Extremely tough block polymer-based thermoplastic elastomers with strongly associated but dynamically responsive noncovalent cross-links

Kajita, Takato; Tanaka, Haruka; Noro, Atsushi; Matsushita, Yushu; Nozawa, Atsushi; Isobe, Kousuke; Oda, Ryoji; Hashimoto, Sadaharu

doi:10.1016/j.polymer.2021.123419

Cited by 20 publications

(24 citation statements)

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“…The morphology of ABC triblock copolymer is dependent on the chain length [22,25] and compatibility of A and C blocks [26]. Other researchers developed A-BC-A triblock copolymers, where they incorporated the hydrogen bonding containing-C unit into the central block to form weak crosslinks in the soft domain [27][28][29]. These crosslinks dissociated and associated dynamically during elongation, which effectively dissipated energy and prevented local stress concentration.…”

Section: Introductionmentioning

confidence: 99%

Quadruple Hydrogen Bond-Containing A-AB-A Triblock Copolymers: Probing the Influence of Hydrogen Bonding in the Central Block

et al. 2021

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This work reveals the influence of pendant hydrogen bonding strength and distribution on self-assembly and the resulting thermomechanical properties of A-AB-A triblock copolymers. Reversible addition-fragmentation chain transfer polymerization afforded a library of A-AB-A acrylic triblock copolymers, wherein the A unit contained cytosine acrylate (CyA) or post-functionalized ureido cytosine acrylate (UCyA) and the B unit consisted of n-butyl acrylate (nBA). Differential scanning calorimetry revealed two glass transition temperatures, suggesting microphase-separation in the A-AB-A triblock copolymers. Thermomechanical and morphological analysis revealed the effects of hydrogen bonding distribution and strength on the self-assembly and microphase-separated morphology. Dynamic mechanical analysis showed multiple tan delta (δ) transitions that correlated to chain relaxation and hydrogen bonding dissociation, further confirming the microphase-separated structure. In addition, UCyA triblock copolymers possessed an extended modulus plateau versus temperature compared to the CyA analogs due to the stronger association of quadruple hydrogen bonding. CyA triblock copolymers exhibited a cylindrical microphase-separated morphology according to small-angle X-ray scattering. In contrast, UCyA triblock copolymers lacked long-range ordering due to hydrogen bonding induced phase mixing. The incorporation of UCyA into the soft central block resulted in improved tensile strength, extensibility, and toughness compared to the AB random copolymer and A-B-A triblock copolymer comparisons. This study provides insight into the structure-property relationships of A-AB-A supramolecular triblock copolymers that result from tunable association strengths.

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Section: Introductionmentioning

confidence: 99%

Quadruple Hydrogen Bond-Containing A-AB-A Triblock Copolymers: Probing the Influence of Hydrogen Bonding in the Central Block

et al. 2021

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“…These were observed at 1595 and 1422 cm –1 for the lithium carboxylate and 1580 and 1433 cm –1 for the sodium carboxylate, respectively ( Figure 2 A). 20 , 23 The effect of the extent of sodium neutralization of the carboxylic acids was also investigated using 1 -COOH. Neutralization extents from 25, 50, and 75 mol % ( vs COOH) were achieved by adding substoichiometric quantities of sodium hydroxide versus the starting carboxylic acid concentration and were verified by the relative band integrals of sodium carboxylate at 1580 cm –1 and polyester carbonyl signal at 1730 cm –1 in the FTIR spectra ( Figure S8 ).…”

Section: Resultsmentioning

confidence: 99%

“…The ionomers were soluble in a mixture of THF and water. Lithium or sodium ions were also confirmed in all samples using either 7 Li or 23 Na NMR spectroscopy of the polymer films dissolved in 1:1 THF/D 2 O (Figure S9). SEC data showed that the neutralization process did not affect the backbone chemistry; for example, the molar mass distribution of 1-COONa25 remained monomodal with comparable M n to 1-COOH (Figure S10).…”

Section: ■ Results and Discussionmentioning

confidence: 99%

“…22 Partially ionized “soft” blocks in the poly(styrene- b -isoprene- b -styrene) (SIS) Kraton family of commercial TPEs show an excellent toughness of 480 MJ m –3 . 23 The limitation of these commercial ionomers is that both the polymerization methods and ionic group functionalization lack control; this means that material property optimization is somewhat empirical. Important questions remain regarding how the ionizable group, the extent of ionization, or choice of counterions influence the thermomechanical properties.…”

Section: Introductionmentioning

confidence: 99%

“…For example, a poly(ethylene- co -methacrylic acid)-based TPE, developed by DuPont under the name Surlyn, shows impressive tensile strengths (22 MPa) when sodium cations partially neutralize the carboxylic acid groups . Partially ionized “soft” blocks in the poly(styrene- b -isoprene- b -styrene) (SIS) Kraton family of commercial TPEs show an excellent toughness of 480 MJ m –3 . The limitation of these commercial ionomers is that both the polymerization methods and ionic group functionalization lack control; this means that material property optimization is somewhat empirical.…”

Section: Introductionmentioning

confidence: 99%

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Exploiting Sodium Coordination in Alternating Monomer Sequences to Toughen Degradable Block Polyester Thermoplastic Elastomers

Gregory

Williams

2022

Macromolecules

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Thermoplastic elastomers (TPEs) that are closed-loop recyclable are needed in a circular material economy, but many current materials degrade during recycling, and almost all are pervasive hydrocarbons. Here, well-controlled block polyester TPEs featuring regularly placed sodium/lithium carboxylate side chains are described. They show significantly higher tensile strengths than unfunctionalized analogues, with high elasticity and elastic recovery. The materials are prepared using controlled polymerizations, exploiting a single catalyst that switches between different polymerization cycles. ABA block polyesters of high molar mass (60–100 kg mol –1 ; 21 wt % A-block) are constructed using the ring-opening polymerization of ε-decalactone (derived from castor oil; B-block), followed by the alternating ring-opening copolymerization of phthalic anhydride with 4-vinyl-cyclohexene oxide (A-blocks). The polyesters undergo efficient functionalization to install regularly placed carboxylic acids onto the A blocks. Reacting the polymers with sodium or lithium hydroxide controls the extent of ionization (0–100%); ionized polymers show a higher tensile strength (20 MPa), elasticity (>2000%), and elastic recovery (>80%). In one case, sodium functionalization results in 35× higher stress at break than the carboxylic acid polymer; in all cases, changing the quantity of sodium tunes the properties. A leading sample, 2 -COONa75 ( M n 100 kg mol –1 , 75% sodium), shows a wide operating temperature range (−52 to 129 °C) and is recycled (×3) by hot-pressing at 200 °C, without the loss of mechanical properties. Both the efficient synthesis of ABA block polymers and precision ionization in perfectly alternating monomer sequences are concepts that can be generalized to many other monomers, functional groups, and metals. These materials are partly bioderived and have degradable ester backbone chemistries, deliver useful properties, and allow for thermal reprocessing; these features are attractive as future sustainable TPEs.

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Toughening CO₂‐Derived Copolymer Elastomers Through Ionomer Networking

et al. 2023

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Utilizing carbon dioxide (CO2) to make polycarbonates through the ring‐opening copolymerization (ROCOP) of CO2 and epoxides valorizes and recycles CO2 and reduces pollution in polymer manufacturing. Recent developments in catalysis provide access to polycarbonates with well‐defined structures and allow for copolymerization with biomass‐derived monomers; however, the resulting material properties are underinvestigated. Here, new types of CO2‐derived thermoplastic elastomers (TPEs) are described together with a generally applicable method to augment tensile mechanical strength and Young's modulus without requiring material re‐design. These TPEs combine high glass transition temperature (Tg) amorphous blocks comprising CO2‐derived poly(carbonates) (A‐block), with low Tg poly(ε‐decalactone), from castor oil, (B‐block) in ABA structures. The poly(carbonate) blocks are selectively functionalized with metal‐carboxylates where the metals are Na(I), Mg(II), Ca(II), Zn(II) and Al(III). The colorless polymers, featuring <1 wt% metal, show tunable thermal (Tg), and mechanical (elongation at break, elasticity, creep‐resistance) properties. The best elastomers show >50‐fold higher Young's modulus and 21‐times greater tensile strength, without compromise to elastic recovery, compared with the starting block polymers. They have wide operating temperatures (−20 to 200 °C), high creep‐resistance and yet remain recyclable. In the future, these materials may substitute high‐volume petrochemical elastomers and be utilized in high‐growth fields like medicine, robotics, and electronics.

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Extremely tough block polymer-based thermoplastic elastomers with strongly associated but dynamically responsive noncovalent cross-links

Cited by 20 publications

References 49 publications

Quadruple Hydrogen Bond-Containing A-AB-A Triblock Copolymers: Probing the Influence of Hydrogen Bonding in the Central Block

Quadruple Hydrogen Bond-Containing A-AB-A Triblock Copolymers: Probing the Influence of Hydrogen Bonding in the Central Block

Exploiting Sodium Coordination in Alternating Monomer Sequences to Toughen Degradable Block Polyester Thermoplastic Elastomers

Toughening CO₂‐Derived Copolymer Elastomers Through Ionomer Networking

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Extremely tough block polymer-based thermoplastic elastomers with strongly associated but dynamically responsive noncovalent cross-links

Cited by 20 publications

References 49 publications

Quadruple Hydrogen Bond-Containing A-AB-A Triblock Copolymers: Probing the Influence of Hydrogen Bonding in the Central Block

Quadruple Hydrogen Bond-Containing A-AB-A Triblock Copolymers: Probing the Influence of Hydrogen Bonding in the Central Block

Exploiting Sodium Coordination in Alternating Monomer Sequences to Toughen Degradable Block Polyester Thermoplastic Elastomers

Toughening CO2‐Derived Copolymer Elastomers Through Ionomer Networking

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Toughening CO₂‐Derived Copolymer Elastomers Through Ionomer Networking