The invention of inverse vulcanization provides great opportunities for generating functional polymers directly from elemental sulfur, an industrial by‐product. However, unsatisfactory mechanical properties have limited the scope for wider applications of these exciting materials. Here, we report an effective synthesis method that significantly improves mechanical properties of sulfur‐polymers and allows control of performance. A linear pre‐polymer containing hydroxyl functional group was produced, which could be stored at room temperature for long periods of time. This pre‐polymer was then further crosslinked by difunctional isocyanate secondary crosslinker. By adjusting the molar ratio of crosslinking functional groups, the tensile strength was controlled, ranging from 0.14±0.01 MPa to 20.17±2.18 MPa, and strain was varied from 11.85±0.88 % to 51.20±5.75 %. Control of hardness, flexibility, solubility and function of the material were also demonstrated. We were able to produce materials with suitable combination of flexibility and strength, with excellent shape memory function. Combined with the unique dynamic property of S−S bonds, these polymer networks have an attractive, vitrimer‐like ability for being reshaped and recycled, despite their crosslinked structures. This new synthesis method could open the door for wider applications of sustainable sulfur‐polymers.

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Interest in using dynamic covalent bonds to construct dynamic polymer materials have been attracted to flourish the smart, responsive and adaptive polymeric materials. However, it is a challenge to design...

Polyurethane polymers were synthesized as novel solid-solid phase change materials (SSPCMs) by bulk polyaddition in the absence of organic solvents, in which polyethylene glycol (PEG) was selected as the working phase change substance and Span 80 and Tween 80 were used as crosslinking agents for the first time. The chemical structures, crystalline properties, phase change properties and thermal stability of the synthesized SSPCMs were characterized by Fourier transform infrared spectroscopy (FTIR), X-ray diffraction (XRD), differential scanning calorimetry (DSC) and thermogravimetric analysis (TG). An accelerated thermal cycling test was carried out to reveal the thermal reliability of the synthesized SSPCMs. The XRD patterns showed that the synthesized SSPCMs have a completely crystalline structure and defective crystallization compared with the pristine PEG. The DSC results showed that the synthesized SSPCMs have suitable phase change temperatures of 37-48 C and high latent heats in the range of 120-130 J g À1 . TG results showed that the synthesized SSPCMs possess good thermal stability.

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