SciFinder Strategies - Formatting Polymer Formulas


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Formatting Polymer Formulas

Introduction

This section gives guidelines for formatting molecular formulas for the following kinds of polymers:

Homopolymers
Copolymers
Monomer salts of acids and amines

Homopolymers

Homopolymers are polymers formed by linking together one type of monomer. Follow these steps to determine the molecular formula for homopolymers.

Step

Do this

Example

Write the chemical formula for the monomer as it is known.

H2C=CH-C6H5

Determine element counts. No count is used for element counts of 1.

Format the homopolymer formula:

List individual elements, followed by their element counts.
Enclose the formula in parentheses, followed by X.

(C8H8)X

Copolymers

Copolymers are polymers formed by linking together more than one type of monomer unit. Follow these steps to determine the molecular formula for copolymers.

Step	Do this	Example
1	Write the chemical formula for each monomer as it is known.	CH3CO-O-CH=CH2 H2C=CH-Cl H2C=CH-F
2	Determine element counts for each monomer. No count is used for element counts of 1.	4 C, 6 H, 2 O 2 C, 3 H, Cl 2 C, 2 H, F
3	Format monomer formulas by listing individual elements, followed by their element counts.	C4H6O2 C2H3Cl C2H2F
4	Format the copolymer formula: List monomer formulas in any order, separating each formula by a period. Enclose the copolymer formula in parentheses, followed by X.	(C4H6O2.C2H3Cl.C2H3F)X

Monomer salts

Formulas for monomers that are salts of acids or salts of amines have special representations.

Salt form	Example
Salt of an acid	Sodium acetate
Salt of an amine	Trimethylammonium chloride

Salts of acids

Follow these steps to determine the formula for monomers that are salts of acids.

Step	Do this	Example
1	Write the chemical formula as it is known.	CH3COONa
2	Remove the metal from the formula to create two fragments.	CH3COO Na
3	Add H to the non-metal fragment to create the formula for the neutral acid.	CH3COOH Na
4	Determine element counts for each fragment. No count is used for element counts of 1.	2 C, 4 H, 2 O Na
5	Format fragment formulas by listing individual elements, followed by their element counts.	C2H4O2 Na
6	Format monomer salt formula by listing the fragment formulas in any order, separated by a period.	C2H4O2.Na

Salts of amines

Follow these steps to determine the formula for salts of amines.

Step	Do this	Example
1	Write the chemical formula as it is known.	(CH3)3-NH-Cl
2	Move the H from the N to the anion to create two fragments.	(CH3)3-N HCl
3	Determine element counts for each fragment. No count is used for element counts of 1.	3 C, 9 H, N H, Cl
5	Format fragment formulas by listing individual elements, followed by their element counts.	C3H9N HCl
6	Format monomer salt formula by listing the fragment formulas in any order, separated by a period.	C3H9N.HCl

Updated 3/2/2007 1:20:42 PM