Skin-Inspired Zero Carbon Heat-Moisture Management Based on Shape Memory Smart Fabric

Mechanical Engineering Environmental Engineering Organic Polymeric Materials Chemistry Materials Science Engineering Polymer Chemistry
smart fabric heat-moisture management shape memory zero carbon unidirectional moisture transport

Academic Background

With the continuous increase in global greenhouse gas emissions, environmental temperatures are rising, posing potential threats to human health and productivity due to extreme weather conditions. Especially in summer, the widespread use of cooling devices such as air conditioners and electric fans has led to a sharp increase in energy consumption, further exacerbating greenhouse gas emissions. According to statistics, summer cooling equipment currently accounts for 40% of global carbon dioxide emissions, and this figure is expected to rise to 50% by 2050. Additionally, cold environments also pose a threat to human life, as seen in the 2021 Gansu Baiyin Marathon incident, where extreme weather conditions resulted in multiple deaths. Therefore, developing sustainable, zero-energy, zero-emission smart textiles that can regulate human body heat and moisture balance without external energy input has become a key focus of current research.

Smart heat-moisture management textiles can effectively regulate the thermal and moisture comfort between the environment and the skin, significantly reducing energy consumption and aligning with sustainable development goals. However, existing heat-moisture management textiles still have shortcomings in terms of smart responsiveness and real-time regulation, particularly in research on textiles based on shape memory polymers (SMPs). This study, through biomimetic design, combines shape memory ethylene vinyl acetate copolymer (EVA) fibers with traditional cotton fabrics to develop a smart textile with unidirectional moisture transport functionality, aiming to achieve environment-adaptive heat-moisture management and zero carbon emissions.

Source of the Paper

This paper was co-authored by Jing Zou, Yongzhen Wang, Xiang Yu, Rulin Liu, Weiqiang Fan, Jing Cheng, and Weiyi Cai, all from the School of Textile Science and Engineering at Xi’an Polytechnic University in China and the Key Laboratory of Functional Textile Materials and Products under the Ministry of Education. The paper was accepted by the journal Advanced Fiber Materials on October 22, 2024, and submitted on June 5, 2024. The DOI of the paper is 10.1007/s42765-024-00496-4.

Research Process and Results

1. Preparation and Optimization of Shape Memory Polymers

This study first prepared a two-way shape memory polymer (2W-SMP) through thermal cross-linking, with specific steps including: - Dissolving ethylene vinyl acetate copolymer (EVA) in chloroform, heating to 55°C, and stirring for 3 hours. - Adding the cross-linking agent dicumyl peroxide (DCP) and continuing to stir for 1 hour. - Pouring the solution into a glass dish, evaporating the solvent to obtain the EVA-DCP film. - Using a miniature single-screw extruder to prepare EVA-DCP fibers of different diameters, followed by heating at 170°C for 2 hours for cross-linking.

Fourier transform infrared spectroscopy (FTIR) and X-ray diffraction (XRD) analyses confirmed the polymer’s cross-linked structure and crystallinity. The study also optimized the shape memory response temperature range through differential scanning calorimetry (DSC) and dynamic mechanical analysis (DMA), ultimately selecting EVA3.0 (25 wt% VA content) as the base material.

2. Preparation of Shape Memory Composite Fabrics

Shape memory fibers were woven with cotton yarns in a plain weave structure to form composite fabrics, with specific steps including: - Selecting 87texx5 cotton yarn as the warp yarn and 1.5 mm diameter shape memory fibers as the weft yarn. - Weaving using a hand knitting machine, optimizing yarn selection, warp yarn fineness, and fabric structure. - Applying one-sided hydrophobic finishing to the fabric to achieve unidirectional moisture transport functionality.

Infrared thermal imaging and thermal conductivity tests verified the fabric’s dynamic thermal regulation capability during the shape memory process. Experiments showed that the fabric’s thermal conductivity reached 0.091 W/m·K at 48°C, with air permeability of 461.7 mm/s and moisture evaporation rate of 2021.5 g/(d·m²).

3. Research on Unidirectional Moisture Transport Function

One-sided hydrophobic treatment of the fabric was achieved through spray coating, with specific steps including: - Using sodium methyl silicate solution as the hydrophobic agent, spraying it onto the fabric surface. - Optimizing the hydrophobic agent concentration (0.5 wt%, 1.0 wt%, 1.5 wt%, 2.0 wt%) and the number of sprays (1, 3, 5 times). - Assessing the fabric’s unidirectional moisture transport performance through liquid moisture management testing (MMT).

Experimental results showed that after spraying 1 wt% hydrophobic agent 3 times, the fabric’s unidirectional moisture transport index reached 193.2, with an overall moisture management capacity (OMMC) of 0.74.

4. Heat-Moisture Management Performance of Smart Fabrics

The unidirectional moisture transport performance of the fabric was tested using a 1 wt% povidone-iodine solution to simulate human sweat. Results indicated that the fabric could rapidly transport moisture from the skin contact layer to the outer layer within 12 seconds, significantly improving human comfort. Additionally, infrared thermal imaging showed that the fabric significantly increased radiation transmittance at 48°C, achieving effective thermal regulation.

Conclusion and Significance

This study successfully developed a biomimetic zero-carbon heat-moisture management system based on shape memory smart textiles. Through the shape memory effect, the fabric achieved temperature-adaptive pore opening and closing functions, significantly improving air permeability and moisture evaporation capacity. Combined with unidirectional moisture transport technology, the fabric can quickly transport sweat from the skin layer to the outer layer for evaporation, thereby enhancing the comfort of the human microenvironment. This research provides new insights for the design of smart thermal regulation textiles and wearable devices, with broad application prospects, especially in outdoor, medical, military, and energy-saving fields.

Research Highlights

  1. Biomimetic Design: Developed smart textiles with dynamic responsiveness by mimicking the thermal regulation mechanism of the skin.
  2. Zero Carbon Emissions: Achieved zero-carbon heat-moisture management without external energy input.
  3. Two-Way Shape Memory: Realized two-way shape memory effects by optimizing the cross-linking degree and response temperature of shape memory polymers.
  4. Unidirectional Moisture Transport: Achieved excellent unidirectional moisture transport performance through one-sided hydrophobic treatment, significantly improving human comfort.

Other Valuable Information

This study also demonstrated the application potential of smart textiles in daily life and sports. Experiments showed that in an outdoor environment of 39°C, the fabric could reduce skin temperature by 4.35°C, significantly improving human thermal comfort. Additionally, the fabric remained intact after 100 abrasion cycles and exhibited minimal dimensional changes (less than 2%) after washing, demonstrating good durability.

This research provides new solutions for future low-carbon and environmentally friendly living, holding significant scientific and application value.