Amphiphilic Triblock Copolymers Containing Polypropylene as the Middle Block

Abstract

The synthesis of stereoregular telechelic polypropylene (PP) and their use to access triblock amphiphilic copolymers with the PP block located in the center is described. The strategy consists of selectively copolymerizing propylene and a di-functional co-monomer (1,3-diisopropenylbenzene) to yield a a,w-substituted polypropylene. Initiation of the copolymerization favors insertion of DIB over propylene; propagation steps favor insertion of propylene. Termination via a chain-transfer reaction yields the terminal unsaturation of the polymer. The telechelic polypropylene is then converted into a,w-hydroxyl-terminated polypropylene and used as a macroinitiator for the synthesis of triblock copolymers. Water-soluble amphiphilic triblock polymers are also synthesized. The use of catalytic reactions simultaneously provides the stereocontrol of the polypropylene and high productivity (multiple chains of block copolymer per metal center).

Stereoselective Copolymerization of Olefin with Polar Monomers to Access Stereoregular Functionalized Polyolefins

“…Based on this, triblock amphiphilic copolymers with iPP in the middle can be prepared after functionalization. 31 Figure 4 Chain transfer in the presence of CTA during stereoselective propylene polymerization and subsequent functionalization.…”

Highly Versatile Strategy for the Production of Telechelic Polyolefins

“…16,19 The results presented in Table 1 for runs 2 and 3 confirmed this expectation with proof of the production of atactic α-iodo, ω-phenyl polypropene (I-aPP-Ph, a-IIb) and atactic α-iodo, ω-phenyl poly(4-methyl-1pentene) (I-aPMP-Ph, a-IIc) when propene and 4-methyl-1pentene were, respectively, employed as the α-olefin monomer. 22 In each case, a very narrow and monomodal MMD was established by ambient-temperature SEC, while 13 C NMR spectroscopy confirmed an atactic microstructure that renders these materials amorphous with only a glass transition temperature, T g , being observed by differential scanning calorimetry (DSC; see Table 1). 22,23 As further detailed with the results of runs 4 and 5 of Table 1, we also now report the first example of stereomodulated LCCTP of propene that was achieved using varying excess equivalents of ZnPh 2 as a CTA in combination with the chiral (racemic) C 1 -symmetric CPAM zirconium dimethyl complex Ib as preinitiator and the borate B1 as co-initiator (see Scheme 1).…”

“…Unfortunately, in contrast to well-established categories of telechelic polymers obtained through step-growth polymerization (e.g., polyesters, polyamides, and polyurethanes), the polymer science and technology of telechelic polyolefins are surprisingly still largely unexplored areas . Ideally, a general strategy for obtaining telechelic polyolefins should be able to provide control over (1) molar mass, (2) MMD, as defined by the breadth, skewness, and modality (e.g., monomodal, bimodal, or multimodal), (3) tacticity, with this parameter ranging from being stereorandom (i.e., atactic) to highly stereoregular (e.g., isotactic), (4) a broad structural scope of polymerizable olefin monomers, (5) a highly versatile range of end-group functionalities, and most importantly, (6) the ability to generate practical quantities of these telechelic polyolefin products from readily available and inexpensive reagents and standard reactor and polymerization techniques. − Indeed, finding a viable solution to the challenge of meeting all of these goals for the production of telechelic polyolefins is so difficult that, to the best of our knowledge, it has never been achieved. − Herein, we now report a general and highly versatile strategy for the production of semicrystalline telechelic α,ω-bis­(phenyl)-terminated polyethene and either amorphorus, atactic or semicrystalline, isotactic α,ω-bis­(phenyl)-terminated poly­(α-olefins) via (stereomodulated) living coordinative chain transfer polymerization (LCCTP) using a group 4 metal ion-pair initiator, and excess equivalents of diphenylzinc (ZnPh 2 ) as a chain transfer agent (CTA), followed by reactive quench with molecular iodine (I 2 ) and Cu-catalyzed phenylation according to Scheme . We further demonstrate that the phenyl group in these polyolefins can serve as a synthon for an extensive array of different functionalities that can be “unmasked” by industrially relevant, high-yielding transformations, such as the electrophilic aromatic substitution and reduction chemistry reported in the present study.…”

Photoinduced SET to access olefin-acrylate copolymers

“…Indeed, post-polymerization methods [20][21][22][23][24] to produce polymers and copolymers containing olefins have been recently reported via either deoxygenation of poly(methyl acrylate) 25 or post-functionalization and subsequent grafting-from polymerization from polyethylene or polypropylene. 26,27 In this work, we report a post-polymerization modification strategy that enables synthesis of statistical copolymers of olefins and acrylates. Single electron transfer (SET) decarboxylative alkyl radical generation has been heavily represented in recent literature as a facile means to exploit the high reactivity of alkyl radicals.…”