Reprocessable polyhydroxyurethane networks reinforced with reactive polyhedral oligomeric silsesquioxanes (POSS) and exhibiting excellent elevated temperature creep resistance

Hu, Sumeng; Chen, Xi; Rusayyis, Mohammed A. Bin; Purwanto, Nathan S.; Torkelson, John M.

doi:10.1016/j.polymer.2022.124971

Cited by 33 publications

(37 citation statements)

References 87 publications

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“…Below this temperature, E ′ reduction with increasing temperature occurs due to the increasing exchangeability of the BiTEMPS dynamic bonds. The generally very good thermal stability and robust properties of the PE CANs suggest that our approach could also be used to develop reprocessable CAN nanocomposites 75,104,105 and foams 106,107 with PE as the base polymer.…”

Section: Resultsmentioning

confidence: 97%

Simple upcycling of virgin and waste polyethylene into covalent adaptable networks: catalyst-free, radical-based reactive processing with dialkylamino disulfide bonds

2022

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Section: Resultsmentioning

confidence: 97%

Simple upcycling of virgin and waste polyethylene into covalent adaptable networks: catalyst-free, radical-based reactive processing with dialkylamino disulfide bonds

2022

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“…Torkelson and co-workers reported that PHU networks prepared from five-membered cyclic carbonates and a simple organocatalyst (DMAP) were able to combine within the same chemical network structure both associative (TC exchange reaction) and dissociative (reversible cyclic carbonate ring-opening/ring-closure) (Scheme a,b) processes. − The retro-formation of five-membered cyclic carbonates was evidenced by FTIR measurement, and the side reactions previously observed by Fortman et al were limited by the use of nonvolatile reactant . In this particular case, i.e., in the presence of DMAP as catalyst, complete recovery of the initial mechanical properties was recorded by both tensile and dynamic mechanical analysis after 1 h at 140 °C.…”

Section: Covalent Adaptable Network Based On Transcarbamoylation Reac...mentioning

confidence: 69%

Transcarbamoylation in Polyurethanes: Underestimated Exchange Reactions?

et al. 2022

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While transesterification has been largely explored by chemists, only a few studies comparatively dealt with its “sluggish cousin”, transcarbamoylation. Originally suggested 70 years ago to explain the stress decay observed at high temperature in polyurethane chemical networks, transcarbamoylationalso called transurethanization or urethane exchangeis still underexploited in both organic and polymer chemistry. This is mainly related to the use of toxic reactants such as isocyanates and tin-based catalysts involved during the preparation of molecular carbamates or polyurethanes (PUs) as well as harsh conditions required to observe such exchanges in molecular transformations. Many studies have focused their interest in alternatives to the use of isocyanates, underestimating the potential of transcarbamoylation to produce, recycle, or reprocess PUs (wastes). This Perspective presents the latest developments and plausible future directions to prepare sustainable PU-based materials by using transcarbamoylation with a focus on covalent dynamic networks.

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“…We sought to fabricate enaminone-cross-linked vitrimers while maintaining a high level of POSS filler content, anticipating this would result in vitrimers that could be easily shaped and reprocessed yet provide robust thermomechanical stability, features demonstrated by Liang and co-workers in their report on a dynamic covalent elastomer composite with excellent ablative properties . We further hypothesized that with high POSS loadings these networks would provide significant char yields following pyrolysis.…”

Section: Resultsmentioning

confidence: 99%

Dynamic Ablative Networks: Shapeable Heat-Shielding Materials

Stewart

DeLellis

Lessard

et al. 2023

ACS Appl. Mater. Interfaces

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Thermoset materials sacrifice recyclability and reshapeability for increased chemical and mechanical robustness because of an immobilized, cross-linked polymeric matrix. The robust material properties of thermosets make them well-suited for applications such as heat-shielding materials (HSMs) or ablatives where excellent thermal stability, good mechanical strength, and high charring ability are paramount. Many of these material properties are characteristic of covalent adaptable networks (CANs), where the static connectivity of thermosets has been replaced with dynamic cross-links. This dynamic connectivity allows network mobility while retaining cross-link connectivity to permit damage repair and reshaping that are traditionally inaccessible for thermoset materials. Herein, we report the synthesis of hybrid inorganic−organic enaminone vitrimers that contain an exceptionally high weight percent of polyhedral oligomeric silsesquioxane (POSS)-derivatives. Polycondensation of β-ketoester-containing POSS with various diamine cross-linkers led to materials with facile tunability, shapeability, predictable glass transition temperatures, good thermal stability, and high residual char mass following thermal degradation. Furthermore, the char materials show notable retention of their preordained shape following decomposition, suggesting their future utility in the design of HSMs with complex detailing.

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Reprocessable polyhydroxyurethane networks reinforced with reactive polyhedral oligomeric silsesquioxanes (POSS) and exhibiting excellent elevated temperature creep resistance

Cited by 33 publications

References 87 publications

Simple upcycling of virgin and waste polyethylene into covalent adaptable networks: catalyst-free, radical-based reactive processing with dialkylamino disulfide bonds

Simple upcycling of virgin and waste polyethylene into covalent adaptable networks: catalyst-free, radical-based reactive processing with dialkylamino disulfide bonds

Transcarbamoylation in Polyurethanes: Underestimated Exchange Reactions?

Dynamic Ablative Networks: Shapeable Heat-Shielding Materials

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