Polymerization Of Allene Derivates Catalyzed By Rare Earth Catalysts/Transition Metal Complexes And Synthesis Of Functional Materials Based On Poly (Allenes)

Allene derivatives have cumulated double bonds, either part of the cumulated double bonds can be polymerized selectively to obtain polymers having reactive exomethylene substituents. The possibility reactions for the vinyl double bonds indicate the potential applicability of polymers from allene derivatives as novel functional materials. The homopolymerization of n-octylallene, n-octyloxyallene and copolymerization of the allenes with styrene by rare earth catalysts or titanium complex were studied. The influences of reaction conditions on the polymerization, the characteristics, kinetics, and the mechanism of the polymerizations were investigated. The structure and the properties of the polymers obtained were characterized.Polymerization of n-octylallene was successfully carried out using a conventional binary rare earth catalytic system composed of rare earth tris(2-ethylhexylphosphonate) (Ln(P204)3) and tri-isobutyl aluminum (Al(i-Bu)3) for the first time. The effects of solvent, reaction time and temperature on the polymerization of n-octylallene by Y(P204)3/Al(i-Bu)3 were studied. The resulting poly(n-octylallene) has weight-average molecular weight of 11000, molecular weight distribution of 1.4 and 96% yield under the moderate reaction conditions:[Al]/[Y]=50 (molar ratio), [n-octylallene]/[Y]=100 (molar ratio), polymerized at 80℃for 20h in bulk. The poly(n-octylallene) obtained consists of 1,2- and 2,3-polymerized units, and was characterized by FT-IR,'H-NMR and GPC. Further investigation shows that the polymerization of n-octylallene has some living polymerization characteristics preparing the polymer with controlled molecular weight and narrower molecular weight distribution.Lanthanide Schiff-base complexes with the formula of [3,5-tBu2-2-(O)C6H2CH=NC6H5]3Ln(THF) (Ln=Sc, Y, La, Nd and Gd) have been synthesized by metathesis reaction of anhydrous LnCl3 with Schiff-base sodium salt in good yields. The complex with neodymium center was characterized by X-ray diffraction, the geometry around neodymium atom could be described as pentagonal bipyramid. It was found that the rare earth catalytic systems composed of Ln(Salen)3 and Al(i-Bu)3 are efficient for the homopolymerization of n-octyloxyallene, and show some characteristic of controlled polymerization; Y(Salen)3/Al(i-Bu)3 catalytic system can initiate the copolymerization of n-octyloxyallene with styrene. The ring-opening polymerization (ROP) ofε-caprolactone (CL) was successfully carried out by using these lanthanide Schiff-base complexes as catalysts, and neodymium complex leads to controlled ROP of CL. The influence of the reaction conditions on the monomer conversion, molecular weight, and molecular weight distribution of the resultant polymers was investigated. The polymerization rate was first-order with respect to the monomer concentration.Complex [Ti(salen)2Cl2] was synthesized with high yield by reacting the Schiff-base ligand with TiCl4 in n-hexane. This titanium Schiff-base complex combined with Al(i-Bu)3 has high catalytic performance for the polymerization of n-octylallene. The optimum reaction conditions for the polymerization are:[n-octylallene]/[Ti]=100, [Al]/[Ti]=50, aged at 80℃for 1h, polymerized at 80℃for 16h in bulk, and the Poly(n-octylallene) obtained has 100% yield, Mw=6.6×104, MWD=1.77 and 50% 1,2-polymerized units. Poly(n-octylallene-co-styrene) (PALST) was prepared from the copolymerization of n-octylallene and styrene with high yield by using the coordination catalyst system composed of Ti(salen)2Cl2 and Al(i-Bu)3. The molar ratio of each segment in the copolymer, and the molecular weight of the copolymer as well as the microstructure of the copolymer could be adjusted by varying the feeding ratio of both styrene and n-octylallene. A coordination-insertion mechanism was proposed for the copolymerization of n-octylallene and styrene.Novel graft copolymers consisting of poly(n-octylallene-co-styrene) (PALST) as backbone were synthesized using "grafting-from" or "grafting-onto" approaches based on thiol-ene reaction. The hydroxyl functionalized copolymer PALST-OH was prepared by the reaction of mercaptoethanol with the pendant double bond of PALST in the presence of radical initiator AIBN. The graft copolymer [poly(n-octylallene-co-styrene)-g-polycaprolactone] (PALST-g-PCL) was synthesized through a grafting-from strategy via the ring-opening polymerization (ROP) using PALST-OH as macroinitiator and Sn(Oct)2 as catalyst. Structures of resulting copolymer were characterized by means of gel permeation chromatography (GPC) with multi-angle laser light scattering (MALLS),1H NMR, DSC, polarized optical microscope (POM) and contact angle measurements. The amphiphilic graft copolymer PALST-g-PEG was synthesized through a grafting-onto strategy via the coupling reaction between the mercaptoacetic functionalized copolymer PALST-COOH and PEG-OH. Meanwhile, a one-spot strategy was developed for the synthesis of PALST-g-PEG by the thiol-ene reaction of PEG-SH and PALST.