Novel thermoplastic elastomers. II. Properties of star-block copolymers of PSt-b-PIB arms emanating from cyclosiloxane cores

Shim, Jung S.; Kennedy, Joseph P.

doi:10.1002/(sici)1099-0518(19990315)37:6<815::aid-pola17>3.0.co;2-5

Cited by 40 publications

(15 citation statements)

References 11 publications

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“…With this in mind, star functionalities of 2 (the parent ABA triblock case or 2-arm "star"), 4, and 6 were selected based on previous reports where the ultimate tensile strength in star polymers reaches a plateau at around n ≥ 5. 28,29,31 Recent work from our group has suggested that the high-performance poly(L-lactide)-b-poly-(γMCL)-b-poly(L-lactide) APTPEs can be accessed through a bulk, one-pot strategy. 9,42 However, that work focused on the synthesis of lower-molar-mass materials (<50 kg mol −1 ).…”

Section: ■ Results and Discussionmentioning

confidence: 99%

“…Interestingly, the ultimate tensile strengths of (LLM) 4 and (LLM) 6 are similar, suggesting that these APTPE star polymers may reach a plateau in the ultimate tensile strength at an arm functionality of 4 rather than the range of n = 5−10 that has been observed in previously studied star polymer systems. 28,29,32 Simulations by Spencer and Matsen 60 have shown that (AB) n star polymers display an increased fraction of bridging chains (e.g., chains that connect two discrete hard domains) compared to linear ABA triblocks. As the number of arms increases, the proportion of these bridging chains also rapidly increases, and they suggest for (AB) n stars with a spherical or cylindrical morphology that almost all stars form bridges once n = 9.…”

Section: ■ Results and Discussionmentioning

confidence: 99%

“…28−31 The improved mechanical properties in star TPEs are thought to result from the core of the star, which acts to more effectively distribute applied stresses during deformation. 28,29 While the implementation of star architectures in styrenic TPEs has been well studied, 26−33 reports of aliphatic polyester star block TPEs are comparatively rare. 35−38 In 2000, Joziasse et al 35 detailed the synthesis and characterization of star block polymers of poly(trimethylene carbonate-co-(ε-caprolactone)) from a variety of initiators.…”

Section: ■ Introductionmentioning

confidence: 99%

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Enhanced Mechanical Properties of Aliphatic Polyester Thermoplastic Elastomers through Star Block Architectures

Liffland

2021

Macromolecules

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A series of sustainable aliphatic polyester thermoplastic elastomers (APTPEs) consisting of multi-arm star polymers with arms of poly(l-lactide)-b-poly(γ-methyl-ε-caprolactone) were investigated and compared to analogous linear poly(l-lactide)-b-poly(γ-methyl-ε-caprolactone)-b-poly(l-lactide) triblock polymers. Linear analogues with comparable arm molar mass and comparable overall molar mass were synthesized to distinguish architectural and molar mass effects. Overall, the star block polymers significantly outperformed their linear analogues with respect to ultimate tensile strength and tensile toughness, exhibiting more pronounced strain hardening than corresponding linear APTPEs. The stars exhibited high ultimate tensile strengths (∼33 MPa) and large elongations at break (∼1400%), outperforming commercially relevant, petroleum-derived, and non-degradable styrenic TPEs. The star polymers also exhibited superior recovery characteristics during cyclic strain cycles and reduced stress relaxation compared to the linear APTPEs, highlighting the impact of architecture on improved TPE mechanical properties. Dynamic mechanical thermal analysis suggests that the star architecture increases the usage temperature range and does not negatively influence processability, an important feature for future applications. Overall, this work illustrates that simple and convenient changes in the macromolecular architecture in sustainable APTPEs result in materials with greatly enhanced mechanical properties. A comprehensive understanding of the relationship between polymer architecture and mechanical properties can be capitalized on to develop property-specific and industrially relevant sustainable materials.

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Section: ■ Results and Discussionmentioning

confidence: 99%

Section: ■ Results and Discussionmentioning

confidence: 99%

Section: ■ Introductionmentioning

confidence: 99%

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Enhanced Mechanical Properties of Aliphatic Polyester Thermoplastic Elastomers through Star Block Architectures

Liffland

2021

Macromolecules

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“…To overcome these disadvantages, more complex molecular architectures may be utilized, such as star polymers and graft polymers. − Branched structures such as these tend to have lower viscosities at high shear rates and improved processability compared to linear chains with similar molar mass . Of the numerous possible branched structures, the graft polymer architecture is particularly attractive because of its intrinsic tunability.…”

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confidence: 99%

Tough and Sustainable Graft Block Copolymer Thermoplastics

Zhang¹,

Mannion

et al. 2016

ACS Macro Lett.

105

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Fully sustainable poly[HPMC-g-(PMVL-b-PLLA)] graft block copolymer thermoplastics were prepared from hydroxypropyl methylcellulose (HPMC), β-methyl-δ-valerolactone (MVL), and l-lactide (LLA) using a facile two-step sequential addition approach. In these materials, rubbery PMVL functions as a bridge between the semirigid HPMC backbone and the hard PLLA end blocks. This specific arrangement facilitates PLLA crystallization, which induces microphase separation and physical cross-linking. By changing the backbone molar mass or side chain composition, these thermoplastic materials can be easily tailored to access either plastic or elastomeric behavior. Moreover, the graft block architecture can be utilized to overcome the processing limitations inherent to linear block polymers. Good control over molar mass and composition enables the deliberate design of HPMC-g-(PMVL-b-PLLA) samples that are incapable of microphase separation in the melt state. These materials are characterized by relatively low zero shear viscosities in the melt state, an indication of easy processability. The simple and scalable synthetic procedure, use of inexpensive and renewable precursors, and exceptional rheological and mechanical properties make HPMC-g-(PMVL-b-PLLA) polymers attractive for a broad range of applications.

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“…For the "arm-irst" strategy: at the end of living cationic polymerization, vinyl functionality was introduced by reacting the living cation of with allyltrimethylsilane. The vinyl end functionality further reacted with Si-H on cyclosiloxane by Pt-catalyzed hydrosilylation and produced star polymers with diferent number of arms based on diferent numbers of Si-H on cyclosiloxane [100][101][102]. Similar to arm-irst divinylbenzenelinking strategy for anionic polymerization, 1,4-cyclohexane dimethanol divinyl ether was applied as the linking agent for arm-irst cationic polymerization to prepare star polymers with poly(2-admantyl vinyl ether) as hard segment and poly(n-butyl vinyl ether) as elastic segment [103].…”

Section: Star-branched Copolymer-type Tpesmentioning

confidence: 99%

Thermoplastic Elastomers Based on Block, Graft, and Star Copolymers

Wang¹,

Lu²,

Kang³

et al. 2017

Elastomers

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In this book chapter, we focus on recent advances in thermoplastic elastomers based on synthetic polymers from the aspects of polymer architectures such as linear block, graft, and star copolymers. The irst section is an introduction that covers a brief history and classiication of thermoplastic elastomers (TPEs). The second section summarizes ABA triblock copolymers synthesized by various methods for TPE applications. The third section reviews TPEs based on graft copolymers, and the fourth section reviews TPEs based on star copolymers. The diferences between TPE research in academia and industry are addressed in the last section as a perspective, with a view toward the generation of new, advanced, commercially viable TPEs.

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Novel thermoplastic elastomers. II. Properties of star-block copolymers of PSt-b-PIB arms emanating from cyclosiloxane cores

Cited by 40 publications

References 11 publications

Enhanced Mechanical Properties of Aliphatic Polyester Thermoplastic Elastomers through Star Block Architectures

Enhanced Mechanical Properties of Aliphatic Polyester Thermoplastic Elastomers through Star Block Architectures

Tough and Sustainable Graft Block Copolymer Thermoplastics

Thermoplastic Elastomers Based on Block, Graft, and Star Copolymers

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