Synthesis Of Helical Substituted Polyacetylenes Via Catalytic Emulsion Polymerization

Helical polymers can present optical activities and chiral amplification due to the asymmetric secondary structures, which endow them with wide applications in many areas, such as chiral recognition, asymmetric catalysis, stimuli-response materials, switching materials, and so on. Therefore, the helical polymers play an important role in chemistry, life science and new materials. In this thesis, optically active helical substituted polyacetylenes with fluorescence properties were synthesized; in order to improve the applications of helical polymers, optically active helical polymers and polymers emulsions were prepared via catalytic emulsion polymerization; on the basis of catalytic emulsion polymerization, asymmetric polymerizations were developed for achiral monomers in chiral micelles, producing preferential helical polymers and optically active polymers emulsions, which open up a novel way toward asymmetric polymerizations.The major contents are as follows:1. Acetylene monomer, containing carbazole group and urea group, was synthesized from carbazole, and was then polymerized by Rh catalyst, from which poly(1) was produced. According to UV-vis, CD spectra, and fluorescence spectra, poly(1) had fluorescence properties but without helical conformation and optical activity. Accordingly, monomer 1 was copolymerized with a chiral poly(N-propargylurea) monomer 2, providing copolymers poly(1-co-2)s. The obtained copolymers exhibited optical activities and adopted helical conformation with a predominantly one-handed screw sense. The fact that the optical activity increased with increasing the chiral monomer units in the copolymers indicated that the copolymers followed the well-known "Sergeants and Soldiers" rule. The copolymers also possessed fluorescence properties originated from carbazole groups in the side chains. Moreover, optically active composite film with fluorescence property was prepared from the copolymers, using PVB as the supporting material.2. Monomers 1,2,3 and 4 were polymerized via catalytic emulsion polymerization in the presence of (nbd)Rh+B-(C6H5)4 as the catalyst. Among the obtained polymer emulsions, both poly(2) and poly(3) emulsions presented optical activities due to the preferential helical screw sense, but poly(1) emulsions had fluorescence properties. The polymerization time was found to have effects on the optical activity of poly(2) emulsions. In addition, monomer 3 was polymerized via catalytic emulsion polymerization in the presence of varied contents of SDS, by which polymer 3 emulsions containing nanoparticles with a wide rage of size were prepared. Optical activities were found in the polymer 3 emulsions and were affected by the varied size of nanoparticles. Polymer 3 was collected from the nanoparticles and presented optical activites in CHC13. Moreover, via catalytic emulsion polymerization, monomers 1 and 2, monomers 3 and 4 were copolymerized respectively, providing optically active copolymers poly(1-co-2)s and poly(3-co-4)s emulsions. Especially, poly(1-co-2)s emulsions possessed fluorescence properties. The "Sergeants and Soldiers" rule was only found in poly(1-co-2)s but not in poly(3-co-4)s. Optically active composite films were also obtained from poly(3) emulsions and PVA aqueous solutions.3. Monomers 4,5 and 6 were polymerized in the chiral micelles consisting of SDS and amino acids via catalytic emulsion polymerization, by which the obtained polymers emulsions exhibited optical activities except for poly(4) emulsions. The above results were resulted in that monomers 5 and 6 but without monomer 4 underwent asymmetric polymerization. Poly(5) was collected from nanoparticles and dissolved in CHCl3, and the obtained solution cannot present optical activity, which showed that the asymmetric polymerization may be under thermodynamic control.Dodecanoyl chloride and phenylalanine were chosen to synthesize chiral emulsifier DPA, which was coordinated with [(nbd)RhCl]2 catalyst. The obtained complex then formed chiral micelles, in which monomers 6 and 7 were carried out asymmetric catalytic emulsion polymerization; therefore, both poly(6) and poly(7) emulsions presented optical activities. The asymmetric polymerization may be under kinetic control, supported by the fact that the CHCl3 solutions of polymers collected from nanoparticles also had optical activities.