Polymer backbone

The character of the backbone, i.e. its flexibility, determines the properties of the polymer (such as the glass transition temperature).

For example, in polysiloxanes (silicone), the backbone chain is very flexible, which results in a very low glass transition temperature of −123 °C (−189 °F; 150 K).

[2] The polymers with rigid backbones are prone to crystallization (e.g. polythiophenes) in thin films and in solution.

Examples include polyolefins such as polyethylene ((CH2CH2)n) and many substituted derivative ((CH2CH(R))n) such as polystyrene (R = C6H5), polypropylene (R = CH3), and acrylates (R = CO2R').

Some uncommon but illustrative inorganic polymers include polythiazyl ((SN)x) with alternating S and N atoms, and polyphosphates ((PO3−)n).

The glycosidic linkages are designated as alpha or beta depending on the relative stereochemistry of the anomeric (or most oxidized) carbon.

The bases project from the pentose-phosphate polymer backbone and are hydrogen bonded in pairs to their complementary partners (A with T and G with C).

This creates a double helix with pentose phosphate backbones on either side, thus forming a secondary structure.

Formation of polystyrene, a polymer with an organic backbone.
Polydimethylsiloxane is classified as an " inorganic polymer ", because the backbone lacks carbon.
A simplified example of condensation showing the alpha and beta classification. Glucose and fructose form sucrose . The synthesis of glycogen in the body is driven by the enzyme glycogen synthase which uses a uridine diphosphate (UDP) leaving group.
Condensation of adenine and guanine forming a phosphodiester bond , the triphosphorylated ribose of the incoming nucleotide is attacked by the 3' hydroxyl of the polymer, releasing pyrophosphate .