.org
Polyethylene teraphthalate has two structural units but only has one repeating unit.

Structural units are substructures that are derived directly from the inputs.

If you call the repeating unit [-R-], then you can write a polymer as -[-R-]-n.

So while polyethylene teraphthalate has the repeating unit [-O-CH2-CH2-O-CO-Ph-CO-], it's built from two distinct inputs and each of those is a different structural unit.

To take another example, polyethylene, which once was also called polymethylene, -[-CH2-]-n, has the repeating unit [-CH2-] but has the structural unit [-CH2-CH2-] because it is derived from ethylene, not methyl radical.
 
Last edited:

Similar threads

What is the difference between amu and u in atomic mass units?
  • · Replies 1 ·
Replies
1
Views
7K
Calculate Moles of Terephthalic Acid from PET Depolymerization
  • · Replies 3 ·
Replies
3
Views
5K
What are the units for Ksp and why are they not always included in calculations?
  • · Replies 1 ·
Replies
1
Views
13K
Drawing Lewis structure and structural formula
  • · Replies 2 ·
Replies
2
Views
3K
Are These Condensed Structural Formulas for C7H16 Correct?
  • · Replies 4 ·
Replies
4
Views
3K
What Are the Ionic Radii of Mg2+ and O2- in MgO's Crystal Structure?
  • · Replies 4 ·
Replies
4
Views
14K
Chemistry Understanding Simple Molecular Structures in Chemistry
  • · Replies 3 ·
Replies
3
Views
2K
Undergrad Time rondeau crystals, experimental observations
  • · Replies 1 ·
Replies
1
Views
3K
Genetic sequence multiple choice question
  • · Replies 5 ·
Replies
5
Views
2K
Which Lewis Structure is the Most Stable?
  • · Replies 2 ·
Replies
2
Views
5K