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Title: The synthesis and application of novel anionic agents which prevent dye staining during laundering
Author: Biolchi, Francesca S.
Awarding Body: University of Manchester
Current Institution: University of Manchester
Date of Award: 2008
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This thesis describes the design, synthesis and technical evaluation of a series of novel anionic agents designed to prevent the staining of cotton, by loose dye residues, during laundering. These Resist Agents, which were added to the wash liquor, became bound to the cotton by intermolecular bonding, thus increasing the net negative charge at the surface of the cotton and thereby increasing its resistance to staining by anionic dye residues. Each agent comprised two triazine rings joined by one of three linking groups: 4,4'- diaminostilbene-2,2'-disulphonic acid, p-phenylenediamine or piperazine, and possessed a number of anionic sulphonate residues. 23 of the synthesised agents were tested as wash bath additives. All resulted in a reduction in the level of staining of cotton by a reactive dye; the magnitude of this effect varied greatly but, generally, it was observed that larger agents with a greater level of sulphonation provided the greatest resist effect, though none was as effective as the commercially available dye transfer inhibitor Sokalan HP 56. Surprisingly, one of the stilbene based agents (FB1) was significantly better than Sokalan HP 56 in reducing the staining of nylon fibres by C.1. Acid Blue 113. Further tests showed that all of the stilbene based bis(monochlorotriazinyl) agents with arylamine substituents attached to the triazine rings reduced the staining of nylon fibres by a number of acid dyes, whereas agents with alkylamino groups showed no such effect. In order to gain further insight, the adsorption of some of the agents onto ~ndyed cotton was studied and found to adhere to the Langmuir adsorption Isotherm model, indicating a monomolecular layer at the outer surface of the fibres. This build-up of anionic sulphonate groups at the fibre surface appeared to provide an effective barrier against approaching anionic dye residues and may account for the high levels of stain resist efficacy that were observed. Interestingly, when a similar concentration of sulphonate groups were uniformly distributed within the fibre, a much lower level of resist effect was observed. The percentage exhaustion of the agents onto undyed cotton during a 30 minute wash test was less than 50%, even at low concentrations of agent applied. Additionally, the agents took 24 hours to reach an equilibrium level of uptake onto cotton, much longer than a typical domestic laundering cycle. A Quantitative Structure Activity Relationship Study was conducted to identify the molecular features required for effective dye transfer inhibition on cotton fibres. 13 stilbene based agents were modelled and from these optimised structures, the values for 36 molecular descriptors were obtained. No statistically significant correlations were found between the measured stain resist efficacy and the molecular descriptors, suggesting that the interaction of the resist agents with cellulose is complex. The QSAR study did not yield a reliable predictive model to describe resist agent efficacy, possibly because the number of molecules used in the study was too small and the molecular structures were too closely related, to obtain any meaningful correlations.
Supervisor: Not available Sponsor: Not available
Qualification Name: Thesis (Ph.D.) Qualification Level: Doctoral
EThOS ID:  DOI: Not available