| Author: | Luk, Ming Yin Anson |
| Title: | A study of developing metal phthalocyanines for self-cleaning cotton |
| Advisors: | Xin, H. John (ITC) Cheuk, Kevin (ITC) |
| Degree: | Ph.D. |
| Year: | 2021 |
| Subject: | Cotton -- Cleaning Textile fabrics -- Cleaning Hong Kong Polytechnic University -- Dissertations |
| Department: | Institute of Textiles and Clothing |
| Pages: | xvii, 206 pages : color illustrations |
| Language: | English |
| Abstract: | Busy lifestyles drive growth in convenience products. This trend dramatically expands the functionality of easy-care textiles by developing diverse functional and smart fibrous materials. Self-cleaning is an advanced treatment that renders the treated material an ability to clean itself with automatic manner or minimal manual cleaning effort; such popular technology in textile material chemistry has been making considerable contributions to functional, hygienic and sustainable textiles. Organic photocatalysts for self-cleaning possess a number of advantages over the widely-studied nano-scale titanium dioxide (TiO2), such as light harvesting over the UV-visible spectrum and ease of property modifications via chemical tailoring. Porphyrin is one of the most important and efficient singlet oxygen generators among a family of organic photocatalysts. While metal phthalocyanine(s) (MPc(s)) has very similar properties to those of porphyrin, it has more intense light absorption in visible spectrum, superior stability against chemical, thermal and light and much material costs. Equal quantities of a number of copper phthalocyanine (CuPc) in various sulphonated forms were loaded to cotton fabric via exhaustion dyeing manners; whereas, the extents of photocatalytic stain decolourisation by such functionalised cotton fabrics were not consistent. Electronic absorption spectroscopies and liquid chromatography-electrospray ionisation-mass spectrometry (LC-ESI-MS) were the major means to determine varied molecular aggregation-dissociation behaviours resulted from different molecular configurations of the CuPc dyes. Other sulphonated phthalocyanines were also applied to cotton fabric for further analysis of phthalocyanine as organic photocatalyst for self-cleaning cotton. The performances of stain decolourisation of the MPc candidates are listed in descending order as: mixture of tetra- and tri- sulphonated zinc phthalocyanines (ZnPcS3-4) > di-sulphonated zinc phthalocyanine (ZnPcS2) > di-sulphonated metal-free phthalocyanine (H2PcS2) >> poly-sulphonated copper phthalocyanines (DB86) >> tetra-sulphonated nickel phthalocyanine (NiPcS4). However, the worse stability of ZnPcS3-4 drove the development of cotton fabric co-applied with slightly-aggregated ZnPcS2 and DB86 in different ratios to relieve the shortcoming of ZnPc stability. This co-system probably enhanced the ZnPc stability estimated by K/S measurement. On the other hand, it is discovered that NiPcS4 even accommodated in cotton fibre in improved monomeric state could not promote its photocatalytic power due to deficient electron configuration of Ni ion in NiPc; thus, its excellent stability and photocatalytic suppression is a potential for developing it as photocatalytic inhibitor. The visible-light-triggered stain degradation abilities of cotton fabric treated with anatase-TiO2-coated was found to be weaker than that dyed with CuPc under the identical photocatalytic condition; hence, sulphonated metal phthalocyanines with considerable photo-excited activities undeniably can compete and exceed TiO2 under the environment with visible light. Criticism of dye stain decolourisation as photocatalytic activity assessment and separation of the poly-sulphonated MPcs of derivatives by reversed-phase column for LC-ESI-MS analysis were two challenges met in the study. A series of experimental evidences revealed that decolourisation of dye stain is actually more suitable for evaluating the visible-light-driven self-cleaning effect contributed by MPc than that by inorganic photocatalysts on cotton textiles. Through an intensive investigation of the reversed-phase liquid chromatography for sulphonated molecules, unique, simple and efficient separation methods, termed as "gradient elution based on double- and triple- isocratic runs", were established to separate the poly-sulphonated MPcs using neutral mobile phase and conventional C18 columns only. The outcomes acquired from these addressed challenges could certainly raise the overall significance of this research project. |
| Rights: | All rights reserved |
| Access: | open access |
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