New Cyclocarbonate Building Blocks Reactive at Room Temperature for Environment Friendly Polyurethane Adhesives and Sealants – CYRRENAS

The methodological approach is based on six Work Packages (WP) under environmental, health and regulatory (REACH) constraint :

WP1 - Determination of reactivity conditions for cyclocarbonate / amine couples vs. five-membered cyclocarbonates from prior art.
WP2 - Processes for the production of new building blocks towards non-isocyanate polyurethanes (NIPUs)
WP3 - Structure / Reactivity / Properties Relationship of the dicyclocarbonate / diamine and the corresponding NIPUs for the formulation of mastics and adhesives
WP4 - Optimization of mastics and adhesives compositions based on NIPU technology
WP5 - Cradle to Customer Gate Analysis of mastics and adhésives compositions based on NIPU technology
WP6 - Industrial schemes for the production of cyclocarbonate monomers and/or biscyclocarbonate prepolymers

WP1 et WP2 have allowed for study of comparative reactivities for different five-membered (5CC) and six-membered cyclocarbonates, rank them according to industrial accessibility and direct research towards two types of activated five-membered cyclocarbonates (5CC) in combination with -NH2 terminated polyamines. It was also highlighted the impact of some physico-chemical parameters on the reaction kinetics of 5CC 6CC with polyamines. A first patent application was filed to protect one of two 5CC chosen solutions, others patent applications are expected to follow. Note that 6CC are more difficult to access than 5CC in terms of yield and selectivity.

Monomers and prepolymers with activated cyclocarbonates functions, reactive at room temperature, were synthesized in significant quantities in order to study physico-chemical, rheological and (thermo) mechanical properties prior to formulation work (adhesive) itself.

Moreover, the volume of results obtained over 18 months already provides a fairly accurate idea of ??correlations between structure and reactivity of 5CC and 6CC at room temperature, failing to have highlighted the existence of effective catalysts.

Concerning the future prospect, it is a matter of :
- Continuing the study of activated 5CC derivatives, including processes of corresponding monomers and prepolymers synthesis
- Improving access to 6CC thanks to original and industrialize processes
- Synthesizing and evaluating curable 5CC and 6CC monomers
- Continuing the study of physico-chemical, rheological and (thermo) mechanical properties of NIPUs from activated 5CC prepolymer / polyamine couples
- Studying two-component adhesive formulations based on 5CC activated prepolymer / polyamine couples

A first patent application was filed in May 2015.

Communications and conferences :
1. «Original strategies towards Non-Isocyanate PolyUrethanes (NIPUs)Original strategies towards non-isocyanate polyurethanes (NIPUs)« - 35ème Journées du GFP, Section Grand Ouest, Rouen, France, Juin 2014
2. «Two strategies for the synthesis of Non-Isocyanate PolyUrethanes (NIPUs)« - 43ème Colloque du Groupe Français d’études et d’applications des Polymères, GFP, Saint Malo, France, Novembre 2014
3. «Original strategies towards Non-Isocyanate PolyUrethanes (NIPUs)Original strategies towards non-isocyanate polyurethanes (NIPUs)« - Journée des doctorants de l'Ecole Doctorale des Sciences de la Matière, Rennes, France, Janvier 2014

International Journals with Reading Committee
1. Thiol-ene coupling: an efficient tool for the synthesis of new biobased aliphatic amines for epoxy curing, Adrien Cornille, Vincent Froidevaux, Claire Negrell, Sylvain Caillol*, Bernard Boutevin, Polymer, 2014, 55, 5561-5570,
2. A New Way of Creating Cellular Polyurethane Materials: NIPU Foams, Adrien Cornille, Sylwia Dworakowska, Dariusz Bogdal, Bernard Boutevin, Sylvain Caillol*, European Polymer Journal, 2015, 66, 129–138

Conventional polyurethanes (PUs) involve the use of isocyanates, which require hazardous and toxic phosgene for their manufacture. These monomers cannot be manufactured without elaborate safety devices and huge investments. Isocyanates are also considerably toxic (i.e methylenediphenyl diisocyanate (MDI) in entry 56 of Annex XVII to Regulation (EC) since December 28,2010) and moisture sensitive. Growing global awareness of the need to protect our environment and continually strive to ensure the safety, health and well-being of those in the industry and consumers, has created a demand for environment-friendly products. The cyclic carbonate-primary amine addition reaction, which results in hydroxyurethanes, is a unique reaction which has been quite studied over the last few years but without industrial development. This chemistry is now attracting much research interest due to its potential application in the preparation of “green” isocyanate-free PUs (for example NIPUs) in a regulatory context (REACH, CLP, ...) increasingly burdensome for manufacturers and users of PUs-based formulations.

The two main issues that the CYRRENAS project aims to solve are on one hand, the low reactivity of cyclocarbonates at room temperature and on the other hand, the development of original highly reactive telechelic cyclocarbonate pre-polymers with strictly controlled functionality (F = 2 and 3) according to innovative processes that will meet functional requirements for adhesives and sealants.

The expected benefits are important, for both academic and industrial partners, since the CYRRENAS project will allow the development of a new generation of sealants and adhesives without residual isocyanate monomer, thereby giving them a competitive advantage in an extremely innovative and competitive global market.

The scientific and technological targets of the CYRRENAS project include: (i) the design and preparation of elementary “pre-polymers” and cyclocarbonate building blocks through environmental friendly and sustainable processes, (ii) the design and the end-capping of these “pre-polymers” with cyclocarbonate functions will assist in efficient conversion in NIPUs by the action of co-reactive products like diamines, (iii) the molecular design and fine adjustment of internal structure of these “cyclocarbonate end-capped pre-polymers” to access to a variety of NIPUs with thermo-mechanical properties adjustable to different applications and customer needs (industrial assembly, transportation, construction and consumers), mimicking the best properties of current traditional PUs, (iv) the screening of “telechelic cyclocarbonate pre-polymers” in sealants and adhesives formulations (lab scale) when the problem of reactivity of cyclocarbonate functions at low temperature will be solved, (v) the development of two-component sealants and adhesives formulations (pilot scale) based on highly reactive “telechelic cyclocarbonate prepolymers” and polyamines (vi) the proposal for an industrial production scheme of building blocks and “telechelic cyclocarbonate prepolymers”.

The CYRRENAS project thus focuses, for the academic part, on catalysis, mechanistic insights on the formation of Non-Isocyanate Polyurethanes (NIPUs) from five-membered cyclic carbonates (CC5) and the reaction kinetics for their synthesis, as well as on the original higher homologues (CC6, CC7) of the cyclic carbonate family (the six-membered cyclic carbonates (CC6) being more reactive than five-membered cyclic carbonates) which can also serve as a source for production of “telechelic cyclocarbonate pre-polymers”. The CYRRENAS project focuses, for the industrial part, on the evaluation and formulation of telechelic cyclocarbonate pre-polymers in two-component adhesives and sealants. A Life Cycle Assessment (LCA) will also be conducted to take the environmental impacts of the project into account.