Dynamic Crosslinking Research Articles

Intrinsically self-healing crosslinked elastomer with mechanically robust based on dynamic urea bond and hydrogen bond for smart humidity sensor

Employment of noncovalent bonds as reversible crosslinks have been applied in weldable and self-healing crosslinked polymer networks but result in limited mechanical properties. Herein, a robust, tunable, and fast healable poly(urethane-urea)-GMA (PG) elastomer with a combination of multiple hydrogen bonds and dynamic covalent urea bonds was designed via a photo-induced copolymerization. The resultant PG60 exhibited a tensile strength of 12.3 MPa, an elongation at break of 229%, a toughness of 16.08 MJ m−3, and a self-healing efficiency of 100.0%. By adjusting the content of dynamic crosslinkers, the mechanical strength and self-healability of the resulting elastomers can be optimized. The exceptional properties of the networks, including self-healing capability and remarkable robust mechanical behavior, are attributed to the presence of reversibly noncovalent hydrogen bonds and dynamically covalent urea bonds, which have been confirmed through stress relaxation tests. More importantly, this study not only presents a facile fabrication method for designing mechanically robust and fast self-healing crosslinked elastomers, but also shows great potential in smart humidity sensor.

A Double-Layer Polysaccharide Hydrogel (DPH) for the Enhanced Intestine-Targeted Oral Delivery of Probiotics

Transplantation of probiotics to the intestine can positively regulate the gut microbiota, thereby promoting the immune system and treating various diseases. However, the harsh gastrointestinal environment and short retention time in the gastrointestinal tract significantly limit the bioavailability and intestinal colonization of probiotics. Herein, we present a double-layer polysaccharide hydrogel (DPH) in the form of a double-layer structure composed of a carboxymethyl cellulose (CMCL) supramolecular inner layer and a dialdehyde alginate (DAA) cross-linked carboxymethyl chitosan (CMCS) outer layer. This double-layer structure allows DPH to encapsulate and deliver probiotics in a targeted manner within the body. In the stomach, the cage structure of the DPH is closed, and the outer layer absorbs surrounding liquids to form a barrier to protect the probiotics from gastric fluids. In the intestine, the cage structure opens and disintegrates, releasing the probiotics. Thus, DPH endows probiotics with excellent intestine-targeted delivery, improved oral bioavailability, enhanced gastrointestinal tract tolerance, and robust mucoadhesion capacity. The encapsulated probiotics exhibit almost unchanged bioactivity in the gastrointestinal tract before release, as well as improved oral delivery. In particular, probiotics encapsulated by DPH exhibit 100.1 times higher bioavailability and 10.6 times higher mucoadhesion than free probiotics in an animal model 48 h post-treatment. In addition, with a remarkable ability to survive and be retained in the intestine, probiotics encapsulated by DPH show excellent in vitro and in vivo competition with pathogens. Notably, DAA-mediated dynamic crosslinking not only maintains the overall integrity of the hydrogels but also controls the release timing of the probiotics. Thus, it is expected that encapsulated substances (probiotics, proteins, etc.) can be delivered to specific sites of the intestinal tract by means of DPH, by controlling the dynamic covalent crosslinking.

Noncovalent crosslinked liquid metal-incorporated polymer binder based on multiple dynamic bonds for silicon microparticle anode

Silicon (Si) has been deemed as the most promising anode for next-generation lithium-ion batteries due to its high specific capacities. However, the massive volume expansion and contraction during cycling cause severe pulverization of silicon particles and structural collapse of electrodes. Binders play a very critical role in alleviating large stress, while ensuring interparticle adhesion and electrode integration. Herein, we reported a novel multifunctional liquid metal-incorporated (LM) polymer binder for high-capacity silicon anodes by noncovalent assembly of eutectic gallium indium (EGaIn) and polymer matrix. The dynamic crosslinking network with excellent toughness and high mechanical strength is capable of continuously dissipating huge mechanical stress and tolerating the volume change inside the Si particles during repeated cycling. The flowable LM can repair the strain-induced microcracks and maintain the electrically connected integrity of the electrode. As expected, the resultant Si electrode delivers a high initial Coulombic efficiency and a stable cycling performance over 300 cycles at 1 C. Specially, a Si||LiNi0.8Co0.1Mn0.1O2 cell can stably operate for 100 cycles even at a high areal capacity. This conceptual design of liquid metal- incorporated polymer binder offers a new opportunity to promote practical high-capacity anodes for high-energy-dense lithium-ion batteries.

Programmable and Self‐Healable Liquid Crystal Elastomer Actuators Based on Halogen Bonding

AbstractShape‐changing polymeric materials have gained significant attention in the field of bioinspired soft robotics. However, challenges remain in versatilizing the shape‐morphing process to suit different tasks and environments, and in designing systems that combine reversible actuation and self‐healing ability. Here, we report halogen‐bonded liquid crystal elastomers (LCEs) that can be arbitrarily shape‐programmed and that self‐heal under mild thermal or photothermal stimulation. We incorporate halogen‐bond‐donating diiodotetrafluorobenzene molecules as dynamic supramolecular crosslinks into the LCEs and show that these relatively weak crosslinks are pertinent for their mechanical programming and self‐healing. Utilizing the halogen‐bonded LCEs, we demonstrate proof‐of‐concept soft robotic motions such as crawling and rolling with programmed velocities. Our results showcase halogen bonding as a promising, yet unexplored tool for the preparation of smart supramolecular constructs for the development of advanced soft actuators.

Programmable and Self-Healable Liquid Crystal Elastomer Actuators Based on Halogen Bonding.

Shape-changing polymeric materials have gained significant attention in the field of bioinspired soft robotics. However, challenges remain in versatilizing the shape-morphing process to suit different tasks and environments, and in designing systems that combine reversible actuation and self-healing ability. Here, we report halogen-bonded liquid crystal elastomers (LCEs) that can be arbitrarily shape-programmed and that self-heal under mild thermal or photothermal stimulation. We incorporate halogen-bond-donating diiodotetrafluorobenzene molecules as dynamic supramolecular crosslinks into the LCEs and show that these relatively weak crosslinks are pertinent for their mechanical programming and self-healing. Utilizing the halogen-bonded LCEs, we demonstrate proof-of-concept soft robotic motions such as crawling and rolling with programmed velocities. Our results showcase halogen bonding as a promising, yet unexplored tool for the preparation of smart supramolecular constructs for the development of advanced soft actuators.

Injectable and Self-Adaptive Gel Scaffold Based on Heparin Microspheres for Adipogenesis of Human Adipose-Derived Stem Cells.

An injectable and self-adaptive heparin microsphere-based cell scaffold was developed to achieve adipose regeneration. Simultaneously, the cell scaffold exhibited a dynamic architecture, self-regulated glucose levels, sustained insulin delivery, and steady viscoelastic properties for adipogenesis. The dynamic cell scaffold is cross-linked by the boronate-diol interaction among heparin-based microspheres, which have boronate and maltose groups. Because of the boronate-maltose ester bonds, the gelatinous complex would be partially dismantled and readily display glucose-sensitive performance by free glucose via competitive displacement. The dynamic cross-linking heparin microsphere scaffold can deliver the lipogenic drug insulin to enhance lipid filling, which has an impact on fat tissue enhancement. A 4-week in vitro cell culture demonstrated that the dynamic heparin microsphere-based cell scaffold, through loading with insulin, showed significantly higher efficiency in promoting ASC differentiation compared with traditional 3D culture methods. In vivo histological results further demonstrated that there was a significant increase in adipose in the proposed cell scaffold, which proved to be statistically significant compared with traditional biomaterials. Notable stain expression of the FABP4 and PPAR-γ genes was also observed in the dynamic cell scaffold containing insulin, which was more similar to natural fat.

Preparation and characterization of polyurethane-modified asphalt containing dynamic covalent bonds

Self-healing behavior of binder has important potential for promoting low-carbon service and extending service life of asphalt pavement. A novel self-healing polyurethane modified asphalt with dynamic covalent bonds was prepared in this work. The chemical structure, thermal-oxygen stability, rheological properties, fatigue properties and self-healing capability of polyurethane modified asphalt with dynamic covalent bonds were systemically investigated through Fourier infrared spectrum test, thermal gravimetric test, dynamic shear rheology test, linear amplitude sweep(LAS) test and multiple fatigue-healing-fatigue test. The result indicates disulfide dynamic covalent bond and oxime urethane dynamic covalent bond were successfully introduced into polyurethane cross-linking structure in asphalt, and the thermal-oxygen stability of asphalt has a significant increase after modification under the environmental conditions of construction and service. Rheological properties analysis suggests the introduction of dynamic covalent bonds is beneficial to improve the low-temperature toughness of polyurethane modified asphalt, and enhances its low-temperature cracking resistance. LAS analysis indicates the fatigue life of polyurethane modified asphalt can also be lengthened by over 70% at different strain levels(1.5%, 2.5% and 5%) with the introduction of dynamic covalent bonds, which is attributed to the excellent conformation adjustment ability and stress dissipation ability of dynamic cross-linking structure in asphalt. The multiple fatigue-healing-fatigue test shows the self-healing capability of polyurethane modified asphalt has an improvement with the introduction of dynamic covalent bonds, especially at the later stage with serious fatigue damage, and oxime urethane dynamic covalent bond shows the better contribution effect as compared with disulfide bond. This is due to the reversible fracture-rearrangement characteristics of dynamic covalent bonds. This work provides a new idea for improving the self-healing capacity and rheological properties of binder, reducing the frequency of pavement maintenance and extending the pavement service life.

Strong and Ultra-tough Ionic Hydrogel Based on Hyperbranched Macro-cross-linker: Influence of Topological Structure on Properties.

The application of hydrogels often suffers from their inherent limitation of poor mechanical properties. Here, a carboxyl-functionalized and acryloyl-terminated hyperbranched polycaprolactone (PCL) was synthesized and used as a macro-cross-linker to fabricate a super strong and ultra-tough ionic hydrogel. The terminal acryloyl groups of hyperbranched PCL are chemically incorporated into the network to form covalent cross-links, which contribute to robust networks. Meanwhile, the hydrophobic domains formed by the spontaneous aggregation of PCL chains and coordination bonds between Fe3+ and COO- groups serve as dynamic non-covalent cross-links, which enhance the energy dissipation ability. Especially, the influence of the hyperbranched topological structure of PCL on hydrogel properties has been well investigated, exhibiting superior strengthening and toughening effects compared to the linear one. Moreover, the hyperbranched PCL cross-linker also endowed the ionic hydrogel with higher sensitivity than the linear one when used as a strain sensor. As a result, this well-designed ionic hydrogel possesses high mechanical strength, superior toughness, and well ionic conductivity, exhibiting potential applications in the field of flexible strain sensors.

Tough and Photo-Plastic Liquid Crystal Elastomer with a 2-Fold Dynamic Linker for Artificial Muscles.

Liquid crystal elastomers (LCEs) have been optimized by combining cross-linkers and dynamic bonds to achieve a reversible actuation behavior comparable to living skeletal muscles. In this study, one unique type of segment with 2-fold dynamic properties was introduced into LCEs, which offered not only dynamic diselenide covalent bonds for thermo-/photoplasticity but also H-bond arrays for dynamic cross-linking and mechanical robustness. Besides self-healing, self-welding, and recyclability, the LCEs were reprogrammable with elevated temperature or intensive visible light irradiation. The resultant LCEs gave an actuation blocking stress of 1.96 MPa and an elastic modulus of 14.4 MPa at 80 °C. The actuation work capacity reached 135.2 kJ m-3. When incorporating the Joule electrode or photothermal materials, the LCEs could be programmed as the electricity-driven and photothermal artificial muscles and thereby promised the application both as a biomimetic artificial hand and as an energy collector from sunlight. Thus, the 2-fold dynamic LCEs offered the pathway of enabling the reversible actuation behavior comparable to living skeletal muscles and promising applications in sustainable actuators, artificial muscles, and soft robots.

An Investigation of the Healing Efficiency of Epoxy Vitrimer Composites Based on Zn2+ Catalyst.

The need to recycle carbon-fibre-reinforced composite polymers (CFRP) has grown significantly to reduce the environmental impact generated by their production. To meet this need, thermoreversible epoxy matrices have been developed in recent years. This study investigates the performance of an epoxy vitrimer made by introducing a metal catalyst (Zn2+) and its carbon fibre composites, focusing on the healing capability of the system. The dynamic crosslinking networks endow vitrimers with interesting rheological behaviour; the capability of the formulated resin (AV-5) has been assessed by creep tests. The analysis showed increased molecular mobility above a topology freezing temperature (Tv). However, the reinforcement phase inhibits the flow capability, reducing the flow. The fracture behaviour of CFRP made with the vitrimeric resin has been investigated by Mode I and Mode II tests and compared with the conventional system. The repairability of the vitrimeric CFRP has been investigated by attempting to recover the delaminated samples, which yielded unsatisfactory results. Moreover, the healing efficiency of the modified epoxy composites has been assessed using the vitrimer as an adhesive layer. The joints were able to recover about 84% of the lap shear strength of the pristine system.

Intermittent Exothermic and Self-Healing Hydrated Salt Gels for Advanced Thermal Management of Underfloor Radiant Heating System.

Phase change materials (PCMs) have great prospects in thermal management applications because they can store and release latent heat. However, they are not suitable for on-demand heating as they can only release heat once. Herein, this work reports the intermittent exothermic of PCMs based on a supersaturated salt solution, exhibiting fully controlled long-term storage of energy, releasing and suspending heat on demand. Due to the high energy barrier, it is difficult for the supersaturated salt solution to nucleate; thus, it can store energy for a long time. Contact with seeds or other foreign objects can destroy the metastable state of the supersaturated salt solution and promote the formation of crystal nuclei, enabling crystallization and heat release on demand. The release of crystallization heat can be interrupted using scissors dip in water. Additionally, self-healing behavior allows it to be recycled and last longer, due to the presence of Fe3+ , inducing strong dynamic reversible non-covalent crosslinking through metal coordination bonds. Furthermore, the hydrated salts gels are applied for thermal management of underfloor radiant heating system, demonstrating four types of intermittent exotherms sequences amazingly. Further, the intermittent exothermic hydrated salts gels provide a more user-friendly thermal management of underfloor radiant heating systems.

Design and Applications of Dynamic Hydrogels Based on Reversible C═N Bonds

AbstractDynamic hydrogels offer the opportunity to meet the expectations of smart materials with adaptable properties such as stimuli responsiveness, self‐healing, shear thinning, stress relaxation, dynamic viscoelasticity, energy dissipation mechanisms, time‐dependent adaptation, etc. In the past decades, reversible C═N bonds including imine, hydrazone, and oxime have received great research interest in the design of dynamic polymer networks (DPNs). Moreover, reversible C═N bonds can be well‐integrated into DPNs in combination with permanent covalent crosslinks and/or other dynamic bonds (supramolecular interactions and dynamic covalent bonds), thus outfitting the hydrogels with enhanced mechanical properties, multiresponsiveness, printability, adhesion, and various other functions. This literature review first describes how reversible C═N bonds can be introduced into hydrogels from the perspective of dynamic bonds and network topologies. The design strategies (building blocks, crosslink type combinations, network topologies) reported in the literature are then discussed, as well as the effects of dynamic crosslinking on the hydrogel properties and the potential applications.

Preparation and properties of multiple dynamically crosslinked self-healing poly(siloxane-urethane) flexible sensor

The flexible sensor with self-healing performance can heal itself when the sensor is damaged by the outside world, so it can significantly improve the service life of the sensor and reduce the repair cost, which has attracted widespread attention. However, currently, most flexible sensors with self-healing performance have problems such as single repair conditions and difficulty in balancing mechanical performance and repair efficiency. In this study, polypyrrole modified carbon nanotubes (PPY/CNTs) were first made, and then, inspired by the Chinese traditional myth “Nuwa Fuxi”, a multiple dynamic crosslinking self-healing composite poly(siloxane-urethane) conductive elastomer (CPUSi) was successfully developed. The prepared CPUSi has excellent mechanical properties (11.27 MPa) and total shear repair efficiency (84%) under the excitation of multiple dynamic reversible interactions. At the same time, the surface scratch of CPUSi can be self-healing under multiple conditions such as heating at 60 °C, infrared light and ultraviolet light. The scratch repair efficiency is up to 99.9% under infrared light for 2 h. in addition, CPUSi has cyclic response to temperature and strain, so the material has broad application prospects in sports monitoring, electronic skin, intelligent wear, brain-computer interface and other fields

Highly Conductive Polysiloxane Elastomers with Excellent Transparency, Resilience, and Stretchability.

Flexible transparent conductive materials show great potential in wearable electronics, flexible sensors, and so on. But the most used flexible conductive materials like hydrogels and ionogels suffer from evaporation and solvent leakage. For the application in these fields, integrated performances of preeminent resilience, transparency, stability, and conductivity that do not change with deformation are prerequisites. It is still challenging to handle the trade-off among these performances. Herein, a facile approach is established to balance these properties into one elastomer. Through the thiol-ene click reaction, mercaptopropyl-modified polydimethylsiloxane (mPDMS) is cross-linked and grafted by PEG-based macromonomers to prepare conductive elastomers. By anchoring with mPDMS through carbon-sulfur bonds, PEG can be evenly dispersed, resulting in ultratransparency (97%) and stable conductivity of as high as 1.68 × 10-2 S m-1, comparable to pure PEG/lithium salt conductivity. It also has a wide electrochemical stability window with a high voltage of 4.8 V. Moreover, the multibond network strategy is employed through grafting ligand 1-vinylimidazole to mPDMS to construct dynamic cross-links between Zn(II) and 1-vinylimidazol, bestowing excellent properties to the elastomers. Overall, elastomers with a well-balanced performance of high resilience, good conductivity, and ultratransparency are obtained, providing promising applications for soft electronics, lithium battery electrolytes, and flexible devices.

Exploring Lipoic Acid-Mediated Dynamic Bottlebrush Elastomers as a New Platform for the Design of High-Performance Thermally Conductive Materials.

The development of high-performance thermally conductive interface materials is the key to unlocking the serious bottleneck of modern microelectronic technology through enhanced heat dispersion. Existing methods that utilize silicone composites rely either on loading large doses of randomly distributed thermal conductive fillers or on filling prealigned thermal conductive scaffolds with liquid silicone precursors. Both approaches suffer from several limitations in terms of physical traits and processability. We describe an alternative approach in which malleable silicone matrices, based on the dynamic cyclic disulfide nature cross-linker (α-lipoic acid), are readily prepared using ring-opening polymerization. The mechanical properties of the resultant dynamic silicone matrix are readily tunable. Stress-dependent depolymerization of the disulfide network demonstrates the ability to reprocess the silicone elastomer matrix, which allows for the fabrication of highly efficient thermal conductive composites with a 3D interconnecting, thermally conductive network (3D-graphite/MxBy composites) via in situ methods. Applications of the composites as thermal dispersion interface materials are demonstrated by LEDs and CPUs, suggesting great potential in advanced electronics.

High-strength, self-reinforcing and recyclable multifunctional lignin-based polyurethanes based on multi-level dynamic cross-linking

The preparation of lignin-based polyurethanes with excellent mechanical properties and recyclability remains extremely challenging because of the poor compatibility of lignin and matrix. Inspired by the multiple structures of spider silk and pearl layers, high-strength, heat-resistant and recyclable lignin-based polyurethanes (LPUs) were prepared by introducing weak hydrogen bonds, strong hydrogen bonds and dynamic silyl ether covalent bonds. Multiple hydrogen bonds provided a large energy dissipation mechanism. The covalent linkage between lignin and matrix promoted their compatibility and formed a robust cross-linking network. Depending on the multi-level dynamic interactions, the prepared elastomer exhibited a mechanical strength of 73 MPa, which was 1.9 times higher than that of the blank sample, with an initial thermal decomposition temperature of 310.5 °C and a good recyclability. Especially, the mechanical strength of LPUs was up to 99 MPa after mechanical training. In addition, the abundant conjugated structure of lignin endowed LPUs with an excellent photothermal conversion ability. Under the irradiation of NIR light with 4000 w m−2, the surface temperature increased to 95 °C within two minutes, exhibiting a stable photothermal performance even after 6 cycles. This work showed the application prospects of LPUs in the fields of high strength engineering materials and photo-induced actuators.

Unravelling the dynamic crosslinking mechanism in polyborosiloxane

This study offers a comprehensive investigation into the mechanism behind the dynamic crosslinking of polyborosiloxane (PBS). Despite this material being well known for over 70 years, the origin of PBS's unique viscoelastic properties has been a topic of debate in the literature. Through combined FTIR and solid-state 29Si and 11B MAS NMR analyses, this study provides evidence that the formation of Si–O–B dynamic covalent bonds, along with their associative exchange with neighboring hydroxyl-bearing species (free silanol, water, alcohol, etc.), drives the gelation and viscoelastic behavior of PBS. Results show no indication of hydrogen or dative bonding, instead the low energy barrier for formation and breakage of Si–O–B bonds allows for easy exchange at room temperature. Moreover, the study finds that the viscoelastic properties of PBS can be adjusted by the choice of boron B–O functionality, leading to n-functional dynamic crosslinking through Si–O–B bonds. This research provides a clear understanding of the mechanism of dynamic crosslinking in PBS, resolving long-standing controversies in the field.

Benzene Tetraamide: A Covalent Supramolecular Dual Motif in Dynamic Covalent Polymer Networks.

In dynamic polyamide networks, 1,2,4,5-benzene tetraamide (B4A) units act simultaneously as a dynamic covalent cross-linker and as supramolecular stacking motif. This results in materials with a rubbery plateau modulus that is about 20 times higher than that of a corresponding reference network in which the supramolecular interaction is suppressed. In branched polyamides with the same B4A dynamic motif, hydrogen bonding and stacking lead to strong and reversible supramolecular networks, whereas a branched polyamide with the nonstacking reference linker is a viscous liquid under the same conditions. Wide-angle X-ray scattering and variable-temperature infrared experiments confirm that covalent cross-linking and stacking cooperatively contribute to the dynamics of the network. Stress relaxation in the reference network is dominated by a single mode related to the dynamic covalent chemistry, whereas relaxation in the B4A network has additional modes assigned to the stacking dynamics.

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.

Fabrication of triple-crosslinked gelatin/alginate hydrogels for controlled release applications

Hydrogels have been demonstrated as smart drug carriers to recognize the tumor microenvironment for cancer treatment, where the dynamic crosslinks in the hydrogel network contribute to the stimuli-responsive features but also result in poor stability and weak mechanical property of the hydrogels. Here, phenylboronic acid-grafted polyethyleneimine (PBA-PEI)-modified gelatin (PPG) was synthesized to crosslink alginate dialdehyde (ADA) through imine bonds and boronate ester bonds, and then calcium ions (Ca2+) were added to introduce the third calcium-carboxylate crosslinking in the network to form the triple-crosslinked PPG/ADA-Ca2+ hydrogels. Given the three types of dynamic bonds in the network, PPG/ADA-Ca2+ hydrogels possessed a self-healing manner, stimuli-responsiveness, and better mechanical properties compared to single- or double-crosslinked hydrogels. The controlled release capability of PPG/ADA-Ca2+ hydrogels was also demonstrated, showing the encapsulated molecules can be rapidly released from the hydrogel network in the presence of hydrogen peroxide while the release rate can be slowed down at acidic pH. Furthermore, PPG/ADA-Ca2+ hydrogels presented selected cytotoxicity and drug delivery to cancer cells due to the regulated degradation by the cellular microenvironment. Taken together, PPG/ADA-Ca2+ hydrogels have been demonstrated as promising biomaterials with multiple desirable properties and dynamic features to perform controlled molecule release for biomedical applications.