[MahoneyTree]

I am working on my Thesis in which i synthesised PLA out of L-lactic acid. I am using the Methods from a research paper from the HEIA-FR which i linked here aswell.

https://www.chimia.ch/chimia/article/view/2012_951/4616

The second step is to perform a polymerisation of pure lactic acid to a prepolymer of PLA. I have done this and know what the educt aswell as product formulas are, but I don't know what happens in terms of a chemical process during the polymerisation.

Simply put, I need someone to explain to me what happens to the lactic acid molecule durng the polymerisation so that it turns into the prepolymer.

Thank you very much for your help

[Hunter2]

Ist a simple polycondensation with the Carboxyl and Hydroxylgroups of the acid. Using catalyst to get the chain length or cyclisation.

[rolnor]

Here is one way to make esters

https://en.wikipedia.org/wiki/Fischer%E2%80%93Speier_esterification

[Babcock_Hall]

https://www.spectroscopyonline.com/view/infrared-spectroscopy-of-polymers-viii-polyesters-and-the-rule-of-three


This is a good discussion of the infrared spectroscopy of related polymers, just in case you might be interested.