Degree Of Polymerization Research Articles

Versatile and Controlled Synthesis of Degradable, Water-Soluble Bottlebrush Polymers with Poly(disulfide) Backbones Derived from α-Lipoic Acid.

Bottlebrush (BB) polymers, with their densely grafted side chains and unique architecture, are highly advantageous for drug delivery due to their high functional group density for drug conjugation, unimolecular nature, and enhanced biodistribution properties. These attributes enable extended blood circulation half-life, improved tumor tissue penetration, and high tumoral drug accumulation. However, the typically nondegradable, all-carbon backbones of most BB polymers limit their suitability for applications requiring controlled clearance and biodegradability. To address this, we developed degradable BB polymers with poly(disulfide) backbones synthesized via reversible addition-fragmentation chain transfer (RAFT) copolymerization of α-lipoic acid (LA), a renewable and readily available compound, with acrylate-based inimers. These copolymers feature degradable backbones and initiating sites for subsequent BB synthesis. Using an atom transfer radical polymerization (ATRP) grafting-from methodology, we synthesized BB polymers with relatively low dispersities (Đ = 1.30-1.53), high backbone degrees of polymerization (DPbb), and high molar masses (Mn,MALS = 650-2700 kg/mol). The easily cleavable disulfide bonds enabled backbone degradation under mild reducing conditions. Beyond hydrophilic BB with tri(ethylene glycol) methyl ether acrylate (TEGA) side chains, we synthesized BB with cationic, anionic, and zwitterionic side chains, demonstrating broad monomer compatibility. This scalable approach produces water-soluble, degradable BB polymers with tunable architectures and predictable molecular weights. By addressing the need for degradability in BB polymers, this work advances their potential for drug delivery, offering enhanced functionality, biocompatibility, and sustainability.

Ultraviolet-enhanced Fe0-activated H2O2 process for the removal of refractory organic matter from landfill leachate: Performance and mechanism.

The Fenton-like process, utilizing zero-valent iron (Fe0) and hydrogen peroxide (H2O2), is employed to degrade refractory organic matter in membrane bioreactor (MBR) effluent derived from landfill leachate. However, the rate-limiting Fe2+/Fe3+ redox step diminishes treatment efficacy and generates substantial iron sludge. This study elucidates the mechanism by which ultraviolet (UV) irradiation augments the Fe0/H2O2 process for the removal of refractory organic matter in MBR effluent. The results show that the UV-enhanced H2O2 process effectively disrupts the aromatic structure of organic compounds, reducing molecular weight, degree of polymerization, and humification. Compared with the Fe0/H2O2 process, the removal efficiency of UV254, color number, and total organic carbon in the effluent treated by the UV/Fe0/H2O2 process increased by 24.16%, 14.62%, and 57.46%, respectively. Concurrently, the generation of iron sludge was reduced by 21.6%. This enhancement is primarily attributed to UV's ability to intensify the Fe2+/Fe3+ redox cycle and expedite the surface corrosion of Fe0, yielding more iron oxides. This accelerates the decomposition of H2O2, generating a higher quantity of •OH through both homogeneous and heterogeneous Fenton-like reactions. The refractory organic matter is removed through the oxidation by •OH, as well as the adsorption and precipitation facilitated by iron-based colloids. PRACTITIONER POINTS: UV promotes Fe0/H2O2 process to degrade refractory organic matter in MBR effluent. UV promotes Fe0 to dissolve more Fe2+ and the redox cycle of Fe2+ and Fe3+. The dosage of H2O2 or Fe0 influences the treatment effect of the process.

Preparation of modified epoxy resin with high hydrophobicity, low dielectric constant, toughness, and flame retardant by epoxy-functionalized siloxanes

A series of α, ω-dimethylglycidoxypropyl-terminated PDMS oligomer (PDMS-GE) oligomers with different polymerization degrees were synthesized and used to modify the bisphenol-A diglycidyl ether E51 (DGEBA) / 4,4-diaminodiphenylmethane (DDM) epoxy resin, resulting in epoxy resins with high hydrophobicity, low dielectric constant, good impact toughness, low combustion heat release rate, and low total heat release. The combustion heat release rate and total heat release of the material decreased with the increase in the loadings of PDMS-GE. Relative to pure epoxy resin, the composite E51/D30–10, which using DGEBA as the matrix, PDMS-GE with a degree of polymerization of 30 as the modifier in an amount of 10 phr relative to the mass sum of DGEBA, PDMS-GE and DDM, exhibited the best comprehensive performance with a water contact angle of 102.42°, a dielectric strength of 6.49 kV/mm, a dielectric constant of 2.93 at 14.2 GHz, the peak rate of heat release (PRHR) and total heat release (THR) are of 378.3 kW/m2 and 134.4 MJ/m2, respectively. These comprehensive performances underscore the potential of PDMS-GE oligomers in significantly improving epoxy resin properties. When the loadings of PDMS-GE oligomers are less than 5 wt%, PDMS-GE with a lower degree of polymerization can improve the toughness of epoxy resins. The impact strength of the composite E51/D24–5, which uses DGEBA as the matrix, PDMS-GE with a degree of polymerization of 24 as the modifier in an amount of 5 phr relative to the mass sum of DGEBA, PDMS-GE, and DDM, reaches 98.1 kJ/m2, which is about 28.9 % higher than that of pure epoxy resin. The results also indicated that the degree of polymerization of PDMS-GE oligomers has less influence on the dielectric properties and mechanical properties of composite materials.

Recent trends in the separation and analysis of chitooligomers

Chitosan is a widely used linear biopolymer composed mainly of glucosamine and to a lesser extent of N-acetylglucosamine units. Many biological activities of chitosan are attributed to its shorter oligomeric chains, which consist of chitosan prepared either by enzyme activity (lysozyme, bacterial chitinase) or chemically by acid-catalyzed hydrolysis (e.g. in the stomach). However, these processes always result in a mixture of shorter chitooligosaccharides with varying degrees of acetylation whereas for relevant results of biological studies it is necessary to work with a precisely defined material. In this review, we provide an overview and comparison of analytical methods leading to the determination of the degree of polymerization (DP), the degree of acetylation (DA), the fraction of acetylation (FA) and the acetylation patterns (PA) of chitooligosaccharide chains and of the current state of knowledge on chitooligosaccharide separation. This review aims to present the most promising routes to well-defined low molecular weight chitosan with low dispersity.

Debranched rice starch with highly enriched B1 chains enhanced the encapsulation of aroma molecules.

Three debranched rice starch (DBS) with varying chain lengths were isolated in the hydrolysate solution-to-ethanol ratio of 1:3, 1:1.5, and 1:0, which were named as DBS1:3, DBS1:1.5, and DBS1:0, respectively. Three C8 aroma molecules with distinct functional groups, namely 1-octanol, 1-octen-3-ol, and γ-octalactone, were selected as the research objects. DBS1:1.5 exhibited a narrow chain length distribution and the content of B1 chains with degree of polymerization 13-24 was 58.77%. The inclusion rates of DBS1:1.5 with the aforementioned aroma molecules ranged from 42.30% to 68.09%, which were higher than those of DBS1:0 (8.72%-12.16%) and DBS1:3 (24.26%-48.24%). Additionally, DBS1:1.5-aroma complexes showed high crystallinity, short-range order, and thermal stability. DBS1:0-aroma and DBS1:3-aroma complexes possessed a hybrid crystal structure combining B-type and V-type arrangements, characterized by low short-range order and thermal stability. The mechanism by which aroma molecules affected their interaction with starch was associated with their structure and hydrophobicity. High hydrophobicity and linear structure facilitated the interaction of 1-octanol with starch, thereby enhancing its encapsulation effect. Contrastingly, the low hydrophobicity and large size of the lactone ring attenuated the interaction between γ-octalactone and DBS. This research held significant implications for improving aroma quality in starch-based food processing.

Upcycling industrial peach waste to produce dissolving pulp.

This study investigates the production of high-purity cellulose pulp from peach (Prunus persica) fruit wastes generated during the processing of a Greek compote and juice production industry. A three-step chemical process is used, including alkaline treatment with NaOH, organic acid (acetic and formic) treatment, and hydrogen peroxide treatment, with the goal of cellulose extraction and purification. A fractional factorial design optimized reagent levels, revealing the strong influence of NaOH concentration on α-cellulose content and degree of polymerization. The extraction yield ranged between 9.7 and 12.3%, and a yield of 11.6% was achieved under the optimal conditions (NaOH, 3%w/v; acid-to-solid ratio, 6l/kg; H2O2, 0.5% v/v) of the factorial experiment. The resulting samples were further characterized by XRD, FTIR, SEM, and TGA techniques. The results of the XRD and FTIR spectra confirmed the presence of cellulose, with a crystallinity index of approximately 57%, balancing strength and reactivity. The SEM analysis demonstrated a strong morphological similarity between the extracted pulp and commercial dissolving-grade pulp (Södra Purple), while images of the raw material confirmed effective purification. Additional evaluations included color, lightness, and lignin content. These findings suggest that cellulose extracted from peach waste is suitable for textile applications, offering a sustainable alternative to conventional cellulose sources and supporting industrial resource efficiency.

Efficient Double-Layer Evaporators with Adjustable Pores for Sustainable Solar Evaporation.

Solar-driven desalination technology is currently an important way to obtain freshwater resources. Significantly, porous materials are used as substrate materials of interface solar evaporator, and their specific impact of water transport property and thermal management during evaporation is worth exploring. In this paper, poly(vinyl alcohol) (PVA) sponges were prepared by a chemical foaming method, adjusted the PVA polymerization degree, and formaldehyde-hydroxyl ratio to regulate the pore size, and polypyrrole (PPy) was grown in situ on the surface skeleton of PVA sponge to construct a new interfacial solar evaporator (PPy/PVA) with different pore structures. As the size of the evaporator pore changes, the trends in the water transport property and thermal management capability are opposite. Among them, the PPy/PVA-3 evaporator achieves a surface temperature of 38.9 °C and an evaporation rate of 1.764 kg m-2 h-1 under 1 Sun light. And the evaporation efficiency exceeds the theoretical limit (100%). This is because it has the optimal pore structure to balance the competition mechanism between the two aspects. At the same time, the evaporator exhibits good cyclability, stability, and self-cleaning capability. In addition, the evaporator has practical applicability with good purification of both organic dyes and seawater.

Variations in carbohydrates molar mass distribution during chemical degradation and consequences on fibre strength

Abstract Industrial oxygen-delignified and fully-bleached hardwood kraft pulps were treated with chemicals to provoke carbohydrates depolymerisation: ozone, hypochlorous acid, and cellulase. The degrees of polymerisation (DP) of cellulose obtained by pulp viscosity measurement in Cuen and by size-exclusion chromatography after direct dissolution in DMAc/LiCl indicated the extent of the chemical degradation inflicted to the fibres. Molar mass distributions (MMD) described the carbohydrates depolymerisation patterns. Fibre strength was assessed by measuring the zero-span tensile index at never-dried state. Fibre strength deterioration seemed to be mainly driven by the topochemistry of the cellulose degradation (homogeneous or localised), rather than by its intensity usually measured as an average DP loss. In fact, depolymerisation by cellulase was found critically detrimental to fibres strength whereas ozone and hypochlorous acid induced little harm to the fibres despite a significant cellulose depolymerisation. According to these results, in line with several past studies, fibre strength measurements should be performed systematically as the sole pulp viscosity is an inadequate indicator. Alternatively, albeit being insufficient strength predictors on their own MMD can give valuable insight on the topochemistry of the cellulose degradation, a key aspect when monitoring fibre strength preservation during pulping and bleaching.

Phase Behavior Determines Morphology of Amylose Crystallized From Aqueous Solutions

ABSTRACTBackground and ObjectivesHere, we present a simplified system comprising amylose of varying degrees of polymerization in water, with the goal of probing the temperature–concentration phase diagram to determine if a miscibility gap leading to liquid−liquid phase separation might serve as a model for starch granule initiation and, if so, under what conditions.FindingsA miscibility gap in the cooling‐rate‐dependent phase behavior is demonstrated for the amylose−water system, with its temperature and concentration depending on the degree of polymerization (DP) of the starch. Liquid–liquid phase separation within this miscibility gap followed by crystallization of the polymer‐rich phase produced spherulites. If crystallization preceded liquid–liquid phase separation, a precipitate or gel was formed. The upper critical solution temperature appeared between 60°C and 70°C, and the miscibility gap was observed between 5% and 30%–50% w/w starch, depending on DP for DP ≥ 68. For DP 29, the miscibility gap occurred at concentrations ≥ 20% w/w.ConclusionsA cooling‐rate‐dependent miscibility gap in the temperature–concentration phase diagram has been observed in aqueous amylose solutions under reasonable ambient conditions of temperature and starch concentration, allowing phase separation to occur within plastids in vivo.Significance and NoveltyThis work provides a biophysical complement to the biochemistry associated with starch granule initiation.

In silico Study of Neoagaro-Oligosaccharides (NAOS) Anti-Inflammatory Activity: Molecular Docking with iNOS and COX-2 Proteins

Neoagaro-Oligosaccharides (NAOS) arise from the enzymatic hydrolysis of agarose employing β-agarases enzymes. Comprising diverse monomers such as neoagarobiose (NA2), neoagarotetraose (NA4), neoagarohexaose (NA6), and neoagarooctaose (NA8), NAOS are characterised by their Degree of Polymerization (DP). Extensive investigations have delineated the potential of various NAOS monomers, particularly anti-inflammatory agents, owing to their capability to impede iNOS and COX-2, pivotal mediators of inflammation. Nevertheless, the molecular interplay between NAOS and inflammatory mediators remains unexplored. Thus, this study aimed to elucidate the interaction dynamics between NAOS with iNOS and COX-2. Employing ligands neoagarobiose (ID: 275080182), neoagarotetraose (ID: 130476782), neoagarohexaose (ID: 131485243), and neoagarooctaose (ID: 54758640) in conjunction with target proteins iNOS (3E7G) and COX-2 (5F19), analyses were conducted utilising ProTox-II and SwissADME. Protein preparation was carried out using Discovery Studio, while ligand preparation entailed PyRx, with docking facilitated by CBDock2.0. Absorption, distribution, metabolism, and excretion (ADME) evaluations revealed that neoagarobiose, neoagarotetraose, neoagarohexaose, and neoagarooctaose did not adhere to Lipinski’s Rule of Five. Docking simulations exhibited the capacity of all ligands to engage with the binding site of iNOS, forming diverse bond types. Notably, neoagarobiose, neoagarotetraose, and neoagarohexaose demonstrated enhanced affinity towards COX-2, whereas neoagarooctaose exhibited heightened binding affinity towards iNOS.

Investigation on the Regulation Mechanisms of Viscosity–Temperature Characteristics of High Calcium–Iron Coal by Coal Blending

ABSTRACTEntrained‐flow bed gasification was an important way to realize clean coal conversion. However, the high calcium–iron coal ash had a low flow temperature, low viscosity, and strong fluctuations in viscosity, which severely affected the service life of the gasifier. It was necessary to regulate its ash fusion temperature and viscosity–temperature characteristics (AFV). In the paper, the AFV of Datong coal (DTC, a high calcium–iron coal) and its regulation mechanism were investigated by ash fusion temperature tester, high‐temperature viscometer, Raman spectrometer, differential scanning calorimetry, X‐ray diffractometer, FactSage software, and activation energy calculation. With the increasing Pingdingshan coal (PDS, a high silicon–aluminum coal) mass ratio, the AFV of DTC mixtures increased, and the viscosity fluctuation of DTC mixtures disappeared gradually. When PDS mass ratio is in the range of 18%–24%, the flow temperature and viscosity of DTC ash were 1375°C–1400°C and 18–22 Pa·s, respectively. The increasing PDS mass ratio, the formation of high melting point anorthite and its increasing content, the polymerization degree of DTC mixed ash increasing, and a gradual increase in activation energy as well as their corresponding crystallization behavior led to the increase in the AFV. The mineral transformations and the position variation in the ternary phase diagram of ash compositions with PDS addition by FactSage calculation also explained the variations in the viscosity–temperature characteristics.

Improved Oxygen Barrier Properties of Polypropylene/Polyvinyl Alcohol Blends Through Reactive Compatibilization

ABSTRACT The relatively poor oxygen barrier property limits broad application of polypropylene (PP) as packaging materials, pipes, etc. while incorporation of nanoparticles, EVOH etc. faces problems of poor compatibility and dispersion, and high price. In this work, in light of polyvinyl alcohol (PVA) with polyhydroxy structure and excellent barrier properties, PP was blended with PVA through reactive compatibilization by using polypropylene grafted maleic anhydride (PgM) as compatibilizer. A strong intermolecular interaction and entanglement between the two phases formed, leading to an increase of interfacial transition area, and the phase size decreased, changing from “sea-island” to “co-continuous” structure, while a relatively high PVA polymerization degree would lead to a decrease of intermolecular entanglement. In addition, the hydrogen bonding in the system was enhanced, although the crystallinity of the two phases decreased by blending. As a result, the oxygen transmission coefficient of the PP/PVA/PgM blends reached as low as 6.48 × 10−14 cm3·cm/(cm2·s·Pa), which was 48.1% lower than that of PP, while the impact toughness was improved by 56.5%. This work provides a feasible and economic method for enhancing the oxygen barrier ability of PP.

Active starch-based film using polyvinyl alcohol and chlorogenic acid for strawberry preservation: A comparative analysis of mechanical, barrier, and antibacterial properties.

The broad application of starch films has been significantly limited by their insufficient hydrophobicity and antibacterial activity. To overcome these challenges, this study developed a new starch film by incorporating polyvinyl alcohol (PVA) and chlorogenic acid. The study explored the impact of PVA polymerization on the physical and functional characteristics of the resulting films, with particular emphasis on enhancing antimicrobial functionality by incorporating chlorogenic acid. Scanning electron microscopy (SEM) and rheological tests demonstrated the excellent compatibility and exceptional film-forming performance. Fourier transform infrared spectroscopy (FTIR) and X-ray diffraction (XRD) analyses validated the presence of intermolecular entanglements and hydrogen bonding within the films. Incorporating PVA with a polymerization degree of 2400 resulted in a contact angle (CA) of 79.81±1.74°, a water absorption capacity (WAC) of 10.29±0.71%, and a water vapor permeability (WVP) of (0.44±0.11)×10-11g×m-1×s-1×Pa-1. Notably, the SCP 2488 film exhibited superior mechanical properties, including the highest Young's modulus of 71.29MPa, tensile strength of 11.77MPa, and elongation at break of 106.75%. Additionally, such a modified film displayed enhanced UV-blocking performance and antibacterial efficacy. Consequently, the SCP 2488 film showed great potential for maintaining the freshness and quality of strawberries.

Basic Composition and Synthesis Process and Representative Molecule of the Branched Polyethyleneimines With Low Molecular Weight

ABSTRACTBranched polyethyleneimines (B‐PEIs) have been widely used in industries and researches, such as the papermaking, water treatment, and enzyme immobilization. However, they exhibit a complex composition, leading to ambiguity in understanding the B‐PEIs' synthetic process and relevant influencing factors. Additionally, no representative molecule of B‐PEIs has been identified, leading to subjective selections when studying structure–performance relationships. This study focused on three commercially low‐molecular‐weight B‐PEIs: 300, 600, and 1800. It identified that they primarily consisted of C, H, and N elements in the form of methylene and primary, secondary, and tertiary amine groups. The ratios of amine groups were also revealed, offering guidance for application. Moreover, the types of polymerization degrees and their proportions were determined, with the free ends identified as primary amino groups. Based on these, this study proposed synthetic processes and potential influencing factors. This provided valuable insights into the synthesis of B‐PEIs with varying compositions and properties. Furthermore, the stability of over 527 potential molecular structures was calculated. By weighing above features, the representative model molecules used to analyze B‐PEIs' structure–performance relationships was identified. These results had significant implications for the synthesis, application, and functional analysis of B‐PEIs.

Production, structure, and performance of guar gum based bacterial cellulose generated from soy sauce residue hydrolysate by in-situ fermentation.

Guar gum based bacterial cellulose (GG-BC) was generated from the soy sauce residue hydrolysate by in-situ fermentation, and its structure and performance were learned systematically. The GG concentration of 0.2 % was most suitable for GG-BC production with the yield of 1.21 g/L. During the in-situ fermentation, GG was implanted into the nano network of BC and thus altered its microstructure and properties. According to the FT-IR and NMR results, GG-BC had similar functional group structure and cellulose structural framework to those of BC. The degree of polymerization (DP) of GG-BC was 526.32-832.16, which was higher than that (426.32) of BC. Also, the GG-BC with low GG addition (0.2 % and 0.4 %) had a higher crystallinity than BC. Moreover, the GG-BC had a better heat tolerance than BC based on its higher temperature reaching the maximum degradation rate. The GG-BC with suitable GG addition had better texture characteristics, UV barrier property, swelling rate, and antioxidant activity than those of BC, showing that the in-situ fermentation with GG addition could promote the performance of GG-BC. Overall, this study can provide an attractive technology for both solving the environmental issue brought by soy sauce residue and producing high value-added GG-BC with good performance efficiently.

Scalable and Precise Synthesis of Structurally Colored Bottlebrush Block Copolymers: Enabling Refined Color Calibration for Sustainable Photonic Pigments.

Self-assembled bottlebrush block copolymers (BBCPs) offer a vibrant, eco-friendly alternative to traditional toxic pigments and dyes, providing vivid structural colors with significantly reduced environmental impact. Scaling up the synthesis of these polymers for practical applications has been challenging with conventional batch methods, which suffer from slow mass and heat transfer, inadequate mixing, and issues with reproducibility. Precise control over molecular weight and dispersity remains a significant challenge for achieving finely tuned color appearances. Here, we present an alternative strategy to overcome the challenges by integrating a rapid continuous flow technique with an in-line self-assembly procedure. This strategy enables the rapid, stable and large-scale synthesis of narrow-dispersed BBCPs, exceeding 2 kg/day, a significant improvement over conventional gram-scale methods. Furthermore, precise control over the degree of polymerization is achieved with an unprecedented interval accuracy of four repeat units. This level of precision enables refined color calibration in the resulting photonic pigments, effectively eliminating the need for labor-intensive and costly multiple batch syntheses.

Scalable and Precise Synthesis of Structurally Colored Bottlebrush Block Copolymers: Enabling Refined Color Calibration for Sustainable Photonic Pigments

Self‐assembled bottlebrush block copolymers (BBCPs) offer a vibrant, eco‐friendly alternative to traditional toxic pigments and dyes, providing vivid structural colors with significantly reduced environmental impact. Scaling up the synthesis of these polymers for practical applications has been challenging with conventional batch methods, which suffer from slow mass and heat transfer, inadequate mixing, and issues with reproducibility. Precise control over molecular weight and dispersity remains a significant challenge for achieving finely tuned color appearances. Here, we present an alternative strategy to overcome the challenges by integrating a rapid continuous flow technique with an in‐line self‐assembly procedure. This strategy enables the rapid, stable and large‐scale synthesis of narrow‐dispersed BBCPs, exceeding 2 kg/day, a significant improvement over conventional gram‐scale methods. Furthermore, precise control over the degree of polymerization is achieved with an unprecedented interval accuracy of four repeat units. This level of precision enables refined color calibration in the resulting photonic pigments, effectively eliminating the need for labor‐intensive and costly multiple batch syntheses.

Anhydrous HCl gas-induced alcoholysis of cotton linter fibers

Abstract Abstract Alcoholysis has attracted attention because of its potential to isolate platform chemicals and biofuel precursors from cellulosic biomass. We investigated the degradation of native cellulose fibers via alcoholysis using various alcohols (ethanol, 2–propanol, t–butanol, and ethylene glycol) and anhydrous HCl gas as an acid catalyst. We explored the impact of these different systems on the leveling-off degree of polymerization (LODP). Fibers soaked in ethylene glycol and t–butanol reached LODP under the default conditions, i.e., 50 wt.% alcohol content. When subjected to a post-hydrolysis step, the fibers previously alcoholyzed in ethanol and 2–propanol attained the LODP level as well. However, the production of monosaccharides during post–hydrolysis was 20 times higher from the fibers that had been alcoholyzed previously by ethanol than with 2–propanol. Graphical abstract

Thermophysical properties of graphene reinforced with polymethyl methacrylate nanoparticles for technological applications: a molecular model.

"Nanostructure of graphene-reinforced with polymethyl methacrylate" (PMMA-G), and vice versa, is investigated using its molecular structure, in the present work. The PMMA-G nanostructure was constructed by bonding PMMA with graphene nanosheet in a sense to get three different configurations. Each configuration consisted of polymeric structures with three degrees of polymerization (such as monomers, dimers, and trimers polymers, respectively). The results obtained make this new PMMA-G material more reliable and useful for several important technological applications, such as the construction of devices for hydrogen storage, batteries, super-capacitors, sensors and solar cells, and dental materials, among others. The PMMA reinforcement with graphene favors its thermal stability maintaining greater dimensional stability against thermal variations (minimal deformation); this is crucial for electronic devices and for packaging systems that undergo repeated thermal cycles during their manufacture, and also they are good thermal insulators. For microelectronic devices, such as chips and sensors, with low thermal expansion coefficients, it may prevent unwanted deformation. The PMMA density increases when it is reinforced with graphene, the polymers tend to be stiffer and stronger, important for applications where greater structural strength is required, and also become less soluble in solvents than pure PMMA and more resistant to the action of chemicals. Comparing a common polyvinyl chloride (PVC) material with the PMMA-G polymer, we found more advantages, such as the PMMA-G is less expensive, it has improved aesthetics, it is less rigid, it has more stable color, and it is less prone to keeping microorganisms alive, among others advantages. Materials Studio (MS) software is used as the best and most reliable computational tool in the sense of analyzing some thermophysical properties of graphene reinforced with polymethyl methacrylate nanoparticles. The most stable PMMA nanostructures, graphene and PMMA-G, were obtained by applying density functional theory methods implemented by a DMol3 computational code under the MS software. The Synthia computational code, also under MS software, which is based on connectivity indices methods derived from graph theory combined with geometric variables, was also applied, to each polymerized structure, obtaining some of the important thermophysical properties; i.e., Van der Waals volume, molar volume, coefficient of volumetric thermal expansion, density, solid phase molar heat capacity at constant pressure, thermal conductivity, glass transition temperature, secondary relaxation temperature, and half decomposition temperature. The best-used hardware was a T7500 Dell Workstation, with 3.47GHz Quad-Core Processors, 96Gb RAM memory, and a perpetual MS software license.

Effect of Load Vector Orientation on Uniaxial Compressive Strength of 3D Photoresin

Rapid prototyping has a wide range of applications across various fields, both in industry and for private use. It enables the production of individual parts in a short time, independent of supply chains, which is particularly important in remote locations. Among all 3D printing technologies, stereolithography using photo resins is the most accessible and offers the highest printing quality. However, the strength properties of parts made from photo resins remain a critical concern. In this study, we conducted experimental research to investigate the effect of load vector orientation under uniaxial compression on the elastic and mechanical properties of 3D-printed cylindrical samples. The results revealed that samples with layers oriented at 60° to the load vector exhibited the highest strength, while those with layers at 30° to the load vector showed the lowest strength. Samples with layers aligned parallel or perpendicular to the load vector demonstrated similar strength properties. Under quasi-elastic loading, samples with layers parallel to the load vector exhibited the highest Young’s modulus and the lowest Poisson’s ratio. Conversely, samples with layers oriented at 30° to the load vector displayed the highest Poisson’s ratio. Microstructural analysis revealed that the anisotropy in the mechanical properties of the 3D-printed samples is attributed to the layered, heterogeneous structure of the photoresin, which exhibits varying degrees of polymerization along the printing axes. The upper part of each layer, with a lower degree of polymerization, contributes to the ductile behavior of the samples under shear stresses. In contrast, the lower part of the layer, with a higher degree of polymerization, leads to brittle behavior in the samples.