| Functionalization of fiber surface with nanoparticles has become an important way to improve fiber property and develop novel functional fabrics.Elucidating the influencing factors that drive the nanoparticle deposition and assembly on fiber surface,and revealing the control methods of nano-coating structure will provide theoretical guidance for the rational design of functional nanomaterials and the optimization of fabric finishing processes.However,most of the current researches focus on the realization of a specific function or the preparation of materials,a deep understanding of the interaction mechanism between nanoparticles and fibers,especially on the nanoand micro-scale,is deficient.In this thesis,we designed an aqueous suspension system consisted of spherical silica with sizes ranging from 12 to 105 nm and silk fibers to explore the mechanism underlying the nanoparticle deposition on the fibrous materials from both kinetic and thermodynamic aspects.Also,we established a green approach to prepare fragrance-loaded nanoparticles on the basis of the host-guest chemistry and electrospray technique.The main achiements are as follows.1.Deposition kinetics and thermodynamics of nanoparticles on the silk fiber surfaceMonodisperse silica nanoparticles(NPs)with different particle sizes and silk fibers with different surface properties are selected as the functional particle/fabric fiber interaction models.The driving force of the particle deposition process was studied by an immersion-adsorption method.It was found that the particle deposition was mainly driven by electrostatic interaction,and the hydrogen bond interaction could further stabilize the particle attachment.During particle deposition,only the first layer of particles can be firmly attached;the multilayer deposition was prone to fall off until a stable monolayer deposition is remained.A modified theoretical model was proposed to quantitatively describe the particle deposition kinetics.The results showed that the deposition of particles on the fiber surface in the aqueous medium conforms to a collision model,and therefore,the nanoparticle coatings under different conditions can be predicted and controlled through the collision kinetics equation.Isothermal titration calorimetry was used for direct measurement of the thermodynamic parameters in the particle deposition process,and the relative contribution of hydrogen bonding and electrostatic interaction to the total deposition enthalpy can be quantified based on the proposed particle/fiber contact model.The contribution of hydrogen bonding to particle-fiber deposition enthalpy is less than 10%.2.Conformational states of polyelectrolytes on fiber surface and their affinity for nanoparticlesSilk fibers with different surface zeta potentials were obtained by changing the concentration of polycations used in the surface modification.A conformational effect of polycation was found when we use the different modified silk fibers for particle deposition.It was found that the polycation concentration not only affected the zeta potentials of the obtained fibers,but also formed a polycation modified layer with different chain conformations.At low polycation concentration,the polyelectrolyte molecular chains were in a flat conformation,whereas in high concentration the chain conformation was in vertical state.In the latter case,the electrostatic attraction between nanoparticles and the polycation layer was stronger,and the number of particles deposited on the surface was greater.Some nanoparticles could even be embedded in the polycation layer.3.All-aqueous preparation of fragrance-loaded nanoparticles by electrospraying processWe established an efficient approach to produce fragrance-loaded nanoparticles on the basis of the host-guest chemistry of cyclodextrin and electrospray technique,which allows for more than 90% encapsulation efficiency of fragrances in substrates and direct deposition of nanoparticles on the fabrics.Fragrance molecules were first complexed with 2-hydroxypropyl-β-cyclodextrin,and then the resulted inclusion complexes were blended with the aqueous solution of regenerated silk fibroin.The composite fragrant nanoparticles were prepared by electrospraying and deposited directly on a silk fabric.It was found that both rose oxide and limonene could form water-soluble inclusion complexes with 2-hydroxypropyl-β-cyclodextrin at a stoichiometric ratio of 1 : 1.The apparent stability constants of the corresponding inclusion complexes at 25 ℃ are 3156,221 L/mol.Under the optimal electrospray conditions(silk fibroin concentration 4%,inclusion complex/silk fibroin weight ratio 3/4,flow rate 1 μL/min,voltage 16 k V,collection distance 16 cm),we obtained the composite nanoparticles with a particle size of 300 ～ 400 nm.Alcohol-treatment solidified the as-sprayed nanoparticles and reduced the particle size to below 300 nm.The composite nanoparticles showed an ideal zeroorder fragrance release kinetics within the time peroid studied.The fragrant nanoparticles deposisited on silk fabrics by electrospray showed strong affinity to the substrate,the particle retention percentage was more than 80% after 10 runs of washing with water. |
