Complex Macromolecular Architectures Utilizing Metallocene Catalysts

Abstract

Graft copolymers having poly(methyl methacrylate), PMMA, backbone and polystyrene, PS, polyisoprene, PI, poly(ethylene oxide), PEO, poly(2-methyl-1,3-pentadiene), P2MP, and PS-b-PI branches were prepared using the macromonomer methodology and high-vacuum techniques. The methacrylic macromonomers, mMM, were synthesized by anionic polymerization, whereas their homopolymerization and copolymerization with MMA were performed by metallocene catalysts. Relatively high macromonomer conversions were obtained in all cases. The parameters affecting the polymerization characteristics were examined. Well-defined poly(butyl methacrylate)-b-poly(methyl methacrylate) block copolymers were prepared for the first time by sequential addition of monomers starting from n-butyl methacrylate. The samples were characterized by size exclusion chromatography, SEC, 1 H and 13 C NMR spectroscopy, low-angle laser light scattering, LALLS, and differential scanning calorimetry, DSC.

Polymerization of acrylates and bulky methacrylates with the use of zirconocene precursors: Block copolymers with methyl methacrylate

“…This behavior can be attributed to the low polymerization ability of c HMA and TMSiOEMA, as previously mentioned, bearing in mind that the active center is sterically hindered by the presence of the bulk ligand (PMMA chain) of the zirconocene complex. Similar problems have been encountered in the synthesis of PMMA‐ b ‐P n BuMA block copolymers starting from the polymerization of MMA 9. Consequently, the sequence of monomer addition was reversed, starting from the polymerization of c HMA or TMSiOEMA, followed by the addition of MMA.…”

“…The crucial parameter defining the success of the synthetic procedure lies in the addition sequence of the monomers. Earlier studies9, 15 have shown that during the synthesis of MMA block copolymers with other methacrylates, the procedure is not successful when MMA is polymerized first. This behavior can be attributed to the slower polymerization rate of the second monomer, which enables side reactions, thus terminating many or even all of the growing chains.…”

“…Previous studies 4(f) have demonstrated the impact of the catalytic system on the homopolymerization of MMA, showing that rac ‐Et(Ind) 2 ZrMe 2 /[Me 2 NHPh] + [B(C 6 F 5 ) 4 ] − (3) as the catalytic system leads to a decrease in the polymerization rate and to better control of the molecular characteristics. Elsewhere,9 it has been reported that catalytic system 3 leads to the synthesis of block copolymers with better control with respect to both the molecular weights and molecular weight distributions. As an extension, the influence of the catalytic system on the polymerization of acrylates is examined here, and it can be concluded that this particular system provides the best possible control for the polymerization of acrylates.…”

“…Hadjichristidis and coworkers9 reported the synthesis of well‐defined poly(methyl methacrylate)‐ b ‐poly( n ‐butylmethacrylate), (PMMA‐ b ‐P n BuMA) block copolymers by sequential monomer addition. In this study, the importance of the order of monomer addition was highlighted.…”

Styrene‐assisted melt free‐radical grafting of pentaerythritol triacrylate onto polypropylene and its crystallization behavior

“…Therefore, PP with long grafted chains has become one of the major themes in recent PP modification research 2–6, 8–15. Up to now, several approaches have been developed to prepare branched PP, including high‐energy electron‐beam irradiation,10, 12, 14 peroxide curing,16, 17 azide coupling,18 and in‐reactor metallocene copolymerization of propylene with in situ generated or externally added macromonomers 2, 4, 6, 11, 19–25. For example, several research groups13, 22, 26, 27 have reported the synthesis of long‐chain‐branched PP by the copolymerization of propylene and macromonomers, such as atactic PP, polyethylene, or poly(ethylene‐ co ‐propylene) macromonomers.…”