In-Depth Analysis of the Nonuniform Chain Microstructure of Multiblock Copolymers from Chain-Shuttling Polymerization

Urciuoli, Gaia; Vittoria, Antonio; Talarico, Giovanni; Luise, Davide; Rosa, Claudio De; Busico, Vincenzo; Cipullo, Roberta; Ballesteros, Odda Ruiz de; Auriemma, Finizia

doi:10.1021/acs.macromol.1c01824

Cited by 18 publications

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References 45 publications

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“…Images taken at a higher magnification (Figure 2c−e) highlight the inner structures of said objects, which consist of tightly stacked lamellar crystals with a separation distance of ≈20 nm. Due to the moderate incompatibility between hard and soft blocks, edge-on lamellae are also present in the soft matrix in a less regular arrangement and at a larger separation distance, interconnecting individual rounded hard domains with a passthrough morphology (as described before for similar Infuse materials [45][46][47][48][49][50][51][52]55 ). The TEM images of the benchmark sample BM (Figure 2f and g) can hardly be distinguished from those of the PPR samples.…”

Section: ■ Experimental Sectionmentioning

confidence: 99%

Extending the High-Throughput Experimentation (HTE) Approach to Catalytic Olefin Polymerizations: From Catalysts to Materials

et al. 2022

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In this study, a state-of-the-art high-throughput experimentation (HTE) workflow for catalytic olefin polymerization, covering an unprecedented wide part of the polymer knowledge and value chains from catalytic synthesis all the way down to "engineering" microrheology, was thoroughly assessed with respect to its ability to prepare new materials and produce large and accurate databases for the investigation of quantitative structure−property relationships (QSPRs). Olefin blocks copolymers (OBCs) produced under chain-shuttling polymerization conditions were used as a demonstration case. The results of a thorough microstructural, structural, mechanical, morphological, and rheological characterization of OBC replicas prepared with the HTE synthetic platform and a commercial sample, chosen as a benchmark, demonstrate the robustness of the approach. The proposed workflow can become a paradigm for the high-throughput synthesis and investigation of novel materials, thus reducing the time to market of new products. In our opinion, this opens the door to integrated HTE and artificial intelligence approaches to QSPR problem solving in the numerous cases for which a thorough understanding of the theory is not sufficient to deterministically unravel the complexity of practical applications.

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Section: ■ Experimental Sectionmentioning

confidence: 99%

Extending the High-Throughput Experimentation (HTE) Approach to Catalytic Olefin Polymerizations: From Catalysts to Materials

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“…23−41 These differences should be strictly dependent on the distribution of block length at both inter-and intra-chain level. 23,32,34,35,38 In a recent article, the analysis of the heterogeneous composition of ethylene/1-octene OMBCs was tackled. 38 The samples were subjected to exhaustive Kumagawa extractions with solvents of increasing boiling temperature, namely, diethyl ether (EE), n-hexane (C6), and cyclohexane (CC6), obtaining an EE soluble fraction (EEs), an EE insoluble/C6 soluble fraction (EEi-C6s), a C6 insoluble/CC6 soluble fraction (C6i-CC6s), and a CC6 insoluble fraction (CC6i).…”

Section: ■ Introductionmentioning

confidence: 92%

“…23,32,34,35,38 In a recent article, the analysis of the heterogeneous composition of ethylene/1-octene OMBCs was tackled. 38 The samples were subjected to exhaustive Kumagawa extractions with solvents of increasing boiling temperature, namely, diethyl ether (EE), n-hexane (C6), and cyclohexane (CC6), obtaining an EE soluble fraction (EEs), an EE insoluble/C6 soluble fraction (EEi-C6s), a C6 insoluble/CC6 soluble fraction (C6i-CC6s), and a CC6 insoluble fraction (CC6i). The fractionation behavior of the OMBCs is the hallmark that the chains are not constitutionally uniform, as the average chain microstructure is different for each fraction.…”

Section: ■ Introductionmentioning

confidence: 99%

“…The fractionation behavior of the OMBCs is the hallmark that the chains are not constitutionally uniform, as the average chain microstructure is different for each fraction. 38 In particular, the hard block average content and the 1-octene average concentration are almost null and the highest, respectively, for the EEs fraction, and the highest and the lowest, respectively, for the CC6i fraction. As a consequence, the EEs and EEi-C6s fractions with the lowest hard block content and the highest 1-octene concentration are almost amorphous and/or poorly crystalline, whereas the C6i-CC6s and CC6i fractions with the highest hard block content and the lowest octene concentration are crystalline.…”

Section: ■ Introductionmentioning

confidence: 99%

“…Furthermore, the length of the amorphous and crystalline blocks changes not only from chain to chain but also within the same chain, entailing inter-and intra-chain heterogeneity of chain constitution. 38 Quantitative information about the molecular mass of the hard (M H ) and soft (M S ) blocks was achieved by resorting to small angle X-ray scattering. Data analysis revealed the tendency of OMBCs to give rise to molecular fractionation upon crystallization, due to the tendency of the hard blocks of different molecular mass to crystallize in distinct populations of stacks of lamellar crystals, characterized by similar values of the lamellar thickness but different chain periodicity.…”

Section: ■ Introductionmentioning

confidence: 99%

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Thermal Fractionation of Ethylene/1-Octene Multiblock Copolymers from Chain Shuttling Polymerization

et al. 2022

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Ethylene/1-octene statistical multiblock copolymers (OMBCs) consisting of the alternation of crystalline, hard blocks and amorphous, soft blocks, with ≈0.5 and 20 mol % of 1-octene units, respectively, are subjected to thermal fractionation resorting to successive self-nucleation and annealing (SSA). The study is extended to random copolymers (RCs) of high (44 kDa) and low (3.4 kDa) number average molecular mass M n, mimicking in 1-octene content the crystalline hard blocks and to the OMBC fractions extracted in boiling n-hexane and cyclohexane through a suitable solution fractionation protocol. For all the samples, the melting endotherms are well resolved in a multiplicity of peaks corresponding to the melting of crystals of different thicknesses generated in the SSA protocol that reflect the distribution of the methylene sequence length (MSL) in between consecutive interruptions along the chains. It is shown that, regardless of molecular mass, the MSL distributions of the RC samples are shifted toward greater values than those of the OMBC samples, and that also the shapes of the distributions are different. Since the MSL distribution depends on the frequency and distribution of the defects along the chains, and the defects act as interruption points, the higher fraction of long crystallizable sequences in the RC samples suggests that whereas for the RC samples the interruptions are merely represented by the 1-octene units that are rejected outside the crystals, for the OMBCs, the interruption of the regular methylene sequences belonging to the crystalline hard blocks due to the amorphous soft blocks linked to them should also play a role. Indeed, due to the partial miscibility of the hard and soft blocks, the hard blocks of major length tend to crystallize in a confined environment. This prevents the formation of thicker crystals and induces decrease of the MSL values as well as changes in the shape of the MSL distributions (topological confinement). On the other hand, the hard blocks of shorter length tend to crystallize, crossing the hard block rich regions and causing melting point depression and consequent shift of the MSLs toward lower values with respect to RCs (diluent effect). It is shown that differences in the MSL distribution of OMBCs are the result of the interplay between topological confinement and diluent effect, which in turn reflects differences in the OMBC chain microstructure, that is, differences in the distribution of block length at the inter- and intra-chain level.

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Molecular Architecture of Multiblock Copolymers Synthesized by the Chain Shuttling Technology

Urciuoli

Ballesteros

Auriemma

2023

Macro Chemistry & Physics

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Recent advances in the characterization of ethylene/1‐octene‐based statistical multiblock copolymers (MBCs) synthesized via chain shuttling copolymerization are illustrated. The Perspective focuses on the peculiarity of MBC systems that consists in the nonuniform chain architecture of these intriguing systems due to compositional heterogeneity occurring at inter‐ and intra‐chain level. In the first part, the effect of dispersity on the phase behavior and properties of MBCs and block copolymers in general is discussed along with the consequences of crystallization of one of the blocks on microphase separation, domain spacing, and morphology. In the second part, the main results achieved in the elucidation of details of the chain microstructure in terms of average length of the blocks and block length distribution are presented. It is shown that solvent and thermal fractionation techniques, coupled with other techniques such as transmission electron microscopy (TEM) and small angle X‐ray scattering (SAXS) represent powerful tools to elucidate the inter‐ and intra‐chain heterogeneous composition of the MBCs. Guidelines on how to establish structure/properties relationships for such polydisperse systems are also provided.

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In-Depth Analysis of the Nonuniform Chain Microstructure of Multiblock Copolymers from Chain-Shuttling Polymerization

Cited by 18 publications

References 45 publications

Extending the High-Throughput Experimentation (HTE) Approach to Catalytic Olefin Polymerizations: From Catalysts to Materials

Extending the High-Throughput Experimentation (HTE) Approach to Catalytic Olefin Polymerizations: From Catalysts to Materials

Thermal Fractionation of Ethylene/1-Octene Multiblock Copolymers from Chain Shuttling Polymerization

Molecular Architecture of Multiblock Copolymers Synthesized by the Chain Shuttling Technology

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