Biobased, reprocessable, self-blown non-isocyanate polyurethane foams: Influence of blowing agent structure and functionality

Purwanto, Nathan S.; Chen, Yixuan; Torkelson, John M.

doi:10.1016/j.eurpolymj.2024.112775

Cited by 8 publications

(2 citation statements)

References 108 publications

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“…In order to precisely identify the sol-gel transition, the gel time, tgel, was determined using the Winter-Chambon criterion (detailed procedure in ESI, section 1.2). 15,[35][36][37][38][39] According to this criterion, the relaxation modulus of the network at the gel point, also called the critical gel, follows a power law: G(t) ~ 𝑡 !" , where t is the time and n is called the critical exponent.…”

Section: Resultsmentioning

confidence: 99%

The multifaceted role of water as an accelerator of the crosslinking reaction of isocyanate-free polyurethane net-works

Monie,

Vidil,

Grau

et al. 2024

Preprint

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Polyhydroxyurethane (PHU) thermosets are the most promising isocyanate-free substitutes to polyurethane ones when targeting the main applications of the PU business (coatings, adhesives, foams). However, the curing of their solvent-free formulations at near room temperatures is often very slow and requires the utilization of organocatalysts, limiting the large-scale deployment of the technology. Herein, we study the impact of water, introduced as an additive (2 to 10 wt.%), on the crosslinking rate of common solvent-free thermosetting PHU formulations composed of a polycyclic carbonate and a diamine. Rheology measurements, using a multi-frequency approach, indicate that even very small amounts of water (< 5 wt.%) impressively shorten gel times, by up to 5 folds at 40 °C. The multi-frequency methodology highlights for the first time the strong interactions of water with the growing PHU network during the crosslinking reaction. It suggests that water breaks down the multiple intra-/inter-molecular H-bond interactions within the PHU clusters, consequently enhancing the molecular mobility and delaying the vitrification (hydroplasticization), both phenomena contributing to accelerate the crosslinking rate. On top of that, through a combination of model reactions and computational calculations, we demonstrate that water is an actual catalyst of the cyclic carbonate aminolysis. Eventually, thanks to its multifaceted role, water can efficiently substitute the organocatalysts (e.g. TBD, DBU) usually required to cure PHU formulations at near ambient temperature. This work demonstrates that the use of additive amounts of water in solvent-free formulations is a cost-effective, non-toxic, and robust solution to accelerate the production of PHU materials, free of any organocatalyst. It offers promising prospects for the deployment of PHU-based materials requiring mild processing conditions.

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Section: Resultsmentioning

confidence: 99%

The multifaceted role of water as an accelerator of the crosslinking reaction of isocyanate-free polyurethane net-works

Monie,

Vidil,

Grau

et al. 2024

Preprint

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show abstract

“…Polyurethane (PU) has a very wide range of mechanical properties, such as excellent elasticity, toughness, and abrasion resistance, because its chemical structure and composition can be easily changed . PU has become the sixth-largest synthetic material in the world andis widely used in the fields of transport, construction, petrochemical, light industry, textile, electromechanics, electronics, aerospace, healthcare, and agriculture. − Generally, PU is synthesized from the polyaddition reaction of polyols and isocyanates, which are highly toxic and harmful to the environment and human health. − Phosgene is a highly reactive and readily available reagent for the production of isocyanates. However, phosgene is highly toxic and corrosive. , In addition, most raw materials for the preparation of PU are petroleum-based and nonrenewable.…”

Section: Introductionmentioning

confidence: 99%

Nonisocyanate Polyurethanes Originated from Biobased Isosorbide with Good Combined Properties

Song,

He,

Xie

et al. 2024

ACS Appl. Polym. Mater.

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Polyurethane (PU) is conventionally synthesized via the isocyanate route, which has been widely reported to be hazardous to the environment and humans. Consequently, there is an urgent need to develop an environmentally friendly method for the preparation of nonisocyanate polyurethanes (NIPUs). Herein, a green nonisocyanate synthetic route to polyurethane, originating from dimethyl carbonate, 1,6-hexanediamine, 1,6-hexanediol, and rigid biobased isosorbide is introduced to enhance the mechanical properties and heat deflection temperature of NIPUs. A series of biobased isosorbide nonisocyanate polycarbonate-based polyurethanes (ISPCUs) were synthesized by adjusting the isosorbide content in the hard segments. The results show that the rigid ring structure of isosorbide enhances the mechanical and thermal properties of PU. Notably, the melting point of ISPCUs increased from 93 to 119 °C, and the heat deflection temperature has been enhanced to 85 °C from 41 °C of NIPUs without isosorbide. The mechanical properties improved substantially, especially the tensile strength, which increased evidently from 18 MPa of PU to 65 MPa of ISPCUs. This work provides a method to synthesize biobased NIPUs with exceptional heat resistance and mechanical properties.

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Biobased, catalyst-free non-isocyanate polythiourethane foams: Highly dynamic nature affords fast reprocessability, extrudability and refoamability

Chen,

Purwanto,

Chen

et al. 2024

Chemical Engineering Journal

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Biobased, reprocessable, self-blown non-isocyanate polyurethane foams: Influence of blowing agent structure and functionality

Cited by 8 publications

References 108 publications

The multifaceted role of water as an accelerator of the crosslinking reaction of isocyanate-free polyurethane net-works

The multifaceted role of water as an accelerator of the crosslinking reaction of isocyanate-free polyurethane net-works

Nonisocyanate Polyurethanes Originated from Biobased Isosorbide with Good Combined Properties

Biobased, catalyst-free non-isocyanate polythiourethane foams: Highly dynamic nature affords fast reprocessability, extrudability and refoamability

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