| Nowadays, polypropylene fabric industry occupies more than30%of incessantly expanding global polypropylene market share. However, there are still two remaining challenges to overcome:the diameters of conventional textile fibers made by typical industrial manufacturing processes are usually about10to20um; polypropylene is well known as a hydrophobic polymer and without polar functional groups. These futures greatly limit the end-use performance of polypropylene fabrics, especially in non-woven mesh applications. It is of significant importance to develop efficient methods for mass-production of polypropylene nanofiber and modification of polypropylene fabric for both academic research and practical application.In this thesis, we explored the factors determining the electrospinning behavior of polypropylene to modulate the fiber diameter, morphology and hierarchically structure. Furthermore, we developed various facile methods to fabricate glycosylated affinity and CaCO3biomineralizd membranes. The main results of this work are summarized as below.The effects of ionic liquid doping and ionic liquid bound on electrospinning of chlorinated polypropylene (CPP) nanofibers were carefully studied. It was found both methods could greatly improve the electrospinnability and smooth nanofibers could be produced under optimized conditions, which was ascribed to the enhanced conductivity. Ionic liquid doping CPP was a neutral polymer system while ionic liquid bound CPP displayed typical polyelectrolyte behavior.We found that nanofibrous mats with bird’s nest patterned structures can be directly electrospun from chlorinated polypropylene solutions doped with an ionic liquid. Various parameters including solution viscosity, ionic liquid content, collection time, humidity, voltage, the design of collector were systematically studied and Ansoft Maxwell version12software (3D, electrostatic solver) was further used to simulate the electrical field distribution of the electrospinning setup, both experimental and calculation results proved that the electrostatic repulsion interactions between the residual surface charges and the upcoming fibers play a key role. The proposed mechanism can be well extended to other polymer systems including polystyrene, poly(acrylonitrile-co-acrylic acid) and chitosan/poly(ethylene oxide).By using home-made high temperature electrospinning set-up, we successfully electrospun isotactic polypropylene nanofibers at120℃and isotactic polypropylene fibers with hierarchically porous structure could be produced by electrospinning at200℃combined with thermally induced phase separation (TIPS). Theoretical calculation demonstrates that the jet cools rapidly, and phase separation takes place in the jet during its travelling path, as the system traverses across the phase diagram from single phase region to metastable region. The pore formation process has a precise mechanism and the pore morphology is well correlated with the phase diagram. Furthermore, it is readily extended to other polymers with TIPS like PVDF.Glycosylated polypropylene non-woven meshes were achieved by a versatile UV grafting and chemical reaction process. SEM, WCA and FT-IR/ATR were used to characterize the physical and chemical changes of the mesh surfaces. The glycosylated meshes showed specific multilayer adsorption behavior of Con A with high binding capacity and increased chain length had positive effects due to improved chain mobility. However, some residual carboxylic groups would cause non-specific adsorption of proteins. CaCO3biomineralizd polypropylene non-woven mesh was fabricated on the basic principle of biomineralization by using a facile alternate soaking process (ASP) within20minutes. A uniform PAA layer was firstly tethered on the fiber surface, which can induce CaCO3nucleation. The biomineralizd meshes were endowed with superhydrophilicity and underwater superoleophobicity, and thus they showed prominent application prospects in oil/water separation and wastewater treatment. |
PDF Full Text Request