RAFT Soap-free Emulsion Polymerization And Preparation Of Binds With ABA Triblock Structures

Being advantageous (e.g. very cost-effective, simple process, brilliant colors, highly efficient process for poly-blend textiles), pigment dyeing technology was termed as ways for printing and dyeing industry to achieve cleaner production, energy-saving and emission reduction. However, it was limited by the physiochemical properties of the binders that the handle and the color fastness of dyed fabric could be contradicted, which deteriorated the quality of the dyed fabrics. Aiming at solving the problem, the thesis dedicated to synthesis ABA triblock copolymers with different copolymerization compositions. And the copolymers with low modulus and high breaking strength characters were pursued and engaged as binders to endow the dyed fabrics with soft handle together with high color fastness. So, the copolymer synthesis technology was first investigated, then PSt-b-PnBA-b-PSt triblock copolymers were prepared followed by the investigation of their mechanical properties, finally the triblock copolymers were used as binder during pigment dyeing process and the properties of dyed fabrics were evaluated. The following points were concluded:(1) Compared with the RAFT miniemulsion polymerization, RAFT soap-free emulsion polymerization controlled over the distribution of molecular weigh and particle size in a better way, resulting in a narrow distribution. Therefore, RAFT soap-free emulsion polymerization was more helpful to efficiently prepare block copolymers with fine chemical structures.(2) PSt-b-PnBA-b-PSt triblock copolymers could be prepared using a so called batch-semibatch RAFT soap-free emulsion polymerization technology. While the copolymerization compositions were tuned by variations of the monomer recipes. It was interesting to found that the PDIs of the copolymers increased dramatically since the formation of the block structure, which was proved to be connected with the formation of microphase separation structure within latex particles. The block copolymer microphase separation structure was confirmed by TEM combined with DSC. Then the mechanical properties of the triblock copolymer solvent films and latex films properties were compared by universal tensile tester. It was found that solvent films'ultimate tensile strengh and enlongation at break were controlled respectively by PSt content in positive and negative linear relationship. When the content of PSt was less than 30%, the mechanical properties of the solvent film showed low modulus and high breaking strengh characteristics. However, the"hard shell layer"of the acquired latex restricted the polymer chain diffusion during latex film formation, it deteriorated the continuity of PBA phase in the latex films. The modulus of latex film was always much higher that those of the solvent film consequently.(3) PSt-b-PnBA-b-PSt triblock copolymer with low PSt content (<30%) were used as binders during pigment dyeing. It was found that the resulting fabrics had excellent rubbing fastness and soaping fastness than those with commercial binders except for the slightly hard handle. Compared with the binders with statistic copolymerization structures, the one with triblock structures imposed the fabrics with higher fastness together with smoother handling.