Meiting Fu,Kai Jin,Yue Zhang,Richmond Polley,Ruoyu Zhang,Shigang Yang,Debiao Liu
With rising interest in various offshore equipment, bridges, and marine engineering, it is necessary to develop an epoxy resin adhesive that can cure quickly under seawater and has high bonding performance. In this paper, through mimicking mussel adhesive proteins, a biomimetic epoxy resin is designed and prepared for seawater adhesion. A mussel dopamine-like structure with cashew phenol and catechol as the main structure is prepared by the Mannich reaction, and the amino acids in mussel adhesive protein are simulated by the addition of decamethylene diamine. The results show that the adhesive has higher seawater bonding strength (17.65 MPa) and tensile strength (30.31 MPa) under the condition of seawater solidification. The cross-section morphology of the adhesive is still a typical ductile fracture due to the adhesive retaining the toughened properties of the cashew phenol structure, while the catechol structure provides a stronger bonding ability. The apparent activation energy is 45.22 kJ mol −1 indicating in a high curing activity. The ions in seawater can participate in the bonding process of the adhesive, and non-covalent bonds can be formed in the process. The construction strategy that mimics the mussel adhesive protein structure can also be used to design other seawater adhesives.
Abstract Linear 1,10-decanediamine was chosen as a modified monomer to prepare modified poly(ethylene terephthalate) (PET) with a low content of amide bonds through two different synthetic methods. To evaluate the effect of amide bonds on the properties of poly(ester amide) analogs (PETAs), the performance of this new type of PET was compared with 1,10-decanediol-modified PET as a control group. The formation of hydrogen bonds in the PETAs was confirmed, and the stability of hydrogen-bonding interactions based on the low content of amide bonds at high temperature was discussed. Interestingly, physical cross-linking networks formed by hydrogen-bonding interactions improved the thermal stability, rheology, and mechanical properties of the PETAs. The crystallization properties were studied in depth by a series of tests, the results of which illustrated that the low content of amide bonds acted as a critical crystallization accelerator in the PETAs. A feasible strategy to prepare high-performance PET, which may be used as a packaging material, was introduced in this work. Graphical abstract
Liuchun Zheng,Qiqi Xie,Guangjun Hu,Bing Wang,Danqing Song,Yunchuan Zhang,Yi Liu
Polyureas have been widely applied in many fields, such as coatings, fibers, foams and dielectric materials. Traditionally, polyureas are prepared from isocyanates, which are highly toxic and harmful to humans and the environment. Synthesis of polyureas via non-isocyanate routes is green, environmentally friendly and sustainable. However, the application of non-isocyanate polyureas is quite restrained due to their brittleness as the result of the lack of a soft segment in their molecular blocks. To address this issue, we have prepared polyester polyureas via an isocyanate-free route and introduced polyester-based soft segments to improve their toughness and endow high impact resistance to the polyureas. In this paper, the soft segments of polyureas were synthesized by the esterification and polycondensation of dodecanedioic acid and 1,4-butanediol. Hard segments of polyureas were synthesized by melt polycondensation of urea and 1,10-diaminodecane without a catalyst or high pressure. A series of polyester polyureas were synthesized by the polycondensation of the soft and hard segments. These synthesized polyester-type polyureas exhibit excellent mechanical and thermal properties. Therefore, they have high potential to substitute traditional polyureas.
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