Resin Formulations Research Articles

Restorative Dental Resin Functionalized with Calcium Methacrylate with a Hydroxyapatite Remineralization Capacity.

The ability of dental materials to induce the mineralization of enamel like hydroxyapatite (HA) is of great importance. In this article, a novel kind of dental restorative material characterized by a mineralization ability was fabricated by photopolymerization. Calcium methacrylate (CMA) was introduced into the classical bisphenol A-glycidyl methacrylate (Bis-GMA) and triethylene glycol dimethacrylate (TEGDMA) dental resin formulation. This functional dental resin (BTCM) was calcium-rich and can be prepared simply by one-step photopolymerization. The influence of CMA on the photopolymerization kinetics, the dental resin's mechanical properties, and its capacity to induce dynamic in situ HA mineralization were examined. Real-time FTIR, compression modulus, scanning electron microscopy, X-ray spectroscopy, MTT assay, and cell attachment test were carried out. The obtained data were analyzed for statistical significance using analysis of variance (ANOVA). Double bond conversion could be completed in less than 300 s, while the compression modulus of BTCM decreased with the increase in CMA content (30 wt%, 40 wt%, and 50 wt%). After being soaked in Ca(NO3)2 and Na2HPO4 solutions alternatively, dense HA crystals were found on the surface of the dental resin which contained CMA. The amount of HA increased with the increase in CMA content. The MTT results indicated that BTCM possesses good biocompatibility, while the cell adhesion and proliferation investigation demonstrated that L929 cells can adhere and proliferate well on the surface of BTM. Thus, our approach provides a straightforward, cost-effective, and environmentally friendly solution that has the potential for immediate clinical use.

Flexible Allyl-Modified Gelatin Photoclick Resin Tailored for Volumetric Bioprinting of Matrices for Soft Tissue Engineering.

Volumetric bioprinting (VBP) is a light-based 3D printing platform, which recently prompted a paradigm shift for additive manufacturing (AM) techniques considering its capability to enable the fabrication of complex cell-laden geometries in tens of seconds with high spatiotemporal control and pattern accuracy. A flexible allyl-modified gelatin (gelAGE)-based photoclick resin is developed in this study to fabricate matrices with exceptionally soft polymer networks (0.2-1.0kPa). The gelAGE-based resin formulations are designed to exploit the fast thiol-ene crosslinking in combination with a four-arm thiolated polyethylene glycol (PEG4SH) in the presence of a photoinitiator. The flexibility of the gelAGE biomaterial platform allows one to tailor its concentration spanning from 2.75% to 6% and to vary the allyl to thiol ratio without hampering the photocrosslinking efficiency. The thiol-ene crosslinking enables the production of viable cell-material constructs with a high throughput in tens of seconds. The suitability of the gelAGE-based resins is demonstrated by adipogenic differentiation of adipose-derived stromal cells (ASC) after VBP and by the printing of more fragile adipocytes as a proof-of-concept. Taken together, this study introduces a soft photoclick resin which paves the way for volumetric printing applications toward soft tissue engineering.

Polymer nanocomposite adhesives with internal nano-heaters to facilitate multilayer laminate separation

Laminating adhesives used in multilayer films present strong, irreversible adhesion that limits the produced packaging systems to single-use applications. From a sustainability point of view, the recovery of individual polymers after use is imperative and a pivotal step is to make this adhesion reversible via breakdown of the adhesive structure. This work describes a promising strategy based on the incorporation of graphene into thermoreversible adhesive resin formulations to trigger the rupture of the adhesive network by exposure to IR radiation. Graphene is a thermal absorber that abruptly heats up under irradiation and efficiently dissipates this heat to the surrounding environment causing the adhesive network to collapse, resulting in remarkable changes in its mechanical properties. In this study, graphene was incorporated at low concentrations (0.25–1 wt %) into solvent-free polyurethane adhesives containing thermoreversible moieties. The photothermal effect at different loadings was evaluated and the formulation displaying the best balance between photothermal effect and optical properties was selected. Furthermore, the effect of irradiation on cyclability, fluidity and mechanical properties of the graphene-containing adhesives is evaluated. Good cyclability was observed and samples with a graphene loading of 0.25 wt % and 11.5 wt % of thermoreversible bonds (TRB) showed the largest difference in elongation under IR irradiation with respect to the neat adhesive. Creep testing demonstrated that the strain of this sample increases by almost 200% after irradiation due to the breakdown of the three-dimensional adhesive network triggered by the photothermal effect of graphene.

Fabrication and characterization of microfluidic devices based on boron-modified epoxy resin using CO2 laser ablation for bio-analytical applications

CO2 laser ablation is a rapid and precise technique for machining microfluidic devices. And also, low-cost epoxy resin (ER) proved the great feasibility of fabricating these devices using the CO2 laser ablation technique in our previous studies. However, such a technique has shown negative impacts on such ER-based microfluidics as rough surface microchannels, and thermal defects. Therefore, incorporating different proportions of boric acid (BA) into epoxy resin formulation was proposed to obviate the genesis of these drawbacks in ER-based microfluidics. The structural and optical properties of plain ER- and B-doped ER-based chips were characterized by Fourier transform infrared (FT-IR) and UV/Vis spectral analyses. Furthermore, their thermal properties were studied by thermo-gravimetric (TGA) and differential scanning calorimetric (DSC) analysis. A CO2 laser ablation machine was used in vector mode to draw the designed micro-channel pattern onto plain ER- and B-doped ER-based chips. The quality of microchannels engraved onto these chips was assessed using 3D laser microscopy. This microscopic examination showed a noticeable reduction in the surface roughness and negligible bulge heights in the laser-ablated micro-channels. On the other hand, overall and specific migration using gravimetric methods and gas chromatography-mass spectrometry (GC–MS), respectively, and PCR compatibility test were performed to explore the convenience of these micro-plates for the biological reactions. These findings validated the applicability of B-doped ER-based microfluidics in bio-analytical applications as a result of the effective role of boric acid in enhancing the thermal properties of these chips leading to get micro-channels with higher quality with no effect on the biological reactions.

Failure Mode Effect Analysis of Composites Prepreg Manufacturing Process for Airworthiness Certification - A Case Study

Airworthiness certification of aircraft structures requires a holistic approach ranging from material manufacturing process to design evaluation of airframe components. Present day airframe structures find greater applications of composite materials owing to their extraordinary mechanical properties on pro rata weight basis. In case of polymer based composites, the prepreg form of material is preferred for several applications due to matrix efficiency (high fiber-to-volume ratio) and ease of application. As part of composite material certification, the design audit of composite prepreg manufacturing process is carried out to assess the possible failure scenarios. Manufacturing Process Design and Control plays a significant role in satisfactory realization of composite parts right from raw material stage. Process variability/ scatter can lead to large variation in performance of the final product and thus stringent control of process parameters is essential to achieve aero-grade composite structures. This study provides basic understanding of composite prepreg manufacturing process and application of FMEA as a process design tool to detect and assess potential failures with an aim to devise preventive measures for improved process control. The complete process of manufacturing prepregs is divided into three stages viz.: Fabric weaving, Resin formulation and Prepregging operation. FMEA principles are used to identify the predominantly vulnerable operations and to quantify the inherent risk associated. Risk Priority Numbers (RPN) are evaluated for various operations in these three stages. Based on process technology and engineering expertise, suitable corrective and preventive measures are offered according to the potential risk factors and failure types. Emphasis is to prioritize the efforts and attention towards major preventive measures by targeting the least number of factors causing the maximum impact for failures (Pareto principle). Present study substantiates the significance of trained personnel, proper documentation of operating procedures and work instructions along with contamination control as critical factors in eliminating failures in composite prepreg manufacturing process.

Formulation, Configuration, and Physical Properties of Dental Composite Resin Containing a Novel 2π + 2π Photodimerized Crosslinker - Cinnamyl Methacrylate: An In Vitro Research.

To formulate and characterize the chemical structure of a new dental composite with photodimerized cinnamyl methacrylate (PD-CMA) photo-crosslinking comonomer and to evaluate the monomer-to-polymer conversion (MPC) and glass transition temperature (Tg) of the new composite copolymers. CMA was PD by ultraviolet C-type (UVC) irradiation. The research groups were a control group C0 without PD-CMA and two trial groups: E10 (10 wt. % PD-CMA substituted in the base comonomers (B) and diluent (D) mixture); E20 (20 wt.% PD-CMA completely replacing the diluent (D) monomer). Infrared (FTIR) and nuclear magnetic resonance (NMR) spectroscopies were employed for ascertaining copolymerization (CP). The surface features and composition of the copolymers were explained by field-emission scanning electron microscopy (FESEM) and energy dispersive X-ray (EDX) spectroscopy, respectively. The MPC and Tg of the copolymers were assessed using FTIR and differential scanning calorimetry, respectively. Statistical tests were used to compare the groups. The configuration of the new copolymers P (BD-Co-CMA) and P(B-Co-CMA) was confirmed. The MPC% and T g of the copolymers were better than the control. PD-CMA at 20 wt. % in the P (B-Co-CMA) copolymer exhibited the highest MPC% and Tg. The incorporation of PD-CMA in the composite resin resulted in new P (BD-Co-CMA) and P (B-Co-CMA) copolymers with improved MPC% and Tg. The substitution with PD-CMA offset the shortcomings of the conventional BD comonomers concerning the mechanical properties and biocompatibility of the restorative composite resin. This might ameliorate the restorations in vivo longevity and serviceability.

Reversible bond formation via sulfur free reversible addition fragmentation in photo-3D printing

An addition-fragmentation monomer (AFM) has been used as a crosslinker in photopolymerization-based 3D printer resins in order to try and reduce shrinkage due to polymerisation. This results in reversible network formation via photo crosslinking with reversible covalent bond formation to effect mechanical performance. The 3D printing conditions were optimized with regards to print quality, print speed, etc. The AFM was synthesized via catalytic chain transfer polymerization (CCTP) and characterized using NMR and size exclusion chromatography (SEC). The incorporation of the AFM as a crosslinker allows for rapid reversible covalent bond formation during network formation in 3D photopolymerization printing resulting in a reduction in both polymerisation shrinkage and stress higher molecular weight crosslinkers lead to less shrinkage and reversible bond formation to less stress build up. Curing was monitored via photo-rheology and Fourier Transform Infrared Spectroscopy (FT-IR). At lower contents of AFM, the mechanical properties (strength and Young’s modulus) are improved without compromising material properties, printing conditions and curing time. At higher AFM content, the kinetic analysis of the photopolymerization reaction shows a reduced final conversion of the vinylic bonds along with a delay of the gel point. The thermal and mechanical properties were evaluated with incorporation of different concentrations of AFM added to the resin formulations.

Array Tomography of mm-sized Biosamples: Impact of Resin Formulations on Sample Fidelity and Image Quality.

Array Tomography of mm-sized Biosamples: Impact of Resin Formulations on Sample Fidelity and Image Quality.

Fabrication and characterization of light-curing soybean oil-based epoxy resin applied for LCD additive manufacturing

In this work, we developed a photocurable vegetable oil-based resin with suitable curing properties for use in 3D printing. The acrylated epoxidized soybean oil (AESO), which was synthesized by the catalytic ring-opening reaction of the epoxidized soybean oil (ESO) and acrylic acid (AA), replaced the oligomer in conventional light-curing petroleum-based resins. In order to optimize the various properties of the soybean oil-based epoxy resin, the performance parameters of the resin were analyzed by numerical simulation. It was also combined with the parameters of the printing equipment to better guide the 3D printing process of the resin. The results showed that the esterification rate of acrylic acid (AA) with epoxidized soybean oil (ESO) was higher than that of methacrylic acid (MAA) during the arylation of epoxidized soybean oil (ESO), and AESO had moderate viscosity and was suitable as an oligomer for 3D printing. When the diluent of the oligomer has an ACMO to HDDA ratio of 3:2, the cured parts exhibit the optimum mechanical properties, hydrophobic properties, and thermal stability. All properties of the resins were further improved and giving the formulation the best 3D printing performance when 10% of epoxy resin E44 was added to the soybean oil-based epoxy resin. In addition, the numerical simulations indicate that this soybean oil-based epoxy resin formulation has the highest printing efficiency when the single layer thickness of the cured layer is set to 0.2 mm with the exposure time of 4 s, where the wavelength of UV is 405 nm and the light intensity is 40 W/m2. In conclusion, the light-curing resin developed through the soybean oil-based epoxy resin exhibits excellent performance in all aspects. The optimal printing process was also derived by combining the results obtained from numerical simulations of the resin performance parameters with the device parameters, which significantly improved the efficiency of the 3D printing with the fabricated soybean oil-based epoxy resin, making it has great application potential for the biomedical materials.

High performance foams and their nanocomposites generated via liquid state frontal polymerization

AbstractAnisotropy in naturally occurring or synthetic microcellular structures is an important feature for the development of materials with high specific stiffness and strength, in addition to creating materials with unique physical properties. Polymeric foams constitute a broad class of materials that are widely used for their advantages of low density, high specific mechanical properties and high insulative properties. Traditional synthetic routes are slow, energy demanding processes that employ the use of high temperature ovens, freezers, or high‐pressure equipment. Herein we present a convenient and energy efficient method to produce anisotropic high performance polymeric foams via rapid radically induced cationic frontal polymerization coupled with chemical blowing agents. The degree of pore orientation and degree of anisotropy are a result of the propagating front working in concert with the foam volume expansion. This paper presents results into FP foam formation to illustrate how changes in boundary conditions and front initiation position affect both the microcellular structure and their resulting physical and mechanical properties. Additionally, results are presented to show how changes in resin formulation, such as the addition of nanoparticles affect both properties as well as the microcellular structure and anisotropy.

Evaluation of eugenol‐derived monomers as antimicrobial agents in dental resin composites

AbstractThe aim of this study is to synthesize two eugenol‐derived halogenated monomers and to evaluate their properties as antibacterial and antifungal agents in the formulation of dental composite resins. The 4‐allyl‐2‐methoxyphenyl (2‐chloroethyl) carbonate (ECl) and 4‐allyl‐2‐methoxyphenyl 2,2,3,3,4,4,4‐heptafluorobutanoate (EF) monomers have halogens, chlorine or fluorine bonded in their structure, whose antibacterial activity is known. The characterization of ECl and EF monomers was made by Fourier transform infrared and 1H and 13C NMR. dental resin composites are formulated by mixing the BisGMA/TEGDMA, photoinitiator system, inorganic filler, and the ECl or EF monomer, respectively. The antimicrobial and antifungal activity of the experimental resins is determined using the strains of Staphylococcus aureus and Candida albicans. After copolymerization, DCRs with ECl or EF monomers significantly stop antibacterial growth and show excellent antifungal effect. The best results in the antibacterial test are using 0.5 or 3 wt% of the ECl monomer, while for the EF monomer is 5 wt%. On the other hand, the most adequate concentration of ECl and EF monomers in the antifungal activity is 0.5 wt%. The above demonstrates the ability of ECl and EF monomers to prevent antibacterial and antifungal growth in a dental composite resin, which would extend the useful life of a dental restoration.

Lignin nanoparticle-enhanced biobased resins for digital light processing 3D printing: Towards high resolution and tunable mechanical properties

The more widespread applicability of photopolymerization-based three-dimensional (3D) printing is limited by the availability of light-curable resins, most of which are based on fossil-derived compounds. We developed a biobased lignin-derivable resin by utilizing methacrylated derivatives of vanillin, vanillyl alcohol, and eugenol as aromatic monomers. Lignin nanoparticles (LNPs) were incorporated as functional fillers that enhance print resolution and material properties. The crosslinking degree, and thereby the tensile properties, was modulated through the use of mono- or dimethacrylated vanillin derivatives in the resin formulation. The LNPs acted as UV absorbers, conferring better control of the photopolymerization process by preventing light penetration across unintended layers, leading to enhanced print resolution. The LNPs showed excellent dispersion stability due to their size and morphology. The inclusion of up to 2 wt% of LNPs improved the ductility of the 3D printed nanocomposites through toughening mechanisms enabled by the rigid nanoparticles. Finally, exploiting the differences in crosslinking degree of the resin formulations, a multi-material model featuring both soft and rigid domains was fabricated. This study demonstrates a simple but effective strategy for the design of biobased photocurable resins with tailorable mechanical properties that are suitable for high-resolution and multi-material 3D printing.

Radical-Mediated Ring-Opening Photopolymerization for Semicrystalline Thermoplastic Additive Manufacturing

Conventional approaches to stereolithographic additive manufacturing (SLA) employ liquid resin formulations based on multifunctional (meth)acrylates and epoxides that afford cross-linked polymeric networks upon polymerization. Nevertheless, the utilization of resins that yield semicrystalline thermoplastics provides facile access to physical and mechanical properties that are otherwise difficult to attain, such as high toughness and resistance to solvent swelling as well as additional postfabrication processing options that can be used to extend the life cycle of three-dimensional printed polymers. Here, we report the SLA-based additive manufacturing of semicrystalline thermoplastics utilizing the radical-mediated ring-opening photopolymerization of seven- and eight-membered cyclic allylic sulfides. Photopolymerization of resin formulations incorporating seven- and eight-membered cyclic allylic sulfides and crystallization of the resultant (co)polymers were examined using Fourier transform infrared spectroscopy, photorheology, and isothermal photo-differential scanning calorimetry. The formulated resins were found to polymerize and subsequently crystallize rapidly upon irradiation under ambient conditions. The mechanical properties of stereolithographically printed copolymers approached the bulk copolymer mechanical properties, demonstrating unusually strong interlayer adhesion atypical of layerwise, stereolithographic printing of semicrystalline polymers. Finally, high-quality, recyclable, semicrystalline thermoplastic parts were printed and melted down, demonstrating the potential for these semicrystalline materials to provide a path for improved sustainability of polymeric parts produced via SLA.

Fully biobased composite made with epoxidized‐lignin, reinforced with bamboo fibers

AbstractIn this study, we entirely replaced petroleum‐based bisphenol A (BPA) with unmodified kraft softwood lignin in epoxy resin formulation. Epoxidized lignin was prepared by reacting lignin with biobased epichlorohydrin (ECH) made from glycerol, and the formation of epoxide rings was confirmed by measuring the epoxy content of the epoxidized lignin using titration and Fourier‐transform infrared spectroscopy (FTIR). A fully biobased epoxy resin was then prepared by mixing the epoxidized lignin with a biobased curing agent derived from chew nutshell (from Cardolite Co.). Pre‐impregnated composite sheets were fabricated by impregnating unidirectional bamboo fibers with the developed water‐dispersion epoxy resin. The properties of the biobased composite samples were measured using a dynamic mechanical analyzer (DMA), scanning electron microscope (SEM), and a universal testing machine. The flexural strength of the lignin‐based epoxy composite was found to be 36% lower (14 MPa) compared to commercial epoxy (22 MPa). However, when bamboo fibers were added to the lignin‐based biocomposite (containing 25 wt.%), a higher flexural strength (116 MPa) was observed, representing an increase of 11% compared to the biocomposite made with EPON and bamboo fiber (104 MPa). Similarly, the addition of bamboo fibers to the lignin epoxy resulted in an increase in the flexural modulus by 1255% (from 0.42 to 5.69 GPa), while the flexural modulus of commercial epoxy was increased by only 736% (from 0.58 to 4.85 GPa). This was attributed to the higher compatibility of bamboo fiber with lignin, which is known to act as a natural glue in plants.

Development of 3D DLP Printed Sustained Release Ibuprofen Tablets and Their Pharmacokinetic Evaluation in Rats.

The objective of the present study was to develop digital light processing (DLP) 3D printed sustained release ibuprofen (IBU) tablets using 3D DLP printers for evaluation in in vitro release and in vivo pharmacokinetic studies with their in vitro-in vivo correlation. The resin formulation and printing parameters were optimized using quality by design (QbD) approach, and IBU tablets were printed using DLP printers which works at 385 and 405nm wavelengths. Our results demonstrated that formulation consisting of polyethylene glycol diacrylate (PEGDA) 700, water, IBU, and riboflavin printed at 40-s bottom layer exposure time and 30-s exposure time produced tablets using both 385 and 405nm wavelengths. In vitro dissolution studies showed > 70% drug release at the end of 24h when printed at 405nm wavelength with no significant difference between tablets printed at 385nm. In vivo pharmacokinetic evaluation of the optimized 3D printed tablets printed at 405nm at oral dose of 30mg/kg in rats showed sustained release of IBU with significantly (p < 0.05) higher Cmax of 30.12 ± 2.45µg/mL and AUC(0-24h) of 318.97 ± 16.98 (µg/mL × h) compared to marketed IBU tablet (control). In vivo-in vitro correlation studies showed 80% of drug was absorbed in vivo within 3h from the pulverized 3D printed tablet, whereas intact 3D tablet showed sustained release of IBU with > 75% IBU release in 24h in vitro. Overall, IBU tablets fabricated using DLP printing demonstrated sustained release and enhanced systemic absorption with no significant difference in their release profile at different wavelengths.

Development of hesperetin methacrylates and their high performance thermosets

AbstractHesperetin based monomers substituted to varying degrees of methacrylate functionality were synthesized namely trimethacrylate, dimethacrylate and monomethacrylated hesperetin monomers, HTM, HDM and HMM respectively. Resins employing reactive diluents 4‐acryloylmorpholine (4AM) and styrene (Sty) were formulated. Resin formulations were determined to be Newtonian fluids with viscosities below 800 cP. Thermosets of hesperetin monomers were produced with glass transition temperature (Tg) values up to 225°C. Ultimate strength up to 20 MPa and tensile modulus of 5.0 GPa were also observed. Additionally, thermosets with char yield near 30% were measured. Char yield, ultimate strength and tensile modulus of hesperetin based thermosets were superior to those derived from the petrochemical bisphenol A dimethacrylate (BPAM). However, thermosets that employed hesperetin derived monomers displayed properties that were less than expected compared to Bicerano model predictions. Also, select HTM:Sty thermosets displayed a noticeable holographic type morphology. Reactivity ratios, spectroscopy, microscopy and structure property relationships indicated that poor copolymerization behavior during cure and high degrees of crosslinking during postcure were responsible for the microcrack formation in the material. This also caused the observed morphology and resulted in reduced properties relative to Bicerano predictions.

Improved properties of particleboards produced with urea formaldehyde adhesive containing nanofibrillated cellulose and titanium dioxide

Urea-formaldehyde is one of the commonly used resin types in the particleboard industry. In this study, the effect of nanofibrillated cellulose (NFC) and titanium dioxide (TiO2) addition in the formulation of the urea formaldehyde resin on the physical, mechanical, and morphological properties of particleboard samples was investigated. The NFC (0.5% and 1%) and TiO2 (0.5%, 1%, and 2%) were added to the 10% adhesive formulation. Two different pressure times, 4 and 8 min, were applied during the production of samples. Subsequently, the water absorption (WA), thickness swelling (TS), internal bonding strength (IB), modulus of rupture (MOR), modulus of elasticity (MOE), scanning electron microscopy (SEM), and statistical analysis of test samples were determined. The thickness swelling values ranged from 19.9% to 34.9% and WA values were from 74.50% to 110.6%. However, the maximum MOR, MOE, and IB values were 22.2 MPa, 2570 MPa, and 1.1 MPa, respectively.

Thermal and Electrical Characterization of Polyester Resins Suitable for Electric Motor Insulation

This paper undertakes the thermal and electrical characterization of three commercial unsaturated polyester imide resins (UPIR) to identify which among them could better perform the insulation function of electric motors (high-power induction motors fed by pulse-wide modulation (PWM) inverters). The process foreseen for the motor insulation using these resins is Vacuum Pressure Impregnation (VPI). The resin formulations were specially selected because they are one-component systems; hence, before the VPI process, they do not require mixing steps with external hardeners to activate the curing process. Furthermore, they are characterized by low viscosity and a thermal class higher than 180 °C and are Volatile Organic Compound (VOC)-free. Thermal investigations using Thermogravimetric Analysis (TGA) and Differential Scanning Calorimetry (DSC) techniques prove their excellent thermal resistance up to 320 °C. Moreover, impedance spectroscopy in the frequency range of 100 Hz-1 MHz was analyzed to compare the electromagnetic performance of the considered formulations. They manifest an electrical conductivity starting from 10-10 S/m, a relative permittivity around 3, and a loss tangent value lower than 0.02, which appears almost stable in the analyzed frequency range. These values confirm their usefulness as impregnating resins in secondary insulation material applications.

Lignin‐based covalent adaptable network resins for digital light projection 3D printing

Abstract3D printing is a low cost, customizable, and fast‐growing technology with the potential to revolutionize plastic manufacturing. Vat photopolymerization 3D printing technologies stand out for their high resolution, however, the resulting printed materials are made from petroleum feedstocks and are covalently crosslinked which renders them unrecyclable. Here, resin formulations with 70 wt% bio‐based content and dynamic functionality are synthesized and printed using lignin, vanillin, and soybean oil components. These printed polymers can undergo dynamic transesterification due to the methacrylated lignin (LMA) to allow for self‐healing capabilities; therefore, potentially increasing the materials lifetimes compared to traditional thermoset materials, offsetting the use of traditional petroleum‐based resins, and lowering their environmental impact. The LMA also provides the thermosets with better mechanical performance and thermal stability in comparison to the controls. Additionally, compatibility with 3D printing technologies improves the competitiveness of biobased plastics with conventional materials.

Isolating Chemical Reaction Mechanism as a Variable with Reactive Coarse-Grained Molecular Dynamics: Step-Growth versus Chain-Growth Polymerization

We present a general approach to isolate chemical reaction mechanism as an independently controllable variable across chemically distinct systems. Modern approaches to reduce the computational expense of molecular dynamics simulations often group multiple atoms into a single "coarse-grained" interaction site, which leads to a loss of chemical resolution. In this work we convert this shortcoming into a feature and use identical coarse-grained models to represent molecules that share non-reactive characteristics but react by different mechanisms. As a proof of concept we use this approach to simulate and investigate distinct, yet similar, trifunctional isocyanurate resin formulations that polymerize by either chain- or step-growth. Since the underlying molecular mechanics of these models are identical, all emergent differences are a function of the reaction mechanism only. We find that the microscopic morphologies resemble related all-atom simulations and that simulated mechanical testing reasonably agrees with experiment.