Polyurethanes (PUs) are a class of versatile materials with great potential for use in different applications, especially based on their structure–property relationships. Their specific mechanical, physical, biological, and chemical properties are attracting significant research attention to tailoring PUs for use in different applications. Enhancement of the properties and performance of PU-based materials may be achieved through changes to the production process or the raw materials used in their fabrication or via the use of advanced characterization techniques. Clearly, modification of the raw materials and production process through proper methods can produce PUs that are suitable for varied specific applications. The present study aims to shed light on the chemistry, types, and synthesis of different kinds of PUs. Some of the important research studies relating to PUs, including their synthesis method, characterization techniques, and research findings, are comprehensively discussed. Herein, recent advances in new types of PUs and their synthesis for various applications are also presented. Furthermore, information is provided on the environmental friendliness of the PUs, with a specific emphasis on their recyclability and recoverability.

https://ir.unikl.edu.my/jspui/bitstream/123456789/15237/1/Polyurethane%20types%2c%20synthesis%20and%20applications%20%e2%80%93%20a%20review.pdf

Polyurethane types, synthesis and applications – a review

Oils and fats of vegetable and animal origin have been the most important renewable feedstock of the chemical industry in the past and in the present. A tremendous geographical and feedstock shift of oleochemical production has taken place from North America and Europe to southeast Asia and from tallow to palm oil. It will be important to introduce and to cultivate more and new oil plants containing fatty acids with interesting and desired properties for chemical utilization while simultaneously increasing the agricultural biodiversity. The problem of the industrial utilization of food plant oils has become more urgent with the development of the global biodiesel production. The remarkable advances made during the last decade in organic synthesis, catalysis, and biotechnology using plant oils and the basic oleochemicals derived from them will be reported, including, for example, ω-functionalization of fatty acids containing internal double bonds, application of the olefin metathesis reaction, and de novo synthesis of fatty acids from abundantly available renewable carbon sources.

Oils and Fats as Renewable Raw Materials in Chemistry

Most of biobased polyols for polyurethanes are synthesized from vegetable oils. In the first part, the present review goes into details of these different synthetic routes to obtain polyols. First, olefinic functionalities of triglycerides could easily be epoxidized, leading to reactive epoxide groups. Second, triglycerides double bonds could undergo a wide ranges of reactions to yield polyols. Finally, the carbonyl group could also be used as a reactive group to yield various polyols. In the second part, the present review is dedicated to the commercial biobased polyols, and, based on the patent literature focuses on the industrial synthetic routes.

/pdf/from-vegetable-oils-to-polyurethanes-synthetic-routes-to-myhmv56j8u.pdf

From Vegetable Oils to Polyurethanes: Synthetic Routes to Polyols and Main Industrial Products

https://pubs.rsc.org/en/content/articlepdf/2015/cc/c4cc10113h

Ring-opening copolymerization (ROCOP): synthesis and properties of polyesters and polycarbonates

Polymeric foams can be found virtually everywhere due to their advantageous properties compared with counterparts materials. Possibly the most important class of polymeric foams are polyurethane foams (PUFs), as their low density and thermal conductivity combined with their interesting mechanical properties make them excellent thermal and sound insulators, as well as structural and comfort materials. Despite the broad range of applications, the production of PUFs is still highly petroleum-dependent, so this industry must adapt to ever more strict regulations and rigorous consumers. In that sense, the well-established raw materials and process technologies can face a turning point in the near future, due to the need of using renewable raw materials and new process technologies, such as three-dimensional (3D) printing. In this work, the fundamental aspects of the production of PUFs are reviewed, the new challenges that the PUFs industry are expected to confront regarding process methodologies in the near future are outlined, and some alternatives are also presented. Then, the strategies for the improvement of PUFs sustainability, including recycling, and the enhancement of their properties are discussed.

https://www.mdpi.com/1996-1944/11/10/1841/pdf/1

Polyurethane Foams: Past, Present, and Future

The effects of the molecular weight and structure of polycarbonatediols on the properties of waterborne polyurethanes

Carbonated soybean oil (CSBO) can be used as intermediate for the synthesis of non-isocyanate polyurethanes (NIPUs). In this work, CSBO was prepared by the reaction of epoxidized soybean oil (ESBO) with carbon dioxide (CO2) using a novel composite catalyst comprising SnCl4 · 5H2O and tetrabutylammonium bromide (TBABr). The evolution of the reaction process and structure of CSBO were studied by means of IR, 1H-NMR, and GPC techniques. Effects of catalyst formulation and various reaction conditions on the reaction were examined. The results showed that the obvious improvement in ESBO conversion using the present composite catalyst under mild conditions was achieved. Moreover, it was interesting to note that very high purity of CSBO was not a prerequisite for the synthesis of NIPUs with good performance.

Catalytic synthesis of Carbonated Soybean Oil

A series of waterborne polyurethane adhesives (WPUAs) were prepared from diphenylmethane-4,4′-diisocyanate (MDI), 1,6-hexamethylene diisocyanate (HDI), poly(1,4-butanediol adipate) diol (PBA), 1,4-butanediol (BDO), and internal-emulsifying agents by the prepolymer mixing method. The viscosity, mechanical properties, thermal properties, and adhesion strength of the samples were measured. The structure–property relationship was discussed primarily. The results indicated that the MDI/HDI and PBA/BDO molar ratio influenced these properties. The WPUA exhibited excellent T-peel strength and mechanical properties at a suitable MDI/HDI (or PBA/BDO) molar ratio. Moreover, higher MDI/HDI (or PBA/BDO) molar ratio resulted in higher thermal stability. © 2008 Wiley Periodicals, Inc. J Appl Polym Sci, 2008

Synthesis and characterization of waterborne polyurethane adhesive from MDI and HDI

Structure-activity correlations of LiNO3/Mg4AlO5.5 catalysts for glycerol carbonate synthesis from glycerol and dimethyl carbonate

A phosgene-free route for the synthesis of methyl N-phenyl carbamate (MPC) by the reaction of aniline with methyl carbamate in the presence of methanol was studied. Effects of catalysts, reaction temperature, reaction time, and catalyst content, the molar ratio of reactants and the content of water on the reaction were investigated. The results demonstrated that an aniline conversion of 90.1% and MPC selectivity of 99.7% were achieved when the reaction was carried out at 433 K for 4 h using ZnCl2 as a catalyst. A possible reaction mechanism was proposed based on the product distribution.

Xinkui Wang

Papers

The effects of the molecular weight and structure of polycarbonatediols on the properties of waterborne polyurethanes

Catalytic synthesis of Carbonated Soybean Oil

Synthesis and characterization of waterborne polyurethane adhesive from MDI and HDI

Structure-activity correlations of LiNO3/Mg4AlO5.5 catalysts for glycerol carbonate synthesis from glycerol and dimethyl carbonate

A phosgene-free process for the synthesis of methyl N-phenyl carbamate by the reaction of aniline with methyl carbamate