| Author: | Pu, Yi |
| Title: | Temperature-responsive skin-like directional liquid flow and water repellent fabric |
| Advisors: | Fan, Jintu (SFT) |
| Degree: | Ph.D. |
| Year: | 2026 |
| Subject: | Smart materials Textile fabrics -- Thermal properties Moisture in textiles Water repellents Hong Kong Polytechnic University -- Dissertations |
| Department: | School of Fashion and Textiles |
| Pages: | 184 pages : color illustrations |
| Language: | English |
| Abstract: | In the context of global climate change, high-temperature conditions are becoming increasingly prevalent. Outdoor workers during summer months frequently encounter extreme heat conditions that significantly affect comfort levels, with severe cases potentially leading to heat exhaustion or even life-threatening heat stroke. Acting as a second skin for the human body, clothing plays a critical role in maintaining thermoregulatory and moisture comfort. However, current garment technologies often fail to address thermal and moisture regulation requirements during heavy perspiration. Conventional moisture management textiles typically operate by rapidly transporting sweat away from the skin surface and facilitating quick liquid spreading for enhanced evaporative cooling. Nevertheless, these traditional fabrics exhibit significant limitations when excessive sweating takes place. When wet with excessive sweat, they become heavy, clingy, and uncomfortable after-chill against the skin. Prolonged wear of sweat-soaked garments may also cause potential health problems. Furthermore, unlike human skin, existing thermoregulatory textiles lack the ability to dynamically adjust their moisture management performance in response to temperature variations, which substantially restricts their practical utility in various applications. An ideal moisture management fabric should dynamically regulate the liquid water transport properties in response to temperature variations like human skin. If the moisture management fabric could enhance liquid water transport property at higher temperatures while suppressing liquid water transport to reduce evaporative cooling at lower temperatures, it will critically improve thermal and moisture comfort. This research aims to develop temperature-responsive skin-like directional flow and water repellent fabrics as well as understanding the underlining mechanisms of its unique directional liquid water transport and water repellent properties. The research contains three parts: (1) development of fabrication method of skin-like fabrics for scalability, (2) development of poly([2-(Methacryloyloxy)ethyl] dimethyl-(3-sulfopropyl) ammonium hydroxide) (PDMAPS)-based temperature-responsive skin-like fabrics, and (3) development of poly(acrylamide-co-acrylonitrile) [poly(AAm-co-AN)]-based non-ionic temperature-responsive (NiTR) skin-like textiles. To address the issues of conventional moisture management fabrics (e.g., heaviness and wet clinginess when saturated with sweat), skin-like fabrics have already been reported in previous work. However, the existing plasma-based fabrication method presents several drawbacks, including high energy consumption, low production efficiency, and poor durability. This study improved the fabrication process of existing skin-like fabric, proposing a new polyvinyl alcohol (PVA)-based fabrication approach of skin-like fabrics. First, PVA solution was printed onto the fabric surface by screen printing technique as a coverage pattern, followed by hydrophobic treatment via dip coating. After hot washing for the removal of PVA, the covered areas by PVA formed gradient wettability channels. These channels enabled directional liquid water transport from the inner side to the outer surface of the fabric, where droplets accumulated and rolled off, while most areas remain dry, which effectively prevented moisture-induced heaviness and coldness. Additionally, the predominantly hydrophobic outer surface provides water repellency against contamination. The wettability, directional liquid transport property, water repellency, and air permeability of the prepared skin-like fabric were evaluated. This method offered simplicity, cost-effectiveness, and compatibility with various substrates. The resulting samples demonstrated excellent durability and showed potential for industrial-scale production. To achieve the temperature-responsive property on the skin-like fabric, zwitterionic upper critical solution temperature (UCST)-type temperature-responsive polymer PDMAPS was grafted onto the surface of the skin-like fabric using a "grafting-from" approach. Before the grafting process, 3-(trimethoxysilyl) propyl methacrylate (TMSPMA) was applied onto the fabric as a coupling agent to enhance grafting durability. The TMSPMA-treated fabric was then dip-coated with the [2-(Methacryloyloxy)ethyl] dimethyl-(3-sulfopropyl) ammonium hydroxide (DMAPS) monomer solution and subjected to ultraviolet (UV)-initiated graft polymerization, resulting in (PDMAPS)-based temperature-responsive fabric. The fabricated fabric not only remained the characteristics of skin-like fabric but also exhibited dynamically switchable moisture management properties in response to temperature changes. At higher temperatures, the fabric demonstrated enhanced liquid water transport efficiency, while at lower temperatures, it showed decreased liquid water transport capability and improved water repellency. The directional liquid water transport property, temperature responsiveness, water resistance, air permeability, and handle of the fabric were systematically evaluated. The mechanism of the temperature-responsive directional liquid transport property of the fabric was also discussed. This functional fabric holds potential as a multifunctional smart moisture management textile, particularly suitable for next-generation intelligent sportswear applications. The combination of temperature-responsive behavior with inherent skin-like fabric properties offers promising opportunities for advanced textile development. The (PDMAPS)-based temperature-responsive fabric, while offering advantages such as easy preparation and rapid temperature response, exhibits sensitivity to electrolyte concentration variations due to its zwitterionic nature. Since human sweat electrolyte levels fluctuate with health status and exercise intensity, the practical applications of (PDMAPS)-based temperature-responsive fabrics are limited. To solve this problem, we developed a non-ionic UCST-type temperature-responsive fabric. The non-ionic UCST-type temperature-responsive polymer, poly(AAm-co-AN) was grafted onto the cotton knitted fabric for the first time via a novel site-specific grafting method. The fabric underwent mixed silane pretreatment before grafting with the polymer, followed by photo-initiated grafting of poly(AAm-co-AN). The mixed silane contains a hydrophobic silane to adjust the fabric surface wettability, a grafting-functionalized silane to control the concentration of grafting sites on the fabric surface, and a silane crosslinker to increase the coating stability. By adjusting the ratio of the hydrophobic silane and the grafting-functionalized silane, the grafting ratio of poly(AAm-co-AN) could be controlled, enabling the surface to achieve stable temperature-responsive performance. By precisely controlling both the silane composition and acrylamide-to-acrylonitrile (AAm:AN) ratio, we fabricated NiTR fabrics with tunable transition temperatures, excellent reversibility, and remarkable electrolyte stability. The resulting smart textiles demonstrate superior performance in various applications including being used for the substrate of skin-like fabric for personal moisture management, smart oil-water separation and advanced wound dressings, representing significant improvements over conventional temperature-responsive fabrics. |
| Rights: | All rights reserved |
| Access: | open access |
Files in This Item:
| File | Description | Size | Format | |
|---|---|---|---|---|
| 8805.pdf | For All Users | 6.89 MB | Adobe PDF | View/Open |
| 8805__Corrigendum.pdf | For All Users | 396.33 kB | Adobe PDF | View/Open |
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