Linear Polyurethanes Research Articles

Nanofiber anchoring graphene oxide/N-halamine nanocomposites to construct multi-dimensional blended yarns for renewable and high-efficiency antibacterial textiles

Antibacterial textiles possess a crucial application in personal and public health protection. However, limited by antibacterial materials and processing methods, traditional antibacterial textiles still suffer from low antibacterial efficiency and poor durability. Herein, an preparation strategy of novel multi-dimensional blended yarn with efficient and renewable antibacterial properties was proposed.A precursor of high antibacterial activity N-halamine, 6-phenyl-1,3,5-trialkane-2,4-dione (PTD), was synthesized. PTD was grafted onto polyethyleneimine (PEI)-modified graphene oxide (GO) to form a novel nanocomposite antibacterial material (GO-PEI-PTD) with high active chlorine loading and stability. Utilizing alternating configurations of linear electrostatic spinning modules, GO-PEI-PTD and polyurethane nanofibers were simultaneously sprayed onto cotton webs and further spun into GO-PEI-PTD yarns. GO-PEI-PTD nanosheets are tightly wrapped around nanofibers or entangled in the nanofiber networks, achieving a solid combination of antibacterial agent on the yarn. The prepared antibacterial fabric shows rapid and efficient antibacterial properties. The inhibition rate of E. coli and S. aureus is up to 99.99% after 50 times of washing. High activated chlorine content(3700 ppm) and tensile strength(30.77 MPa) after 10 cycles of chlorination indicate its excellent reusability. The multi-dimensional blended yarn developed by multicomponent alternating electrospinning provides an ideal strategy for the development of high-performance functional textiles.

Intrinsic photothermal phase change materials with enhanced toughness and flexibility for thermal management in extreme environments

Polymeric solid–solid phase-change materials (SSPCMs) are capable of reversibly absorbing or releasing high latent heat and have been widely studied for thermal energy storage (TES) due to their excellent shape stability and certain mechanical properties. The photothermal fillers were introduced to impart SSPCMs with photo-responsive ability. However, the incompatibility interface between fillers and SSPCMs matrix always causes serious deterioration of mechanical toughness and flexibility. Herein, we report an intrinsic photothermal SSPCM by incorporating a reactive photothermal agent (dihydroxy naphthalene (DN)) into linear polyurethane SSPCMs. The prepared SSPCMs have adjustable phase transition enthalpy and temperature as well as long-term cycle stability. The highest efficiency of SSPCM in near-infrared photothermal conversion including sensible and latent heat is 59.7 %, and the solar photothermal conversion efficiency is 48.1 %. Moreover, SSPCMs exhibit superior mechanical toughness of 193 MJ/m3 and flexibility, which can withstand repeated rotation, folding and stretching. The SSPCMs developed in this work can enable the human body to obtain the heat needed for life through photothermal conversion in extreme environments such as the Arctic, increasing the probability of survival. Therefore, this study provides a facile strategy for fabricating intrinsic photothermal SSPCMs with high toughness and flexibility properties, which have great potential in wearable device for thermal management in extreme environments.

Vitrimerization of Linear Polyurethane via Group Revival-Induced Crosslinking

Vitrimerization of Linear Polyurethane via Group Revival-Induced Crosslinking

Reprocessing and shape recovery of polyurethane enabled by crosslinking with poly(β-cyclodextrin) via host-guest interactions

A 1,3-diol bearing an 18-carbon alkyl chain was synthesized via the esterification of stearyl alcohol with 2,2-bis(hydroxymethyl)propionic acid. This 1,3-diol was employed as the chain extender to synthesize a linear multi-segmented polyurethane (PU) carrying long alkyl side chains. It was found that the linear PU was readily crosslinked with poly(β-cyclodextrin) [viz. P(β-CD)], i.e., the supramolecular networks were obtained. The supramolecular crosslinking was generated via the inclusion complexation of P(β-CD) with the long alkyl chains of PU. The more the incorporation of P(β-CD), the higher the crosslinking densities. Compared to the linear PU, the PU-CD networks had the enhanced Yong's moduli and tensile strengths. Thanks to the supramolecular crosslinking, the PU-CD networks had the shape memory properties. It was found that the recovery of shape was quite dependent on the quantity of the inclusion complexation linkages. In addition, the PU-CD networks can be reprocessed (or recycled); the reprocessed PU-CD networks had the recovery of mechanical properties as high as 95%. The dynamic exchange of inclusion complexation is responsible for the reprocessing properties. Furthermore, the reprocessing behavior was successfully utilized to reprogram the original shapes of the shape memory networks.

Synthesis of segmented polyurethanes based on furazan units

Linear polyurethane thermoplastics comprising furazan blocks soluble in organic solvents and having low melting points were obtained by nonequilibrium polycondensation of 3,4-bis(hydroxymethyl)furazan, butane-1,4-diol and 2,4-di-isocyanatotoluene. The thermal behavior of some copolymers was studied by DSC and TGA methods.

A Strategy of Thiolactone Chemistry to Construct Strong and Tough Self-Healing Supramolecular Polyurethane Elastomers via Hierarchical Hydrogen Bonds and Coordination Bonds

Self-healing elastomers with extended service life and enhanced reliability have attracted extensive attention in recent years due to their broad application in fields such as protective coatings, wearable electronics, shape memory materials, and health-care monitoring. However, it is challenging to simultaneously optimize the mechanical properties (strength and toughness) and self-healing capacity of the elastomers. Herein, thiolactone chemistry was delicately used as a bridge to address this conundrum by incorporating 2-ureido-4[1H]-pyrimidinone (UPy) motifs and imidazole ligands into the side chains of linear polyurethane. The synergistic cross-linking of UPy H-bonds and Zn2+-imidazole coordination afforded a robust supramolecular network to significantly improve the strength. Meanwhile, these dynamic cross-linking points acted as sacrificial bonds for energy dissipation under external stress, which played a dominant role in toughening. Therefore, the resultant elastomer (PU-Im-UPy-Zn) exhibited a tensile strength of 9.1 MPa, a breaking elongation of 989%, and toughness up to 62.1 MJ m–3. In addition, the reversible exchange of hierarchical hydrogen bonds (single H-bonds between the carbamate groups and quadruple H-bonds of the UPy dimers) and coordination bonds as well as the high mobility of side chains were conducive to repairing under mild conditions. The superficial scratches completely disappeared at 60 °C, and a satisfactory healing efficiency of 78% was observed after 24 h. This work provides some insights into future design of self-healable supramolecular polyurethane elastomers integrated with conspicuous strength and toughness.

A thermodynamic study on relationship between gas separation properties and microstructure of polyurethane membranes

The lattice fluid (LF) thermodynamic model and extended Vrentas’ free-volume (E-VSD) theory were coupled to study the gas separation properties of the linear thermoplastic polyurethane (TPU) membranes with different chemical structures by analyzing their microstructures. A set of characteristic parameters were extracted using the repeating unit of the TPU samples and led to prediction of reliable polymer densities (AARD < 6%) and gas solubilities. The viscoelastic parameters, which were obtained from the DMTA analysis, were also estimated the gas diffusion vs. temperature, precisely. The degree of microphase mixing based on the DSC analysis was in order: TPU-1 (4.84 wt%) < TPU-2 (14.16 wt%) < TPU-3 (19.92 wt%). It was found that the TPU-1 membrane had the highest degree of crystallinity, but showed higher gas solubilities and permeabilities because this membrane has the least degree of microphase mixing. These values, in combination with the gas permeation results, showed that the content of the hard segment along with the degree of microphase mixing and other microstructural parameters like crystallinity were the determinative parameters.

Polymer/Layered Clay/Polyurethane Nanocomposites: P3HB Hybrid Nanobiocomposites-Preparation and Properties Evaluation.

This paper presents an attempt to improve the properties of poly(3-hydroxybutyrate) (P3HB) using linear aliphatic polyurethane (PU400) and organomodified montmorillonite (MMT)-(Cloisite®30B). The nanostructure of hybrid nanobiocomposites produced by extrusion was analyzed by X-ray diffraction and transmission electron microscopy, and the morphology was analyzed by scanning electron microscopy. In addition, selected mechanical properties and thermal properties were studied by thermogravimetric analysis, TGA, and differential scanning calorimetry, DSC. The interactions of the composite ingredients were indicated by FT IR spectroscopy. The effect of the amount of nanofiller on the properties of prepared hybrid nanobiocomposites was noted. Moreover, the non-equilibrium and equilibrium thermal parameters of nanobiocomposites were established based on their thermal history. Based on equilibrium parameters (i.e., the heat of fusion for the fully crystalline materials and the change in the heat capacity at the glass transition temperature for the fully amorphous nanobiocomposites), the degree of crystallinity and the mobile and rigid amorphous fractions were estimated. The addition of Cloisite®30B and aliphatic polyurethane to the P3HB matrix caused a decrease in the degree of crystallinity in reference to the unfilled P3HB. Simultaneously, an increase in the amorphous phase contents was noted. A rigid amorphous fraction was also denoted. Thermogravimetric analysis of the nanocomposites was also carried out and showed that the thermal stability of all nanocomposites was higher than that of the unfilled P3HB. An additional 1% mass of nanofiller increased the degradation temperature of the nanocomposites by about 30 °C in reference to the unfilled P3HB. Moreover, it was found that obtained hybrid nanobiocomposites containing 10 wt.% of aliphatic polyurethane (PU400) and the smallest amount of nanofiller (1 wt.% of Cloisite®30B) showed the best mechanical properties. We observed a desirable decrease in hardness of 15%, an increase in the relative strain at break of 60% and in the impact strength of 15% of the newly prepared nanobiocomposites with respect to the unfiled P3HB. The produced hybrid nanobiocomposites combined the best features induced by the plasticizing effect of polyurethane and the formation of P3HB-montmorillonite-polyurethane (P3HB-PU-MMT) adducts, which resulted in the improvement of the thermal and mechanical properties.

The characteristics and mechanism of hydrogen bonding assembly in linear polyurethane with multiple pendant 2‐ureido‐4[1H]‐pyrimidone units

Abstract2‐Ureido‐4[1H]‐pyrimidone (UPy) can form strong quadruple hydrogen bonding (H‐bonding) and is widely used to construct supramolecules. Though the H‐bonding assembly of UPy‐containing polymers has been widely reported, little attention is paid to the H‐bonding characteristics and mechanism of UPy‐containing polyurethanes. Here, by using UPy‐p‐PDLLA‐SMPU, a linear polyurethane with multiple pendant UPy units as the model polymer, the H‐bonding assembly characteristics in solution, solid film and melt are systematically investigated. It is found that the UPy units mainly exist as free monomers in DMSO, UPy dimers in CHCl3, and both free monomers and dimers in DMF. The dimerization of UPy can promote the H‐bonding of urea and urethane groups and thus the formation of hard segment aggregates. Thereby, the thermal resistance and reversibility of the H‐bonds are significantly enhanced in both UPy‐p‐PDLLA‐SMPU film and melt. UPy‐p‐PDLLA‐SMPU can transition from a rubber state (70°C–85°C) to a viscous flow state (≥120°C), presenting the characteristics of both chemically crosslinked and linear polyurethanes. This work provides a clear picture on the H‐bonding assembly of UPy units together with urea and urethane groups in UPy‐p‐PDLLA‐SMPU. The obtained assembly characteristics and mechanism are beneficial for the design and processing of UPy‐based physically crosslinked polyurethanes.

New polyurethanes containing cycloaliphatic units in the hard segments. The influence of the microstructure on the thermo‐mechanical and surface properties

AbstractNew linear and cross‐linked polyurethanes with cycloaliphatic units and renewable cross‐linkers (Span 20 and Tween 20) were obtained by two steps polyaddition reaction. The degree of microphase separation was calculated by FTIR‐ATR spectroscopy with higher values for the linear polyurethane with the highest hard segment content (0.88) and lower values for the cross‐linked polyurethane with Tween 20 as cross‐linker (0.35). The results were in accordance with the DSC analysis. The linear or cross‐linked character of the polyurethane structure influenced the thermal, mechanical, and surface properties. The obtained polyurethanes had good thermal stability, with a 5% mass loss at 321°C (HMC 1) and 329°C (HMC 2) for linear polyurethanes and 330°C (HMC 3) and 342°C (HMC 4) for the cross‐linked ones. The morphology and wettability of the cycloaliphatic polyurethanes presented different behavior depending on the amount of the hard segment content and also the chemical structure of the cross‐linker. Linear polyurethanes were characterized by a globular morphology and hydrophobic character, while the use of Tween 20 as cross‐linker led to a fibrillar morphology with a low water contact angle (62°). Mechanical measurements showed that all polyurethanes present elastomeric behavior with high tensile strength values for the linear polyurethanes (33 MPa for HMC 1 and 39 MPa for HMC 2) and lower values of tensile strength for the cross‐linked ones (12 MPa for HMC 3 and 11 MPa for HMC 4), but high elongation at break for all samples (780%–1100%).

Self-healed microcracks in polymer bonded explosives via thermoreversible covalent bond and hydrogen actions

Polymeric materials used for the polymer bonded explosive (PBX) or other energetic composite materials (ECMs) that simultaneously possess excellent mechanical properties and high self-healing ability, convenient healing, and facile fabrication are always a huge challenge. Herein, self-healing linear polyurethane elastomers (PTMEG2000-IPDI-DAPU, denoted as 2I-DAPU) with high healing efficiency and mechanical properties were facilely fabricated by constructing reversible covalent bonds and dynamic hard domains into polymer chains. Furthermore, a TATB-based PBX using as-prepared 2I-DAPU polymer as the binder was constructed, disclosing an excellent self-healing property to heal cracks generated during fabrication, transportation and storage. The damage healing manner of such a PBX sample was investigated by means of prefabricated damage through mechanical load, heal treatment via heating at high temperature, and CT-scanning the inner structure and mechanical property characterization via Brazilian test. The self-healing mechanism of internal damage in PBX was preliminarily explored. We propose that this 2I-DAPU binder with Diels-Alder bonds could generate plentiful active surface groups resulting from damage and drive self-healing at fitting temperature and increase the slightly packed hard phase via incorporating a small amount of hydrogen bonds. This work may offer a novel strategy for improving mechanical property and healing ability in the field of self-healing material which could help expand its applications with enhanced versatility in mechanical-enhanced functional materials.

Organic-inorganic composite polyurethane vitrimers with high toughness, self-healing ability and recyclability

Polyurethanes (PUs) have become a class of promising and popular materials in households and industries due to its versatility in chemistry. The combination of self-healing ability, reprocessability with high strength and great toughness for PUs is highly desired in the practical applications, which remains a challenge as the mechanisms for the above properties are normally conflictive. Herein, we proposed a novel concept of PU vitrimers with superb mechanical properties, improved solvent resistance and excellent recyclability. Specifically, linear PUs with maleimide pendant groups was covalently crosslinked with the dithiol-bearing boronic ester cross-linker through thiol-ene “click” chemistry reaction, forming a self-healable and recyclable PU vitrimer network. Furthermore, 2-ureido-4-[1H]-pyrimidione (UPy) motifs capable of forming quadruple hydrogen bonds as the physical cross-linkages were successfully introduced into the vitrimer network, significantly enhancing the mechanical properties. Finally, 2.5 wt% of SiO2 nanofillers functionalized with UPy motifs (SiO2-UPy) were added into the polymer matrices to further improve the mechanical properties of PU vitrimers. Due to the strong interfacial interactions via H-bonds between SiO2-UPy nanofillers and UPy motifs in the PU chains, the PU vitrimer composites exhibited excellent comprehensive performance, including high strength (∼60 MPa) and great toughness (520 MJ m−3) without sacrificing the elongation at break (∼2500 %), excellent self-healing ability and recyclability. Overall, this study offers a strategy to achieve comprehensive enhancement of mechanical properties as well as self-healing/recycling ability with the incorporation of dynamic covalent and non-covalent bonds, which would forward the broad applications of PUs in various industrial scenarios.

Microplastics can affect soil properties and chemical speciation of metals in yellow-brown soil

Although the influence of microplastics (MPs) in different soil environments has been investigated, their effects on the physiochemical properties and chemical speciation of heavy metals in yellow-brown soil remains unknown. This study aimed to determine the effects of various concentrations of linear low-density polyethylene (LLDPE), polyamide (PA), polyurethane (PU), polystyrene (PS), and low-density polyethylene (LDPE) MPs on the yellow-brown soil environment and chemical speciation of the heavy metals cadmium (Cd), copper (Cu), lead (Pb), and zinc (Zn). MPs influenced the physicochemical properties and chemical speciation of heavy metals in yellow-brown soil. The physicochemical properties of yellow-brown soil can be altered by changing the concentrations of LDPE MP. The relationship between changes in field capacity (FC) and LDPE concentrations was approximately linear. The physiochemical properties of yellow-brown soil containing added PA, PU, and LDPE MPs were substantially improved (control vs. MPs): FC, 39 % vs. 42.50 % for PU, cation exchange capacity (CEC) 45.77, 56.65, and 57.44 cmol.kg−1 for PA, PU, and LDPE respectively, and organic matter (OM) content, 40.16 vs. 51.68 g.kg−1 for PA. The LLDPE and PU MPs also simultaneously affected the chemical speciation of heavy metals in yellow-brown soil. The LLDPE MPs increased the acid-soluble (45.17–54.67 % (Cd-F1), 7.24–11.30 % (Cu-F1), 4.20–7.23 % (Pb-F1), 21.21–31.47 % (Zn-F1)) and reducible (24.02–29.41 % (Cd-F2), 25.69–34.95 % (Cu-F2), 74.29–81.07 % (Pb-F2), 28.77–34.19 % (Zn-F2)) fractions of heavy metals, which increased their bioavailability. However, PU MPs reduced the ecological risk of heavy metals in yellow-brown soil by increasing the content of the residual fraction (26.11–40.21 % (Cd-F4), 47.63–59.67 % (Cu-F4), 17.25–26.76 % (Pb-F4), 32.63–50.46 % (Zn-F4)). Changes in the properties of yellow-brown soil and the impact of MPs on heavy metals, might change the chemical speciation of heavy metals. The impact of MPs on heavy metals in yellow-brown soil requires further investigation.

Synthesis and Properties of Thermally Self-Healing PET Based Linear Polyurethane Containing Diels-Alder Bonds.

A Diels–Alder (DA) bond containing poly(tetrahydrofuran)-co-(ethyleneoxide) (PET) based linear polyurethane (PET-DA-PU) was synthesized via a prepolymer process using PET as raw material, DA diol as chain extender agent, and toluene-2,4-diisocyanate (TDI) as coupling agent. The structure of PET-DA-PU was characterized by attenuated total reflectance-Fourier transform-infrared spectroscopy (ATR-FTIR), proton nuclear magnetic resonance spectrometry (1H NMR) and carbon nuclear magnetic resonance spectrometry (13C NMR). The thermal performance and self-healing behavior of PET-DA-PU were investigated by differential scanning calorimetry (DSC), polarized optical microscope, universal testing machine, scanning electron microscopy (SEM) and NMR, respectively. The glass transition temperature of PET-DA-PU was found to be −59 °C. Under the heat treatment at 100 °C, the crack on PET-DA-PU film completely disappeared in 9 min, and the self-healing efficiency that was determined by the recovery of the largest tensile strength after being damaged and healed at 100 °C for 20 min can reach 89.1%. SEM images revealed the micro-cracks along with the blocky aggregated hard segments which were the important reasons for fracture. NMR spectroscopy indicated that the efficiency of retro DA reaction of PET-DA-PU was 70% after 20 min heating treatment at 100 °C. Moreover, the PET-DA-PU/Al/Na2SO4 composite was also prepared to simulate propellant formulation and investigated by universal testing machine and SEM; its healing efficiency was up to 87.8% under the same heat treatment process and exhibits good self-healing ability. Therefore, PET-DA-PU may serve as a promising thermally self-healing polymeric binder for future propellant formulations.

Turning a linear waterborne polyurethane into a crosslinked counterpart with improved water resistance and mechanical strength through a fast post metal-organic crosslinking

ABSTRACT Covalent crosslinking can improve the water resistance of waterborne polyurethanes (WPUs), but the preparation time of WPUs will be greatly extended by the crosslinking process, and the long-term storage stability of WPU emulsions will decrease because the crosslinked molecular chains cannot disperse in any organic solvents or water. In this paper, a crosslinked WPU was prepared through a post metal-organic crosslinking toward a conventional linear WPU. This post crosslinking is quite fast since it is based on the ionic bond interaction between metal cations and organic anions. The crosslinked WPU emulsion has narrow particle size distribution and small average size, giving rise to excellent long-term storage stability. Additionally, the water absorptions of the crosslinked WPU at 25°C and 60°C are 6.3% and 8.6% respectively, which decrease by 47.9% and 39.4% compared with those of the linear counterpart, indicating that the post metal-organic crosslinking highly improves the water resistance of the WPU. The mechanical strength of the crosslinked WPU also improves compared with the linear WPU.

ISO2‐PU Honeycomb Porous Films with a Peculiar Crystalline Structure by the Breath Figure Method Promote Osteogenic Differentiation of Stem Cells

AbstractThe breath figure (BF) method is a handy strategy to prepare porous films. Linear shape memory polyurethanes (SMPUs) are among the most promising polymers for bone repair or regeneration. However, little attention has been paid to the fabrication of SMPU films by using the BF method. In this work, an amorphous SMPU containing isosorbide (ISO) in the long‐chain hard segments (ISO2‐PU) is fabricated into honeycomb porous films. Strikingly, a peculiar crystalline structure with a “Z” configuration and highly regional orientation is formed on the hexagonal holes of the porous films, which results in significantly enhanced mechanical properties. Moreover, the ISO2‐PU honeycomb porous films can markedly accelerate the osteogenic differentiation of rat mesenchymal stem cells, indicating that the porous films have great potentials as bone repair materials. It is further speculated that the Marangoni effect in the condensed water droplets and the molecular assembly of ISO2‐PU due to the strong hydrogen bonds and the chiral center effect of ISO are key contributors. This work, to the best of authors’ knowledge, is the first time that this special crystalline structure on BF‐based porous films is observed and also the first speculation that combines Marangoni effect with the microstructure of BF‐based porous films.

Dynamic Urea Bond‐Mediated Polymerization for Solvent‐Free Low‐ Ð Linear Polyurethanes of Controlled Molar Mass: Hypothesis of Diffusion Control

Dynamic urea bond-mediated polymerization (DUBMP) has been employed for the synthesis of linear, branched, telechelic, and random-block polyurethanes (PUs) with low molar-mass dispersity relative to conventionally synthesized PUs (Đ < 1.5). However, the reason for the improved control of the molar mass and reduction in dispersity, promoted by DUBMP, has not been explained. In this paper, the DUBMP synthesis of linear PU based on low-molar-mass poly(ethylene glycol) (PEG) and isophorone diisocyanate is studied comprehensively. The lower viscosity of the PEG-based PU allows DUBMP to reach high conversions (≈0.97) for the first time, while molar mass and Đ vary substantially with reaction conditions, despite yielding similar/equal conversion values. Both molar mass and Đ increase with an increase in reaction temperature, or with a reduction of the amine/isocyanate molar ratio. Therefore, evidence suggests that DUBMP provides diffusion control due to the lower mobility of the longer chains associated with an isocyanate-deactivator-rich environment. An increase in the reaction temperature, and/or a decrease in the amine/isocyanate molar ratio, reduces the diffusion control, leading to higher Đ values and molar mass. Tuning of the reaction conditions allows obtaining PU of controlled molar mass (11 kDa ≤ Mw ≤ 42 kDa) and 1.3 < Đ < 1.75.

Linear polyurethane ionenes for stable interlayer of organic photovoltaics

Non-conjugated polymer electrolytes (nCPEs) are applied as electron transporting layers (ETLs) in organic photovoltaic (OPV) devices with conventional structures and used as competent interfacial layers. The new nCPEs are prepared from dihydroxyl pyrrolidinium bromide ionic liquid monomers and m-diphenylene diisocyanate to create linear polyurethane ionenes with main-chain ionic salt moieties. The ultraviolet photoelectron spectroscopy (UPS) results reveal that the formation of an interfacial dipole by the nCPEs facilitates electron transfer from the photoactive layer to the electrode. The OPV devices with the new nCPEs show a power conversion efficiency (PCE) comparable to that with the well-known conjugated polymer electrolyte poly(9,9-bis(3’-(N,N-dimethyl)-N-ethylammoinium-propyl-2,7-fluorene)-alt-2,7-(9,9-dioctylfluorene))dibromide (PFN), which possesses charged sites on its pendants, as an ETL. The OPV device with the synthesised nCPE exhibits superior stability compared to the PFN-based OPV devices. Our results suggest that the nCPEs containing ionic salt structures on polymer main chains are more suitable ETLs for OPV devices than PFN-based layers with pendant salt moieties.

Upcycling Polytetrahydrofuran to Polyester

Upcycling Polytetrahydrofuran to Polyester

Near-infrared radiation and heat dual-induced self-healing polyurethane with anti-abrasion ability

Disulfide bonds are widely used in self-healing materials owing to their dynamic nature under mild conditions. However, their practical application is severely limited by their low tensile strength. In this work, a linear polyurethane (CHPU) containing disulfide bonds and crystalline polycaprolactone diol is designed and synthesized. The infiltration of polypyrrole (PPy) nanoparticles endows the CHPU/0.5PPy nanocomposites with a high tensile strength (26.23 MPa), high toughness (119.71 MJ/m3), and a remote self-healing ability that can be triggered by heat or low-intensity (near-infrared) NIR radiation. A cut CHPU/0.5PPy film can recover 77.35% and 64.77% of its original tensile strength under 808 nm NIR radiation (118.46 mW/cm2) and 50 °C, respectively. In addition, CHPU/0.5PPy can bear 300 reciprocating linear abrasion cycles (0.5 N load force) with a stable friction coefficient, delivering a performance superior to those of many commercial anti-abrasion polyurethane coatings.