Study On Metathesis Cyclopolymerization And Properties Of A New Family Of Metathesis Polymers With Multifunctionality

Grubbs’ruthenium carbene catalyst could initiate metathesis cyclopolymerization (MCP), acyclic diene metathesis (ADMET) polymerization, and ring-opening metathesis polymerization (ROMP) effectively, due to the versatile and well catalytic activity, good stability in air, and the endurance to functional groups. Ruthenium-catalyzed olefin metathesis polymerization is an attractive and powerful tool to synthesize highly functionalized polymers, which has attracted considerable research attention recently in the field of polymer chemistry. This dissertation described the research work on obtaining a series of metathesis polymers with different structure and functionality via olefin metathesis polymerizations. This methodological innovation of MCP reaction can rich ideological function of polymer research and has important scientific significance and application prospects.MCP of ionic 1,6-heptadiyne is successfully applied to synthesize polyacetylene (PA) ionomer. The polymerization activity of the ionic monomer and the influence of catalysts and solvents on polymerization behavior and chain microstructure were investigated. The structure and propertities of PA ionomer was confirmed by FT-IR, NMR, GPC, UV-vis, CV, and TGA measurements. The results illustrated that PAs incorporating imidazolium pendent contained≥ 95%five-membered-ring structure and almost all trans-double bonds along the backbone. PAs formed in different solvents reflected significant variance in optical absorption properties, and a bathochromic shift effect was observed with the mixture of THF/ionic liquid. The imidazolium moiety has a great contribution to the stability of the conjugated polymer backbone.An efficient protocol to obtain n-type conjugated PAs bearing perylene bisimide (PBI) chromophore was stated. By tailoring the linkage on the N atom of PBI, three conjugated single-or double-stranded PAs, poly(1) and poly(2), were synthesized via MCP of 1,6-heptadiyne-based monomers, and a non-conjugated double-stranded poly(norbornene-dicarboximide) with the same PBI bridge, poly(3), was also prepared by ROMP of bis(norbomene) derivative. Monomers and polymers were identified by MS, IR, NMR, and GPC techniques. TEM measurement confirmed that the double-stranded poly(1) has an ordered ladder-like architecture, oppositely, the single-stranded poly(2) and double-stranded poly(3) own amorphous structure. UV-vis and CV characterizations revealed that conjugated poly(1) and poly(2) have lowered LUMO energy levels of -4.25 and -3.93 eV, and narrowed bandgap (Eg) of 1.70 and 1.80 eV, respectively, which precede the non-conjugated poly(3) having LUMO energy level of-3.86 eV and Eg of 2.07 eV. Compared to the single-stranded poly(2), the double-stranded poly(1) exhibited higher thermal stability with Td(5 wt%loss) of 367 ℃. Consequently, the conjugated backbone along main chain is greatly beneficial to enlarge the utility of solar energy and enhance the ambient stability of polymers.A facile synthesis of novel bridge-like polymer was accomplished by the combined procedure of MCP and ADMET polymerization. A telechelic double-stranded PA with two terminal alkenyl groups was firstly prepared through the third generation Grubbs catalyst-mediated chain terminating MCP of bis(l,6-heptadiyne) containing PBI segment in the presence of 1,4-bis(10-undecenyloxy)-cis-2-butene, a symmetrical tri-olefinic ether acted as the functional terminating agent, and then utilized as the macromonomer in subsequent ADMET polymerization to yield the resultant bridge-like polymer, consisting of the nonconjugated polyolefin backbone and the separated pier-like double-stranded PA, with an increased molecular weight as the reaction time prolonged and relatively broad polydispersity index. The bridge-like polymer can assemble into an ordered ladder-like architecture and the fence-like ribbon morphology, and displayed excellent thermal stability with Td of above 300 ℃ and high Tg between 175 and 189℃, which is important for application in devices.A simple synthetic strategy toward the precision polyethylene (PE) with PBI branches has been illustrated on the basis of ADMET polymerization of the structurally symmetrical PBI-contained α,ω-diene, giving the unsaturated polymer with increased molecular weight (Mn= 21.2-87.6 kDa) and decreased polydispersity index (PDI= 2.31-1.76) as the reaction time prolonged. The following hydrogenation of the unsaturated ADMET polymer was readily accomplished, affording the desired PE with a saturated backbone and the bulky PBI branches. This type of precise PBI-substituted PE displayed high glass transition temperature (Tg= 51.8-75.8℃), wide range of light absorption, and highly ordered architecture and pillar morphology, which may be facilitatory to the electron mobilities in optoelectronic device. Therefore, it can serve as a superior model for simply construction of functional PE with precise bulky branches, high glass transition temperature, and ordered architecture, which should be suitable for the large body of utilization involving the field of flexible polymer solar cells.