Methacrylate Groups Research Articles

Hydrophobically Modified Polyacrylamide Incorporating Both Hydrophilic and Hydrophobic Units: Enhanced Printability and Stability in Aqueous Ink.

For this research, three hydrophobically modified polyacrylamides, HPAAB, HPAAF, and HPAAS, with multiple hydrophobic monomers were designed, synthesized, and used as thickeners in aqueous ink for digital ink-jet printing. The structures were characterized by Fourier transform infrared (FTIR) analysis and nuclear magnetic resonance (NMR) spectroscopy. The viscosity-average molecular weight was determined by intrinsic viscosity determination and was adjusted according to hydrophobic content. The critical association concentration (CAC) of polymers was measured simultaneously using the apparent viscosity method and the fluorescence spectrum. The formation of a network structure and the mechanism of hydrophobic association are visualized dynamically with a scanning electron microscope (SEM) at different concentrations. Under the same conditions, HPAAB exhibited excellent thickening ability across different pH levels, temperatures, and shear rates, which is caused by the longer hydrophobic side chain and the stronger hydrophobic effect of the behenyl polyoxyethylene ether methacrylate (BEM) group. Furthermore, an aqueous ink using HPAAB as a thickener displays significant printability and stability, functioning much better than a corresponding aqueous ink that uses a commercial thickener. This is the first example of a hydrophobic associating polyacrylamide, incorporating both hydrophilic and hydrophobic units within a single hydrophobic chain, thereby serving as an efficient thickener for aqueous ink.

Water-based synthesis of dextran-methacrylate and its use to design hydrogels for biomedical applications

Polysaccharide-based hydrogels are desirable for biomedical applications owing to their biocompatibility and physicochemical tunability. The chemical modification of polysaccharides with photo-sensitive groups, such as methacrylates is a common method to obtain new hydrogel materials. This study introduces a non-toxic water-based method to effectively functionalize dextran with methacrylate groups. The methacrylation reaction with methacrylic anhydride in water in the presence of NaOH was rapid and efficient (85 % − 92 % yield), permitting degrees of substitution (DS) up to 62 % within 60 min. An unconventional solid-state photo-crosslinking method was employed to form chemically crosslinked dextran-based hydrogels with LAP (lithium phenyl-2,4,6-trimethylbenzoylphosphinate) as the photoinitiator. By varying the polymer formulations (DS, polymer mass, LAP concentration), a wide range of hydrogels were obtained with various swelling ratios (40–250 %) and release kinetics of model drug and protein biomolecules. Compression modulus values ranged from 32 ± 1 to 342 ± 10 MPa (dry state) and 87 to 8500 kPa (swollen state). Cytotoxicity experiments indicated good biocompatibility for the crosslinked dextran hydrogels. The green synthesis protocols and obtained dextran-based hydrogels with high mechanical strength open up perspectives for applications from tissue engineering to the design of medical devices such as microneedles.

Synthesis and characterization of the dental adhesive monomer 10-MDP

Many studies have demonstrated the excellent performance of 10-MDP (10-methacryloyloxydecyl dihydrogen phosphate) as a functional monomer for dental adhesive materials and as a primer for ceramic surfaces. Although adhesive performance is affected by the purity level of 10-MDP, this parameter is rarely described, and possible byproducts have been suggested in the literature, but have not been identified to date. The present study aims to present an accessible 10-MDP synthesis strategy with easily handled reagents and address the characterization challenges, especially in identifying byproducts. 10-MDP was synthesized from 10-hydroxydecyl methacrylate and phosphorus pentoxide in acetone. The final product was characterized by nuclear magnetic resonance (NMR), infrared spectroscopy (FTIR) and mass spectrometry MALDITOF/TOF. The main chemical groups associated with 10-MDP were identified by 1H, 31P, and 13C NMR analyses. Only mass spectrometry analyses (MALDITOF/TOF) could identify the presence of dimers as byproducts. Its proposed chemical structure indicates that the dimers were formed by the reaction between the phosphate ester groups and others formed by the reaction of the methacrylic group of 10-MDP molecules. Careful adjustment of the synthesis conditions to reduce the formation of these byproducts is also described. The results indicate that the characterization of 10-MDP batches as raw materials is an important task because, depending on the byproduct present, its ability to polymerize or acid etching capacity may be compromised.

3D-printed injectable nanocomposite cryogel scaffolds for bone tissue regeneration

Cryogels are known for their high water content and interconnected macroporosity, two relevant features in tissue engineering approaches. The cryogel structure can support tissue growth as it allows nutrient and oxygen diffusion, removal of waste products, as well as an enhancement of cell infiltration and proliferation. Bioactive glass nanoparticles are biocompatible and clinically approved bioactive materials widely used as implants in the human body to repair or replace diseased or damaged bones. They are known to facilitate bone binding while stimulating bone growth. Indeed, the combination of cryogels with bioactive nanoparticles has already demonstrated promising results for bone regeneration. Although the developed biomaterials succeed in bone regeneration, they lack suitability for minimal invasive procedures or patient-specificity. Here, we demonstrate a freeform 3D printed nanocomposite cryogel, resorting to an ink composed of functionalized gelatin and bioactive glass nanoparticles with methacrylate groups. Complex structures with multiple layers were 3D printed in a xanthan gum supporting bath. The developed 3D printed nanocomposite cryogels demonstrate the ability to recover their shape without any permanent damage, withstanding up to 65 % compression upon injection. Additionally, they stimulate the differentiation of human adipose-derived stem cells into the osteoblast lineage, therefore promoting bone tissue growth. We further demonstrated their suitability for minimal invasive therapeutics by filling a reproduction of a maxillofacial defect. The developed 3D-printed nanocomposite cryogels offer robust shape-recovery properties, easy injectability, tailored geometry into patient-specific injuries, and high osteogenic bioactivity, showcasing its versatility for bone regeneration purposes.

Acrylated epoxidized natural rubber/functionalized organoclay hybrid networks: In‐situ production and characterization study

AbstractThis study is dedicated to the fabrication of acrylated epoxidized natural rubber (AENR)/dual‐functionalized organoclay (DF‐C30B) hybrid networks using an in‐situ light‐induced crosslinking polymerization technique. The process begins with the successful synthesis of DF‐C30B, which contains methacrylate groups, achieved by reacting 3‐methacryloxypropyltrimethoxysilane (MPS) with cloisite 30B (C30B). During fabrication, DF‐C30B nanolayers are dispersed within the AENR matrix at various feed ratios, ranging from 1 to 8 parts per hundred of rubber (phr). The photocrosslinking polymerization is then initiated using 2,2‐dimethoxy‐2‐phenylacetophenone (DMPA) as the photoinitiating agent. Subsequent analysis of the nanocomposites involves evaluating their structure and morphology using established techniques such as Fourier transform infrared (FTIR) spectroscopy, x‐ray diffraction (XRD), thermogravimetric analysis (TGA), and transmission electron microscopy (TEM). The FTIR analysis enables comparing distinct bands of the nanocomposite's components, affirming the integration and covalent attachment of nanoclay in the AENR matrix. Results from TEM and XRD illustrate the uniform distribution of DF‐C30B throughout the AENR matrix without significant agglomeration. TGA results indicate that the hybrid networks exhibit enhanced thermal stability, with degradation onset temperatures of 306°C, 308°C, 315°C, and 318°C for DF‐C30B loadings of 1, 2, 4, and 8 phr, respectively, compared to 198°C for pure AENR. Correspondingly, char residue levels increased to 4.3%, 5.6%, 7.8%, and 11.7% for the respective DF‐C30B contents. This research underscores the promising role of DF‐C30B as a strengthening component in nanocomposites based on NR, contributing to improved thermal endurance, enhanced uniformity, and offering insightful directions for future advancements.Highlights Fabricated acrylated epoxidized natural rubber (AENR)/dual‐functionalized organoclay (DF‐C30B) hybrid networks via light‐induced crosslinking polymerization. Enhanced compatibility and performance of DF‐C30B within the AENR matrix. Successful integration and stability confirmed by Fourier transform infrared spectroscopy, x‐ray diffraction (XRD), transmission electron microscopy (TEM), and thermogravimetric analysis (TGA). Uniform dispersion of DF‐C30B within the matrix demonstrated by XRD and TEM. Improved thermal stability compared to neat AENR, as evidenced by TGA results.

Development of nanocomposite hydrogel using citrate-containing amorphous calcium phosphate and gelatin methacrylate.

Nanocomposite hydrogels are suitable in bone tissue engineering due to their resemblance with the extracellular matrix, ability to match complex geometries, and ability to provide a framework for cell attachment and proliferation. The nanocomposite hydrogel comprises organic and inorganic counterparts. Gelatin methacrylate (GELMA) is an extensively used organic biomaterial in tissue engineering due to its excellent biocompatibility, biodegradability, and bioactivity. The photo-crosslinking of GELMA presents a challenge when aiming to create thicker nanocomposite hydrogels due to opacity induced by fillers, which obstructs the penetration of ultraviolet (UV) light. Therefore, using a chemical crosslinking approach, we have developed nanocomposite GELMA hydrogel in this study by incorporating citrate-containing amorphous calcium phosphate (ACP_CIT). Ammonium persulfate (APS) and Tetramethylethylenediamine (TEMED) were deployed to crosslink the methacrylate group of GELMA. The oscillatory shear tests have confirmed that crosslinking enhances both storage (G') and loss modulus (G″) of GELMA. Subsequently, incorporation of ACP_CIT in GELMA hydrogel shows further enhancement in G' and G″ values. In vitro analysis of the developed hydrogels revealed that chemical crosslinking and incorporation of ACP_CIT do not compromise the cytocompatibility of the GELMA. Hence, for developing nanocomposite GELMA hydrogels employing APS/TEMED crosslinking emerges as a promising alternative to photo-crosslinking.

Photo-responsive decellularized small intestine submucosa hydrogels.

Decellularized small intestine submucosa (dSIS) is a promising biomaterial for promoting tissue regeneration. Isolated from the submucosal layer of animal jejunum, SIS is rich in extracellular matrix (ECM) proteins, including collagen, laminin, and fibronectin. Following mild decellularization, dSIS becomes an acellular matrix that supports cell adhesion, proliferation, and differentiation. Conventional dSIS matrix is usually obtained by thermal crosslinking, which yields a soft scaffold with low stability. To address these challenges, dSIS has been modified with methacrylate groups for photocrosslinking into stable hydrogels. However, dSIS has not been modified with clickable handles for orthogonal crosslinking. Here, we report the development of norbornene-modified dSIS, named dSIS-NB, via reacting amine groups of dSIS with carbic anhydride in acidic aqueous reaction conditions. Using triethylamine (TEA) as a mild base catalyst, we obtained high degrees of NB substitution on dSIS. In addition to describing the synthesis of dSIS-NB, we explored its adaptability in orthogonal hydrogel crosslinking and used dSIS-NB hydrogels for cancer and vascular tissue engineering. Impressively, compared with physically crosslinked dSIS and collagen matrices, orthogonally crosslinked dSIS-NB hydrogels supported rapid dissemination of cancer cells and superior vasculogenic and angiogenic properties. dSIS-NB was also exploited as a versatile bioink for 3D bioprinting applications.

The Impact of the Methacrylation Process on the Usefulness of Chitosan as a Biomaterial Component for 3D Printing.

Chitosan is a very promising material for tissue model printing. It is also known that the introduction of chemical modifications to the structure of the material in the form of methacrylate groups makes it very attractive for application in the bioprinting of tissue models. The aim of this work is to study the characteristics of biomaterials containing chitosan (BCH) and its methacrylated equivalent (BCM) in order to identify differences in their usefulness in 3D bioprinting technology. It has been shown that the BCM material containing methacrylic chitosan is three times more viscous than its non-methacrylated BCH counterpart. Additionally, the BCM material is characterized by stability in a larger range of stresses, as well as better printability, resolution, and fiber stability. The BCM material has higher mechanical parameters, both mechanical strength and Young's modulus, than the BCH material. Both materials are ideal for bioprinting, but BCM has unique rheological properties and significant mechanical resistance. In addition, biological tests have shown that the addition of chitosan to biomaterials increases cell proliferation, particularly in 3D-printed models. Moreover, modification in the form of methacrylation encourages reduced toxicity of the biomaterial in 3D constructs. Our investigation demonstrates the suitability of a chitosan-enhanced biomaterial, specifically methacrylate-treated, for application in tissue engineering, and particularly for tissues requiring resistance to high stress, i.e., vascular or cartilage models.

Functional Upcycling of Polyurethane Thermosets into Value-Added Thermoplastics via Small-Molecule Carbamate-Assisted Decross-Linking Extrusion.

The cross-linked structures of most commodity polyurethanes (PUs) hinder their recycling by common mechanical/chemical approaches. Catalyzed dynamic carbamate exchange emerges as a promising PU recycling strategy, which converts traditional static PU thermosets into reprocessable covalent adaptable networks (CANs). However, this approach has been limited to thermoset-to-thermoset reprocessing of PU CANs, accompanied by their well-preserved network structures and extremely high viscosities, which pose challenges to processing and certain applications. This study reports a catalytic decross-linking extrusion process aided by small-molecule carbamates, which can upcycle PU thermosets into easily processable and functional PU thermoplastics in a solvent-free and high-throughput manner. Key to this process is the employment of small-molecule carbamates as decross-linkers to simultaneously deconstruct cross-linked PUs and functionalize the decross-linked PU chains, through catalyzed carbamate exchange reactions in a twin-screw extruder. This strategy applies to both aromatic and aliphatic cross-linked PU films and foams, and the amount of small-molecule carbamates required to decross-link PU networks is determined through thermal, chemical, and structural analyses of the resulting extrudates. This approach is generalizable to small-molecule carbamates with various steric/electronic structures and chemical functionalities including methacrylate, anthracene, and stilbene groups. The chain-end functionalization is confirmed by analyzing the purified decross-linked extrudates after dialysis. This thermoset-to-thermoplastic extrusion process represents a powerful approach for upcycling postconsumer PU thermosets into a library of thermoplastic PUs with controlled molecular weights and chain-end functionalities for diverse applications, including adhesives, photoresins, and stimuli-responsive materials, as demonstrated herein. In the future, this strategy could be extended to upcycle many other step-growth networks capable of undergoing catalytic bond exchange reactions, such as cross-linked polyureas and polyesters, contributing to plastic waste management in general.

High flexural modulus of polilactide composites for 3D printing technology using multifunctional octaspherosilicates

AbstractIn recent years, there has been a growing research interest focused on employing organosilicon compounds, including silsesquioxanes, as modifiers for different polymers. This work describes the methodology for obtaining a new nanocomposite using functionalized spherosilicates, which belong to the general group of silsesquioxane compounds. These modifiers are used as additives to polylactide to improve its properties in the context of the additive technology fused deposition modeling/fuse fabrication filament. The developed materials were characterized by better rheology compared to neat PLA. Differential scanning calorimetry analysis of the additives confirmed their reactive nature. Based on water contact angle tests, it was observed that up to 1.5% of the load, none of the additives influenced the wetting of the material surface. Microscopic images revealed visible agglomerations for the OSS-6MA-2TMOS system, while in samples with a lower share of methacrylic groups, very good dispersion of the additive in the matrix was observed. Also, the microscopic observations showed better melting of the composite layers containing additives in the 3D printing process, combined with the appropriate printing parameters, can ultimately produce more robust objects with fewer voids and discontinuities. The addition also resulted in an increase in mechanical parameters, mainly in terms of bending strength and impact strength. Graphical abstract

Fabrication of oxygen-releasing dextran microgels by droplet-based microfluidic method.

In the tissue engineering field, the supply of oxygen to three-dimensional (3D) tissues is an important aspect to avoid necrosis due to hypoxia. Although oxygen-releasing bulk materials containing calcium peroxide (CaO2, CP) have attracted much attention, micrometer-sized oxygen-releasing soft materials would be advantageous because of their highly controllable structures, which can be applied for cell scaffolds, injectable materials, and bioink components in 3D bioprinting. In this study, oxygen-releasing microgels were fabricated via a droplet-based microfluidic system. Homogeneous, monodisperse and stable oxygen-releasing microgels were obtained by photo-crosslinking of droplets composed of biocompatible dextran modified with methacrylate groups and CP nanoparticles as an oxygen source. We also used our microfluidic system for the in situ amorphous calcium carbonate (CaCO3, ACC) formation on the surface of CP nanoparticles to achieve the controlled release of oxygen from the microgel. Oxygen release from an ACC-CP microgel in a neutral cell culture medium was suppressed because incorporation of CP in the ACC suppressed the reaction with water. Strikingly, stimuli to dissolve ACC such as a weak acidic conditions triggered the oxygen release from microgels loaded with ACC-CP, as the dissolution of CaCO3 allows CP to react. Taken together, applications of this new class of biomaterials for tissue engineering are greatly anticipated. In addition, the developed microfluidic system can be used for a variety of oxygen-releasing microgels by changing the substrates of the hydrogel network.

Lignin and functional polymer-based materials: Synthesis, characterization and application for Cr (VI) and As (V) removal from aqueous media

In this study, lignin derived from corncobs was chemically modified by substituting the hydroxyl groups present in its structure with methacrylate groups through a catalytic reaction using methacrylic anhydride, resulting in methacrylated lignin (ML). These MLs were incorporated in polymerization reaction of the monomer 2-[(acryloyloxy)ethyl trimethylammonium] chloride (Cl-AETA) and Cl-AETA, Cl-AETA/ML polymers were obtained, characterized (spectroscopic, thermal and microscopic analysis), and evaluated for removing Cr (VI) and As (V) from aqueous media in function of pH, contact time, initial metal concentrations and adsorbent amount.The Cl-AETA/ML polymers followed the Langmuir adsorption model for the evaluated metal anions and were able to remove up to 91 % of Cr (VI) with a qmax (maximum adsorption capacity) of 201 mg/g, while for As (V), up to 60 % could be removed with a qmax of 58 mg/g. The results demonstrate that simple modifications in lignin enhance its functionalization and properties, making it suitable for removing contaminants from aqueous media, showing promising results for potential future applications.

Synthesis and challenges of fluorinated divinyl urethane monomers as a strategy for masking hydrolytic sensitive methacrylate groups in resin composites

ObjectiveThe biodegradation of methacrylate (MA)-based dental restoratives has been suggested to contribute to a loss of adhesion and subsequent detachment, or secondary caries, both major causes of restoration failure. Previous studies have demonstrated that intermolecular interactions between resin monomers may affect the hydrolytic-susceptibility of composites. Altering the intermolecular interactions by shielding or masking the hydrolytically-susceptible ester groups found in MA monomers could be an effective strategy to mitigate the biodegradation of resin composites. The objective of this work was to assess whether shielding/masking MAs using fluorinated groups could improve the biostability of experimental composites. MethodsEight fluorinated monomers (FM) were synthesized, characterized (1H NMR), and formulated into experimental resin composites (FC, 65 wt%, microfill). FCs were assessed for interactions with water (water contact angle, water sorption, gel fraction), mechanical properties (both compressive and flexural strength and modulus), cytocompatibility, resistance to biodegradation using simulated human salivary esterase (SHSE) and compared to a control composite (CC) without FM. ResultsIntegration of FMs was found to generally decrease both the physical and mechanical properties under all incubation conditions when compared to the CC. Additionally, all FCs had a negative influence on composite biodegradation following immersion in SHSE when compared to the CC. SignificanceShielding/masking MA-esters inherently inserts molecular spaces between the polymer chains within the resin network, and shielding is likely not possible while also maintaining the necessary cohesive forces that regulate the physical and mechanical properties of resin composites. Novel dental resin development should seek to remove/replace vulnerable ester-containing MAs rather that adopting a shielding/masking approach.

Novel quinoline photoinitiators for dimethacrylate monomer photopolymerization under UV and blue light

Composite resins based on methacrylated monomers are the main materials for dental restorations, however, incomplete polymerization and leaching have been identified as the major problems in this process, highlighting the importance of a search for new photoinitiating materials with improved properties and, therefore, can produce cheaper and stronger polymers with reduced toxicity. In this work, two novel quinoline derivatives were evaluated to obtain dimethacrylate-based polymers. Here we present the synthesis and characterization of a quinoline derivative containing a hydroxyl group and another containing a methacrylate group, as type II photoinitiator materials for UDMA-based resins polymerization. The photoinitiators were analyzed through photolysis (at two distinct wavelengths) and theoretical calculations were performed via a DFT-based approach, to provide a better understanding of the photoexcitation process of quinoline-based photoinitiators. The thermal stability, mass loss rate and glass transition of the generated polymers and the quinoline photoinitiators were analyzed via TG-DTA and DSC. The morphological characteristics of final polymerized compounds were performed with scanning electron microscopy. The water sorption and solubility were also investigated. Our results indicate that hydroxyl-containing quinoline promotes an efficient photopolymerization of UDMA resin precursors under blue light (65.9 %), while methacrylate-containing quinoline presents higher conversions under ultraviolet irradiation (66.3 %). The polymerization of the compounds presented 40 % to 66 % conversion under 60 s, comparable to the camphorquinone standard at the same conditions. The polymer of UDMA with hydroxyl-containing quinoline, showed a slightly higher water sorption than the methacrylate-containing one and both indicate no solubility in water at 37 °C. Overall, the results show that quinoline-based photoinitiators present an efficient photopolymerization of UDMA and produce fluorescent polymers, similarly to commonly used resin materials.

The Effect of Macromonomer Surfactant Microstructure on Aqueous Polymer Dispersion and Derived Polymer Film Properties.

Water-borne coatings were prepared from poly(methyl methacrylate-co-butyl acrylate) latexes using different methacrylic acid containing macromonomers as stabilizers, and their physical properties were determined. The amphiphilic methacrylic acid macromonomers containing methyl, butyl, or lauryl methacrylate as hydrophobic comonomers were synthesized via catalytic chain transfer polymerization to give stabilizers with varying architecture, composition, and molar mass. A range of latexes of virtually the same composition was prepared by keeping the content of methacrylic acid groups during the emulsion polymerization constant and by only varying the microstructure of the macromonomers. These latexes displayed a range of rheological behaviors: from highly viscous and shear thinning to low viscous and Newtonian. The contact angles of the resulting coatings ranged from very hydrophilic (<10°) to almost hydrophobic (88°), and differences in hardness, roughness, and water vapor sorption and permeability were found.

Synthesis and Electrophoretic Deposition of Polyimide with Methacrylic Groups on the Side Chain

Synthesis and Electrophoretic Deposition of Polyimide with Methacrylic Groups on the Side Chain

Evaluation of novel urethane dimethacrylates as crosslinkers for the development of fracture tough dental materials containing a poly(ε‐caprolactone)‐polydimethylsiloxane‐poly(ε‐caprolactone) triblock copolymer

AbstractPhotocuring 3D printing of materials exhibiting high fracture toughness and excellent mechanical properties (flexural strength/modulus) is challenging. Nowadays, most of the photocurable 3D printing resins are based on a mixture of multifunctional (meth)acrylates and provide therefore brittle materials. This article describes further developments of a toughening strategy based on the incorporation of block copolymers in low crosslink density methacrylate‐based materials. Six dimethacrylates bearing a bisphenol A core and urethane groups are successfully synthesized. Various spacers between the bisphenol A core and the methacrylate groups are selected. Each monomer is combined with (octahydro‐4,7‐methano‐1H‐indenyl)methyl acrylate as a monofunctional monomer and a poly(ε‐caprolactone)‐polydimethylsiloxane‐poly(ε‐caprolactone) triblock copolymer is added as toughener. It is shown that the addition of the triblock copolymer results for all mixtures in a strong increase of the fracture toughness. Moreover, the higher the amount of monofunctional monomer, the stronger the increase. The nature of the urethane dimethacrylate is found to have a significant influence on the fracture toughness, flexural strength, and flexural modulus of cured materials. Two of the synthesized dimethacrylates are identified as promising candidates for the development of fracture‐tough photocuring 3D printing materials.

Tailoring of Physical Properties in Macroporous Poly(isocyanopeptide) Cryogels.

Over the years, synthetic hydrogels have proven remarkably useful as cell culture matrixes to elucidate the role of the extracellular matrix (ECM) on cell behavior. Yet, their lack of interconnected macropores undermines the widespread use of hydrogels in biomedical applications. To overcome this limitation, cryogels, a class of macroporous hydrogels, are rapidly emerging. Here, we introduce a new, highly elastic, and tunable synthetic cryogel, based on poly(isocyanopeptides) (PIC). Introduction of methacrylate groups on PIC facilitated cryopolymerization through free-radical polymerization and afforded cryogels with an interconnected macroporous structure. We investigated which cryogelation parameters can be used to tune the architectural and mechanical properties of the PIC cryogels by systematically altering cryopolymerization temperature, polymer concentration, and polymer molecular weight. We show that for decreasing cryopolymerization temperatures, there is a correlation between cryogel pore size and stiffness. More importantly, we demonstrate that by simply varying the polymer concentration, we can selectively tune the compressive strength of PIC cryogels without affecting their architecture. This unique feature is highly useful for biomedical applications, as it facilitates decoupling of stiffness from other variables such as pore size. As such, PIC cryogels provide an interesting new biomaterial for scientists to unravel the role of the ECM in cellular functions.

Gelatin methacrylate/poly(2-ethyl-2-oxazoline) porous hydrogel loaded with kartogenin drug as a biocompatible scaffold for cartilage tissue regeneration

Gelatin methacrylate (GelMA) is a biocompatible, and biodegradable macromolecule developed from a natural polymer, gelatin, via covalent bonding with methacrylic groups. In this research, GelMA/poly(2-ethyl-2-oxazoline) (PEtOx) hydrogel loaded with Kartogenin (KGN) drug was developed with the aim to regenerate the extracellular matrix of cartilage. The morphology, swelling ratio, degree of hydrophilicity, biodegradability, elastic modulus, blood compatibility, drug release and cytotoxicity were assessed. The hydrogel was found to be hydrophilic, highly porous and biodegradable, with 92 % porosity and ∼ 43 % weight loss within 14 days. Mechanical testing revealed that the elastic modulus of GelMA (20 wt%)/PEtOx (45 wt%) was close to that of cartilage. Good blood compatibility and sustained drug release in the damaged cartilage tissue environment were also detected. According to flow cytometry and MTT tests, due to the presence of KGN, up to 75 % of the cells can survive and easily adhere to the developed scaffold. The results confirm the ability of GelMA/PEtOx hydrogel containing KGN to increase cell adhesion by preserving cell population combined with minimal cytotoxicity, which may be advantageous for use in cartilage regeneration following in-vivo implantation.

Effect of catalysts on the mechanical, thermal, and adhesive properties of polyrotaxane-modified epoxy resin

Polyrotaxane (PR) is a supramolecular polymer, in which an axial polymer extends through multiple cyclic molecules. PR specifically comprises polyethylene glycol, α-cyclodextrin, and adamantane as the axial polymer, cyclic molecule, and terminal blocking group, respectively. It is a useful stress-relaxing material because the cyclic polymers can freely slide and rotate in cyclic motions on the axial polymer. In this study, epoxy resin (DGEBA) cured with phenolic resin (PN) was blended with PR, which has methacryl groups at the ends of side chains of the cyclic molecules, as a toughness modifier. The effect of the methacryl group polymerization catalyst (DCP) on the cured properties of epoxy resin was reported. PR was homogeneously dispersed in the DGEBA/PN resin matrix. Increasing the PR concentration significantly improved the toughness, impact resistance, and adhesive properties of the DGEBA/PN/PR alloy. Moreover, adding DCP resulted in an increase in the glass transition temperature due to the decreased molecular mobility of the network. This phenomenon was attributed to the synergistic effect of the formation of an interpenetrating polymer network, which is an entangled network of the curing reaction of the DGEBA/PN resin and polymerization of PR, and the intermolecular hydrogen bonds between carbonyl and hydroxyl groups of PR and hydroxyl groups of the DGEBA/PN resin. In contrast, the increased interfacial adhesion between PR and the DGEBA/PN did not result in significant improvement of flexural properties.