Structural colors are bright and possess a remarkable resistance to light exposure, humidity, and temperature such that they constitute an environmentally friendly alternative to chemical pigments. Unfortunately, upscaling the production of photonic structures obtained via conventional colloidal self-assembly is challenging because defects often occur during the assembly of larger structures. Moreover, the processing of materials exhibiting structural colors into intricate 3D structures remains challenging. To address these limitations, rigid photonic microparticles are formulated into an ink that can be 3D printed through direct ink writing (DIW) at room temperature to form intricate macroscopic structures possessing locally varying mechanical and optical properties. This is achieved by adding small amounts of soft microgels to the rigid photonic particles. To rigidify the granular structure, a percolating hydrogel network is formed that covalently connects the microgels. The mechanical properties of the resulting photonic granular materials can be adjusted with the composition and volume fraction of the microgels. The potential of this approach is demonstrated by 3D printing a centimeter-sized photonic butterfly and a temperature-responsive photonic material.

Soil freezing is observed throughout almost the entire forested area of the Russian Federarion in winter. The effect of negative temperatures on dusty-clay soils causes a number of adverse processes that change the properties of the soils themselves. One of the most unfavorable of these processes is the accumulation of moisture in soils under the influence of the movement of the freezing front. When freezing, water-saturated clay soils increase dramatically in volume. This leads to the appearance of frost heaving in the active zone of the forest roadbed, which has an extremely adverse effect on the structure of the entire pavement and can lead to damage to the pavement with a sharp deterioration in the transport and operational qualities of forest roads. To combat frost heaving, it is necessary to study the patterns of changes in the water-thermal regime of road structures. The depth of freezing of the pavement and the roadbed is of the greatest importance for predicting frost heaving and developing measures to combat this phenomenon. The article describes the developed system for monitoring the temperature of the road structure to a depth of 3 m and the measurement results which allow us to evaluate the temperature change at different depths from the road surface and determine the freezing depth. A total of 32 sensors have been installed with a step of 10 cm. A numerical simulation of the freezing process of the pavement and the upper part of the roadbed of a forest road has been performed, with the results compared with the indicators of field observations. Good data convergence has been revealed. According to the results of experimental studies, the freezing value has been 173 cm, and according to the results of numerical simulation - 190 cm. The average error in the results of numerical simulation of the freezing process of the pavement and the upper zone of the forest roadbed has been 8-10 % compared to the experimental data.