1,1-Dimethylsilacyclobutane-Mediated Living Anionic Block Copolymerization of [1]Dimethylsilaferrocenophane and Methyl Methacrylate

Abstract

An efficient synthesis is described of diblock copolymers from [1]dimethylsilaferrocenophane (FS) and methyl methacrylate (MMA). First, living anionic polymerization of FS is carried out in THF. When the FS polymerization is complete, 1,1-dimethylsilacyclobutane (DMSB) and 1,1-diphenylethylene (DPE) are added in order to modify the living PFS chain ends in an appropriate way for the subsequent growth of the second block. This combination of an accelerator (DMSB) and an end-capping agent (DPE) is shown to be necessary to suppress side reactions which otherwise lead to significant quantities of PFS homopolymers. When all the PFS chain ends bear an anionic DPE end group, block copolymerization of MMA follows. Under optimum conditions, PFS-b-PMMA block copolymers can be obtained in >90% yield (in addition to <10% PFS homopolymer), having molar masses ranging from 27 000 to 85 000 and different PFS contents. Finally, the PFS homopolymers can be removed quantitatively by redissolving the raw product in THF followed by reprecipitation of the pure diblock copolymer using n-hexane. The obtained material has polydispersity indices clearly below 1.1.

Equilibrium Melting Temperature of Poly(ferrocenyl dimethylsilane) in Homopolymers and Lamellar Diblock Copolymers with Polystyrene

“…PFDMS homopolymers having molar masses of 4.9 kg Á mol À1 (P n % 20; ''PFDMS-1'') and 60.7 kg Á mol À1 (P n % 250; ''PFDMS-2''), were prepared following published procedures, i.e., by anionic polymerization of dimethylsila [1]ferrocenophane (FS). [16] The polydispersity was PDI ¼ 1.05 and 1.03, respectively. The PS-b-PFDMS diblock copolymer was synthesized by sequential living anionic polymerization in glass reactors equipped with break-seals for the addition of the reagents (Scheme 1).…”

“…Dimethylsila [1]ferrocenophane (FS) was prepared as described recently [16,44] and purified by repeated crystallization from hexane at À60 8C in the presence of trioctyl aluminum. Purification of styrene and the solvents was carried out as described elsewhere.…”

“…Purification of styrene and the solvents was carried out as described elsewhere. [16] sec-BuLi was prepared from sec-butyl chloride and lithium dispersion. PFDMS homopolymers having molar masses of 4.9 kg Á mol À1 (P n % 20; ''PFDMS-1'') and 60.7 kg Á mol À1 (P n % 250; ''PFDMS-2''), were prepared following published procedures, i.e., by anionic polymerization of dimethylsila [1]ferrocenophane (FS).…”

“…[1][2][3][4][5][6][7] Moreover, it counts among the very few metallopolymers accessible by living chain-growth protocols which give access not only to products of defined molar mass and narrow polydispersity but also to a broad variety of copolymer architectures: plenty of PFDMS block copolymers with, e.g., polystyrene (PS), [8][9][10][11] polyisoprene (PI), [12] poly(dimethyl siloxane) (PDMS), [8,12,13] poly(ethylene oxide) (PEO), [14] poly(methyl methacrylate) (PMMA), [15][16][17][18][19][20][21] and poly(2-vinylpyridine) [22] have been synthesized, and they have been shown to develop fascinating morphologies at the nanometer to micrometer scale. [2,7,23] Another important feature of PFDMS is its ability to crystallize.…”

Synthesis and Solution Self‐Assembly of Polyisoprene‐block‐poly(ferrocenylmethylsilane): A Diblock Copolymer with an Atactic but Semicrystalline Core‐Forming Metalloblock

“…50 Subsequent end functionalisation can occur at the lithiated site on the polymer using a variety of reagents to modify the polymer properties or yield block and graft copolymers. 51,52 In addition, sequential polymerisation of different monomers can occur to produce a range of block copolymers. 53 If post-polymerisation, 4-[(trimethylsilyl)ethynyl]-benzaldehyde is used to trap the living chain, a terminal alkyne is generated.…”