Solvent and catalyst-free synthesis of sunflower oil based polyurethane through non-isocyanate route and its coatings properties

Green synthesis of non-isocyanate hydroxyurethane and its hybridization with carboxymethyl cellulose to produce films

Non-isocyanate polyurethanes (NIPUs) have attracted increasing attention as a sustainable alternative to conventional isocyanate-based polyurethanes. This study synthesized non-isocyanate hydroxyurethanes (NIHUs) through an addition reaction between propylene carbonate (PC) and 1,2-ethylenediamine (EDA). The resulting NIHU was then hybridized with carboxymethyl cellulose (CMC) to investigate its hybridization potential. Structural analysis through FTIR, NMR, and XRD confirmed the crystalline nature of NIHU, featuring urethane bonds and abundant hydroxyl groups. It was found that NIHU and CMC interacted by forming hydrogen bonds between hydroxyl groups of NIHU and carboxyl groups of CMC, resulting in a dense CMC/NIHU hybrid structure. NMR and XRD analyses revealed changes in the hybrids' chain mobility, the Young's modulus of the hybrid with 30 % NIHU content decreased from 1627 MPa to 502 MPa relative to CMC, and the elongation at break increased from 4.44 % to 17.2 %. Increasing the concentration of NIHU in CMC reduced the hydrophobicity, in terms of water contact angle, from 70° to 41.7°. The simplicity of the synthesis method for NIHU, coupled with the desirable structure, strength, and balanced flexibility of CMC/NIHU hybrids, is expected to facilitate the production of NIHU-rich hybrids and increase their application in packaging.

Eco-Friendly and High-Performance Bio-Polyurethane Adhesives from Vegetable Oils: A Review

Current petrochemical-based adhesives adversely affect the environment through substantial volatile organic compound (VOC) emissions during production, contributing to air pollution and climate change. In contrast, vegetable oils extracted from bio-resources provide a compelling alternative owing to their renewability, abundance, and compatibility with adhesive formulation chemistry. This review aimed to critically examine and synthesize the existing scholarly literature on environmentally friendly, sustainable, and high-performance polyurethane adhesives (PUAs) developed from vegetable oils. The use of PUAs derived from vegetable oils promises to provide a long-term replacement while simultaneously maintaining or improving adhesive properties. This quality renders these adhesives appropriate for widespread use in various sectors, including construction, automotive manufacturing, packaging, textile, and footwear industries. This review intended to perform a comprehensive assessment and integration of the existing research, thereby identifying the raw materials, strengths, weaknesses, and gaps in knowledge concerning vegetable oil-based PUAs. In doing so, it responded to these gaps and proposes potential avenues for future research. Therefore, this review accomplishes more than merely evaluating the existing research; it fosters the advancement of greener PUA technologies by identifying areas for improvement and innovation towards more sustainable industrial practices by showcasing vegetable oil-based PUAs as viable, high-performance alternatives to their petroleum-based counterparts.

Preparation of Non-Isocyanate Polyurethanes from Mixed Cyclic-Carbonated Compounds: Soybean Oil and CO2-Based Poly(ether carbonate)

This study presents the synthesis and characterization of non-isocyanate polyurethanes (NIPU) derived from the copolymerization of cyclic-carbonated soybean oil (CSBO) and cyclic carbonate (CC)-terminated poly(ether carbonate) (RCC). Using a double-metal cyanide catalyst, poly(ether carbonate) polyol was first synthesized through the copolymerization of carbon dioxide and propylene oxide. The terminal hydroxyl group was then subjected to a substitution reaction with a five-membered CC group using glycerol-1,2-carbonate and oxalyl chloride, yielding RCC. Attempts to prepare NIPU solely using RCC and diamine were unsuccessful, possibly due to the low CC functionality and the aminolysis of RCC's linear carbonate repeating units. However, when combined with CSBO, solid NIPUs were successfully obtained, exhibiting good thermal stability along with enhanced mechanical properties compared to conventional CSBO-based NIPU formulations. Overall, this study underscores the potential of leveraging renewable resources and carbon capture technologies to develop sustainable NIPUs with tailored properties, thereby expanding their range of applications.

A review on vegetable oil-based non isocyanate polyurethane: towards a greener and sustainable production route

The transition from conventional polyurethane (PU) to non isocyanate polyurethane (NIPU) is driven mainly by safety concerns, environmental considerations, and sustainability issues associated with the current PU technology. NIPU has emerged as a promising alternative, addressing limitations related to traditional PU production. There has been increasing interest in bio-based NIPU aligning with the aspiration for green materials and processes. One important biomass resource for the development of bio-based NIPU is vegetable oil, an abundant, renewable, and relatively low cost feedstock. As such, this review aims to provide insight into the progression of NIPU derived from vegetable oils. This article highlights the synthetic and green approach to NIPU production, emphasizing the method involving the polyaddition reaction of cyclic carbonates and amines. The review includes case studies on vegetable oil-based NIPU and perspectives on their properties. Further, discussions on the potential applications and commercial importance of PU and NIPU are included. Finally, we offer perspectives on possible research directions and the future prospects of NIPU, contributing to the ongoing evolution of PU technology.

Polylactide-Based Nonisocyanate Polyurethanes: Preparation, Properties Evaluation and Structure Analysis

This study investigated the successful synthesis and characterization of nonisocyanate polyurethanes (NIPUs) based on polylactide. The NIPUs were synthesized by a condensation reaction of oligomers with hard segments (HSs) and synthesized carbamate-modified polylactic acid containing flexible segments (FSs). The oligomers with HSs were prepared from phenolsulfonic acid (PSA) or a mixture of PSA and hydroxynaphthalenesulfonic acid (HNSA), urea and formaldehyde. The mixing of oligomeric compounds with different amounts of formaldehyde was carried out at room temperature. Obtained NIPU samples with different hard segment content were tested for their mechanical and thermal properties. The tensile strength (TS) of all NIPU samples increased with an increasing amount of HSs, attaining the maximum value at an HS:FS ratio of 1:3. Samples prepared from PSA and HNSA showed higher tensile strength (TS) without significant change in elongation at break compared to the samples based only on PSA. Thermogravimetric analysis data indicated an absence of weight loss for all samples below 100 °C, which can be considered a safe temperature for using NIPU materials. Maximum degradation temperatures reached up to 385 °C. Fourier transform infrared spectroscopy results confirmed the existence of expected specific groups as well as the chemical structure of the prepared polyurethanes. DSC analysis showed the existence of two characteristic phase transitions attributed to the melting and crystallization of hard segments in the NIPU samples.

Innovations in applications and prospects of non-isocyanate polyurethane bioplastics

Currently, conventional plastics are necessary for a variety of aspects of modern daily life, including applications in the fields of healthcare, technology, and construction. However, they could also contain potentially hazardous compounds like isocyanates, whose degradation has a negative impact on both the environment and human health. Therefore, researchers are exploring alternatives to plastic which is sustainable and environmentally friendly without compromising its mechanical and physical features. This review study highlights the production of highly eco-friendly bioplastic as an efficient alternative to non-biodegradable conventional plastic. Bioplastics are produced from various renewable biomass sources such as plant debris, fatty acids, and oils. Poly-addition of di-isocyanates and polyols is a technique employed over decades to produce polyurethanes (PUs) bioplastics from renewable biomass feedstock. The toxicity of isocyanates is a major concern with the above-mentioned approach. Novel green synthetic approaches for polyurethanes without using isocyanates have been attracting greater interest in recent years to overcome the toxicity of isocyanate-containing raw materials. The polyaddition of cyclic carbonates (CCs) and polyfunctional amines appears to be the most promising method to obtain non-isocyanate polyurethanes (NIPUs). This method results in the creation of polymeric materials with distinctive and adaptable features with the elimination of harmful compounds. Consequently, non-isocyanate polyurethanes represent a new class of green polymeric materials. In this review study, we have discussed the possibility of creating novel NIPUs from renewable feedstocks in the context of the growing demand for efficient and ecologically friendly plastic products.

Chemically Recyclable Biobased Non-Isocyanate Polyurethane Networks from CO2 -Derived Six-membered Cyclic Carbonates

Non-isocyanate polyurethanes (NIPUs) are widely studied as sustainability potential, because they can be prepared without using toxic isocyanates in the synthesis process. The aminolysis of cyclic carbonate to form NIPUs is a promising route. In this work, a series of NIPUs is prepared from renewable bis(6-membered cyclic carbonates) (iEbcc) and amines. The resulting NIPUs possess excellent mechanical properties and thermal stability. The NIPUs can be remolded via transcarbamoylation reactions, and iEbcc-TAEA-10 (the molar ratio of tris(2-aminoethyl)amine in amines is 10%) still get a recovery ratio of 90% in tensile stress after three cycles of remolding. In addition, the obtained materials can be chemically degraded into bi(1,3-diol) precursors with high purity (>99%) and yield (>90%) through alcoholysis. Meanwhile, the degraded products can be used to regenerate NIPUs with similar structures and properties as the original samples. The synthetic strategy, isocyanate-free and employing isoeugenol and carbon dioxide (CO2 ) as building blocks, makes this approach an attractive pathway to NIPU networks taking a step toward a circular economy.

Approach to Circular Chemistry Preparing New Polyesters from Olive Oil

The transformation of cooking oils and their waste into polyesters is a challenge for circular chemistry. Herein, we have used epoxidized olive oil (EOO), obtained from cooking olive oil (COO), and various cyclic anhydrides (such as phthalic anhydride PA, maleic anhydride MA, and succinic anhydride SA) as raw materials for the preparation of new bio-based polyesters. For the synthesis of these materials, we have used the bis(guanidine) organocatalyst 1 and tetrabutylammonium iodide (Bu₄NI) as cocatalyst. The optimal reaction conditions for the preparation of poly(EOO-co-PA) and poly(EOO-co-MA) were 80 °C for 5 h using toluene as solvent; however, the synthesis of poly(EOO-co-SA) required more extreme reaction conditions. Furthermore, we have exclusively succeeded in obtaining the trans isomer for MA-polyester. The obtained biopolyesters were characterized by NMR, Fourier transform infrared, thermogravimetric analysis, and scanning electron microscopy analyses. Since there are few examples of functionalized and defined compounds based on olive oil, it is innovative and challenging to transform these natural-based compounds into products with high added value.

Tailor-Made Bio-Based Non-Isocyanate Polyurethanes (NIPUs)

Non-isocyanate polyurethanes (NIPUs) based on biobased polyamines and polycarbonates are a sustainable alternative to conventional polyurethanes (PU). This article discloses a novel method to control the crosslinking density of fully biobased isocyanate-free polyurethanes, synthesized from triglycerides carbonated previously in scCO₂ and different diamines, such as ethylenediamine (EDA), hexamethylenediamine (HMDA) and Priamine^TM-1075 (derived from a dimerized fatty acid). As capping substances, water or bioalcohols are used in such a way that the crosslinking density can be adjusted to suit the requirements of the intended application. An optimization of the NIPU synthesis procedure is firstly carried out, establishing the polymerization kinetics and proposing optimal conditions set for the synthesis of the NIPUs. Then, the influence of the partial blocking of the active polymerization sites of the carbonated soybean oil (CSBO), using monofunctional amines, on the physical properties of the NIPUS is explored. Finally, the synthesis of fully biobased NIPUs with a targeted crosslinking density is achieved using hybrid NIPUs, employing partially carbonated oil and H₂O or ethanol as blockers to achieve the desired physical properties in a very precise manner.

Biobased Castor Oil-Based Polyurethane Foams Grafted with Octadecylsilane-Modified Diatomite for Use as Eco-Friendly and Low-Cost Sorbents for Crude Oil Clean-Up Applications

Herein we report the synthesis and characterization of novel castor oil-based polyurethane (PU) foam functionalized with octadecyltrichlorosilane (C18)-modified diatomaceous earth (DE) particles, exhibiting superior hydrophobicity and oil adsorption, and poor water absorption, for use in effective clean-up of crude oil spillage in water bodies. High-performance and low-cost sorbents have a tremendous attraction in oil spill clean-up applications. Recent studies have focused on the use of castor oil as a significant polyol that can be used as a biodegradable and eco-friendly raw material for the synthesis of PU. However, biobased in-house synthesis of foam modified with C18-DE particles has not yet been reported. This study involves the synthesis of PU using castor oil, further modification of castor oil-based PU using C18 silane, characterization studies and elucidation of oil adsorption capacity. The FTIR analysis confirmed the fusion of C18 silane particles inside the PU skeleton by adding the new functional group, and the XRD study signified the inclusion of crystalline peaks in amorphous pristine PU foam owing to the silane cross-link structure. Thermogravimetric analysis indicated improvement in thermal stability and high residual content after chemical modification with alkyl chain moieties. The SEM and EDX analyses showed the surface's roughness and the incorporation of inorganic and organic elements into pristine PU foam. The contact angle analysis showed increased hydrophobicity of the modified PU foams treated with C18-DE particles. The oil absorption studies showed that the C18-DE-modified PU foam, in comparison with the unmodified one, exhibited a 2.91-fold increase in the oil adsorption capacity and a 3.44-fold decrease in the water absorbing nature. From these studies, it is understood that this novel foam can be considered as a potential candidate for cleaning up oil spillage on water bodies.

Synthesis and properties of foams from a blend of vegetable oil based polyhydroxyurethane and epoxy resin

This article aims to highlight the synthesis of foams from a blend of hydroxyurethane of castor oil and epoxy resin. An epoxidized castor oil of 4% oxirane oxygen was first converted to cyclic carbonate of castor oil at 120°C, 1 atm CO2 pressure and then it was reacted with three different aliphatic diamines to yield amine terminated Polyhydroxyurethane (PHU). Foams were prepared in a metal mould from the blend of PHU, epoxy resin, epoxy hardener and polymethylhydrogensiloxane blowing agent which releases hydrogen gas upon reaction with amine. FTIR and 1H NMR of cyclic carbonate of castor oil and PHU of castor oil were done to confirm their chemical structures. Optical microscopy and scanning electron microscopy of foams was done to assess their cellular morphology along with DSC and TGA to evaluate their thermal properties. Both flexible and rigid type of foams were synthesised in this study. Resilience of flexible foams was inspected using a ball rebound test and compression-recovery test while thermal insulation property was checked by measuring thermal conductivity, thermal diffusivity and R-values of rigid foams from heat transfer study using a heat transfer apparatus.

PH Responsive Polyurethane for the Advancement of Biomedical and Drug Delivery

Due to the specific physiological pH throughout the human body, pH-responsive polymers have been considered for aiding drug delivery systems. Depending on the surrounding pH conditions, the polymers can undergo swelling or contraction behaviors, and a degradation mechanism can release incorporated substances. Additionally, polyurethane, a highly versatile polymer, has been reported for its biocompatibility properties, in which it demonstrates good biological response and sustainability in biomedical applications. In this review, we focus on summarizing the applications of pH-responsive polyurethane in the biomedical and drug delivery fields in recent years. In recent studies, there have been great developments in pH-responsive polyurethanes used as controlled drug delivery systems for oral administration, intravaginal administration, and targeted drug delivery systems for chemotherapy treatment. Other applications such as surface biomaterials, sensors, and optical imaging probes are also discussed in this review.

Application of biomass derived products in mid-size automotive industries: A review

The automotive industry is directly affected by the shortage of fossil fuels and the excessive pollution resulting from crude oil-based fuels has many adverse effects on the environment. The search for a greener and sustainable source of materials and fuels to power automobiles has ultimately led to the usage of biomass and biobased sources as the main precursor due to its graft availability and renewability. Biobased fuels developed have been shown to easily blend in with the existing automobile engines and to provide sustainable performance. Similarly, the usage of various biobased polymers, plastics, and composite materials as the structural materials for the construction of automobiles instead of crude oil sources have shown to be invaluable. The powering of automobiles with electricity is the future of the transportation industry to address the greenhouse gas emissions caused by fossil fuels. Hence, biobased lithium-ion batteries and supercapacitors have started to enter the mid-sized automotive industry. However, extensive commercialization of biobased products application in the automotive sector is underdeveloped. Hence it is customary to assess the various drawbacks of using biobased materials and identify the correct pathway for new research and development in this field. Therefore, this review covers various applications of biobased products in the automotive industries and mentions the active researches going on in this field to replace petroleum and crude oil-based sources with biobased sources.

Styrenated Oil Synthesis with Cyclic Carbonate Functional Groups on Polystyrene Segment

In this study, an oil-modified copolymer of 4-[(prop-2-en-1-yloxy)methyl]-1,3-dioxolan- 2-one (AGC) with styrene was synthesized, and the resulting copolymer (OBMI-St-AGC) was silane functionalized by inserting (3-aminopropyl) triethoxysilane (APTES) into the polymer backbone. OBMI-St-AGC was prepared by using an oil-based macroinitiator (OBMI) obtained by the esterification of linseed oil partial glycerides (PGs) with 4,4-azobis-4-cyanopentanoyl chloride (ACPC). In the characterization, FTIR, ¹H NMR, TGA, and DSC analyses were applied. The silane-functionalized copolymer (OBMI-St-AGC-APTES) was crosslinked through the sol-gel process, and its crosslinked structure was determined.

Ureido Functionalization through Amine-Urea Transamidation under Mild Reaction Conditions

Ureido-functionalized compounds play an indispensable role in important biochemical processes, as well as chemical synthesis and production. Isocyanates, and KOCN in particular, are the preferred reagents for the ureido functionalization of amine-bearing compounds. In this study, we evaluate the potential of urea as a reagent to graft ureido groups onto amines at relatively low temperatures (<100 °C) in aqueous media. Urea is an inexpensive, non-toxic and biocompatible potential alternative to KOCN for ureido functionalization. From as early as 1864, urea was the go-to reagent for polyurea polycondensation, before falling into disuse after the advent of isocyanate chemistry. We systematically re-investigate the advantages and disadvantages of urea for amine transamidation. High ureido-functionalization conversion was obtained for a wide range of substrates, including primary and secondary amines and amino acids. Reaction times are nearly independent of substrate and pH, but excess urea is required for practically feasible reaction rates. Near full conversion of amines into ureido can be achieved within 10 h at 90 °C and within 24 h at 80 °C, and much slower reaction rates were determined at lower temperatures. The importance of the urea/amine ratio and the temperature dependence of the reaction rates indicate that urea decomposition into an isocyanic acid or a carbamate intermediate is the rate-limiting step. The presence of water leads to a modest increase in reaction rates, but the full conversion of amino groups into ureido groups is also possible in the absence of water in neat alcohol, consistent with a reaction mechanism mediated by an isocyanic acid intermediate (where the water assists in the proton transfer). Hence, the reaction with urea avoids the use of toxic isocyanate reagents by in situ generation of the reactive isocyanate intermediate, but the requirement to separate the excess urea from the reaction product remains a major disadvantage.

Environmentally Friendly Anticorrosive Polymeric Coatings

This paper provides a synthetic and comprehensive overview on environmentally friendly anticorrosive polymeric coatings. Firstly, the economic and environmental impact of corrosion is presented to highlight the need of anticorrosive polymeric coatings as a flexible and effective solution to protect a metal. Secondly, the implementation of regulations together with the consumer awareness for environmental considerations and protection of health are the driving force for a progressive but significant change in the sector. Therefore, within the protective organic coatings market, this article provides a review of the most recent developments in environmentally friendly solutions, including bio-based and water-borne epoxy, hyperbranched polyester for low- volatile organic compounds (VOC) coatings, waterborne polyurethane and non-isocyanate polyurethanes (NIPUs), and graphene or bio-based fillers for acrylics. Moreover, this paper outlines new trends such as smart additives, bio-based corrosion inhibitors, and functional antibiocorrosive coatings as superhydrophobics. Finally, industrially relevant applications of environmentally friendly anticorrosive polymeric coatings including solutions for marine and off-shore industries are summarized.

Yield and Selectivity Improvement in the Synthesis of Carbonated Linseed Oil by Catalytic Conversion of Carbon Dioxide

Carbonation of epoxidized linseed oil (CELO) containing five-membered cyclic carbonate (CC5) groups has been optimized to 95% by reacting epoxidized linseed oil (ELO) with carbon dioxide (CO2) and tetrabutylammonium bromide (TBAB) as catalysts. The effect of reaction variables (temperature, CO2 pressure, and catalyst concentration) on the reaction parameters (conversion, carbonation and selectivity) in an autoclave system was investigated. The reactions were monitored, and the products were characterized by Fourier Transform Infrared Spectroscopy (FT-IR), carbon-13 nuclear magnetic resonance (13C-NMR) and proton nuclear magnetic resonance (1H-NMR) spectroscopies. The results showed that when carrying out the reaction at high temperature (from 90 °C to 120 °C) and CO2 pressure (60-120 psi), the reaction's conversion improves; however, the selectivity of the reaction decreases due to the promotion of side reactions. Regarding the catalyst, increasing the TBAB concentration from 2.0 to 5.0 w/w% favors selectivity. The presence of a secondary mechanism is based on the formation of a carboxylate ion, which was formed due to the interaction of CO2 with the catalyst and was demonstrated through 13C-NMR and FT-IR. The combination of these factors makes it possible to obtain the largest conversion (96%), carbonation (95%), and selectivity (99%) values reported until now, which are obtained at low temperature (90 °C), low pressure (60 psi) and high catalyst concentration (5.0% TBAB).

Self-healable hydrophobic polymer material having urethane linkages via a non-isocyanate route and dynamic Diels-Alder 'click' reaction

Conventional synthesis of polyurethane (PU) often involves the use of inherently toxic and overly moisture-sensitive isocyanates. Herein, we report the preparation of a self-healable hydrophobic polymer network having urethane linkages via a facile non-isocyanate route based on carbonylimidazole-amine reaction and dynamic Diels-Alder (DA) 'click' reaction based on furan-maleimide cycloaddition. This isocyanate-free DA 'clicked' polymer material showed excellent self-healing and hydrophobic characteristics.

Bio-based healable non-isocyanate polyurethanes driven by the cooperation of disulfide and hydrogen bonds

Novel bio-based non-isocyanate polyurethanes with tunable mechanical and self-healing properties are successfully synthesized.

Polymers Based on Cyclic Carbonates as Trait d'Union Between Polymer Chemistry and Sustainable CO2 Utilization

Given the large amount of anthropogenic CO₂ emissions, it is advantageous to use CO₂ as feedstock for the fabrication of everyday products, such as fuels and materials. An attractive way to use CO₂ in the synthesis of polymers is by the formation of five-membered cyclic organic carbonate monomers (5CCs). The sustainability of this synthetic approach is increased by using scaffolds prepared from renewable resources. Indeed, recent years have seen the rise of various types of carbonate syntheses and applications. 5CC monomers are often polymerized with diamines to yield polyhydroxyurethanes (PHU). Foams are developed from this type of polymers; moreover, the additional hydroxyl groups in PHU, absent in classical polyurethanes, lead to coatings with excellent adhesive properties. Furthermore, carbonate groups in polymers offer the possibility of post-functionalization, such as curing reactions under mild conditions. Finally, the polarity of carbonate groups is remarkably high, so polymers with carbonates side-chains can be used as polymer electrolytes in batteries or as conductive membranes. The target of this Review is to highlight the multiple opportunities offered by polymers prepared from and/or containing 5CCs. Firstly, the preparation of several classes of 5CCs is discussed with special focus on the sustainability of the synthetic routes. Thereafter, specific classes of polymers are discussed for which the use and/or presence of carbonate moieties is crucial to impart the targeted properties (foams, adhesives, polymers for energy applications, and other functional materials).