In an effort to develop a green process for the production of elastomeric polyurethane–urea (PUaE) through a nonisocyanate route, a highly practical method was found using diphenyl carbonate (DPC) instead of diisocyanate as the carbonylation agent. The transesterification of aliphatic diamines in a solvent such as tetramethylene sulfone (TMS) with DPC results in a new process obtaining new segmented PUaE with high molecular weights and excellent mechanical performance. The key to the present success lies in the timing and sequence of the diamine addition forming initial carbamate intermediates in situ and then in shifting the equilibrium toward polyurea product formation by phenol removal from the TMS solution so that high‐molecular‐weight polyurea could be formed favorably. The most optimized polyurea films made in this study has a ηinh of 0.64, with high‐performance characteristics showing tensile strength of greater than 30 MPa and elongation exceeding 400% with decomposition temperature (5%) of >280 °C. Well‐defined soft‐ and hard‐segment domains were observed for the products as determined by atomic force microscope. This new improved process to produce segmented polyurea thereby complies fully with the principles of green chemistry using readily available chemicals. © 2014 Wiley Periodicals, Inc. J. Polym. Sci., Part A: Polym. Chem. 2014, 52, 2781–2790
Zinc tetraphenylporphyrin (ZnPP) was bond on the side chains of linear chloromethylated polystyrene (CMPS) through Friedel–Crafts alkylation reaction, and the metalloporphyrin‐functionalized polystyrene (ZnPP/PS) was obtained successfully. Its chemical structure was characterized with FTIR. And the effects of various factors on the bonding reaction of ZnPP had been investigated in detail. In addition, the photophysical properties of ZnPP/PS were studied by means of UV‐Vis spectroscopy and fluorescence spectroscopy. The research results show that ZnPP/PS could be prepared favorably through Friedel–Crafts alkylation reaction between ZnPP and CMPS, and the most bonding degree of ZnPP on PS is up to 7% under the condition of the temperature 25°C and 0.1 mL of SnCl4 lasting 8 h. Moreover, ZnPP/PS show the characteristic photophysical behavior similar to ZnPP. ZnPP moieties in ZnPP/PS interact with terbuthylazine (TBA) and form a complex with a red‐shift of Q‐band of absorbance peak from 559 to 565 nm. Especially TBA quenches ZnPP/PS emission intensity at 610 and 662 nm when excites at 423 nm. The TBA‐ZnPP/PS complex is formed in the ground state and TBA is bonded to the excited state of ZnPP/PS simultaneously on the basis of a non‐linear Stern–Volmer plot indicative of the combined dynamic and static quenching. © 2014 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2014, 131, 40516.
Two solvent-free processes without using volatile organic chemical (VOC) for making polyurea elastomers have been successfully developed from diamines and diphenyl carbonate (DPC) to meet stringent public demands for a high standard green alternative Anastas and Eghbali (Chem Soc Rev 39 (1): [301][302][303][304][305][306][307][308][309][310][311][312] 2010). In this new non-isocyanate route (NIR) which is an improvement over our previous process to polyurea elastomers, molten DPC are utilized as the carbonylation agents, where DPC reacts sequentially with 1,6-hexanediamine (HDA), polyether diamines of 2000 molecular weight and short chain diamines such as isophorondiamine (IPDA) or 4,4′-diaminodicyclohexylmethane (H 12 MDA). No solvent was added in the synthesis of these new non-solvent polyurea. Alternatively, the above process was modified with an 3 % addition of a water dispersant such as 3-[(2-aminoethyl)amino]-1-propane sulfonic acid sodium salt (ESA) to make waterborne polyurea elastomers to facilitate the mixing in the preparation and in the film-making steps for the final products. In both solvent-free processes, the longchained polyether diamine and the phenol generated from the displacement reaction of diphenyl carbonate were utilized as diluents to lower the viscosities of the reaction mixtures. Unexpectedly, ultra high molecular weight products were resulted particularly for the waterborne polyurea products measuring in excess of 1,000,000 g/mol in some cases. All samples were characterized by FT-IR, H-NMR, TGA, DSC, AFM and GPC. Since the polymers were prepared under mild conditions in absence of a VOC solvent, the new products were found to mostly exist in highly phase-segregated states, exhibiting high heat-resistant temperatures with T d(5%) of well over 300°C with high elongation (>600 %) for the optimized products. Thus, this solvent-free syntheses and environmentfriendly polyurea products should find usefulness in many practical applications.
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.
customersupport@researchsolutions.com
10624 S. Eastern Ave., Ste. A-614
Henderson, NV 89052, USA
This site is protected by reCAPTCHA and the Google Privacy Policy and Terms of Service apply.
Copyright © 2024 scite LLC. All rights reserved.
Made with 💙 for researchers
Part of the Research Solutions Family.