Vitrimers are functional cross-linked materials with an associative bond-exchange mechanism. Here, we demonstrate the preparation of colorless and highly transparent epoxy-based vitrimers by using a simple reaction of commercially available, thiol-functionalized, and epoxy-functionalized monomers, that is, trimethylolpropane tris­(3-mercaptopropionate) (Tri-SH) and bisphenol A diglycidyl ether (di-epoxy), which can thus contribute to the practical application of vitrimers because conventional vitrimers, especially epoxy-based vitrimers, suffered from a yellowish color and poor transparency. The present preparation includes another advantage of the efficient progress of the cross-linking reaction under relatively mild and quick reaction conditions (120 °C, 2 h) in comparison with the reported epoxy-based vitrimers, owing to the “click” nature of the thiol–epoxy reaction. Because the T g evaluated by differential scanning calorimetry is close to room temperature, the obtained vitrimer shows a Young’s modulus comparable to glassy polymers and also ductile tensile property, which is another advantage in terms of mechanical properties. Vitrimeric properties, such as the softening temperature and stress relaxation, are first evaluated, and the unique shape-memory property with a shape-editable function owing to the capability of network topology alternation is also demonstrated.

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In Part II, the normal distributions of various quantities related to the radiation budgets of a tropospheric column, the earth's surface, and the troposphere-earth system are presented over the northern hemisphere for January and July.In general, the distribution of radiation quantities has mainly zonal characteristics and intense north-south gradients in January, but has mainly cellular characteristics in July closely corresponding to the distribution of sea-land or the cloud cover. The annual mean value of planetary albedo for the troposphere-earth system averaged over the northern hemisphere is 0.374, which is slightly larger than the 0.34 of Houghton but smaller than the 0.40 adopted by Budyko.Both spatial and seasonal variations of the radiation budget of the troposphere, which contribute directly to the diabatic heating field in the troposphere, are relatively small compared with those of the radiation budgets of the atmosphere-earth system and of the earth's surface.