Synthesis Of Novel Fluorinated Coating Materials And Their Applications On Cotton Fabrics

Fluorocarbons were widely used as coating, surfactant, lubricant and so on due to their exceptionally low surface free energy. It is well known that the finishing agents containing long perfluoroalkyl pendant chains (Rf≥8) have excellent hydrophobic and oleophobic effects and the water and oil repellency ratings of the treated textiles are usually 100 and 6 (AATCC test methods), respectively, without impairing the textile's permeability to air or hand feel. However, there are increasing evidences for bioaccumulation and/or toxicity of compounds containing long perfluoroalkyl chains. The development of environmental benign finishing reagents containing short fluorocarbon chains (Rf< 6) has attracted much attentions.In this dissertation, we designed and synthesized several classes of novel coating materials containing short fluorocarbon chains, and applied them as surface finishing agents to the cotton fabrics. Wetting properties of the treated cotton fabrics were investigated. The main work is described as follows:(1) Fluorinated coatings usually are not stable sufficiently during the use since the coatings are achieved to the surfaces only through physical adsorption or adhesion. Methods for modifying coating materials to form a stable film on substrate through covalent bonds have been developed. Usually, in order to obtain optimal hydro/oleophobicity, the fluoroalkyl pendant groups on the substrate surface should be parallel to each other and vertical to the interface. It has been discovered that the spatial arrangement of pendant fluoroalkyl groups could be consolidated by the presence of urethane groups between the polymer backbone and the fluorinated groups. In this study, A series of novel fluorinated polyacrylate graft copolymer (GPF-1,2,3) containing urethane groups and reactive groups have been prepared. GPF-1,2,3 exhibited very low surface free energy (17.77-25.81 mJ/m2). The cotton fabrics treated by GPF-1 showed the best water and oil repellency, the water and oil repellency ratings were 100 and 6, respectively. And the treated cotton fabrics also presented a very good wash durability, the water and oil repellency ratings were 90 and 5 respectively after 10 soaping cycles. The control experiments of durability studies indicated that GPF-1,2,3 were indeed covalently attached to the cotton fibers.(2) Presently, the studies and applications of macromolecule coating materials with low surface free energy (generally organic silicon compounds or organic fluoro-compounds) are mostly focused on linear polymers. Hyperbranched polymers are highly branched macromolecules with three-dimensional globular architecture, and the large amount of terminal functional groups are tunable by chemical modification to achieve desired properties for some particular applications. In this study, A series of fluorinated hyperbranched polymers with different surface free energy (HPEFs/HPUFs) have been prepared. HPEFs/HPUFs hold very low surface free energies (13.67-24.49 mJ/m2) which almost are independent of their internal backbone but depend on the terminal fluorocarbon chains. The contact angle hysteresis, the water and oil repellency ratings strongly depend on surface free energy of HPEFs/HPUFs. Cotton fabrics treated by HPEF13/HPUF13 presented excellent water and oil repellency properties:the water and oil repellency ratings were 90 and 6, respectively. All of the treated fabric can achieve a very high static contact angle (CA) of water (139-146°).(3) The results in the preceding chapter have indicated that the fluorinated hyperbranched polymers had very low surface energy and excellent water and oil repellency effects when used as finishing agents. For the pursuit of good durability of fluorinated hyperbranched finishing agents, a series of molecular-weight controllable hyperbranched poly(urea-urethane)s containing reactive groups and short fluorocarbon chains (HPRFs) were prepared. HPRFs showed very low surface free energy (15.28-15.49 mJ/m2) which almost had nothing to do with their molecular weight. HPRFs were used as finishing agents to obtain highly hydrophobic and oleophobic cotton fabrics. The water and oil repellency ratings were 90 (CAs 142-143°) and 6(CAs 90-92°), respectively. HPRFs also presented very good wash durability, the water and oil repellency ratings kept 80 and 5, respectively, after 10 soaping cycles at 50℃. The control experiments of durability studies also indicated that HPRFs were covalently attached to the cotton fibers.(4) Superhydrophobic surfaces, generally characterized by both a high water contact angle (greater than 150°) and a low sliding angle (less than 5°), are arousing much interest because of their importance in fundamental research and practical applications. Hydrophobicity can be enhanced by the increase of roughness with micro- and/or nanoscaled structures and the low surface free energy. Therefore, artificial superhydrophobic surfaces are commonly fabricated from the combination of creating micro-/nanostructures and modifying with low surface free energy materials. In this study, superhydrophobic surface materials were synthesized by modifying multiwalled carbon nanotubes (MWCNT) with short fluorocarbon chain terminated hyperbranched polyester/poly(urea-urethane) (HPEF/HPUF). The FT-IR, TGA, XPS, TEM and SEM research of pure nanocomposites product (MWCNT-HPEF/HPUF) indicated that HPEF/HPUF were covalently attached to the MWCNT surface. The surfaces of MWCNT-HPEF/HPUF coatings on slide glass exhibited superhydrophobicity (CA 156°, contact angle hysteresis< 3°). The solution of MWCNT-HPEF/HPUF in ethanol were used as finishing agent and superhydrophobic cotton fabric (CA 151°, contact angle hysteresis< 5°) was achieved.