DOI: 10.21950/ncsijp
title: Tuneable Zinc Scorpionates for CO2 Fixation into Sustainable Materials: Access to Polycarbonates and Tailored Hybrid Poly(L-lactide)s-b-Polycarbonates

description: The production of novel industrially demanded materials mediated by metal-based catalysts under greener and more eco-friendly conditions is a current challenge to aim. This is even more attractive when these materials are capable to uptake different levels of CO2 and show improved properties.

In this contribution we describe the use of inexpensive, low-toxicity and robust mononuclear alkyl zinc complexes of the type [ZnMe(κ3-NNN’)] (4–6), supported by sterically demanding scorpionate ligands, as catalysts for the selective Ring-Opening Co-Polymerization of cyclohexene oxide and CO2. The presence of different electron-withdrawing groups in the scorpionates play a key role in catalysts selectivity. Thus, these species can act efficiently in the absence of co-catalyst to afford poly(cyclohexene carbonate) (PCHC) materials with narrow dispersity values, under mild and solvent-free conditions.

Very interestingly, only complex [ZnMe(κ3-phbptamd)] 4 also exhibited high efficiency as one-component catalyst for the preparation of the terpolymer poly(L-lactide)-b-poly(cyclohexene carbonate) (PLA-b-PCHC) in the form of hybrid diblock materials via a single-feed procedure, in different ratios and under similar conditions. The lower Lewis acidity of catalyst 4 favors the complete ROP of L-LA as the first step in the terpolymerization process, followed by the ROCoP of CHO and CO2. The level of CO2 incorporation in these materials can be easily modulated by simply modifying cyclohexene oxide feed, resulting in hybrid materials with different thermal properties. 

Assessment by Thermogravimetric Analysis and Differential Scanning Calorimetry revealed both that these terpolymers showed to be stable up to 240 °C, due to the higher PCHC content, and that the glass transition temperatures (Tg) for these PLA-b-PCHC hybrids exhibit a single value, approximately 60 °C, corresponding to the lactide portion of the hybrid polymer 12.
description: This dataset contains relevant catalytic data from the literature on zinc-based catalysts active in the ring-opening copolymerization (ROCOP) of CO₂ and cyclohexene oxide (CHO), as well as the terpolymerization of CO₂, CHO, and lactide (LA). Key polymerization parameters are included, such as reaction time, pressure, temperature, turnover frequency (TOF), selectivity, and monomer-to-catalyst ratios.
In addition to the literature data, the dataset also includes results from the polymerization experiments described in the accompanying manuscript. This includes a table summarizing the screening of various synthesized catalysts used for the production of poly(cyclohexene carbonate) (PCHC), along with additional tables showing the influence of temperature, pressure, and reaction time on the polymerization outcomes.
Furthermore, data related to the synthesis of PCHC and PLA copolymers are provided. The dataset includes the initial catalyst screening, followed by detailed results from the optimization of monomer molar ratios using the most active catalyst identified.
description: This publication is accompanied by freely accessible Supporting Information, which provides detailed experimental procedures and additional characterization data. The supplementary material includes NMR and GPC spectra of key compounds and polymers, MALDI-ToF mass spectrometry data, thermal analyses (TGA and DSC), and detailed experimental protocols for the synthesis of poly(cyclohexene carbonate) (PCHC) and hybrid poly(L-lactide)-co-poly(cyclohexene carbonate) (PLA-co-PCHC) copolymers. These figures and procedures offer further insight into the structural and thermal properties of the materials discussed in the manuscript, as well as the methodology used for their preparation.