‹ Chemistry simulationsChemistry · A Level 9701 · 35 Polymerisation (A Level)Five simulations covering Topic 35: a polyester built from a diacid and a diol one ester link at a time with water leaving at each join; nylon-6,6, Kevlar and a protein chain with the amide link highlighted and the hydrogen bonds between Kevlar chains; a click-to-cut finder that takes a chain section back to its monomers; a side-by-side test of addition against condensation with the small molecule counted; and the hydrolysis, photodegradation and disposal of polymers.
An ester forms when a carboxylic acid group meets an alcohol group and a molecule of water is lost. If each monomer has two reactive groups, one at each end, the reaction can happen again and again and the chain keeps growing. Step through it, then use the slider to add more units.
Swap the alcohol for an amine and the same idea gives an amide link instead of an ester link. Nylon-6,6 has chains of CH₂ groups between the links; Kevlar has rigid benzene rings; a protein is a polyamide whose monomers are amino acids. The amide link is picked out in gold.
To find the monomers of a condensation polymer, look for the links and cut each one. Put back an OH on the carbonyl carbon side and an H on the oxygen or nitrogen side and you have the original monomers. Click the links in the chain.
The two kinds of polymer differ in what is in the backbone and in what is left over. Addition polymers have a backbone of carbon atoms only and nothing is lost. Condensation polymers have an ester or amide link in the backbone and a small molecule such as water is lost at every link. Join the monomers and count.
The ester and amide links that make condensation polymers are also their weak points: acid or alkali can hydrolyse them, so these polymers are biodegradable. A poly(alkene) has only C-C and C-H bonds, which nothing in the environment attacks, so it lasts. Light is different: C=O groups absorb ultraviolet. Pick the conditions and watch.
Five interactive simulations for Cambridge A Level Chemistry 9701 topic 35 Polymerisation: 3D step-through condensation polymerisation of benzene-1,4-dicarboxylic acid with ethane-1,2-diol to PET and of 2-hydroxypropanoic acid to PLA with water lost at each ester link, 3D chain sections of nylon-6,6, Kevlar and a polypeptide with the amide link highlighted and the hydrogen bonds between neighbouring chains, a click-to-cut finder that recovers the monomers from a chain section, an addition versus condensation comparison that counts the small molecules lost, and the acid and alkali hydrolysis of a polyester chain against poly(ethene), photodegradation of a polymer with C=O groups and the disposal options of landfill, incineration and recycling.
Five simulations covering Topic 35: a polyester built from a diacid and a diol one ester link at a time with water leaving at each join; nylon-6,6, Kevlar and a protein chain with the amide link highlighted and the hydrogen bonds between Kevlar chains; a click-to-cut finder that takes a chain section back to its monomers; a side-by-side test of addition against condensation with the small molecule counted; and the hydrolysis, photodegradation and disposal of polymers.
Condensation polymers is a free, browser-based simulation for Cambridge International AS & A Level Chemistry 9701 (topic 35 Polymerisation). The course is assessed in Paper 1 (Multiple Choice (AS)), Paper 2 (AS Structured), Paper 3 (Advanced Practical), Paper 4 (A Level Structured), Paper 5 (Planning, Analysis, Evaluation). Syllabus for examination in 2025-2027. There are 5 tabs, each a self-contained experiment with its own controls and live readings, and nothing to install: it runs on a laptop, tablet or classroom projector.
Full syllabus map: A Level Chemistry 9701 topic 35.
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