---
title: "PET: a polyester Template – Chemistry Diagram | MolDraw"
url: https://www.moldraw.com/templates/polymer-pet/
description: "PET: a polyester template: Protonation, attack of the glycol OH, proton transfers, loss of water and deprotonation form each ester link of poly(ethylene…"
lang: en
publisher: Scidart Academy
generated: 2026-10-28
---
[MolDraw](https://www.moldraw.com/) › [Templates](https://www.moldraw.com/templates/) › [Polymers](https://www.moldraw.com/templates/polymers/) › PET: a polyester

[Polymers](https://www.moldraw.com/templates/polymers/)Premium

# PET: a polyester template

![PET: a polyester template: Protonation, attack of the glycol OH, proton transfers, loss of water and deprotonation form each ester link of poly(ethylene terephthalate), [–OCH₂CH₂O–CO–C₆H₄–CO–]n.](https://www.moldraw.com/templates/polymer-pet.webp)

[Edit in MolDraw](https://www.moldraw.com/)Download with Pro

Premium template. Preview and edit it free in MolDraw; downloading and exporting it is part of [MolDraw Pro](https://www.moldraw.com/pricing).

Protonation, attack of the glycol OH, proton transfers, loss of water and deprotonation form each ester link of poly(ethylene terephthalate), [–OCH₂CH₂O–CO–C₆H₄–CO–]n.

## Mechanism step by step

Step growth by acid-catalysed esterification of terephthalic acid with ethylene glycol

1. **Protonation** – Acid activates the carbonyl
2. **Addition** – The glycol OH attacks the carbonyl carbon
3. **Proton transfer 1** – Water takes H⁺ from the new O
4. **Proton transfer 2** – An OH takes H⁺: water becomes a leaving group
5. **Loss of water** – The OH lone pair pushes out H₂O
6. **Deprotonation** – The ester link; H⁺ is regenerated

## Key points

- Every step is reversible: water (or ethylene glycol) must be removed under vacuum to reach high molar mass.
- Industrially PET is made by transesterification of dimethyl terephthalate or by direct esterification, then polycondensation over Sb₂O₃.
- The rigid para-phenylene rings make PET stiff and crystallisable (Tg ≈ 75 °C, Tm ≈ 260 °C): bottles and polyester fibre.
- Like nylon-6,6, chain length follows the Carothers equation and needs an exact 1:1 balance of functional groups.

Drawn with 130 atoms, 19 arrows, 14 shapes – every one editable in MolDraw.

## Sources

- [Odian, Principles of Polymerization, 4th ed., Wiley 2004, ch. 2](https://openlibrary.org/isbn/9780471274001) Textbook
- [Young & Lovell, Introduction to Polymers, 3rd ed., CRC Press 2011](https://openlibrary.org/isbn/9780849339295) Textbook

## How to use this template

1. Press **Edit in MolDraw**. The template opens on the canvas of the free MolDraw editor.
2. Change anything: move structures, edit atoms and labels, recolour highlights or delete what you do not need.
3. Add your own structures, arrows and text next to it, or combine several templates on one page.
4. Export the drawing as PNG, SVG or PDF for slides, worksheets, theses and papers.

## Frequently asked questions

### Is the PET: a polyester template free?

You can preview the PET: a polyester template here and open and edit it in MolDraw for free. Downloading or exporting it is part of MolDraw Pro, together with the other premium templates.

### Can I edit the PET: a polyester template?

Yes. It opens as an ordinary MolDraw drawing, so every structure, arrow, label and colour can be changed, and you can add your own content around it.

### Is the chemistry checked?

Every structure is checked with RDKit and every curly arrow passes MolDraw’s electron-flow audit. The sources used are listed on this page.

### Do the polymer templates show repeat units?

Yes. Each polymer is drawn with its repeat unit in brackets with n, next to the monomers it comes from.

## More polymers templates

[**Free-radical polymerisation**Free · Polymers](https://www.moldraw.com/templates/polymer-free-radical/)[**Cationic polymerisation**Free · Polymers](https://www.moldraw.com/templates/polymer-cationic/)[**Anionic living polymerisation**Free · Polymers](https://www.moldraw.com/templates/polymer-anionic-living/)[**Nylon-6,6: a polyamide**Premium · Polymers](https://www.moldraw.com/templates/polymer-nylon-66/)[**Ring-opening polymerisation**Premium · Polymers](https://www.moldraw.com/templates/polymer-ring-opening/)

## Related pages

[**All Polymers templates**6 templates](https://www.moldraw.com/templates/polymers/)[**All chemistry templates**370 templates in 29 categories](https://www.moldraw.com/templates/)

MolDraw Pro

Download all 370 templates

- Export the 291 premium templates as PNG, SVG or PDF
- AI chemistry assistant
- Structure scanning from images
- Cloud save and teaching slides

[See Pro plans](https://www.moldraw.com/pricing)

Free templates stay free. Every template can be opened and edited in MolDraw.