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About the TROPIC Database

TROPIC (Thermodynamics of Ring-Opening Polymerisation Informatics Collection) is an open-source database of experimental and computational thermodynamic parameters for ring-opening polymerization (ROP) reactions. Our goal is to facilitate the data-driven discovery of novel, functional polymers that are primed for chemical recycling.

Data Collection & Curation

The data in this database has been manually collected from peer-reviewed academic literature. Each entry is linked to its source via a Digital Object Identifier (DOI), allowing for easy access to the original publication and its metadata.

We include key experimental conditions, such as the reaction medium and monomer concentration, as these factors significantly influence thermodynamic values. To ensure data quality, we use a flagging system to highlight entries that are incomplete or appear inconsistent.

Molecule Classes

The current dataset focuses on several classes of polar cyclic monomers (PCMs) used in ring-opening polymerizations.

Classes of polar cyclic monomers
AbbreviationMonomer Class
LLactone
CCCyclic Carbonate
LmLactam
tL, tnL, dtLSulfur-containing Lactone Derivatives
CtC, CdtC, etc.Sulfur-containing Cyclic Carbonate Derivatives

Reaction Types

The database classifies reactions into four distinct categories to provide clear context for the thermodynamic data.

ROP (Ring-Opening Polymerization)

An experimental reaction where cyclic monomers form long-chain linear polymers.

Ring-Opening Polymerization

RCE (Ring-Chain Equilibrium)

An experimental equilibrium between all ring sizes (including monomer) and the final polymer.

Ring-Chain Equilibrium

ROR (Ring-Opening Reaction)

A model reaction, computational or experimental, where one or a few monomers are opened to form a short linear chain.

Ring-Opening Reaction

RER (Ring-Expansion Reaction)

A computational model where cyclic monomers form short cyclic polymer chains or "loops."

Ring-Expansion Reaction

Thermodynamic Principles

The ceiling temperature (TcT_c) is a critical parameter for chemical recyclability. It represents the temperature at which polymerization and depolymerization are in equilibrium. It is derived from the enthalpy (ΔHp\Delta H_p) and entropy (ΔSp\Delta S_p) of polymerization.

The relationship is defined by the Dainton equation, where [M]eq[M]_{eq} is the monomer concentration at equilibrium:
Tc=ΔHpΔSp+Rln([M]eq)T_c = \frac{\Delta H_p}{\Delta S_p^\circ + R \cdot \ln([M]_{eq})}

Methodologies

Experimental Methods

Van't Hoff Analysis

Determining ΔHp\Delta H_p and ΔSp\Delta S_p from the monomer equilibrium concentration at various temperatures, often measured via NMR spectroscopy.

Differential Scanning Calorimetry (DSC)

A thermal analysis technique used to measure heat flow associated with polymer transitions.

Calorimetry

Direct measurement of heat changes during polymerization.

NMR Spectroscopy

Used to monitor monomer conversion and determine equilibrium concentrations.

Computational Methods

Density Functional Theory (DFT)

Used for Ring-Opening Reaction (ROR) models to calculate thermodynamic parameters. The specific functional andbasis_set are recorded.

Molecular Dynamics (MD)

Used to identify stable conformers before DFT calculations. Methods include classical (ffmd), ab initio (aimd), and machine-learned (mlmd) dynamics.

Semi-Empirical Methods

Quantum mechanical methods like xTB that offer a balance between speed and accuracy.