Aminolysis Of Cyclic Carbonates Research Articles

Insights on the polymerization kinetics of non-isocyanate polyurethanes (NIPU) using in situ NMR spectroscopy

An in situ characterization method using liquid Nuclear Magnetic Resonance (NMR) spectroscopy has been developed to aid the preparation of highly reactive non-isocyanate polyurethanes (NIPUs) from cyclic carbonate aminolysis. Using this methodology, the aminolysis kinetics and the final polymer structure of a model NIPU obtained by reaction of a 5-membered bis-cyclic carbonate (5CC) and 1,4-diaminobutane have been fully investigated, as a function of the type and concentration of the aminolysis catalyst, and the reaction temperature. Several catalysts already reported in NIPUs syntheses, including 1,5,7-triazabicyclo[4.4.0]dec-5-ene (TBD) and 1,8-diazabicyclo[5.4.0]undec-7-ene (DBU), have been compared. The kinetics of the 5CC hydrolysis side reaction was also studied. With an activation energy of 29.7 kJ mol−1, TBD was clearly the most efficient catalyst used, allowing 5CC conversion ratio of up to 100 % using a concentration of 0.35 eq5CC. However, under these experiment conditions, TBD concentration also showed to have a non-negligible influence on the hydrolysis rate, representing between 6 and 14 % of the initial 5CC concentrations, at 353 K. Neither the catalyst or the temperature seemed to affect the polymer structure, with secondary hydroxyl-containing isomer proportions of (70 ± 6) %. Finally, this in situ NMR method is paving the way for rapid screening of innovative catalysts for sustainable NIPU synthesis.

Controlling Hybrid Polyhydroxyurethane Adhesive and Rheological Properties by Partial Carbonation of Biobased Epoxy Monomer.

Controlling hybrid material properties by simple monomer design offers an elegant pathway to prepare thermoset adhesives with tunable properties. Herein, biobased hybrid polyhydroxyurethane/polyepoxy is prepared starting from partially carbonated cashew nut shell epoxy derivatives (NC514) and m-xylene diamine (MXDA). The curing reactions, that is, epoxy-amine and cyclic carbonate aminolysis, monitored by ATR-IR spectroscopy at 50°C are found to be concomitant yielding highly homogeneous materials. Hybrid networks are extensively characterized by swelling tests, TGA, DMA, DSC, tensile tests, rheology, and lap-shear-test on aluminum substrates. The introduction of hydroxyurethane moieties within the epoxy-amine networks enhanced the adhesion properties (up to 20% compare to neat epoxy resins) by combining hydrogen bonding capability and vitrimeric properties (thermoset able to flow). Rheological characterizations and reprocessing tests demonstrated that hybrid adhesives with up to 47 mol% of cyclic carbonate groups are capable of covalent exchange (internally catalyzed by tertiary amine) while keeping similar thermomechanical properties and enhanced adhesion strength compare to the permanent epoxy network.

High strength, recyclable and shape memory polyhydroxyurethanes with intrinsic fluorescent properties

AbstractPolyhydroxyurethanes (PHUs), which are synthesized through the aminolysis of cyclic carbonates, avoid the use of toxic isocyanates compared with traditional polyurethanes (PUs) and have aroused great interest. The large number of hydroxyl groups in the network endows PHUs with unique features, such as recyclable properties and fluorescent properties. To establish the high performance and multifunctionality of PHUs, we designed a molecular structure to fabricate PHUs with mechanical robustness, shape memory properties, fluorescent properties, and recyclable properties. The yielded PHU crosslinked by the quaternary thiol and weak but dense hydrogen bonds (H‐bonds) shows unprecedented high mechanical properties with a tensile Young's modulus of 3.13 GPa, comparable to that of polyimide, a tensile strength of 59.2 MPa at room temperature and an excellent toughness of 27.9 MJ/m3 at 50°C, and good damping properties (tanδ ≥ 0.3, temperature range of 35.2°C). Interestingly, fluorescence caused by the aggregation of carbamate within PHUs allows it to be applied for damage self‐reporting to visualize tiny cracks or magnify fractures. Furthermore, both the thermosetting PHUs and recycled thermosetting PHUs presented excellent shape memory performance. This study provides certain inspiration for the design and development of highly rigid multifunctional polymers.

Enhanced aminolysis of cyclic carbonates by β-hydroxylamines for the production of fully biobased polyhydroxyurethanes

β-hydroxylamines exhibit higher reactivity toward cyclic carbonates compare to regular amines and allowed access to fully biobased polyhydroxyurethanes.

Progress in hybrid non‐isocyanate polyurethanes

This mini review highlights recent advances in the field of non‐isocyanate polyurethanes with an emphasis on hybrid chemistries that combine cyclic carbonate aminolysis with other step‐growth and chain‐growth reactions. The origins of hybrid non‐isocyanates polyurethanes, different types of reaction chemistries and synthetic strategies are discussed. In addition, applications where combining different types of chemistries are advantageous are emphasized. Published 2020. This article is a U.S. Government work and is in the public domain in the USA

Hydrolyzable Biobased Polyhydroxyurethane Networks with Shape Memory Behavior at Body Temperature

Among possible routes towards isocyanate-free PUs, aminolysis of cyclic carbonates leading to polyhydroxyurethanes (PHUs) is one of the most promising pathways. Herein, we describe the solvent-free synthesis of shape memory PHU networks from diglycerol dicarbonate through reactive extrusion with varying amounts of primary and secondary triamines, Tris(2-aminoethyl)amine and Tris(2-(methyla-mino)ethyl)amine). Depending on the composition of the system, the glass transition temperature of the PHU networks can be finely tuned in the 20-40°C range and, consequently, affords shape memory recovery at body temperature. In addition, these networks revealed hydro-lysable over a few months and may find uses as bioresorbable templates for medical applications.

Benefit of the Reactive Extrusion in the Course of Polyhydroxyurethanes Synthesis by Aminolysis of Cyclic Carbonates

Replacing toxic isocyanates and petrobased reactants currently employed for polyurethane (PU) synthesis is nowadays a major concern. Among all possible routes to isocyanate-free PUs, aminolysis of ...

Experimental and theoretical assessment of the aminolysis of cyclo carbonate to form polyhydroxyurethanes

Polyurethanes (PU) is one of the most used polymers and finds its applications in many modern technologies. The use of not-environmental-friendly chemicals in the actual manufacturing process claims for new more sustainable synthetic strategies. One of these novel routes is the aminolysis of cyclic carbonates resulting in so-called polyhydroxyurethanes (PHU). So far, this ring opening polymerisation (ROP) was mainly investigated considering aliphatic amines. In this study, both aromatic and aliphatic amines without additional catalysts are studied and their reaction behaviours are compared. For this aim, the ROP reactions were monitored by FTIR and NMR spectroscopies. It turned out that aromatic amines do not react in opposition to aliphatic ones. To gain a deeper insight on the reactivity parameters related to this different reaction behavior, simple molecular models were studied by density functional theory methods. Aiming to assess the impact of different conformations and to determine a statistical mean value of the reaction energy molecular dynamic (MD) simulations of a large set of different conformations was sampled. Moreover, the detailed consideration of the electronic density, revealed that the lone pair of the amine nitrogen is delocalised along the π-system of the aromatic compounds. This positive mesomerie effect results in a planarisation of the amine group, in higher reaction barriers and, smaller reaction energies.

Non-Isocyanate Polyurethane Thermoplastic Elastomer: Amide-Based Chain Extender Yields Enhanced Nanophase Separation and Properties in Polyhydroxyurethane

Non-isocyanate polyurethane (NIPU) was synthesized via cyclic carbonate aminolysis using poly(ethylene oxide) (PEO)- and poly(tetramethylene oxide) (PTMO)-based soft segments, divinylbenzene dicyclocarbonate as hard segment, and diamine–diamide (DDA) chain extender. Characterization of the resulting segmented polyhydroxyurethanes (PHUs) reveals that the use of amide-based DDA chain extender leads to unprecedented improvements in nanophase separation and thermal and mechanical properties over segmented PHUs without DDA chain extender. With PEO-based soft segments, previously known to yield only phase-mixed PHUs, use of DDA chain extender yields nanophase-separated PHUs above a certain hard-segment content, as characterized by small-angle X-ray scattering. With PTMO-based soft segments, previously known to yield nanophase-separated PHUs with broad interphase, use of DDA chain extender produces nanophase-separated PHUs with sharp domain interphase, leading to wide, relatively temperature-independent rubbery ...

DFT investigation of the reaction mechanism for the guanidine catalysed ring-opening of cyclic carbonates by aromatic and alkyl-amines

The bifunctional activity (base/H-bond donor) of TBD allows understanding its higher efficiency compared to its methyl counterpart (MTBD) for the aminolysis of cyclic carbonates by amines.

Reprocessable polyhydroxyurethane networks exhibiting full property recovery and concurrent associative and dissociative dynamic chemistry via transcarbamoylation and reversible cyclic carbonate aminolysis

We developed reprocessable polyhydroxyurethane (PHU) networks with full property recovery and incorporating both associative and dissociative dynamic chemistry.

A study of cyclic carbonate aminolysis at room temperature: effect of cyclic carbonate structures and solvents on polyhydroxyurethane synthesis

In recent years, intensive research and development have been carried out for the synthesis of isocyanate free polyurethanes from the reaction between five-membered cyclic carbonates and amines to yield polyhydroxyurethanes (PHU).

Novel thermoplastic polyhydroxyurethane elastomers as effective damping materials over broad temperature ranges

Non-isocyanate thermoplastic polyhydroxyurethane (PHU) elastomers were synthesized from cyclic carbonate aminolysis using polytetramethylene oxide (PTMO) as soft segment and divinylbenzene dicyclocarbonate and three diamine chain extenders as hard segment with a range of hard-segment content. Characterization was done via Fourier transform infrared spectroscopy, small-angle X-ray scattering (SAXS), uniaxial tensile testing, and dynamic mechanical analysis (DMA). SAXS reveals that these PHUs possess nanophase-separated morphology with 10–20nm interdomain spacings. These PHUs display elastomeric response and tunable tensile properties with Young’s modulus ranging from 27 to 200MPa, tensile strength from 0.3 to 9.7MPa and elongation at break ranging up to greater than 2000%. DMA reveals that nanophase separation in these PHUs is accompanied by broad interphases having a wide range of local composition; this nanophase separation differs significantly from that manifested by thermoplastic polyurethane elastomer (TPU) due to hydrogen bonding of hydroxyl groups in the hard segments to the PTMO soft segment. These PHUs show very good damping performance with tan δ⩾0.30 over broad temperature ranges (⩾60°C), which are tunable through simple variation of hard-segment content and chain extender structures.

Nonisocyanate Thermoplastic Polyhydroxyurethane Elastomers via Cyclic Carbonate Aminolysis: Critical Role of Hydroxyl Groups in Controlling Nanophase Separation.

Thermoplastic polyhydroxyurethanes (PHUs) were synthesized from cyclic carbonate aminolysis. Because of the hydroxyl groups in PHU, the choice of soft segment has a dramatic influence on nanophase separation in polyether-based PHUs. Use of a polyethylene glycol-based soft segment, which results in nanophase-separated thermoplastic polyurethane elastomers (TPUs), leads to single-phase PHUs that flow under the force of gravity. This PHU behavior is due to major phase mixing caused by hydrogen bonding of hard-segment hydroxyl groups to the soft-segment ether oxygen atoms. This hydrogen bonding can be suppressed by using polypropylene glycol-based or polytetramethylene oxide (PTMO)-based soft segments, which reduce hydrogen bonding by steric hindrance and dilution of oxygen atom content and result in nanophase-separated PHUs with robust, tunable mechanical properties. The PTMO-based PHUs exhibit reversible elastomeric response with hysteresis, like that of conventional TPUs. Because of nanophase separation with broad interphase regions possessing a wide range of local composition, the PTMO-based PHUs also demonstrate potential as novel broad-temperature-range acoustic and vibration damping materials, a function not observed with TPUs.

Organocatalytic synthesis of (poly)hydroxyurethanes from cyclic carbonates and amines

The organocatalyzed aminolysis of cyclic carbonates to form (poly)hydroxyurethanes is an important reaction as an alternative to isocyanate based chemistries. In an effort to increase reaction rates between cyclic carbonates and amines to lower cure times and increase molecular weights, various organocatalysts were surveyed. Reaction rates between monofunctional model cyclic carbonates and amines were determined in the presence of a variety of organocatalysts, which operate under different mechanisms to promote the reaction. Of the catalysts investigated, TBD was the most potent, presumably due to its bifunctional activity. TBD was also used to promote step-growth polymerization between difunctional cyclic carbonates and amines. The polymers produced in the presence of TBD at room temperature were much higher in molecular weight than polymers produced in the absence of catalyst at both room temperature and at 80 °C.