Polymers

HDPE

The carbon backbone is the same as LDPE, but fewer branches allow more chain segments to pack into ordered crystalline regions. The repeat unit does not show branch frequency, chain length or the mixture of crystalline and disordered regions.

PVC

The monomer C=C bond becomes part of a saturated backbone; chlorine stays attached to alternate backbone carbons. Plasticisers change how the chains move but are not repeat units covalently inserted into this chain.

PS

The styrene vinyl group makes the backbone while the phenyl ring remains pendant. Typical general-purpose PS is an amorphous glass at room temperature; its clear rigid form and its expanded foam have the same main polymer chemistry.

PMMA

PMMA has an ester side group attached to a carbon–carbon backbone. It is made by addition through MMA double bonds, unlike PET or PBT, whose ester links form part of the backbone.

PET

Ester links connect ethylene-glycol segments to 1,4-terephthalate units in the backbone. The same chemical repeat unit can produce a clear container, a drawn fibre or a more crystalline article because processing changes arrangement rather than monomer identity.

LDPE

The repeat unit shows the carbon backbone, not the short and long branches produced by the radical process. Branching interrupts regular packing, leaving more disordered material than in typical HDPE.

PP

Each repeat unit has a methyl side group. Its stereochemical arrangement along the chain, called tacticity, affects how regularly chains can pack; the flat repeat formula does not specify that arrangement.

Nylon 6,6

Amide links join the six-carbon diamine and six-carbon diacid residues; the diacid count includes its carbonyl carbons. N–H groups and carbonyl oxygen atoms allow hydrogen bonding between adjacent chains.

ABS

ABS has rubbery butadiene-derived domains in a styrene–acrylonitrile-rich matrix, with grafting helping connect the phases. It cannot be described faithfully by one fixed three-monomer alternating repeat unit.

Nylon 6

The ring-opened caprolactam unit contains six carbons, including the amide carbonyl. The amide N–H and C=O groups support hydrogen bonding; each repeat supplies both groups without a separate diamine–diacid pair.

PTFE

The tetrafluoroethene double bond becomes a carbon backbone bearing fluorine atoms. PTFE is an addition polymer; its fluorinated surface gives very different interactions from hydrocarbon polymers such as PE.

EVA

Ethene-derived and vinyl-acetate-derived segments occur in grade-dependent proportions. Both use their C=C bonds for chain growth; the ester groups remain pendant, so EVA is not a backbone polyester.

PC

Carbonate links connect bisphenol-A-derived units. The selected melt route supplies the carbonate carbonyl from diphenyl carbonate and removes phenol; this differs from addition polymerisation of a vinyl monomer.

PBT

Terephthalate units are connected by ester links to four-carbon diol segments. PET uses a two-carbon diol segment instead: sharing the same diacid does not make the two polyesters interchangeable.

PLA

The selected route opens lactide rings to create an ester-linked backbone. Lactide’s stereochemical composition influences how PLA chains can pack; the generic repeat unit omits this stereochemistry.

PPV

Conjugated polymer · Semiconductor. A conjugated polymer used as the emitting layer in an early organic light-emitting diode (OLED).

Para-phenylene rings alternate with vinylene groups along the backbone. Conjugation connects the electronic structure to optical behaviour.