# Multidimensional kinetic study on the organocatalyzed ring-opening polymerization (ROP) of l-lactide via a robotic high-throughput flow platform

## TL;DR

A robotic system was used to study the polymerization of l-lactide with high accuracy, revealing new insights into the reaction's rate law and unusual behavior.

## Contribution

A high-throughput robotic flow platform enabled precise kinetic analysis of TBD-catalyzed ROP of l-lactide, revealing a novel rate law and negative activation energies.

## Key findings

- A rate law was developed showing first-order dependencies on l-lactide and TBD, and half-order on the initiator.
- Negative observed reaction rates were found when increasing monomer, initiator, or catalyst concentrations.
- Lowering the reaction temperature also led to negative activation energies in the studied chemical space.

## Abstract

Ring-opening polymerization (ROP) of l-lactide catalyzed by 1,5,7-triazabicyclo[4.4.0]dec-5-ene (TBD) was efficiently screened via a programmable high-throughput robotic flow platform with very high accuracy (absolute error <5%). With a very significant amount of data being generated, a rate law describing living ROP initiated by TBD that includes a first-order dependency in l-lactide, a first-order dependency in TBD and a half-order dependency in the initiator 4-methylbenzyl alcohol is developed. Additionally, a negative observed reaction rate (kobs) was determined with increasing the initial monomer concentration, initiator or catalyst, or, surprisingly, decreasing the reaction temperature, giving rise to negative activation energies within the chemical space studied.

The ring-opening polymerization (ROP) of l-lactide catalyzed by TBD was efficiently studied using a high-throughput robotic flow platform with very high accuracy, and a rate law of the reaction was revealed based on a comprehensive kinetic study.