Design,Synthesis And Foam Application Property Control Of Photoresponsive Amphiphiles

The printing and dyeing industry is one of the most polluting industries in China.Its high energy-consumption,high pollution and high water-consumption have seriously deteriorated the sustainable development of the textile industry.In this connection,the ecological dyeing and finishing technology has been proposed.Foam dyeing and finishing technique is one of the ecological dyeing and finishing techniques,featuring characteristics with low-liquid and high energy-saving,which shows extensive potentials to solve the“three high”problem of the traditional dyeing and finishing technology,i.e.,high energy-consumption,high pollution and high water-consumption,allowing to enhance the ecological and economic benefits of the textile industry.As foam is a thermodynamically unstable system,the improvement of the foam stability in the foam dyeing and finishing technology is crucial for obtaining an excellent dyeing and finishing effect.However,the removal of stable residual foams at the end of the process is also a major problem,which consumes a large amount of water to clean-up and results in pollutant discharge,as well as results in the waste of chemicals.How to solve the contradiction between the foam stability requirements before and after foam dyeing and finishing processes and allow for a simple and environmentally friendly treatment of residual foams limit the application of foam technique.In this thesis,a series of photoresponsive molecular amphiphiles have been designed and synthesized by modifications of hydrophobic chain,hydrophilic chain,ionic nature and photoresponsive cores,aiming at providing photoresponsive foams to reversibly control the foam stability for textile dyeing and finishing industry.The foam stability can be rapidly controlled between stable state and unstable state by light with different wavelength,allowing to adjust foam stability according to the requirements before and after the foam dyeing and finishing processes.Additionally,controlling foam rupture enabled the recycling of residual foams,which not only solved the problem of difficult removal of residual foams but also significantly reduced pollutants discharge,allowing for a full utilization to avoid chemicals waste.It significantly enhanced the ecological and economic benefit of textile industry and realized the low pollutants discharge in foam dyeing and finishing technology.On the basis of the chemical structures and the resulting functions of photoresponsive molecular amphiphiles,the main contents and conclusions of this thesis were showed as follow:By analyzing the effects of the hydrophobic and hydrophilic structures on the foam properties of traditional polyoxyetherether-type nonionic amphiphiles?C_mEO_n?,it has been found that the EO chain length showed a more significant effect on the foam properties than the hydrophobic alkyl chain.When the alkyl chain length remained unchanged,the foaming ratio increased with the increase of the EO chain length.On the contrary,the half-life of the foam increased with the decrease of the EO chain length.Especially when the EO chain length was 5,the half-life of the foam increased sharply.In this connection,C₁₄EO₅ was selected as the optimal amphiphile to be employed in the pigment foam dyeing technique.The pigment dispersant and binder in the pigment foam dyeing liquid showed a great influence on the viscosity of the C₁₄EO₅ solutions,which can improve the foam stability,but reduce the foaming ratio.Through the process formulation and process optimization of the pigment foam dyeing technique,stable foams with a half-life of⁷0 min were obtained.Additionally,the foam properties of this system were stable.The corresponding stable foams were employed in the dyeing process of cotton fabrics.The color properties of the resulting cotton fabrics showed strong regularity,allowing to obtain cotton fabrics with dark color by adjusting the concentration of pigment dispersion.In addition,the resulting cotton fabrics showed good color fastnesses.The application of C₁₄EO₅ in pigment foam dyeing technique was feasible.The cotton fabrics dyed with the corresponding pigment foam dyeing technique showed excellent color properties.Additionally,C₁₄EO₅ can be used as foaming agent as well as foam stabilizer,reducing the usage of chemicals and allowing to simplify the components of the dyeing liquid,which significantly enhanced the ecological and economic benefit in textile industry.A series of nonionic azobenzene amphiphiles(NAA_Cn)with different hydrophobic chain length were designed and synthesized.The corresponding amphiphiles were designed with an azobenzene core,attached with alkyl chain to form the hydrophobic part and hydroxy group to form the hydrophilic part.The geometrical structure of NAA_Cn can be controlled by UV-light or Vis-light irradiation.Upon UV-light irradiation,trans-NAA_Cn transfer to cis-NAA_Cn and the cis-NAA_Cnn can reversibly switch back to trans-NAA_Cn by exposure to Vis-light.These photoisomerization processes showed high photochemical resistant.With the increasing of the hydrophobic chain length,the photoisomerization of NAA_Cn in ethyl acetate required a longer irradiation time to attain the photostationary state?PSS?.Additionally,the hydrophobic chain length also affected the ratio of trans-NAA_Cn/cis-NAA_Cn in PSS.The photoisomerization process from cis-NAA_Cn to trans-NAA_Cn can be accelerated by exposure to Vis-light at higher temperature.Trans-NAA_Cn showed foam stabilization effects,while cis-NAA_Cn promoted the rupture of foams.NAA_C4 was selected as the optimal structure to control the foam stability in this system.Foams,prepared from the mixture solution of NAA_Cnn and SDS,showed a controllable stablity by light,which was envisioned to emplyed in industrial processes,allowing to reversilbly control the foam stability and for the recycling of residual foams.A series of nonionic azobenzene amphiphiles(NAA_EOn)with different hydrophilic chain length were designed and synthesized.The corresponding amphiphiles were designed with an azobenzene core,attached with butyl-chain to form the hydrophobic part and polyoxyethylene ether chain to form the hydrophilic part.The replacement of hydroxy group with polyoxyethylene ether chain enabled the corresponding amphiphiles(NAA_EOn)to be water-soluble.The photoisomerization of NAA_EOn solution showed high selectivity by controlling UV-light or Vis-light irradiation.In the identical condition,the increasing of hydrophilic chain length allowed NAA_EOnOn solution to attain the PSS with a shorter photoirradiation time.The surface activity parameters between trans-NAA_EOn and cis-NAA_EOn were dramatically different.The critical micelle concentrations?CMC?of trans-NAA_EOn solution were lower than that of cis-NAA_EOn.The surface tension of trans-NAA_EOn solutions also were lower than that of cis-NAA_Eon at CMC.Additionally,the shorten modification of the hydrophilic chain length can decrease the corresponding CMC with a smaller variation of surface tensions at CMC between trans-NAA_EOn solution and cis-NAA_EOn solution.Photoresponsive foams can be obtained from industrial systems with multi-components by doping the trans-NAA_EOn solution,which provided potentials of developing sustainable and environmentally friendly foam dyeing and finishing processes.In order to develop a simple textile dyeing technique,featuring characteristics of both minimum pollutant discharge and versatile for various fibers,NAA_EO19 was applied in the pigment foam dyeing liquid to prepare colorful photoresponsive foams.The corresponding foams were employed in the dyeing process of cotton,silk and polyester fabrics.Stable colorful foams with a half-life of⁶.3 min can be obtained from the pigment foam dyeing liquid with the addition of trans-NAA_EO19,while a rapid rupture of color foams was observed after exposure to UV-light with a foam half-life of¹.0 min.The photoresponsive colorful foams showed a high photochemical resistance.The results demonstrated that the pigment foam dyeing processes were versatile for cotton,silk and polyester fabrics.Based on the photoresponsive nature,the application of photoresponsive foams solved the problem of different foam stability requirement before and after the pigment foam dyeing process.Upon Vis-light irradiation,stable foams,prepared from the pigment foam dyeing liquid with trans-NAA_EO19,can be used for dyeing to obtain excellent color properties.After exposure to UV-light,the photoisomerization of trans-NAA_EO19 to cis-NAA_EO19 induced the rupture of foams,allowing for the recycling of residual foams for re-using.The color properties and fastness of the fabrics,which were dyed with foams prepared from the recycled pigment foam dyeing liquid,were reproduceable.The development of the recycled pigment foam dyeing process based on the photoresponsive foams allowed the full utilization of the dyeing liquid,which significantly reduced the pollutants discharge.In order to reduce the chemical usage in the foam dyeing and finishing technique,the development of amphiphiles featuring characteristics of both foaming and controlling foam stability provides a potential alternative.In this regard,cationic azobenzene amphiphile(CAA_C8),which was designed with an azobenzene core,attached with octyl-chain to form the hydrophobic part and a quaternary ammonium moiety to form the hydrophilic part,was synthesized.CAA_C8 showed excellent photoisomerization properties in aqueous solution.A trans-CAA_C8(0.02 g L^-1)solution can attain to the cis-CAA_C8 PSS by UV-light irradiation for1 s,which was able to switch back to the trans-CAA_C8 PSS upon Vis-light irradiation for 3min.A color change of the CAA_C8 solution was observed during the photoisomerization process.The photoisomerization of CAA_C8 was reversible and showed high photochemical fatigue resistance.Compared to the cis-CAA_C8,the surface tension and critical micelle concentration?CMC?of trans-CAA_C8 were lower,indicating a higher surface activity of trans-CAA_C8.Additionally,the surface excess of trans-CAA_C8 was higher than that of cis-CAA_C8 and the minimum area per trans-CAA_C8 at the air-water interfaces was smaller than that of cis-CAA_C8,indicating a dense packing of trans-CAA_C8 monolayers at the air-water interface.Trans-CAA_C8 showed some foamability,which can be used to prepare photoresponsive foams.The stability of foams prepared from the trans-CAA_C8 varied sharply upon UV-light or Vis-light irradiation.Additionally,the photoresponsive foams have a high photochemical fatigue resistance.However,due to the solubility limitation,trans-CAA_C8solutions with high concentration were unreachable.The foamability and foam stability of foams prepared from the trans-CAA_C8 solutions with low concentration were not good enough for the application in foam dyeing and finishing techniques.In order to provide a novel and coreless photoresponsive foams for foam dyeing and finishing technique,the development of colorless cationic photoresponsive amphiphiles with high solubility and foam properties is a promising solution.In this regard,cationic molecular motor amphiphile?CMA?,which was designed with a first-generation molecular motor core,attached with an alkyl chain to form the hydrophobic part and a quaternary ammonium moiety connected via a triethylene glycol-linker to form the hydrophilic part,was synthesized.From the molecular level,the isomerization of CMA can be controlled selectively by orthogonal external stimuli,i.e.,light and heat,not only in organic solvents but also in aqueous media.On one hand,the reversible photoisomerization between stable trans-CMA and unstable cis-CMA can be obtained by alternating 254 nm?or 312 nm?light and 365 nm light irradiation.On the other hand,stable trans-CMA can transfer to stable cis-MA via a 180 ^o unidirectional rotation by 254 nm light irradiation and a subsequent heating process.From microscopic level,the molecular photoisomerization of CMA induced the transformations of properties at air-water interface and self-assembly structures in solution.The photoisomerization from stable trans-CMA to unstable cis-CMA induced a significant in-situ increase of surface tension.As for the self-assembly transformations,stable trans-CMA or stable cis-CMA formed worm-like micelles or vesicles,respectively.The worm-like micelles from stable trans-MA can be transferred to a mixture of worm-like micelles and vesicles upon254 nm light irradiation.The resulting mixture of worm-like micelles and vesicles was able to switch back to worm-like micelles after exposure to 365 nm light.Alternatively,the resulting mixture of worm-like micelles and vesicles became unsensitive to 365 nm after heating.It was noted that the self-assembly transformations of molecular motor amphiphiles in this system was the most dramatic and sensitive to light and heat stimuli.From the macroscopic responsive foams,the self-assembly transformations induced by the isomerization of CMA resulted in the controllable of foam properties.Stable trans-MA showed excellent foamability.Foams,prepared from stable trans-MA solutions were stable and highly sensitive,which can be triggered by light and heat.This is the first time to identify the key process of the amplification of molecular motion to microscopic structural transformations and to macroscopic responsive foams,which provided a proposed mechanism of photoresponsive foams.In order to develop photoresponsive amphiphiles with excellent solubility to allow for the application in foam dyeing and finishing technique for foaming as well as controlling foam stability,a cationic azobenzene amphiphile(CAA_C4)was designed and synthesized.Compared to CAA_C8,CAA_C4 was designed by replacing the octyl-chain with a shorter butoxy-chain to form the hydrophobic part.A trans-CAA_C4(0.02 g L^-1)solution can attain to the cis-CAA_C4 PSS by UV-light irradiation for 1 s,which was able to switch back to the trans-CAA_C4 PSS upon Vis-light irradiation for 7 min.The photoisomerization of CAA_C4 was reversible and showed high photochemical fatigue resistance.The hydrophobic chain modification by a short butoxy-chain significantly improved the solubility and foamability of trans-CAA_C4,which can be used to generate foams with a much longer half-life,allowing for the application in foam dyeing and finishing technique.The trans-CAA_C8 solution at a maximum concentration was 0.4 g L^-1,while the concentration of trans-CAA_C4 in solution was significantly improved with a minimum concentration of 5.0 g L^-1.The maximum foaming ratio of trans-CAA_C8 solution was⁶.3,while the minimum foaming ratio of trans-CAA_C4 solution was¹1.0.Additionally,the maximum foam half-life of trans-CAA_C8solution was³.5 min,while the minimum foam half-life of trans-CAA_C4 solution was¹9.1min.Photoresponsive foams can be obtained from CAA_C4 solution.With the addition of polyurethane dye,CAA_C4 was applied in the development of a recycled foam dyeing technique for cotton fabrics.The color properties of the resulting cotton fabrics were stable and excellent with a strong color regularity.The recycled foam dyeing process showed great feasibility.The color properties and fastness of the fabrics,which were dyed with foams prepared from the recycled pigment foam dyeing liquid,were reproduceable.The development of the recycled pigment foam dyeing process based on the photoresponsive foams allowed the full utilization of the dyeing liquid,which significantly reduced the pollutants discharge.Additionally,the component of the corresponding dyeing liquid was simplified,mainly contained two types of chemicals,i.e.,CAA_C4 and polyurethane dye,which impacted significantly in enhancing the ecological and economic efficiency as well as the sustainability of the textile industry.