Bio-based Waterborne Polyurethanes Research Articles

Ultra-tough, strong and transparent bio-based waterborne polyurethanes with exceptional anti-corrosion properties

Waterborne polyurethane (WPU) is increasingly favored because of its affordability, eco-friendliness, and water-based storage convenience. However, the inclusion of hydrophilic groups can diminish its mechanical strength and water resistance. Herein, we synthesized a range of bio-based waterborne polyurethanes that exhibit superior mechanical properties, transparency, and corrosion resistance using economical and sustainable bio-based poly(trimethylene ether) glycol (PO3G), isophorone diisocyanate (IPDI), and poly(propylene glycol) (PPG) as raw materials. We explored how varying the PO3G content affects the properties of these bio-based WPU emulsions and films. The findings revealed that films with over 30% PO3G content demonstrated tensile strengths exceeding 10 MPa and maintained a high elongation at break (above 4000%), matching or surpassing existing bio-based WPU systems. The corrosion resistance of these films was also exceptional, with a high inhibition efficiency (above 99.97%). This research introduces a new approach for creating high-performance bio-based WPUs with promising applications in coatings, leather, and biomedical materials.

A concise strategy for enhancing the performance of bio-based polyurethane aerogels using melamine-modified sodium alginate via Aza-Michael addition reaction

Bio-based waterborne polyurethane (PU) has garnered significant attention as a sustainable alternative petroleum-derived counterpart, offering environmentally friendly alternatives. In this work, a new approach is proposed to fabricate two kinds of composite aerogels of lowly/highly melamine-modified sodium alginate (SAML/SAMH) with methacrylate-terminated PU (SAML-PU and SAMH-PU) through dynamic covalent cross-linking via Aza-Michael addition reactions. We aim to improve the poor compatibility of polysaccharide and PU associated with traditional blending methods and impart the resulting aerogels with good biodegradability, compressive strength, thermal insulation, flame-retardant, and self-healing. Comprehensive characterizations, including Fourier transform infrared spectroscopy, nuclear magnetic resonance spectroscopy, Raman spectroscopy, and X-ray photoelectron spectroscopy collectively demonstrate the successful derivatization of alginate and the effective synthesis of the Aza-Michael addition copolymer involving derivate alginate and PU. Substantial improvements in compressive strength and thermal properties are realized at comparable densities. Higher compressive strength, higher decomposition temperature and lower thermal conductivity are significantly achieved for SAML-PU (0.35 MPa, 410 °C and 0.024 W/m/K at 0.13 g/cm3) and SAMH-PU (0.58 MPa, 427 °C and 0.022 W/m/K at 0.12 g/cm3) compared to pristine PU foams (0.15 MPa, 330 °C and 0.031 W/m/K at 0.15 g/cm3). Additionally, molecular simulations of the Aza-Michael addition reaction and finite element simulations of aerogel thermal-insulation properties are conducted to corroborate experimental results. Notably, the dynamic polymers of SAML-PU and SAMH-PU exhibited excellent self-healing, recycling, biodegradability, and flame-retardant attributes. The elucidated preparation methodology and the exceptional performance and versatile applications of sodium alginate-based PU aerogels suggest a promising trajectory for future research endeavors and industrial implementation.

Antibacterial and Antifouling Biobased Waterborne Polyurethane Prepared from Amphiphilic Plant Oil-Based Polyols

Antibacterial and Antifouling Biobased Waterborne Polyurethane Prepared from Amphiphilic Plant Oil-Based Polyols

A sulfonated hyperbranched bio-based waterborne polyurethane sizing coating for the enhancement of mechanical properties and surface wettability of carbon fibres

Wet-weaving and cluster braiding in industrial production processes generate irreversible defects and grooves in carbon fibre (CF) filaments, which reduce the service life and mechanical properties of the fibres. Additionally, the fibre surface covered with numerous inactive carbon-containing groups and presents chemical inertness, which limits the prospects of CF applications. Hence, the hyperbranched bio-based waterborne polyurethanes (SWPU) possessing the synergism of sulfamate and carboxylate complex hydrophilic units were adopted as sizing coatings to improve the flexural and tensile strengths of CF, as well as fibre surface roughness and wettability. The SWPU is designed on dihydroxymethylbutyric acid and sulfamates (A95) as per- and post-chain extenders, respectively, trimethylolpropane (TMP) as an intramolecular cross-linker, and plant-extracts castor oil (CO) replacing petroleum-based petrochemicals as the soft-segments. The construction of CO-TMP hyperbranched cross-linking networks and the strengthened hydrogen-bonding effects of the polar sulfamates positively affect the intermolecular interactions and configuration stability of SWPU sizing coatings. SWPU revealed favourable thermo-mechanical properties achieving a T5% decomposition temperature and toughness of 297.83 °C and 35.24 MJ/m3. The coating effects of the bio-based sizing agents not only repaired defects and improved surface roughness on CF, but the polar groups in SWPU comprising SO3Na, carbamate and polyurea promoted the chemotactic activity and wettability of the fibres. The surface energy and tensile strength of the SWPU sized CF reached 43.75 mN/m and 5.68 GPa, respectively, which were 45.4 % and 30.7 % higher compared to original CF. The research contributes to the development and industrial production of high-performance, eco-friendly bio-based sizing coatings.

Encapsulation films: Investigation into the degradation mechanism of multicomponent bio-based waterborne polyurethane in natural environments

In this study, the impact of different ratios of castor oil (CO) and polycarbonate diol (PCDL) mixed soft segments, as well as the introduction of sodium 2-[(2-aminoethyl)amino]ethanesulphonate (AAS-Na) salt, on the biodegradable waterborne polyurethane (WPU) was investigated. Firstly, various waterborne polyurethanes with different mixed soft segments were prepared by adjusting the ratios of castor oil and polycarbonate diol. Subsequently, varying amounts of AAS-Na salt were introduced to assess their influence on the polymer properties. The results indicated that the ratio of CO to PCDL significantly affected the mechanical properties and biodegradability of WPU. As the ratio decreased from 10:0 to 6:4, the tensile strength of WPU films decreased from 18 MPa to 11 MPa, while the elongation at break increased from 56 % to 258 %. Furthermore, the addition of AAS salt improved the water absorption and biodegradation rate of the material. When the ratio of CO to PCDL within the system is 10:0 and the molar content of AAS-Na is 20 mol%, the sample exhibits optimal water absorption of 132.12 % after 48 h and biodegradability of 30.58 % after 28 days. The degradation mechanism was preliminarily explored using Fourier-transform infrared spectroscopy. In conclusion, by adjusting the ratios of castor oil, polycarbonate diol, and AAS salt, a series of biodegradable waterborne polyurethanes with excellent performance were obtained. This study demonstrates the feasibility of developing biodegradable packaging materials using bio-based waterborne polyurethanes as the main component.

Fabrication of sodium lignosulfonate/waterborne polyurethane composites with high biological content to enhance mechanical properties and UV resistance

The conversion of sodium lignosulfonate (SL) into high-value functional materials remains challenging. Hereon, a bio-based waterborne polyurethane (WPU) was synthesized using castor oil and isophorone diisocyanate as the raw materials. SL was used as a functional filler to prepare transparent or translucent composites of sodium lignosulfonate/waterborne polyurethane with good properties through physical blending method. The influence of varying SL contents on the performance of composite emulsions and films were studied. The results indicated that the composite derived from bio-based materials had an occupancy rate of 89.5 %, and all composite emulsions exhibited outstanding storage stability. Interestingly, the addition of sodium lignosulfonate greatly improved the mechanical properties and heat resistance due to the strong interfacial interaction between WPUs and SL molecular chains. Furthermore, the composite film could achieve complete UV shielding performance when the sodium lignosulfonate content reached 9 wt %. This work had significantly expanded the range of high-value-added applications for lignin and potential prospects for its use in the field of sunscreen coatings.

Multifunctional Fabric Leveraging Coating of Bio-based Waterborne Polyurethane

Multifunctional Fabric Leveraging Coating of Bio-based Waterborne Polyurethane

Novel multifunctional highly crosslinked bio-based waterborne polyurethane networks modified via long fatty hydrophobic side chains

The mechanical properties and water resistance of castor oil-based waterborne polyurethane are mutually limited due to the presence of a hydrophilic chain extender. Herein, Arbutin (AT) was used as a crosslinking agent, and benzimidazole (CR-455) was utilized as an ultraviolet absorber, sustainable long fatty hydrophobic chain extenders, sorbitan monooleate (SP), glycerol laurate (GML), glycerin monostearate (GMS), and trimethylolpropane monooleate (TPM), were introduced into castor oil-based waterborne polyurethane (CWPU) backbones through molecular structure design respectively. Subsequently, the amount of SP was changed to prepare a series of waterborne polyurethane dispersions, and their emulsion and film properties were thoroughly investigated. The finding showed that the incorporation of long fatty hydrophobic chain extenders led to an increase in crosslinking density, thereby endowing CWPU films with good mechanical properties, water resistance, and anti-corrosion efficacy. Moreover, the bio-based content in the CWPU film had reached an impressive 90.9 %. The addition of SP content resulted in a gradual improvement in the mechanical properties, water resistance, and corrosion resistance of CWPU-SP films. When the SP content was 40 %, due to the high strength of hydrogen bonds and the density of crosslinking in systems, the tensile strength, toughness, water absorption rate, and corrosion protection efficiency of the CWPU-SP40 film reached 18.1 MPa, 20 MJ/m3,7.7 %, and 98.47 %, respectively. Particularly, the prepared transparent CWPU films exhibited complete UV shielding. This work would pave the way for the application of bio-based waterborne polyurethanes in high-performance coatings, such as anti-corrosion and sunscreen.

Synthesis of Silanated Coconut Oil-Based Waterborne Polyurethane Coating for Corrosion Protection

In this study, an eco-friendly coconut oil-based polyol blend was synthesized for bio-based waterborne polyurethane (WBPU) and WBPU-silane composite coatings. It was demonstrated that an increase in silane content incorporated into the WBPU matrix significantly enhanced the corrosion protection of WBPU coatings. Results also show a fourfold increase in the adhesion strength of WBPU-silane composite coatings as compared to that of bare WBPU coatings. Further, the water contact angle revealed that hydrophobic properties increase as the silane content incorporated into the WBPU matrix increases. This work provides a novel route for enhanced corrosion protection utilizing a bio-based polyol blend.

Sustainable Strategies for Synthesizing Lignin-Incorporated Bio-Based Waterborne Polyurethane with Tunable Characteristics.

In this study, we introduce a novel approach for synthesizing lignin-incorporated castor-oil-based cationic waterborne polyurethane (CWPU-LX), diverging significantly from conventional waterborne polyurethane dispersion synthesis methods. Our innovative method efficiently reduces the required solvent quantity for CWPU-LX synthesis to approximately 50% of that employed in traditional WBPU experimental procedures. By incorporating lignin into the polyurethane matrix using this efficient and reduced-solvent method, CWPU-LX demonstrates enhanced properties, rendering it a promising material for diverse applications. Dynamic interactions between lignin and polyurethane molecules contribute to improved mechanical properties, enhanced thermal stability, and increased solvent resistance. Dynamic interactions between lignin and polyurethane molecules contribute to improved tensile strength, up to 250% compared to CWPU samples. Furthermore, the inclusion of lignin enhanced thermal stability, showcasing a 4.6% increase in thermal decomposition temperature compared to conventional samples and increased solvent resistance to ethanol. Moreover, CWPU-LX exhibits desirable characteristics such as protection against ultraviolet light and antibacterial properties. These unique properties can be attributed to the presence of the polyphenolic group and the three-dimensional structure of lignin, further highlighting the versatility and potential of this material in various application domains. The integration of lignin, a renewable and abundant resource, into CWPU-LX exemplifies the commitment to environmentally conscious practices and underscores the significance of greener materials in achieving a more sustainable future.

A bio-based waterborne polyurethane with high toughness, superior wear resistance, and water resistance enabled by sorbitol monooleate

Waterborne polyurethanes (WPUs) have recently attracted enormous attentions in extensive industrial applications because of their sustainability and low toxicity. However, due to the use of water as the dispersion medium and abundant hydrophilic moieties of the molecular skeleton, waterborne polyurethanes always suffer from poor mechanical properties and inferior water resistance. In this work, dehydrated sorbitan monooleate (SP), a bio-derived renewable polyol, is introduced into the waterborne polyurethane skeleton to modulate the contents of the traditional trifunctional polyol of trimethylolpropane (TMP). Due to the rigid furan ring and the fatty side chain in the SP, the SP-modulated waterborne polyurethanes (WPU-SP) exhibit simultaneous excellent mechanical properties, high toughness, flexibility, and versatility, with the maximum tensile strength of WPU-SP reaching 39.19 MPa, and the film is capable of lifting weights over 25,000 times its own weight without fracture. Additionally, compared to the traditional waterborne polyurethane extended with TMP, the wear resistance and the water resistance of WPU-SP are significantly improved, as the decreases in wear rate and water absorption rate of WPU-SP are up to 59 % and 45 %, respectively. Benefiting from these unique properties, the WPU-SP shows excellent performance in anticorrosion and exceptional applicability for soft leather materials, in which the corrosion prevention efficiency can reach over 95 % and the wear index can be reduced to within 10 mg as a protective coating. This study represents a facile and effective approach for developing high-performance sustainable waterborne polyurethane materials through the incorporation of SP into polymer networks.

Fabrication of silane and nano-silica composite modified Bio-based WPU and its interfacial bonding mechanism with cementitious materials

Bio-based waterborne polyurethane (WPU) using renewable resources has grown with the increasing scarcity of petroleum resources and people’s awareness of sustainable development and environmental protection. The unfavorable physicochemical properties hinder its further development in the field of concrete protective coatings, also the bonding mechanism between the Bio-based WPU and cementitious materials has little scientific backing. In this work, the environmentally benign bio-based WPU was synthesized by employing soybean oil as the initial raw material, which was prepared by prepolymer method through a series of chemical reactions of epoxidation, hydroxylation and stepwise polymerization. The chemical cross-linking of γ-aminopropyltriethoxysilane(APTES) combined with physical reinforcement of nano-SiO2 strategy was used for the composite modification. The particle size of emulsion, molecular structure, water resistance, tensile and thermal properties, microstructures of the Bio-based WPU were investigated by DLS nanoparticle size measurement, Fourier transform infrared spectroscopy (FT-IR), universal mechanical testing, water immersion, differential scanning calorimetry (DSC) and thermogravimetric analysis (TG), scanning electron microscopy (SEM) respectively. The results shows that the APTES has been successfully grafted into the Bio-based WPU chain and the nano-SiO2 was dispersed homogeneously in the WPU matrix. The Si-O of with low surface energy introduced to the Bio-based WPU by APTES cross-linking and the favourable interfacial covalent bonding between the nano-SiO2 and Bio-based WPU have a synergistic effect in enhancing the water resistance, tensile strength and thermal stability. The pull-off testing shows the cement and interfacial mixed failure was the primary failure mode, the bonding strength of the composite modified Bio-based WPU shows an increasing trend with increasing content of nano-SiO2, which increases by 206.56 % to reach 1.87 MPa compared with Bio-based WPU without modification. The interfacial bonding mechanism of SiO2-SiWPU composite film with cementitious materials are mechanical interlocking effect, coordination bonding, hydrogen bonding and electrostatic adsorption, demonstrating the Bio-based WPU organic–inorganic composites coating can be a promising candidate for concrete protecting.

Bio-Based Waterborne Polyurethane Coatings with High Transparency, Antismudge and Anticorrosive Properties.

Green and environment-friendly preparation are of the utmost relevance to the development of transparent antismudge coatings. To prepare a waterborne polyurethane (WPU) coating with antismudge property, it is challenging to balance the stability of dispersion and the antismudge property of coating. Herein, we prepare a transparent bio-based WPU coating grafted with a minor proportion of poly(dimethylsiloxane) (WPU-g-PDMS) using renewable castor oil, monocarbinol-terminated PDMS, hexamethylene diisocyanate trimer, and 2,2-bis(hydroxymethyl)propionic acid as raw materials. Effects of the dosage of monocarbinol-terminated PDMS, the curing temperature, and the curing time on the antismudge performance were studied. Results showed that rigorous stirring (3000 rpm) is necessary to obtain a stable WPU-g-PDMS dispersion with a storage time longer than 6 months. A high curing temperature (>160 °C) and a period of curing time (>1 h) are indispensable to obtain the excellent antismudge property because they would facilitate the grafted low-surface-tension PDMS chains to migrate from the interior to the coating surface. The facts that simulated contaminated liquids such as water, HCl solution, NaOH solution, artificial blood, and tissue fluid could slide off easily and cleanly, and marker ink lined on the coating surface could shrink, indicated that the WPU-g-PDMS coating has good antismudge properties, which could be self-compensated shortly after deterioration. Due to the high cross-linking degree caused by multifunctional polyol and isocyanate, the WPU-g-PDMS coating has high hardness and good anticorrosive performance. The antismudge functionalization and waterborne technology of bio-based polyurethane coatings proposed in this work could be a promising contribution to the green and sustainable development of functional coatings. This kind of WPU-g-PDMS coating is expected to protect and decorate electronic screens, vehicles, and buildings, especially endoscopes.

The missing piece: Effect of dangling chains on the synthesis and properties of bio‐based waterborne polyurethane

AbstractBio‐based polyols derived from vegetable oils generally contain the dangling chains, which have recently attracted significant attention due to their influence on the preparation and performance of the waterborne polyurethane. Herein, a novel undecylenic‐based primary glycol (UPG) without dangling chains synthesized and the oleic‐based primary glycol (OPG) with dangling chains reported by our previous work were used to prepare straight‐chain and dangling‐chain bio‐based waterborne polyurethane (BWPU), respectively, to study the difference between the two diols and the effects of dangling chains on the synthesis and performance of BWPU. First, the UPG without dangling chains displayed higher activation energy (Ea/Eo = 77.72/80.56 kJ mol−1) and longer reaction end point of prepolymer (240 min), indicating relatively lower reactivity to isocyanate. In addition, the dangling chains were found to influence the dispersion stability of BWPU, and the minimum dosage of DMPA for maintaining dispersion stability was 6.5 wt% for OPG but 5.5 wt% for UPG. The average particle size of BWPU is greater for OPG than for UPG with the same DMPA content. Finally, performance studies revealed that dangling‐chain BWPU showed higher hydrophobicity, extensibility, and low temperature resistance, but lower thermal stability (Td5%) and tensile strength. This work comprehensively clarified the effects of linear and branched bio‐based polyols on the synthesis and properties of BWPU, and provided guidance for the development and application of bio‐based polyols and BWPU coatings.

Synergistic of anionic and nonionic monomers for high solid content bio-based waterborne polyurethane sizing agents

A high solid content bio-based waterborne polyurethane (WPU) was designed by combination of anionic and nonionic monomers, and serving as sizing agent for carbon fibers (CF). The electric double layer was formed by using bio-based tartaric acid (TA) and sodium lignosulfonate (SL) as donor of ionic groups and electrostatic repulsion was generated. Polyethylene glycol (PEG) was used to provide the hydrophilic segment of non-ionic monomer, which reduced the interfacial tension and improved the dispersion of emulsion. The synergistic effect of anionic and nonionic monomers promoted the stability of emulsion and the solid content of WPU sizing agent was arrived at 57%. The effect of sizing agent to the interfacial properties of carbon fiber reinforced nylon 6 (CF/PA6) composites were investigated. The flexural strength and interlaminar shear strength (ILSS) of the CF/PA6 composites exhibited the optimal performance at 1.5 wt% sizing concentration, revealing a considerably increase of 39.8% in ILSS and 38.5% in flexural strength as compared with untreated CF composites. This work contribute a fascinating method for further high solid content commercial production of environmentally-friendly WPU sizing agent.

High Water Resistance and Enhanced Mechanical Properties of Bio-Based Waterborne Polyurethane Enabled by in-situ Construction of Interpenetrating Polymer Network

In this study, acrylic acid was used as a neutralizer to prepare bio-based WPU with an interpenetrating polymer network structure by thermally induced free radical emulsion polymerization. The effects of the content of acrylic acid on the properties of the resulting waterborne polyurethane-poly (acrylic acid) (WPU-PAA) dispersion and the films were systematically investigated. The results showed that the cross-linking density of the interpenetrating network polymers was increased and the interlocking structure of the soft and hard phase dislocations in the molecular segments of the double networks was tailored with increasing the content of acrylic acid, leading to enhancement of the mechanical properties and water resistance of WPU-PAA films. Notably, with the increase in content of acrylic acid, the tensile strength, Young’s modulus, and toughness of the WPU-PAA-110 film increased by 3 times, and 8 times, and 2.4 times compared with WPU-PAA-80, respectively. The WPU-PAA-100 film showed the best water resistance, and the water absorption rate at 96 h was only 3.27%. This work provided a new design scheme for constructing bio-based WPU materials with excellent properties.

Tuning the hydrophobicity of bio-based waterborne polyurethane by leveraging a diol derived from oleic acid

Vegetable oils containing long aliphatic chains are widely used to obtain polyols and further produce eco-friendly bio-based waterborne polyurethanes (BWPU). However, the effect of the long aliphatic chains on the properties of BWPU, especially hydrophobicity, has been awfully neglected in previous works. Here, we have successfully prepared a series of linear anionic BWPU by incorporating an oleic-based primary glycol (OPG) with long aliphatic chains into polytetrahydrofuran ether glycol (PTMG) in different proportions. Firstly, the optimized reaction conditions for efficient synthesis of OPG via the thiol-ene photo-click reaction are: 2 wt% photoinitiator 1173, molar ratio of -SH to -CC- of 2:1, and reaction time of 1 h. Then, the effect of incorporating OPG on BWPU’s properties, especially the intrinsic hydrophobicity, was extensively investigated. Specifically, due to the long hydrophobic aliphatic chain, the particle size of the BWPU dispersions increased with the increase of OPG content, and correspondingly the absolute value of zeta potential decreased. Additionally, the water contact angle of the BWPU films increased from 60.8° to 90.3°, and their water absorption decreased from 7.88% to 3.21%, exhibiting enhanced hydrophobicity and water resistance. This work demonstrates the designed and synthesized vegetable oil-based diol with a long aliphatic chain plays a positive role in tailoring the hydrophobicity of bio-based WPU, which holds great promises for applications in waterproof and self-cleaning coatings.

UV resistance, anticorrosion and high toughness bio-based waterborne polyurethane enabled by a Sorbitan monooleate

Sorbitan monooleate (SP) is considered to be a promising renewable polyol with unique molecular structures for the development and design of bio-based waterborne polyurethane (WPU) with versatility and excellent mechanical properties. In this study, SP was used as a bio-based polyol in combination with castor oil to design and prepare a series of bio-based WPU with anti-ultraviolet, corrosion resistance and excellent mechanical properties. The influence of the hydroxyl ratios between SP and castor oil on the chemical structures and properties of bio-based WPU dispersions and the resulting WPU films was systematically studied. The resulting WPU films exhibited excellent mechanical properties and thermo-physical properties due to the presence of large amounts of hydrogen bonding and rigid furan ring, and high crosslinking densities. The bio-based WPU films could lift heavy objects 10,330 times their own weight. The resulting WPU coatings could resist ultraviolet radiation in the region (200–400 nm) and exhibited excellent UV resistance in outdoor practical application tests. In addition, these WPU coatings demonstrated effectively anticorrosive effect in which the anticorrosion period of the coating on the tinplate outdoors could be as long as 6 months in terms of corrosion potential, corrosion current and corrosion protection efficiency of the coating reached −0.507 V, 2.92 × 10−6 A, and 95.39%, respectively. This study provides a new and simple method for preparing bio-based WPU with excellent anti-ultraviolet performance, anti-corrosion performance and excellent mechanical properties.

Enhanced Water Resistance Performance of Castor Oil—Based Waterborne Polyurethane Modified by Methoxysilane Coupling Agents via Thiol-Ene Photo Click Reaction

Nowadays, waterborne polyurethanes (WPUs) prepared from renewable resources has attracted more and more attention. However, due to its structure, the prepared films easily swells in water and greatly affects the application range of WPUs. Therefore, solving the problem of water resistance is a way to improve the application range of WPUs. In this study, a series of WPU dispersions were prepared using castor oil as the bio-based polyol. Besides, the thiol-ene photo click reaction was carried out on the WPU films for silane modification. The effect of the silane modification on the chemical structures of the WPU dispersions and the properties of the WPU films was investigated and discussed. The results revealed that the WPU dispersions had a smaller particle size and potential, showing excellent stability. In addition, the modified WPU films showed highly water resistance which 72 h water absorption could be reduced to 1.94% and the contact angle was up to 99.34°. Moreover, the modified WPU films also exhibited excellent solvent resistance (in acid and salt solution) and thermal stability. This study can provide a new way to improve the water-resistance, hydrophobicity, and thermal stability of bio-based waterborne polyurethane for potential application in painting, adhesives and inks.

Synthesis of oleic-based primary glycol with high molecular weight for bio-based waterborne polyurethane

Oleic acid, as a renewable resource, exists in almost every vegetable oil, especially olive and camellia oils, which has promising prospects for the preparation of bio-based polymers. In this study, a novel oleic-based primary glycol (OPG) was synthesized from methyl oleate (MO, derived from vegetable oil) via Claisen condensation and thiol-ene photo-click reactions and used as an alternative to petroleum-based glycol for the preparation of bio-based waterborne polyurethane (BWPU), and the differences in reactivity between the OPG and petroleum-based polypropylene glycol (PPG) and properties between BWPU and petroleum-based waterborne polyurethane (PWPU) were investigated. The yield of OPG was approximately 90%, the degree of functionality was 2.0, the hydroxyl value was about 155 mg KOH g−1 and the molecular weight (Mw) varied from 296 g mol−1 to 560 g mol−1 and 716 g mol−1 after the chain extension of Claisen condensation and thiol-ene photo-click reactions. In comparison with PPG, OPG exhibited lower activation energy towards IPDI, and the values showed an order of OPG (Ea/Eo=71.25/74.20 kJ mol−1) < PPG600 (Ea/Eo=106.83/108.03 kJ mol−1) < PPG1000 (Ea/Eo=129.20/129.37 kJ mol−1). Correspondingly, the end point of pre-polymerization appeared in 80 min for OPG and 420 min, 840 min for PPG600 and PPG1000 at 80 °C without catalyst, demonstrating that OPG had higher reactivity. Because of the difference in hydrophobicity, the minimum amount of hydrophilic extender used to obtain stable WPU emulsions was 7 wt% for OPG and 3.5 wt% for PPG respectively. The resulting BWPU films possessed good mechanical properties, including higher tensile strength (19.78 MPa) and Young’s modulus (206.61 MPa). But the thermal stability (Td5% ≤ 250 ℃) and low temperature resistance (Tg ≥ 28 ℃) of BWPU films were inferior to that of PWPU films.