Versatile ionic liquid gels formed by dynamic covalent bonding and microphase separated structures

It is challenging for ionic liquid gels to achieve the combination of rapid self-healing with high toughness. Here, ionic liquid gels (DI-PR) were prepared from readily available materials. A dynamic covalently bonded oxime-carbamate was prepared from polycaprolactone diol, isophorone diisocyanate and dimethylethyleneglyoxime, followed by addition of the "rigid-flexible" cross-linking agent rutin to chemically cross-link the polymer chains and afford the ionic liquid gels, DI-PR. The tensile strength, elongation at break and toughness of the DI-PR gels were as high as 16.5 MPa, 1132.6%, and 52.6 MJ m-3, respectively. The toughness is similar to that of natural silkworm silk (70 MJ m-3) and wool (60 MJ m-3). After stretching, the DI-PR can rebound within 1 s, their room temperature self-healing rate is as high as 92%, they remain functional over the temperature range -50 °C to 140 °C and the interface with a steel plate has an adhesion toughness of >2000 J m-2. These properties mean that the DI-PR gels are particularly suitable for use as anticorrosion coatings for submarine and underground gas and oil pipelines. The use of rutin, which combines rigid quercetin-based structural units with flexible glycoside-based structural units, as a cross-linking agent, provides a new method for improving the toughness of soft materials through its synergistic interaction with hard and soft chain fragments of polyurethanes.

Optically healable polyurethanes with tunable mechanical properties

The mechanical properties of polyurethanes can be nicely tuned by UV irradiation in a reversible way, endowing the polyurethanes with optical healing properties.

Forward and reverse reactions of N-methylaniline-blocked polyisocyanates: a clear step into double Arrhenius plots and equilibrium temperature of thermally reversible reactions

In this paper we report, the reaction parameters playing a vital role in the preparation and applications of industrially importantN-methylaniline blocked polyisocyanates.

Research on the Thermal Decomposition Reaction Kinetics and Mechanism of Pyridinol-Blocked Isophorone Diisocyanate

A series of pyridinol-blocked isophorone isocyanates, based on pyridinol including 2-hydroxypyridine, 3-hydroxypyridine, and 4-hydroxypyridine, was synthesized and characterized by ¹H-NMR, ¹³C-NMR, and FTIR spectra. The deblocking temperature of blocked isocyanates was established by thermo-gravimetric analysis (TGA), differential scanning calorimetry (DSC), and the CO₂ evaluation method. The deblocking studies revealed that the deblocking temperature was increased with pyridinol nucleophilicity in this order: 3-hydroxypyridine > 4-hydroxypyridine > 2-hydroxypyridine. The thermal decomposition reaction of 4-hydroxypyridine blocked isophorone diisocyanate was studied by thermo-gravimetric analysis. The Friedman–Reich–Levi (FRL) equation, Flynn–Wall–Ozawa (FWO) equation, and Crane equation were utilized to analyze the thermal decomposition reaction kinetics. The activation energy calculated by FRL method and FWO method was 134.6 kJ·mol⁻¹ and 126.2 kJ·mol⁻¹, respectively. The most probable mechanism function calculated by the FWO method was the Jander equation. The reaction order was not an integer because of the complicated reactions of isocyanate.

Synthesis and studies on forward and reverse reactions of phenol-blocked polyisocyanates: an insight into blocked isocyanates

Industrially important blocked polyisocyanates were studied in detail using a hot-stage FT-IR spectrophotometer adapting to neat conditions with an aim to resolve complex questions on the relationship between forward and reverse reaction parameters.

Novel Polyurethane Electrical Insulator Coatings Based on Amide-Ester-Ether Polyols Derived from Castor Oil and Re-cycled Poly(ethylene terphthalate)

In order to utilize renewable resource raw materials as well as trying to recycle polymeric materials, three new polyols (PEEA1-3) were prepared. Bottle grade recycled poly(ethylene terphthalate) was subjected to transesterification and an amidation reaction with different molecular weights of poly(ethylene glycol) and diethanol amine. The intermediate hydroxyl-terminated compounds were chain extended via an esterification reaction with adipic acid and the products were reacted with castor oil. Polyurethane networks were prepared through the reaction of PEEA1-3 with librated isocyanate groups of a blocked isocyanate curing agent made from trimethylol propane, toluene diisocyanate and N-methyl aniline. All of the starting materials and final cured films were characterized by conventional methods. The curing condition was optimized via gel content measurements. The crosslink density of the samples was determined via an equilibrium swelling method, using the Flory-Rehner equations. The effects of structural parameters on the physical, electrical, mechanical, and dynamic mechanical properties of the polyurethane coatings were evaluated. Investigation of the results showed that the prepared green coatings have environmental benefits as well as high performance as metal insulator coatings.