Cross-linking Of Chains Research Articles

Blood Coagulation Activities of Cotton-Alginate-Copper Composites.

Alginate-based materials have gained significant attention in the medical industry due to their biochemical properties. In this article, we aimed to synthesize Cotton-Alginate-Copper Composite Materials (COT-Alg(-)Cu(2+)). The main purpose of this study was to assess the biochemical properties of new composites in the area of blood plasma coagulation processes, including activated partial thromboplastin time (aPTT), prothrombin time (PT), and thrombin time (TT). This study also involved in vitro antimicrobial activity evaluation of materials against representative colonies of Gram-positive and Gram-negative bacteria and antifungal susceptibility tests. The materials were prepared by immersing cotton fibers in an aqueous solution of sodium alginate, followed by ionic cross-linking of alginate chains within the fibers with Cu(II) ions to yield antimicrobial activity. The results showed that the obtained cotton-alginate-copper composites were promising materials to be used in biomedical applications, e.g., wound dressing.

Ultra-high molecular weight EPDM composites via crossover curing agents: Stabilized crosslink network structure and performance properties

This study investigates the impact of various crosslinking systems, such as those based on sulfur, peroxide, and their hybrid combinations, on the thermal degradation characteristics of ethylene propylene diene rubber (EPDM). During aerobic degradation, polymer networks undergo reversible physical and irreversible chemical changes. There are two kinds of irreversible chemical changes that may occur: chain scission reactions and crosslinking events. The impact of these reactions on the characteristics of the elastomer is antagonistic. When measuring the properties of an elastomer as it ages, most standard characterization techniques reveal the aggregate impact of two reactions. This work employs a straightforward approach based on compression set measurements to distinguish between the scission and crosslinking events that occur during thermal aging. This work has analyzed hybrid crosslinked materials using this method and demonstrated their remarkable thermal stability, as evidenced by their ability to maintain equilibrium between scission and crosslinking reactions. The stability of performance characteristics, such as tensile strength and crosslink density, in hybrid-cured samples during thermal aging supports the aforementioned. Furthermore, the investigation also delves into the potential of hybrid curing systems using crossover curing agents instead of coagents, which are multifunctional additives, to augment the durability of performance characteristics over an extended period of thermal aging.

Investigating the effect of methacrylic acid on the properties of waterborne epoxy-acrylate core-shell emulsion, film and coating

Waterborne coating has recently become a trend in research, with extensive studies focusing on waterborne epoxy-acrylate (WEA) emulsion. However, the understanding of the role of methacrylic acid (MAA) in the core-shell structure, affecting film and coating performance, is still limited. Here, we investigate the effect of MAA addition on the properties of the WEA core-shell emulsion, film and coating. The WEA core-shell emulsion was synthesized through semi-continuous emulsion polymerization and subsequently cast into WEA film. Two types of crosslinking systems were established by introducing MAA to either the shell layer (interlayer crosslinking) or the core layer (intralayer crosslinking). The interlayer crosslinking provides a high crosslinking density (7.01 × 10−4 mol cm−3), involving the crosslinking of polymer chains between the core and shell layers. Consequently, the film has a compact structure and high modulus (489 MPa) but low elongation at break (3.20 %). Conversely, the intralayer crosslinking has a low crosslinking density (1.59 × 10−4 mol cm−3). Hence, the film has a loose structure and low modulus (0.38 MPa) but high elongation at break (225 %). This occurs because it involves crosslinking with the polymer chains within the same layer, resulting in reduced compatibility between the layers. The inclusion of MAA enhances the clarity in discerning two glass transition temperatures (Tg). Lastly, the stability (shelf-life) of the WEA emulsion remains unaffected by the MAA, with the decisive factor being the presence of the oxirane ring in the Epoxy (EP). We believe that this finding can significantly contribute to a better understanding of the role of MAA in crosslinking systems within WEA core-shell coatings for researchers.

Influence mechanisms of electron beam irradiation on surface flashover in vacuum: Electron modification, deposition, and migration

In surface science, surface flashovers are discharge phenomena that occur at the gas/vacuum-solid interface. Spacecraft in the universe suffers from high-energy electron irradiation while it works under a high DC operating voltage, and thus, surface flashover threatens the safe operation of spacecraft and limits human’s deeper exploration of the universe. To unravel the influence mechanisms of electron beam irradiation (EBI), surface flashover voltages (Vf) of epoxy composites during EBI, short-term after EBI, and long-term after EBI are investigated, and the behaviors of molecular structure, deposited electrons near chains, and radiation electrons under EBI and their effects on Vf are separately clarified. For long-term after EBI, EBI induces crosslinking of molecular chains and introduces deep traps to the solid surface, which impedes electron emission and surface charging, and thus Vf increases. For short-term after EBI, the deposited electrons suppress charge injection to the solid, and Vf further increases. During EBI, the high-energy radiation electrons stimulate gas desorption and directly participate in plasma propagation, leading to a sharp decrease in Vf. This work comprehensively explains the influence mechanisms of EBI electron modification, deposition, and migration on the Vf, which offers a theory to guide the prevention of flashover for spacecraft.

Organosilicon copolymers containing triazole and triethoxysilyl groups as the basis for promising functional hydrophobic materials

New functional heat-resistant poly (1-vinyl-1,2,4-triazole-co-triethoxyvinylsilane) (poly (VT-co-TEVS)) copolymers of various compositions containing triazole and triethoxysilyl groups in the side chains were synthesized by radical copolymerization. Elemental analysis, Fourier transform infrared spectroscopy, NMR spectroscopy, gel permeation chromatography, dynamic light scattering, scanning electron microscopy, thermogravimetric analysis, and differential scanning calorimetry were used to study the composition and structure of poly (VT-co-TEVS) copolymers. The weight average molecular weight of the copolymers varies from 21 to 174 kDa. The reactivity ratios of comonomers in copolymerization (rVT = 4.004 and rTEVS = 0.227) indicate the high reactivity of VT. The resulting copolymers exhibit high thermal stability up to 270 °C. Modification of flexible chain poly (VT-co-TEVS) copolymers was carried out using hydrolytic polycondensation of triethoxysilyl groups. Monitoring of the hydrodynamic diameters of the synthesized copolymers showed intermacromolecular crosslinking of polymer chains due to the formation of Si–O–Si siloxane bonds. Based on spatially cross-linked polyorganosiloxanes containing a functional 1,2,4-triazole fragment, hydrophobic heat-resistant polymeric materials were obtained.

High toughness plant oil-based epoxy resins simultaneous with low dielectric properties

Developing novel multifunctional polymeric materials from biomass to replace traditional electric encapsulation materials such as epoxy resins and polydimethylsiloxane is of great significance for energy consumption and sustainable development. Here, a series of bio-based epoxy thermosets were prepared using a solvent-free ring-opening polymerization-initiated process from different epoxidized plant oils. Key factors such as reactive sites and optimized curing conditions for this system were studied systematically. Moreover, the relative properties of the resulting products, including thermal, mechanical, and dielectric performance were investigated and discussed deeply in correlation with their structure and reactivity. The findings in this work demonstrated that the adjustable chain stiffness and cross-link density of cured networks, achieved through the use of different types of vegetable oils, allows for tailoring the comprehensive properties of these networks. Among the prepared samples, soybean oil-based thermoset exhibited superior tensile strength (7.5 ± 0.28 MPa), elongation at break (87.56 ± 4.80%), glass transition temperature (Tg) of approximately 23 °C, storage modulus of 5.84 MPa, and a dielectric constant of approximately 2.95 at 10 MHz. These properties endow soybean oil-based thermoset as a suitable candidate substrate for encapsulation materials, in comparison with commercial polydimethylsiloxane. The findings suggest that the functional materials designed in this study hold promise as alternatives to petroleum-based polymers and offer paramount potential for applications in diverse electronic device applications.

Impact of the Configurational Microstructure of Carboxylate-Rich Chitosan Beads on Its Adsorptive Removal of Diclofenac Potassium from Contaminated Water.

A novel adsorbent-contaminant system was investigated for its ability to remove a contaminant of emerging concern, diclofenac potassium, from contaminated water. Bio-based crosslinked chitosan beads functionalized with poly(itaconic acid) side chains were examined for their potential to remove the emerging contaminant. To evaluate the impact of the polymeric microstructure on its adsorptive capacity, several adsorbent samples were prepared using different combinations of initiator and monomeric concentrations. Fourier Transform Infrared (FTIR) analysis confirmed the crosslinking of the chitosan chains and the incorporation of the carboxylic groups on the surface of the final chitosan beads. After the grafting copolymerization process, an additional peak at 1726 cm-1 corresponding to the carboxylic C=O groups of the grafted chains appeared, indicating the successful preparation of poly(IA)-g-chitosan. Thermal stability studies showed that the grafting copolymerization improved the thermal stability of the beads. X-ray and Scanning Electron Microscopy confirmed the successful grafting of the itaconic acid on the surface of the beads. The study revealed that the higher the initiator concentration, the greater the number of side chains, whereas the higher the monomeric concentration, the longer the length of these side chains. The adsorption mechanism involved hydrogen bonding to the carboxylic groups of the grafted chains along with n-π* stacking interaction between the amino group of the chitosan and the aromatic rings of diclofenac potassium. The adsorption efficiencies of diclofenac potassium onto the grafted beads were significantly improved compared to the unfunctionalized chitosan beads, reaching values above 90%. The removal efficiency of grafted chitosan increased with an increase in the concentration in the range of 10-30 ppm and then flattened out in the range of 30-50 ppm. The removal efficiencies of 1-50 ppm of DCF ranged between about 75% and 92% for the grafted chitosan and 30-45% for the crosslinked chitosan. Rapid adsorption occurred within 20 min for all grafted sample combinations, and the adsorption kinetics followed a pseudo-second-order model with qe values ranging from 28 to 44.25 g/mg and R2 values greater than 0.9915. The results highlight the potential of grafted chitosan beads in removing emerging contaminants from contaminated water without harming the environment.

Investigation of the ageing conditions of PEEK powder for the selective laser sintering process

ABSTRACT Ageing mechanism of PEEK powders at optimal powder bed temperature (T b) and factors affecting their reusability remain unclear. This study investigated effects of gas type (air, nitrogen, and argon) and holding time (0–8 h) on physico-chemical properties of PEEK powders at optimal T b. The hardness of sintered single-layers was measured to evaluate the quality of the parts. Results revealed that the flowability, morphology, and crystallinity of PEEK powders changed with holding time in different gases. Further, the ageing mechanism involved chain crosslinking within molecular chains in all gases but chain breakage in air. Further, laser power required for SLS decreased with the increase in holding time. However, the hardness of single-layers was stable for powders aged in argon for up to 8 h, but decreased by 7% for powders aged in nitrogen for 4 h. Severe degradation and blackening were observed for single-layers sintered in air using both virgin and aged powders.

Cellulose eutecticgel electrolytes based on ethylene glycol/zinc chloride deep eutectic solvent for flexible solid-state capacitors

In the present work, we successfully prepared a conductive eutecticgel with good mechanical properties, adhesion properties and excellent antifreeze properties by mixing ethylene glycol (EG) as the hydrogen bonding donor and zinc chloride (ZnCl2) as the hydrogen bonding acceptor in different molar ratios to form an anhydrous deep eutectic solvent (DES). Water-soluble cellulose acetate (WSCA), monomer acrylamide (AM), initiator ammonium persulfate (APS) and cross-linking agent MBA (N, N′-methylene bis(acrylamide)) were added into the prepared DES to form a eutecticgel by a simple one-pot cooking strategy. The mechanical properties of the eutecticgel were strengthened by cross-linking of WSCA and PAM chains through hydrogen bonding, and the addition of the DES and ZnCl2 increased the freezing-resistant property of the eutecticgel. The stresses of DES-WSCA/PAM eutecticgel increased with the content of WSCA. The stress of DES-WSCA/PAM eutecticgel gradually becomes larger with the increase of WSCA content, and it can reach 184.07 kPa at 2 % WSCA content. In addition, the capacitor prepared by DES-WSCA/PAM eutecticgel shows excellent performance, with a voltage window of 2 V and a capacitance of 371.5 F/g, which can be operated stably for a long period, and the capacitance can still reach 145.4 F/g even under the condition of −40 °C. Moreover, DES-WSCA/PAM eutecticgel capacitor has a long service life, its capacitance retention rate and coulombic efficiency can reach more than 91 % and 95 %, respectively, after 10,000 times of charging and discharging tests. In summary, DES-WSCA/PAM eutecticgel electrolyte is an ideal material for capacitors, which opens up a new way of thinking for the development of multifunctional cellulose-based eutecticgels with low-temperature resistance, good mechanical properties, and non-irritating for wearable energy storage devices.

Programmable liquid crystal elastomers with dynamic covalent siloxane bonds based on a dual self-catalytic strategy

The exchange reaction of preparing the siloxane-based liquid crystal elastomers (Si-LCEs) always require the acid or base catalysts, which will increase the complexity of the operation and reduces the stability of the Si-LCE materials. In this paper, a novel and simple dual self-catalytic strategy for producing Si-LCEs with dynamic covalent siloxane bonds was proposed. A readily available compound-1,3-bis (aminopropyl) tetramethyldisiloxane (BATS) acts as chain extender and crosslinker for elastomers and provides dynamic covalent bonds (DCBs) as well. More importantly, amino groups of BATS play the role of dual self-catalyst, not only accelerating the thiol Michael addition reaction and aza Michael addition reaction simultaneously during producing Si-LCEs, but also promoting dynamic covalent siloxane bonds exchange reaction at an elevated temperature after the formation of the cross-linked network. With this ingenious design, the obtained fully cured polydomain Si-LCEs possess excellent self-healing and processing abilities enabled by DCBs and outstanding mechanical properties facilitated by hydrogen bond, which can be easily aligned, programmed and recycled. By exploiting these dynamic features, a series of multi-functional soft actuators were realized by simple welding, showing a local fast response and precise control by light and heat. Furthermore, soft robots fabricated with a bilayer structure of Si-LCEs can perform crawling and coiling actuation controlled by near-infrared (NIR) light facilely. These results manifest that the self-catalytic dynamic covalent siloxane bonds strategy is a facile and effective approach for preparing Si-LCEs and provides a new solution for the exploitation of multi-functional liquid crystal elastomers with fast response to various stimulus.

Nitrate Uptake by Cellulose-Based Anion Exchange Polymers Derived from Wheat Straw

Nitrate contamination of ground water is a serious problem due to the intensive agricultural activities needed to feed the world’s growing population. While effective, drinking water treatment using commercial ion exchange polymers is often too expensive to be employed. At the same time, lignocellulosic waste from crop production—an abundant source of the renewable polymer cellulose—is often burned to clear fields. This results in not only adverse health outcomes, but also wastes a valuable resource. In this study, wheat straw was pretreated to extract cellulose, then selectively oxidized with periodate, crosslinked with an alkyl diamine (1,7-diaminoheptane or 1,10-diaminodecane), and functionalized with a quaternary ammonium compound ((2-aminoethyl)trimethyl ammonium chloride) to generate a cellulose-based anion exchange polymer. This polymer lowered aqueous nitrate concentrations to health-based drinking water standards. Unlike commercial ion exchange polymers, its synthesis did not require the use of toxic epichlorohydrin or flammable solvents. The pretreatment conditions did not significantly affect nitrate uptake, but the crosslinker chain length did, with polymers crosslinked with 1,10-diaminodecane showing no nitrate uptake. Agricultural-waste-based anion exchange polymers could accelerate progress toward the sustainable development goals by providing low-cost materials for nitrate removal from water.

MXene-Mediated Cellulose Conductive Hydrogel with Ultrastretchability and Self-Healing Ability.

Constructing natural polymers such as cellulose, chitin, and chitosan into hydrogels with excellent stretchability and self-healing properties can greatly expand their applications but remains very challenging. Generally, the polysaccharide-based hydrogels have suffered from the trade-off between stiffness of the polysaccharide and stretchability due to the inherent nature. Thus, polysaccharide-based hydrogels (polysaccharides act as the matrix) with self-healing properties and excellent stretchability are scarcely reported. Here, a solvent-assisted strategy was developed to construct MXene-mediated cellulose conductive hydrogels with excellent stretchability (∼5300%) and self-healability. MXene (an emerging two-dimensional nanomaterial) was introduced as emerging noncovalent cross-linking sites between the solvated cellulose chains in a benzyltrimethylammonium hydroxide aqueous solution. The electrostatic interaction between the cellulose chains and terminal functional groups (O, OH, F) of MXene led to cross-linking of the cellulose chains by MXene to form a hydrogel. Due to the excellent properties of the cellulose-MXene conductive hydrogel, the work not only enabled their strong potential in both fields of electronic skins and energy storage but provided fresh ideas for some other stubborn polymers such as chitin to prepare hydrogels with excellent properties.

Solvent-free and biodegradable pressure-sensitive adhesive based on chlorosulfonated Poly(propylene carbonate)

The challenge of pressure-sensitive adhesives (PSAs) is to develop solvent-free and biodegradable PSAs. By chlorosulfonated reaction of poly(propylene carbonate)s (PPC) and sulfuryl chloride, a series of biodegradable and solvent-free chlorosulfonated poly(propylene carbonate)s (CSPPCs) with different molecular weight have been acquired. Different from the traditional fabrication of PSAs, introducing polar groups (sulfur and chlorine atoms) onto PPC is combined with the degradation of PPC. For CSPPCs, the elasticity is related to the molecular weight, and the viscosity is related with the polar groups contents, resulting that the balance of the molecular weight and the polar groups contents is significant to adhesion properties. Among CSPPCs, the balance of molecular weight and the polar group contents is most appropriate and the peel strength is highest, when the number-average molecular weight is equal to 15.5 kg/mol. In addition, peel strength can be further improved by chain extension or crosslinking of CSPPCs. From the point of view of environmental protection, the fabrication of CSPPCs is a new and economical method of producing biodegradable and solvent-free PSAs to meet the ever-increasing demands of society.

Evaluating the elastic behaviour of boron nitride nanotube (BNNT) reinforced phenolic nanocomposites

The present analysis concerns investigation of the elastic behavior of boron nitride nanotube (BNNT)-reinforced phenolic nanocomposite using molecular dynamics (MD) simulations. In the investigation, an armchair BNNT with chiral vectors (10, 10) was used as reinforcement and novolac-type phenolic chains and formaldehyde mixture was used as a matrix. The crosslinking of phenolic chains and formaldehyde mixture was achieved to obtain the three-dimensional crosslinked structure reinforced with BNNT. In addition to the tensile elastic modulus, the glass transition temperature was evaluated for the bulk phenolic resin and the nanocomposite using the density-temperature relationship. Based on the results, it was concluded that 6.8% (volume fraction) of BNNT can enhance the elastic modulus of the composite by ∼15 times. Poisson’s ratio was found to be independent of the mixing ratio. It was also observed that reinforcement with BNNT can enhance the glass transition temperature of the nanocomposite. Continuum-based rule of mixture showed a good correlation with the MD predictions.

Reaction kinetics of chitosan nanogels crosslinked by genipin

Crosslinking of chitosan chains in dilute solution by natural crosslinker genipin leads to biocompatible nanogels. Here we investigated the reaction kinetics between chitosan and genipin in a 200 mM acetate buffer at 37 °C, and the structural and conformational evolutions of the nanogels during the crosslinking reaction by multi detection asymmetric flow field-flow fractionation (AF4). Upon crosslinking by genipin, the z-average hydrodynamic radius Rhz of the chitosan chains increased from 26 nm to 130 nm, while the weight average molar mass Mw increased from 2.0 × 105 g/mol to 1.8 × 107 g/mol. The crosslinking reaction appeared to be first-order and size-dependent. In particular, the intrachain crosslinking reaction was preferentially for nanogels having the larger size, leading to formation of branched chains/nanogels having a wide range of molar masses between 106 and 108 g/mol but a similar radius of gyration Rg ∼ 40 nm. For the largest nanogel fractions with M > 2.0 × 108 g/mol, both Rg and Rh showed a scaling relation with exponent 1/3 and a structure parameter Rg/Rh = 0.74, as expected for the hard sphere particle. The reaction was accompanied by a reduction of charge density and an increase in hydrophobicity of chitosan nanogels, which plays a key role in the formation of uniform size nanogels with chain density ρ(Rh) up to 0.45 g/cm3.

Electrical Conduction and Space Charge in Gamma-Irradiated XLPE

It is well known that ionizing radiation impact dielectric and mechanical properties of polymers, as a result of chain scission, crosslinking, and oxidation steps. The electrical conductivity is generally substantially increased after irradiation. We analyze such effects in XLPE after gamma-irradiation. Current measurements reveal a substantial increase in conductivity after irradiation at doses up to 200 kGy. Current-field characteristics change after irradiation and appear indicative of an ionic-type conduction. Space charge measurements confirm the mechanism with obvious heterocharge build-up after irradiation.

Diverse functional polyethylenes by catalytic amination.

Functional polyethylenes possess valuable bulk and surface properties, but the limits of current synthetic methods narrow the range of accessible materials and prevent many envisioned applications. Instead, these materials are often used in composite films that are challenging to recycle. We report a Cu-catalyzed amination of polyethylenes to form mono- and bifunctional materials containing a series of polar groups and substituents. Designed catalysts with hydrophobic moieties enable the amination of linear and branched polyethylenes without chain scission or cross-linking, leading to polyethylenes with otherwise inaccessible combinations of functional groups and architectures. The resulting materials possess tunable bulk and surface properties, including toughness, adhesion to metal, paintability, and water solubility, which could unlock applications for functional polyethylenes and reduce the need for complex composites.

Analysis of bio-based acrylate accelerated weathering: A study of nanocellulose impact on the bulk durability of 3D-printed nanocomposites

Bio-based resins for UV-assisted photopolymerization vat 3D printing have received immense research interest. 3D printing has initiated the 4.0 industrial revolution and is expected to squeeze in more production industries, including making materials for outdoor applications. Weathering investigations have been devoted mainly to fossil acrylic polymers. This research aims to close the gap in understanding bio-based acrylic 3D-printed polymer weathering performance. QUV accelerated weathering was used on vegetable oil-based 3D-printed compositions with nanofibrillated cellulose (NFC) as reinforcing filler. Discoloration, cracking, FTIR measurements of surface chemical degradation, and bulk properties evaluated by changes in mechanical performance were used to characterize materials performance during weathering. NFC reinforcement delays the yellowing and cracking during 1000 h of weathering. After weathering, increased flexural stress and strain were achieved with 0.5 wt% NFC loading. Chemical analysis reveals simultaneous photocleavage and additional crosslinking of the macromolecular chains. The glass transition temperature increased by up to 20 °C. NFC introduction in bio-based polymers increased of weathering endurance and mechanical performance. The NFC is compatible with and a perspective filler in bio-based acrylic resins for 3D printing applications.

Bismaleimide resin co‐modified by allyl ether of resveratrol and allyl ether of eugenol‐grafted polysiloxane with enhanced toughness, heat resistance, and flame retardancy

AbstractModifying bismaleimide (BMI) resin to improve its toughness and flame retardancy without sacrificing the glass transition temperature (Tg) and thermal decomposition stability is still a challenge. In this study, we employed the allyl ether of resveratrol (AER) and eugenol allyl ether grafted polysiloxane (PMES‐Allyl) to co‐modify BMI resin. For the BMI/AER/PMES‐Allyl (BAPA) resin, the content of PMES‐Allyl was 15 wt%, and the molar ratio of maleimide and allyl groups was controlled as 1:0.8. Compared to commercial 2,2′‐diallyl bisphenol A modified BMI (BD) resin, the BAPA resin exhibited superior thermal properties after curing, due to the role of AER in improving the crosslinking density and chain rigidity of the network. The cured BAPA resin had a Tg more than 380°C, and its initial thermal decomposition temperature (Td5%) and char yield (Y800°C) reached 424.8°C and 46.4%, respectively. Meanwhile, PMES‐Allyl as a rubber phase could effectively improve the toughness of the cured resin. The impact strength of the cured BAPA resin was 15.2 kJ/m2. Moreover, the two modifiers both helped to improve the flame retardancy of the material. Compared with the cured BD resin, the cured BAPA resin showed a decrease of peak heat release rate (PHRR), total heat release (THR), and maximum average rate of heat emission (MARHE) by 25.5%, 35.5%, and 31.5%, respectively. Its total smoke production (TSP) was only 35.6% of that of the cured BD resin. In addition, the cured BAPA resin also displayed a lowered water absorption and improved thermal aging resistance. Therefore, it is suggested to be a promising and high‐performance thermosetting resin for cutting‐edge applications.

Applications of Degradable Hydrogels in Novel Approaches to Disease Treatment and New Modes of Drug Delivery.

Hydrogels are particularly suitable materials for loading drug delivery agents; their high water content provides a biocompatible environment for most biomolecules, and their cross-linked nature protects the loaded agents from damage. During delivery, the delivered substance usually needs to be released gradually over time, which can be achieved by degradable cross-linked chains. In recent years, biodegradable hydrogels have become a promising technology in new methods of disease treatment and drug delivery methods due to their many advantageous properties. This review briefly discusses the degradation mechanisms of different types of biodegradable hydrogel systems and introduces the specific applications of degradable hydrogels in several new methods of disease treatment and drug delivery methods.