\”Macromolecules\”: Construction of multi-functional polysulfide urea synthesis strategy without catalytic

Polythiourethane is a typical sulfur-containing polymer, having a self-healing, high refractive index, a high dielectric constant, heavy metals and strong coordination ability and other special properties, is a class of polymer materials useful research value. Currently synthetic methods have been reported mainly diamine monomer with thiourea, phosgene, diisocyanates or elemental sulfur with the sulfur source monomeric diisocyanate, and the like reaction. These methods present several disadvantages such as: large toxic material, structural diversity restricted monomers, monomer synthesis complex, expensive and the like. Therefore, the development of green, low cost, pervasive strong polysulfide urea synthesis process is very scientific and industrial value.

mild conditions, cheap raw materials, wide applicability polythiourethane synthesis is essential.
Figure 1. The polymerization reaction equation

2018, Tokyo University professor Takuzo Aida research team prepared a highly foreground polythiourethane polymer (the structure as shown in P1 1), taking into account the self-healing ability and excellent mechanical properties. Polymer system can be stretched to 393 ± 5%, an elastic modulus of about 1.4 GPa. And applying pressure to the section of the polymer at several tens of seconds and kept at room temperature by breaking the polymer material can be restored as ever, showing a perfect self-healing. The study broke the previous self-repairing material many bottlenecks problems, related papers published in the journal Science [1]. However, this system uses expensive thiocarbonyl imidazole as a sulfur source and a complicated separation and purification of the polymer, resulting in a very high cost of synthesis of the polymer, limiting its application.

To solve the above problems, Changshu Institute of Technology Luo Ming teacher on the basis of its sulfur-containing polymer research for many years, skillfully inexpensive, readily available industrial raw materials carbon disulfide (CS2) is used as a sulfur source, CS2 and diamine compound 1,8-diamino-3,6-dioxa-octane (FIG. 1, DA1) at 45 ℃, air, under mild conditions without copolymerization catalyst, in good yield (96%) polysulfide prepared urea P1. And its molecular weight parameters were better than reported above Science. Sulfur-containing monomer raw material costs this method is only one percent of Science reported, greatly improving the prospects of the polymer, and breaking the monopoly of Japanese scholars polymer synthesis methods.

Of the polymer P1 were NMR, mass spectrometry time of flight matrix assisted characterized, defined its backbone structure. The researchers then examined polythiourethane P1 is self-healing. 2, is first prepared by casting rectangular sheets P1. After the sheet was cut into two pieces, the two fragments attached to the mouth of the extrusion is placed 30 seconds for 10 minutes, the sheet was found stable after healing subjected to a load of 200g. Above show that, Pl may be extruded through rt for rapid self-healing, healing after mechanical strength can still meet the requirements.

Figure 2. The polythiourethane P1 self-healing test
The polymerization process easy to operate, and has a wide range of universal monomers, suitable for a range aliphatic, cycloaliphatic, aromatic diamines and other types of compounds. Based on the successful synthesis of P1, and authors investigated the effect of 24 kinds of commercially available polymerizable monomers and diamine to give 22 kinds of successfully diversified polythiourethane structure (FIG. 3), and generally high yield and high molecular weight. This indicates that the method has excellent generality monomers.
Figure 3 with carbon disulfide diamine monomer copolymerizable different structure
A polythiourethane is excellent heavy metal ion adsorption material. Researchers selected from inexpensive and readily available hexamethylenediamine and CS2 polythiourea prepared by copolymerizing P4 obtained as an adsorbent, the adsorption test the effect of toxic heavy metal ions from water Hg. Experimental results show (FIG. 4), and P4 can be added in an amount sufficient 99.9% removal of mercury ions in aqueous solution, described P4 is efficient, cost mercury ion adsorbent.
Figure 4 a schematic view of the mercury ion removal and absorption table.

The first reported work copolymerizing at room temperature, in air, without a catalyst and carbon disulfide diamine, efficient and convenient, economically prepared polythiourea structural diversity. The synthetic strategy mild conditions, low cost, wide range of monomers suitable. The researchers hope that this work will provide a convenient method for the synthesis of structural and functional diversity polythiourethane a simple and feasible for the majority of the material scholars. This achievement with Catalyst-Free Construction of Versatile and Functional CS2-Based Polythioureas: Characteristics from Self-Healing to Heavy Metal Absorption was published on Macromolecules. First author Changshu Institute of Technology and the University of Suzhou joint training Master Wu Shuang, Corresponding Author Luo Ming teacher. Article link: https: //pubs.acs.org/doi/10.1021/acs.macromol.9b01811# References: [1] Science, 2018, 359, 72-76, DOI: 10.1126 / science.aam7588