---
title: "Ring-opening polymerisation Template | MolDraw"
url: https://www.moldraw.com/templates/polymer-ring-opening/
description: "Ring-opening polymerisation template: An alkoxide adds to the lactone carbonyl, the tetrahedral intermediate opens the ring to a new alkoxide chain end, and…"
lang: en
publisher: Scidart Academy
generated: 2026-10-28
---
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# Ring-opening polymerisation template

![Ring-opening polymerisation template: An alkoxide adds to the lactone carbonyl, the tetrahedral intermediate opens the ring to a new alkoxide chain end, and that end opens the next ring: poly(ε-caprolactone), [–O(CH₂)₅CO–]n.](https://www.moldraw.com/templates/polymer-ring-opening.webp)

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An alkoxide adds to the lactone carbonyl, the tetrahedral intermediate opens the ring to a new alkoxide chain end, and that end opens the next ring: poly(ε-caprolactone), [–O(CH₂)₅CO–]n.

## Mechanism step by step

ε-Caprolactone opened by an alkoxide: the chain end attacks the C=O of the next ring

1. **Addition** – The alkoxide attacks the lactone carbonyl
2. **Ring opening** – C=O re-forms and the ring C–O bond breaks: a new alkoxide chain end
3. **Propagation** – The chain-end alkoxide opens the next ring

## Key points

- Ring strain drives the reaction: no small molecule is lost, so the polymer has the same formula as the monomer.
- Lactide opens the same way to poly(lactic acid), PLA; with Sn(Oct)₂ and an alcohol the ring opens by coordination–insertion.
- Chain growth with living character: DP is set by [monomer]/[initiator] and Đ stays narrow.
- Polyesters from lactones and lactides are biodegradable: sutures, implants and compostable packaging.

Drawn with 94 atoms, 10 arrows, 11 shapes – every one editable in MolDraw.

## Sources

- [Odian, Principles of Polymerization, 4th ed., Wiley 2004, ch. 7](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 Ring-opening polymerisation template free?

You can preview the Ring-opening polymerisation 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 Ring-opening polymerisation 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.

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