Conventional Thermosets Research Articles

Light-Driven, Reversible Spatiotemporal Control of Dynamic Covalent Polymers.

Dynamic covalent polymer networks exhibit a cross-linked structure like conventional thermosets and elastomers, although their topology can be reorganized through externally triggered bond exchange reactions. This characteristic enables a unique combination of repairability, recyclability and dimensional stability, crucial for a sustainable industrial economy. Herein the application of a photoswitchable nitrogen superbase is reported for the spatially resolved and reversible control over dynamic bond exchange within a thiol-ene photopolymer. By the exposure to UV or visible light, the associative exchange between thioester links and thiol groups is successfully gained control over, and thereby the macroscopic mechanical material properties, in a locally controlled manner. Consequently, the resulting reorganization of the global network topology enables to utilize this material for previously unrealizable advanced applications such as spatially resolved, reversible reshaping as well as micro-imprinting over multiple steps. Finally, the presented concept contributes fundamentally to the evolution of dynamic polymers and provides universal applicability in covalent adaptable networks relying on a base-catalyzed exchange mechanism.

Tensile, impact, and the damping performance of woven flax‐carbon hybrid polyamide biocomposites

AbstractFiber hybridization is suggested to enhance the properties of fiber‐reinforced composites. Regarding the matrix, thermoplastic alternatives to conventional thermosets are needed to balance mechanical performance and sustainability. We combined woven flax and carbon fibers with a polyamide 11 matrix into a hybrid biocomposite and studied its manufacturing process as well as its impact, tensile, and damping properties. Mechanical damage was investigated using scanning electron microscopy and X‐ray computed tomography. Hybridization significantly improved the tensile properties: 233% higher modulus and 432% higher strength than pure flax composites and 19% higher failure strain than pure carbon composites. Additionally, the hybrid composites exhibited a positive hybrid effect with respect to the impact resistance, characterized by higher displacement at maximum impact force and occurrence of combined damage mechanisms. Although the damping behavior of the hybrid composites remained inferior to that of pure flax composites, their damping factor was 20% higher than that of pure carbon composites. These results provide valuable insights into the mechanical performance of carbon‐flax hybrid composites.Highlights Enhanced mechanical performance and impact resistance in woven flax‐carbon/PA11 hybrid biocomposite compared to nonhybrid reference composites. Superior tensile modulus and strength of hybrid biocomposite than pure flax fiber composite, and greater failure strain than pure carbon fiber composite. A positive hybridization effect in impact properties with a greater displacement at maximum force and higher dissipated impact energy, indicating enhanced ductility and fracture toughness. Improved damping behavior in hybrid biocomposite compared to the pure carbon composite.

Polybenzoxazine-based covalent adaptable networks: A mini-review

Benzoxazines represent a class of thermoset resins known for their exceptional thermal, fire, and mechanical properties. These resins find wide applications in various industries, including composites and electronic components. However, like conventional thermosets, benzoxazines have limitations in terms of end-of-life options, typically being landfilled or incinerated. To address this concern, researchers have been exploring the incorporation of dynamic bonds into the structure of polybenzoxazines to add functionalities such as reprocessability, self-healing, or recycling capabilities, and to develop polybenzoxazine-based covalent adaptable networks (CANs). This mini-review offers an overview of recent endeavors focused on the introduction of dynamic bonds within polybenzoxazine structures. It emphasizes the synergies between the molecular structure of benzoxazines and dynamic exchanges, such as transesterification or disulfide metathesis, and provides a comparative summary of the properties achieved by the materials developed in this context. By leveraging the strengths of benzoxazine structures, this mini-review aims to foster the exploration and development of innovative approaches that combine the unique properties of benzoxazines and CANs, enabling more sustainable and environmentally friendly materials.

Exploring the Limits of High-Tg Epoxy Vitrimers Produced through Resin-Transfer Molding.

Over the past few years, scientists have developed new ways to overcome the recycling issues of conventional thermosets with the introduction of associative covalent adaptable networks (i.e., vitrimers) in polymer materials. Even though various end-use vitrimers have already been reported, just a few of them have targeted high-performance industrial applications. Herein, we develop a promising high-performance epoxy vitrimer based on a commercially available resin widely used in aeronautics with the highest glass transition temperature (Tg) of 233 °C ever reported for a vitrimer. A complete study of its physicochemical properties and cure kinetics was conducted, enabling the construction of the first time-temperature-transformation (TTT) diagram reported in the literature. This diagram allows a full determination of the processing and curing parameters leading to the manufacturing of vitrimer samples by the resin-transfer molding (RTM) process. The reshapability and limits therefrom of this high-Tg vitrimer were evaluated by three successful thermoforming cycles without degradation.

Dual-responsive epoxy thermosets with controlled degradation and high performance based on serial connection of double dynamic bonds

Covalent adaptable networks relying on dynamic cross-links have been developed to make the conventional thermosets degradable and reprocessable, but the greater challenge lies in how to overcome the trade-off between excellent degradability and mechanical properties. It remains a formidable challenge to achieve complete degradation of high mechanical materials (such as epoxy) especially at more moderate conditions. Herein, dual-responsive epoxy thermosets that were serially cross-linked by double dynamic bonds of disulfide bonds and cation-π interactions were prepared from diglycidyl ether of bisphenol A (DGEBA), dithiodianiline (DTDA), N-expoxypropane-indole (EIN) and MgCl2. The dual-responsive epoxy exhibited moderate mechanical properties with the tensile strength of 55 MPa, while the glass transition temperature (Tg) was 85 °C. In addition, the dual-responsive epoxy could be degraded by either DTT or PPi, due to the thiol-disulfide oxidation/reduction reaction and the complexation reaction of PPi and Mg2+. Furthermore, the degradation times could be controlled from <100 to 2700 min with optimal conditions by varying the concentration of reactive molecules and temperature. Meanwhile, the dual-responsive epoxy also exhibited excellent reprocessing properties. The dual-responsive dynamic epoxy thermoset is expected to be useful for coatings, adhesives, and matrix polymers of composites that require controlled degradation and recyclability.

Reprocessable, chemically recyclable, and flame-retardant biobased epoxy vitrimers

Conventional epoxy thermosets exhibit outstanding mechanical performances, excellent thermal and dimensional stabilities, and prominent resistances to chemical/solvent corrosions but are limited because they are dependent on fossil resources, cannot be reprocessed, and are not fire safe. Herein, we reported biobased, flame-retardant, reprocessable, and chemically recyclable epoxy thermosets synthesized with bio-based glycerol triglycidyl ether (GTE) as an epoxy monomer, vanillin derived imine compound as a hardener, and 9,10-dihydro-9-oxa-10-phosphaphenanthrene-10-oxide (DOPO) as a reactive fire-retardant agent. The curing kinetics investigation manifested that the curing reaction was activated with increasing DOPO content. The relationship between structure and properties of the vitrimers were studied in detail. The BEVs showed excellent physical properties with a tensile strength and glass transition temperature higher than 80 MPa and 100 °C, respectively. They possessed outstanding reprocessability and could be chemically recycled easily owning to the presence of the exchangeable imine bonds. The BEV with 6 wt% DOPO showed excellent fire resistance with a UL-94 V-0 rating and a LOI at 26.4% as well as much lower peak heat release rate and total heat release than the control vitrimer without DOPO. The BEVs with combination of excellent mechanical properties, reprocessability, chemical recyclability, and flame retardancy showed a bright future as an alternative to conventional epoxy thermosets for better sustainability and fire-safety.

Spiroborate-Linked Ionic Covalent Adaptable Networks with Rapid Reprocessability and Closed-Loop Recyclability

Covalent adaptable networks (CANs) represent a novel class of polymeric materials crosslinked by dynamic covalent bonds. Since their first discovery, CANs have attracted great attention due to their high mechanical strength and stability like conventional thermosets under service conditions and easy reprocessability like thermoplastics under certain external stimuli. Here, we report the first example of ionic covalent adaptable networks (ICANs), a type of crosslinked ionomers, consisting of negatively charged backbone structures. More specifically, two ICANs with different backbone compositions were prepared through spiroborate chemistry. Given the dynamic nature of the spiroborate linkages, the resulting ionomer thermosets display rapid reprocessability and closed-loop recyclability under mild conditions. The materials mechanically broken into smaller pieces can be reprocessed into coherent solids at 120 °C within only 1 min with nearly 100% recovery of the mechanical properties. Upon treating the ICANs with dilute hydrochloric acid at room temperature, the valuable monomers can be easily chemically recycled in almost quantitative yield. This work demonstrates the great potential of spiroborate bonds as a novel dynamic ionic linkage for development of new reprocessable and recyclable ionomer thermosets.

Dynamic elastomers based on bio‐derived crosslinker

AbstractPetroleum‐derived monomers are the most common building blocks for ester‐based thermosets. Bio‐derived thermoset elastomers are becoming viable alternatives to conventional thermosets. Herein, we developed a biobased vitrimer‐type thermoset elastomers using abundant and sustainable raspberry ketone as feedstock. We utilize raspberry ketone to create building blocks for dynamic oxime chemistry and crosslinked these through free radical polymerization with poly(ethylene glycol) methyl ether methacrylate as a comonomer. In contrast to other dynamic networks based on ester bonds, which need catalysts, this is undesirable since catalyst deactivation or leaching lowers its effect over time and may impair reuse. This network incorporates catalyst‐free bond exchange reactions in catalyst‐dependent polyester networks by substituting oxime‐esters for typical ester linkages. The elastomer exhibits stress relaxation, a low glass transition temperature (Tg) (−55 to −40.2°C) and tensile strength up to 5.2 ± 3.0 kPa. Furthermore, the dynamic oxime transesterification exchange mechanism allows elastomers to be reprocessed using a hot press at 160°C and 8 × 103 kPa pressure. After reprocessing, the tensile strength of elastomers can be recovered up to 78.1 ± 10.9%. This work integrates the principles of catalyst‐free dynamic exchange process and mechanical recycling coupled with biobased components to provide a rational solution towards conventional elastomers. In the future, these elastomers can be exploited for the development of hydrogels, recyclable elastomers, and commodity plastics.

Rigid-and-Flexible, Degradable, Fully Biobased Thermosets from Lignin and Soybean Oil: Synthesis and Properties

Developing thermosets from lignin has huge significance due to the abundant renewable resources and rigid polyaromatic structure of lignin; nevertheless, it is still a challenge to develop fully biobased thermosets with high performance. Herein, lignin was modified with glycidol and further reacted with maleic anhydride to produce multicarboxyl lignin (MGL) which possessed improved solubility in green solvents such as ethanol and increased reactivity toward the epoxy group. Fully biobased epoxy thermosets were prepared from MGL, citric acid (CA), and epoxidized soybean oil (ESO) with the assistance of ethanol. The thermosets exhibited superior thermal and mechanical properties and degradability. This study provides a straightforward countermove to achieve rigid and flexible thermosets from lignin and other abundant renewable bioresources and also provides a promising sustainable alternative to conventional epoxy thermosets.

Closed-Loop Recycling of Carbon Fiber-Reinforced Composites Enabled by a Dual-Dynamic Cross-linked Epoxy Network

The development of covalent adaptable networks has addressed the issue that conventional epoxy thermosets are difficult to degrade and reprocess, but the greater challenge lies in how to overcome the trade-off between excellent degradability and mechanical properties such as stiffness and extensibility. Herein, a new concept of a dual-dynamic cross-linked network composed of dynamic covalent and non-covalent bonds (imine bonds and hydrogen bonds) was proposed for closed-loop recovery of epoxy thermosets/composites. Among them, the additional non-covalent crosslinks were constructed through the designed imine-containing hardener as the medium. The cooperative effects of hydrogen-bond interactions and molecular interlocking of rigid–flexible molecular chains enhanced greatly the stiffness and ductility, and the recoverable energy dissipation enabled the prepared epoxy thermoset to have excellent fracture toughness. Its tensile strength and impact strength reached ∼80.3 MPa and ∼24.2 kJ/m2, respectively. Importantly, driven by the pH-sensitive feature of the dual-dynamic network, the resultant thermoset was completely degraded within 3 h. Along the closed-loop sustainable route, the recoverable oligomer from the thermoset/matrix resin showed good potential in toughening brittle materials with a 55–94% increase in impact strength. Further, the recovered CF cloths that kept their usage value were re-prepared into new high-performance composites, realizing the conversion of waste to high-value applications.

A Critical Review of Sustainable Vanillin-modified Vitrimers: Synthesis, Challenge and Prospects

Nearly 90% of thermosets are produced from petroleum resources, they have remarkable mechanical characteristics, are chemically durable, and dimensionally stable. However, they can contribute to global warming, depletion of petroleum reserves, and environmental contamination during manufacture, use, and disposal. Using renewable resources to form thermosetting materials is one of the most crucial aspects of addressing the aforementioned issues. Vanillin-based raw materials have been used in the industrial manufacturing of polymer materials because they are simple to modify structurally. Conversely, traditional thermosetting materials as a broad class of high-molecular-weight molecules are challenging to heal, decompose and recover owing to their permanent 3-D crosslinking network. Once the products are damaged, recycling issues could arise, causing resource loss and environmental impact. It could be solved by inserting dynamic covalent adaptable networks (DCANs) into the polymer chains, increasing product longevity, and minimizing waste. It also improves the attractiveness of these products in the prospective field. Moreover, it is essential to underline that increasing product lifespan and reducing waste is equivalent to reducing the expense of consuming resources. The detailed synthesis, reprocessing, thermal, and mechanical characteristics of partly and entirely biomass thermosetting polymers made from vanillin-modified monomers are covered in the current work. Finally, the review highlights the benefits, difficulties, and application of these emerging vanillin-modified vitrimers as a potential replacement for conventional non-recyclable thermosets.

High‐Performance Vitrimeric Benzoxazines for Sustainable Advanced Materials: Design, Synthesis, and Applications

AbstractPolybenzoxazines are high‐performance materials capable of replacing conventional thermosets such as phenolics, epoxies, and bismaleimides in composites manufacturing due to their excellent thermomechanical and chemical behavior. Their versatility and compatibility with biobased precursors make them an attractive option as composite matrices. Like other thermosets, polybenzoxazines are not recyclable and cannot be reprocessed. Incorporating dynamic bonds in benzoxazine monomers can produce vitrimeric polybenzoxazines, which can potentially overcome this limitation and can be tuned to exhibit smart functionalities such as self‐healing and shape memory. Dynamic bond exchange mechanisms for vitrimer development such as transesterification, imine bond, disulfide exchange, transamination, transcarbamoylation, transalkylation, olefin metathesis, transcarbonation, siloxane‐silanol exchange, boronic ester, silyl ether exchange, and dioxaborolane metathesis are potentially applicable to benzoxazine chemistry, with disulfide bond and transesterification having successfully vitrimerized benzoxazines with topological transitions at −8.5 and 88 °C, respectively. Benzoxazine vitrimers featuring glass transitions of 193, 224, and 222–236 °C are now known. These place polybenzoxazines at the forefront of the development of reprocessable and recyclable thermosetting polymers and composite matrices.

Versatile levulinic acid-derived dynamic covalent thermosets enabled by in situ generated imine and multiple hydrogen bonds

Bio-based dynamic covalent thermosets have attracted extensive attention as they are expected to break conventional thermosets' reliance on fossil resources and address the recycling issue after disposal. However, there has always been a contradiction between using bio-based feedstocks and possessing high properties, as well as a conflict between high performance and rapid recycling (reprocessing and degradation). In this work, a simple approach was developed to prepare bio-based thermosets with high performance, rapid reprocessing, high flame retardancy, and antibacterial properties enabled by in-situ generated dynamic covalent imine (Schiff base) bonds and multiple hydrogen bonds. The levulinic acid epoxy (ELA) was successfully synthesized and cured with 2-(4-aminophenyl)-1H-benzimidazol-5-amine (BIA) containing benzimidazole structures. The high concentration of Schiff bases and multiple hydrogen bonds of ELA-BIA endowed it with high glass transition temperature and mechanical properties, as well as satisfactory catalyst-free malleability, rapid reprocessing and repairing. Furthermore, due to the combined effect of the in-situ Schiff base and benzimidazole structure, ELA-BIA exhibited excellent condensed phase char formation ability, resulting in intrinsic flame retardancy with a limiting oxygen index of 33.8 % and a UL-94 V-0 rating, both of which were significantly higher than 4, 4′-diaminodiphenyl methane (DDM) cured ELA or DDM cured bisphenol A epoxy. Moreover, the Schiff bases bonded in the networks provided 100 % of the intrinsic antibacterial rates. This work provides a feasible and simple strategy for the preparation of high-performance and versatile bio-based dynamic covalent thermosets.

High-performance epoxy vitrimer with superior self-healing, shape-memory, flame retardancy, and antibacterial properties based on multifunctional curing agent

The lack of functionalities such as degradability, antibacterial, and flame retardancy is the key to limit the further wide application of conventional epoxy thermosets. In this work, a novel bio-based multifunctional amine curing agent (named HVPA), was successfully synthesized via the Schiff base reaction between six-vanillin functionalized cyclophosphazene and N-methylethylenediamine. And an epoxy vitrimer (HVPA/GDE) was fabricated by utilizing HVPA to cure the bio-based epoxy of glycerol diglycidyl ether (GDE). Ascribing to the even distribution of dynamic imine bond in each crosslinking linkage, this synthetic HVPA/GDE vitrimer presented excellent comprehensive properties including fast self-healing (8 min for 100%, without any pressure), excellent shape memory, easy reprocessability (1.5 MPa, 3 min, 100 °C), mild degradation, and superior bacterial resistance to both Gram-negative bacteria (E. coli) and Gram-positive bacteria (S. aureus). Moreover, due to the high content of N/P elements and benzene groups within the network structure, this HVPA/GDE not only exhibited excellent flame retardancy but also possessed good UV resistance and transparency, while maintaining comparable mechanical strength compared to the control group of commercial amine curing agent 4,4-Diaminodiphenyl methane (DDM) cured epoxy resin (DDM/GDE). Therefore, this work provides a facile strategy for fabricating multi-functional and high-performance bio-based epoxy resins.

Review on intrinsically recyclable flame retardant thermosets enabled through covalent bonds

AbstractDeveloping thermosets with inherent recyclability and flame retardancy is a great importance from the views of fire safety, resource conservation and environmental protection. Owing to their superior mechanical properties, versatility, outstanding adhesion‐ability, durability, thermal, and solvent stability comparable to conventional thermosets while demonstrating end‐of‐life reuse, recyclable thermosetting materials have gained much interest as an attractive class of sustainable thermosets. The chemical structure of thermosets includes dynamic covalent networks that provide durability and reprocessability. However, these recyclable thermosets possess significant flammability, limiting their application in automobiles, railways, aircraft, buildings, and electronic items. Thus, it is urgent to include them with flame retardants. The goal of this review paper is to give a broad understanding of the study by highlighting and discussing recent advances as well as future prospects for inherently recyclable flame retardant thermosets (RFRs). Moreover, synthesis methods have been highlighted to improve the design of internally recyclable fire retardant thermosets. A distinct emphasis will be given on the inherent RFRs in terms of flame retardancy, recycling property, physical properties, and thermal stability. Finally, we will explore the importance and threats that intrinsically recyclable flame retardant thermosets face in the future.

Complete Degradation of a High-Performance Epoxy Thermoset Enabled by γ-ray-Sensitive Motifs Based on the Cascaded Synergetic Strategy

γ-Radiation derived from clean energy has emerged as a promising technology for disposal of waste plastics. However, due to radical-mediated uncontrolled recombination, a foremost challenge remains in radiation-triggered complete degradation for thermoset plastics. Herein, the radiation-sensitive epoxy thermoset (EP-DESN) containing phenyl imine-conjugated N–N bonds (PINN bonds) and S–S bonds was designed to initiate rapid degradation at a dose of 10 kGy. The phenyl imine-conjugated linkages can stabilize the radiation-induced broken N–N bonds, overcoming radical-mediated uncontrolled recombination and cross-linking. Moreover, the phenyl-iminyl-conjugated radicals generated by PINN bond scission can cleave the active S–S bonds to promote subsequent spontaneous degradation for maximum degradation efficiency. Meanwhile, EP-DESN exhibited superior thermal robustness and chemical resistance comparable to some conventional high-performance epoxy thermosets. Using EP-DESN as a binder, we prepared recyclable carbon fiber-reinforced composites, and nondestructive recycling of value-added carbon fiber (CF) is achieved, thus facilitating the concept of a circular CF economy.

Design, production and characterization of high performance 3R composites based on dynamic chemistry for the aerospace industry

The objective of the AIRPOXY project is to reduce production and maintenance, repair &amp; operating (MRO) costs of composite parts in aeronautics, by introducing a new family of enhanced thermoset composites that preserve all the advantages of conventional thermosets, while show unprecedented new features such as Re-processability, Repairability and Recyclability. This new generation of composites, called 3R composites, are obtained using dynamic hardeners which create reversible crosslinks in the cured epoxy resin. Once the 3R composite has been produced, the dynamic chemical bonds in the cured resin can be reshuffled under determined external stimulus, such as temperature or exposure to a specific chemical agent. The study describes the development of a first version of 3R composite that meets the requirements of the aeronautical sector. Firstly the resin has been formulated, then the composite laminates have been produced by Resin Transfer Moulding (RTM) and finally their dynamic and mechanical properties have been studied.

Degradable benzyl cyclic acetal epoxy monomers with low viscosity: Synthesis, structure-property relationships, application in recyclable carbon fiber composite

Degradable thermosets can address the recycle issue of conventional thermosets and downstream materials like carbon fiber composites. Significant advances have been achieved on their recyclability even on high performance, but their processability was neglected. Herein, for the first time, from the processing point of view, degradable epoxy monomers with low viscosity were designed. Ethyl or methyl group was incorporated into the benzyl cyclic acetal structure to obtain three acetal epoxy monomers by the acetalization between p-hydroxybenzaldehyde analogues and triols to achieve diols, followed by reacting with epichlorohydrin. Two benzyl cyclic acetal epoxy monomers with ethyl group are liquid. The viscosity and structure-property relationship of epoxy monomers were systematically investigated from experiments to simulate computation. The cured epoxies possessed favorable thermal properties, mechanical properties and controllable degradability. Furthermore, the epoxy monomer with suitable viscosity was used to prepare carbon fiber composites with excellent performance via vacuum assisted resin transfer molding (VARTM) process. Meanwhile, the non-destructive recovery of carbon fiber was realized by taking advantage of the degradability of the acetal epoxy matrix.

A 4D Printable Shape Memory Vitrimer with Repairability and Recyclability through Network Architecture Tailoring from Commercial Poly(ε-caprolactone).

Vitrimers have shown advantages over conventional thermosets via capabilities of dynamic network rearrangement to endow repairability as well as recyclability. Based on such characteristics, vitrimers have been studied and have shown promises as a 3D printing ink material that can be recycled with the purpose of waste reduction. However, despite the brilliant approaches, there still remain limitations regarding requirement of new reagents for recycling the materials or reprintability issues. Here, a new class of a 4D printable vitrimer that is translated from a commercial poly(ε‐caprolactone) (PCL) resin is reported to exhibit self‐healability, weldability, reprocessability, as well as reprintability. Thus, formed 3D‐printed vitrimer products show superior heat resistance in comparison to commercial PCL prints, and can be repeatedly reprocessed or reprinted via filament extrusion and a handheld fused deposition modeling (FDM)‐based 3D printing method. Furthermore, incorporation of semicrystalline PCL renders capabilities of shape memory for 4D printing applications, and as far as it is known, such demonstration of FDM 3D‐printed shape memory vitrimers has not been realized yet. It is envisioned that this work can fuel advancement in 4D printing industries by suggesting a new material candidate with all‐rounded capabilities with minimized environmental challenges.

Thermomechanical activation achieving orthogonal working/healing conditions of nanostructured tri-block copolymer thermosets

Conventional thermosets, despite their technological significance in today’s materials economy, present a modern sustainability challenge because of their lack of end-of-life options for recyclability or reprocessability. Emerging covalent adaptable networks (CANs) offer sustainable alternatives to permanently crosslinked materials, but ideal orthogonal working/reprocessing conditions are hardly achievable by the current thermochemical activation mechanism. Here we report a CAN system of additive/catalyst-free, fully reprocessable, crosslinked, tri-block copolymer (tri-BCP) thermoplastic elastomer networks based on acid-anhydride bond exchange operated on a thermomechanical activation mechanism. The unique functionality of the tri-BCP architecture enables self-assembly into inter-linked, hexagonally packed cylinder nanostructures that preclude any productive inter-cylinder bond exchange (and, thus, creep) without cooperative thermal and mechanical (heating and compression) processing conditions. Tri-BCP assembly into additive-free, inter-linked hexagonally packed cylinder networks Healable crosslinked networks via thermomechanical-induced inter-domain bond exchange Working conditions restrict creep, establishing orthogonal working/healing behavior Clarke et al. show crosslinked tri-block copolymers with nanostructured networks, constructed by a catalyst/additive-free self-crosslinking and self-assembly process. Compared with analogous random and di-block copolymers, these crosslinked tri-block copolymers show not only superior mechanical performance but also much greater creep resistance when operated on a morphology-regulated and thermomechanical activation mechanism.