Grafting Efficiency Research Articles

Mechanochemical Damage Self‐Repairable Photothermal Anti/De‐Icing Superhydrophobic Coating by Dynamic Bonding Phase‐Change Fillers with the Matrix

AbstractThe development of robust superhydrophobic coatings with the capacity for self‐healing against mechanochemical damage is pivotal for their practical deployment. This study develops a physically and chemically self‐healing superhydrophobic coating with exceptional durability for anti‐icing applications using a simple spray coating method. This is achieved by incorporating phase‐change fillers into a dynamic cross‐linked matrix via dynamic imine bonds. Specifically, oleylamine (ODA) is encapsulated within rigid diatomite nanopores and modified with dopamine (DOA), significantly enhancing the grafting efficiency of aminopropyl‐terminated polydimethylsiloxane (NH₂‐PDMS‐NH₂) (N‐DOA). The incorporation of 15% N‐DOA increases the water contact angle (WCA) of the acrylic resin/aminopropyl‐terminated polydimethylsiloxane (AR/NH₂‐PDMS‐NH₂) matrix to 159.7° and reduces the sliding angle (SA) to 2.9°, while also improving the mechanical durability of coating to withstand 600 abrasion cycles. The dynamic imine bonds between NH₂‐PDMS‐NH₂ and trimesic acid (BTC) facilitate the mobility of N‐DOA and NH₂‐PDMS‐NH₂, enabling rapid recovery of superhydrophobic properties and low ice adhesion strength after abrasions, scratches, oxygen plasma etching, and multiple de‐icing cycles due to the synergistic phase‐change effect of ODA. Thus, the self‐healing coating produced via this simple spray method presents a novel approach for superhydrophobic coatings in anti‐icing applications.

Influence of Different Grafted Natural Rubbers on Electrical and Mechanical Properties of Natural Rubber/Carbon Nanotubes Composites

This study investigates the augmentation of electrical and mechanical characteristics of natural rubber (NR) film with different forms by integrating carbon nanotubes (CNTs). NR with different forms (i.e., natural rubber grafted with polystyrene (NR–g–PS) and polybutyl methacrylate (NR–g–PBMA)) were successfully synthesized. The success of these grafting was confirmed through Proton Nuclear Magnetic Resonance (1H–NMR) and Attenuated Total Reflectance–Fourier Transform Infrared (ATR–FTIR) analyses, which showed that the grafting efficiency exceeded 90%. The properties of ungrafted NR and grafted NRs with CNTs were compared and analyzed. It was found that the NR/CNTs composites with grafting displayed significantly improved electrical properties and mechanical strength when compared to the NR/CNTs composites without grafting. It was found that the NR–g–PBMA exhibited an 860% increase in electrical conductivity at 100 kHz compared to ungrafted NR. This might be attributed to the synergistic of the high specific surface of CNTs and the high polarization of functional groups, which gave a higher value for the CNTs filled grafted NR than the ungrafted NR. Moreover, the mechanical properties of NR–g–PS composites showed a 114% increase in 100% modulus, 127% in tensile strength, and 37% in hardness, while the NR–g–PBMA composites exhibited a 159% increase in 100% modulus, 95% in tensile strength, and 34% in hardness compared to ungrafted NR. This enhancement can be attributed to the formation of chemical linkages between the grafted NR matrix and CNTs through functional groups from both. Consequently, it can be concluded that introducing functional groups on grafted NR assists in establishing a crosslinking network, enhancing both the mechanical and electrical properties. Additionally, this research emphasizes the benefits of producing flexible conductive materials with high modulus and enhanced electrical properties. Keywords: Natural rubber latex, Graft copolymerization, Glutaraldehyde, Natural rubber composites, Electrical properties

Zirconium(IV) coordination-mediated rapid and versatile post-modification of polydopamine coating as stationary phase for open-tubular capillary electrochromatography

In recent years, mussel-inspired polydopamine (PDA)-based materials have attracted significant attention in the field of open-tubular capillary electrochromatography (OT-CEC) owing to their diverse and appealing properties. However, previously established functionalized PDA coating-based CEC stationary phases predominantly relied on the latent reactivity of PDA with amine/thiol-containing molecules, limiting the types of applicable modifiers and requiring time-consuming reaction processes. Herein, we presented a versatile and efficient method for the facile and rapid fabrication of diverse functionalized PDA coatings as OT-CEC stationary phases through a Zr(IV) coordination-mediated post-modification strategy. Different kinds of modifiers, including octadecylamine (ODA), lauric acid (LA), and perfluorooctanoic acid (PFOA), were rapidly and robustly grafted onto the PDA coating, verified through multiple characterization techniques. The influences of preparation parameters on the grafting efficiency of the functionalized PDA coating were systematically investigated. Utilizing the Zr(IV)-mediated ODA-, LA- and PFOA-functionalized PDA-based OT-CEC columns, we achieved high-efficiency baseline separation of a series of neutral analytes with excellent repeatability, good stability, and long lifetime. Given the strong universality of the Zr(IV) coordination-mediated post-modification approach, our study provides an effective pathway for advancing the development of a wider range of functional PDA-based chromatographic stationary phases.

Customization of 2D Atomic-Molecular Heterojunction with Manipulatable Charge-Transfer and Band Structure.

Manipulating the properties of 2Dmaterials through meticulously engineered artificial heterojunctions holds great promise for novel device applications. However, existing research on the crucial charge-transfer interactions and energy profile regulation is predominantly focused on 2D van der Waals structures formed via weak van der Waals forces, limiting regulatory efficiency at high costs. Herein, a refined atomic-molecular heterojunction strategy featuring strong covalent bonds between organic molecule and 2D violet phosphorus (VP) atomic crystal is developed, which enables enhanced charge-transfer dynamics and customizable band structure regulation at the molecular level. Both experimentally and theoretically, it is demonstrated that grafting efficiency, charge redistribution, and energy gap regulation critically depend on organic electronegativity, providing a low-cost yet high-efficiency regulatory effect on a large scale. As a proof of concept, the novel VP-molecular heterojunctions exhibit optimized performance in diverse application domains, presenting a general platform for future high-performance device applications.

Acceleration of propagation of source material for Sorbus Sensu Lato Breeding

Aim. The permanent growth of interest in rowan and other currently underestimated Sorbus sensu lato crops has prompted the search to improve the accelerated propagation technique of its most valuable genotypes for breeding. Methods. The experiments involved 3–7-year-old Sorbus sensu lato plants from the National Dendrological Park "Sofiyivka" of the National Academy of Sciences of Ukraine collection. Statistical analysis of the experimental data was performed according to Ronald Fisher. Results. It was found that the germination rate of the studied sorboid plants depended on the method of seed preparation. In contrast, the grafting efficiency depended more on the grafting method than on the graft genotype. The use of our modified MS media allowed us to obtain clone formation coefficients (6.6–7.9) sufficient for effective micropropagation and to induce morphogenesis with 59.9–88.8 % of rooted microclones, as well as to achieve stable results of adaptation of the studied Sorbus sensu lato to non-sterile ex vitro conditions both in peat disks (69.1–90.3 %) and in containers with soil substrates (70.4–93.0 %). Conclusions. The results of comparing the methods of accelerated propagation of source material for breeding sorboid crops obtained in long-term experiments showed the advantages of micropropagation and the prospects for introducing the micropropagation link into breeding practice and nursery of the most valuable for horticulture Sorbus sensu lato.

Influence of Surface Roughness on Phosphonation and Wettability of Nanosecond Laser‐Treated Titanium Surfaces

The duplex treatments of metal surfaces combining laser‐assisted functionalization and chemical modification attract a growing interest in view of better control of functional properties such as wettability. Patterned titanium oxides layers of different nature and roughness are produced in ambient atmosphere on a titanium surface using a nanosecond 532 nm Nd:YAG laser. Standalone lines and hatched surfaces obtained with different laser parameters are characterized by scanning electronic microscopy coupled with EDS analysis, micro‐Raman, XRD and X‐ray photoelectron spectroscopy (XPS). A set of surfaces having featureless and saw‐tooth morphologies of different roughnesses is modified with octylphosphonic acid (OPA). The effect of surface roughness on the efficiency of OPA grafting is investigated using XPS. It is found that the organic load on the chemically modified surfaces increases with surface roughness. The apparent thickness of the OPA layers is estimated using a standard uniform overlap model and considering the correction due to the corrugated appearance of the laser‐treated surfaces. The wetting properties of the surfaces before and after chemical modification are compared. The laser‐treated surfaces show superhydrophilic behavior consistent with Wenzel model. On the other hand, the chemically modified surfaces demonstrate a strong increase in hydrophobicity along with the roughness increase, in agreement with the Cassie–Baxter model.

Effect of different initiators on the properties of diacetone acrylamide grafted starch-based adhesive

Environmentally friendly and non-toxic bio-based adhesives are emerging as the most promising substitutes for petroleum-based adhesives, attracting increasing attention. This work involved the synthesis of a starch-based adhesive for particleboards by grafting diacetone acrylamide (DAAM) onto starch. The graft polymerization was initiated using three different initiators: ammonium persulfate (APS), hydrogen peroxide (H2O2)/ammonium ferrous sulfate system, and ceric ammonium nitrate (CAN). A comparative study was conducted to assess the varying effects of these initiators. The results showed that in the graft copolymerization of starch with DAAM, different initiators produced different types of free radicals, and CAN initiation produced alkyl radicals and long-chain alkyl radicals with a peak total spin value of 3.96 × 1015, and thus had the highest grafting efficiency and grafting rate of 72.59 % and 16.75 %, respectively. From the comparison of the total number of spins, it can be seen that CAN is more targeted for starch initiation. In addition, characterization results from Fourier transform infrared spectroscopy and confocal Raman spectroscopy showed that DAAM underwent a graft copolymerization reaction with starch. Notably, the adhesive initiated by CAN demonstrated the highest water resistance and mechanical strength, with an absorption thickness expansion and static bending strength of 8.52 % and 10.56 MPa, respectively.

Effect of Surgical Timing to Dental Health in Secondary Alveolar Bone Grafting: Three-Dimensional Outcomes.

There are various opinions on the optimal timing for performing secondary alveolar bone grafting (SABG). This study compared dental health and 3-dimensional outcomes according to the timing of SABG surgery. A retrospective chart review was performed in patients who underwent SABG between January 1996 and October 2020. Patients were divided into early SABG (6-8y old) and traditional SABG (9-13y old) groups. The final dental survival of the lateral incisor and canine teeth, survival of the bone graft, and maxillary growth were analyzed using plain radiographs and computed tomography with a 3-dimensional volumetric analysis tool. Thirty-six patients were divided into an early group (15 patients) and a traditional group (21 patients). Five patients had bilateral cleft lip, and 26 patients had unilateral cleft lip and palate; therefore, 36 alveolar clefts were analyzed in this study. Lateral incisor survival was significantly greater in the early group than in the traditional group (60% vs. 23.5%; P<0.05). Compared with that in the traditional group, graft success in the early group was greater (80% vs. 57.1%; P<0.05). Three-dimensional volumetric analysis revealed superior bone graft efficiency in the early group compared with the traditional group (55.2 vs. 38.5%; P<0.05). There was no significant difference in maxillary growth between the 2 groups. In our study, superior dental and clinical outcomes were observed in the early SABG group without any long-term complications or maxillary retrusion. Our institution cautiously indicated that SABG could be performed at an age earlier than the existing SABG performed after 9 years old.

Enhancing the water dispersibility and intestinal targeting of pterostilbene using tannic acid-whey protein conjugates

In this study, three types of whey protein isolate (WPI)-tannic acid (TA) covalent conjugates (WPI-TA) were synthesized via alkaline treatment, free radical-induced method, and laccase induction. These conjugates were subsequently utilized in the antisolvent precipitation method to encapsulate pterostilbene (Pte). The structural and functional properties of these conjugates as carriers for intestinal-targeted Pte delivery were thoroughly evaluated. SDS-PAGE, total phenolic content measurement, grafting efficiency, and FT-IR analysis confirmed the successful formation of three distinct covalent conjugates. Among them, the laccase-induced WPI-TA conjugates exhibited the highest TA grafting efficiency. The particle size of this conjugate was measured at 115.25 nm with a PDI of 0.31. Upon encapsulation of Pte, this conjugate exhibited superior thermal stability, enhanced antioxidant properties, and sustained release within the gastrointestinal tract. The water solubility of Pte in these nanoparticles was found to be 361.19 times higher than that of free Pte, presenting a promising strategy for targeted intestinal delivery of Pte.

Plasma/Ozone Induced PolyNaSS Graft-Polymerization onto PEEK Biomaterial for Bio-integrated Orthopedic Implants

Owing to its superior bulk mechanical properties, poly (ether ether ketone) (PEEK) has gained popularity over the past 15 years as a metal substitute in biomedical implants. Low surface energy is a fundamental issue with PEEK implants. This low surface energy caused by a moderately hydrophobic surface may be able to inhibit cellular adherence and result in the development of an inflammatory response, which may result in cell necrosis and apoptosis. In this work, plasma and ozone treatments have been utilized to surface activate PEEK and graft ionic bioactive polymer polyNaSS (poly (sodium styrene sulfonate)) successfully on the surface to promote cellular attachment and biomineralization. The main goal of our research has been to find a stable green process for surface modification of PEEK by plasma/ozone approaches to increase PolyNaSS grafting efficiency and biomineralization. To further the field of bioactive orthopedic and dental implant technology, this research attempts to address a significant constraint of PEEK implants while preserving their favorable mechanical properties.

Preparation and Characterization of Supramolecular Bonding Polymers Based on a Pullulan Substrate Grafted with Acrylic Acid/Acrylamide by Microwave Irradiation

A microwave technique was used to prepare a superabsorbent polymer (SAP) by grafting two hydrophilic monomers onto a polysaccharide substrate. The monomers used were acrylic acid (AA) or acrylamide (AM) and were grafted onto a pullulan (PUL) substrate to form PUL-g-AA (SAP1) and PUL-g-AM (SAP2), respectively. The monomers (AM/AA) were grafted together onto a PUL substrate to form PUL-g-(AM/AA) (SAP3). Grafting parameters such as grafting efficiency with the percentage, the conversion of monomer into polymer, gel content, water retention, water adsorption capacity, and swelling kinetics were determined. Additionally, the effect of environmental pH (2, 4, 7, 9, and 12) and sodium dodecylbenzene sulfonate (SDBS) surfactant was evaluated, where 1, 2, 3, 4, and 5 mM of SDBS was added to form SAP4 to SAP8. The FTIR results show that AM was grafted onto PUL through an aliphatic C-N bond, while AA grafting occurred through a single C-C bond. The grafting efficiency with AM was higher than with AA, as well as showing a superior gel content. Water absorbance capacity and water retention increased with the grafting of AA and AM together for SAP3. The highest absorbent capacity, water retention, gel content, and grafting parameters values were obtained with a 3 mM SDBS content and a pH of 7. The swelling kinetics showed that the increases in the theoretical and experimental swelling equilibriums were 72% and 82%, respectively, for SAP6 compared to the values of these parameters for SAP3. The water absorption capacity of the hydrogel increases upon increasing the pH to 7 and then gradually decreases. XRD demonstrated the improved crystallinity and crystalline size of the hydrogel after grafting polymerization of AM/AA onto PUL, in addition to enhanced thermal stability. On the contrary, FE-SEM demonstrated that SDBS improves the porosity and pore size of the hydrogel surface with SAP6.

Structural properties and antioxidant capacity of different aminated starch-phenolic acid conjugates

Different aminated starch (AS) [EEAS (introducing ethylenediamine into starch using cross-linking-etherification-amination method (CEA)), EPAS (introducing o-phenylenediamine using CEA), OEAS (introducing ethylenediamine using cross-linking-oxidation-amination method (COA)), and OPAS (introducing o-phenylenediamine using COA)] were synthesized. The AS-phenolic acids [gallic acid (GA), syringic acid (SA), and vanillic acid (VA)] conjugates were prepared by laccase-catalyzed reaction. The grafting efficiency of EEAS on GA, SA, and VA was 36.59%, 69.71%, and 68.85%, respectively. SA reduced the maximum depolymerization rate of EEAS. The relative crystallinity of EEAS and EPAS grafted phenolic acid increased, and their particles showed severe breakage in appearance. OEAS-phenolic acid conjugates lost its granular structure and behaved as flakes and lumps, while the surface of OPAS-phenolic acid conjugates remained smooth after grafting phenolic acid. GA increased the DPPH· scavenging efficiency of EEAS from 16.12% to 79.92%. The increased antioxidant capacity of the conjugates suggested that AS-phenolic acids conjugates have high potential for applications.

Assembly of polysaccharide-based polymer brush for supramolecular hydrogel dressing

Extracted from Platycodon grandiflorum, platycodon grandiflorum polysaccharides (PGPs) with diverse biological functions have been extensively employed for modification and fabrication of hydrogels for biomedical applications, such as wound dressings. However, since the lack of effective structural design, the reported polysaccharide-based hydrogel dressings are still suffered from structural failures and limited bio-functionality. Herein, we demonstrate a facile and general strategy to fabricate a supramolecular hydrogel composed of PGP-based polymer brush as building blocks combined with a Ca2+-mediated self-assembly process. The specific polymer brush with high branch functionality was achieved with polyacrylamide arms evenly grown on the PGP (grafting efficiency as high as 80 %) with series of chemical modifications. With above structural merits, the resulting hydrogel with densely crosslinked polymer brush featured enhanced mechanical strength as well as self-healing, and shear-thinning behaviors. Further biocompatible investigation indicated the as-prepared hydrogels with admirable performances in self-adhesion (adhesive strength of 16.7–79.5 kPa), a pH-responsive swelling ratio as high as 44 at pH 5.4, and pH-responsive degradation. They also showed antioxidant capacity by scavenging DPPH activity of nearly 80 % in 20 min, hemocompatibility, cell viability and cell migration. Impressively, the PGP-based polymer brush hydrogel served as a wound dressing revealed significant acceleration on wound closure.

EVALUATION OF IN-VITRO ANTIMICROBIAL ANTIOXIDANT AND ANTICANCER ACTIVITY OF A NEW CARBOXYMETHYLCHITOSAN-BASED CYANOGUANIDINE COPOLYMER

A new carboxymethylchitosan-based acryloylcyanoguanidine copolymer (CMCS-g-ACG) has been successfully prepared using the grafting technique. The grafting percentage, grafting efficiency, and homopolymer percentage were 86, 85, and 14%, respectively. The chemical structure and surface morphology of the CMCS-g-ACG copolymer were confirmed using elemental analysis, FTIR, 1H-NMR, XRD, and SEM. The copolymer has greater inhibition activity on both Escherichia coli (E. coli), Staphylococcus aureus (S. aureus), and Candida albicans (C. albicans) in comparison to CMCS. It is more potent against E. coli than S. aureus. At 2000 μg/mL concentration, CMCS and the copolymer exhibited DPPH scavenging of 63.45% ± 4.19 and 78.56% ± 4.61, respectively. The copolymer of concentration less than 62.5 μg/mL was safe on the normal human lung fibroblast cells. The growth inhibition of the breast cancer cells at 500 μg/mL was 79.59% ± 2.12 and 91.41% ± 2.34 for CMCS and the copolymer, respectively. Thus, the insertion of ACG into CMCS highly boosted its antimicrobial, antioxidant and anticancer characteristics. It is a proper strategy to realize good systems to compete the traditional drugs used for such applications.

Amino‐functionalized nano‐hydroxyapatite boosts the grafting efficiency of poly (l‐lactic acid) to enhance interfacial bonding in composite bone scaffold

AbstractNano‐hydroxyapatite (nano‐HAP)/poly (l‐lactic acid) (PLLA) bone scaffold is expected to overcome the deficiencies and achieve the complementary advantages of individual constituents, but the weak interfacial bonding due to their thermodynamic incompatibility is detrimental to the mechanical properties. Herein, the PLLA chains were grafted onto nano‐HAP with 3‐aminopropyltriethoxysilane (KH550) as a coupling reagent to enhance the interfacial bonding with PLLA. Specifically, the silicon hydroxyl group produced by KH550 hydrolysis could form covalent bonding with the hydroxyl group of nano‐HAP, and the amino group of KH550 initiated the ring‐opening polymerization of l‐lactide monomers to graft PLLA chains onto nano‐HAP more effectively, leading to a higher grafting ratio of 16.7% compared with 7.2% in direct grafting without KH550 modification. Consequently, the tensile and compressive strength of the modified nano‐HAP/PLLA scaffold were improved by 40.8% and 59.5% enhancement due to the enhanced interfacial bonding in the composite scaffold, respectively, compared to the original nano‐HAP/PLLA scaffold. Additionally, the bone scaffold was conducive to cell adhesion and proliferation, making it an ideal candidate for bone defect repair.Highlights Amino‐functionalized nano‐HAP boosted the grafting efficiency of PLLA chains. Interfacial bonding between nano‐HAP and matrix was enhanced. Bone scaffold showed better mechanical properties and benign cytocompatibility.

Evaluation of microwave irradiated Polyacrylamide grafted Opuntia leaf mucilage graft copolymer (OPM-g-PAM) as effective controlled release polymer for release of Rosuvastastin as model drug

Controlled drug delivery systems offer numerous advantages. This research evaluates Opuntia leaf mucilage grafted with polyacrylamide (OPM-g-PAM) as a promising controlled-release polymer. PAM chains were grafted onto the backbone of OPM using a microwave-assisted method. Optimization of the best grade was based on % grafting efficiency and intrinsic viscosity, followed by extensive physical and analytical characterizations. Analytical characterizations revealed semicrystalline nature of the biomaterial. SEM and AFM observations revealed rough and porous surfaces, indicating effective grafting. Swelling behavior showed maximum sensitivity at pH 7, with reduced swelling at higher sodium chloride concentrations. A comparative study of % drug release of Rosuvastatin over 24 h showed that the optimized grade controlled drug release effectively, achieving 78.5 % release compared to 98.8 % for GF-3. The release data fitted the Korsmeyer-Peppas model, with an “n” value of 0.8334, indicating non-Fickian (anomalous) diffusion. Bacterial biodegradability studies confirmed the high biodegradability of the graft copolymer. In vitro acute toxicity tests showed no toxicity, as confirmed by histopathological studies of heart, liver, and kidney. Overall, the results indicate that OPM-g-PAM is a highly promising material for use in drug delivery systems, demonstrating potential as a novel controlled-release polymer.

An efficient method to prepare high grafting montmorillonite with silane coupling agent and its improvements for styrene butadiene rubber composites

AbstractThe quantity of silane chemically bonded to the organoclay's surface significantly influences its dispersion within the polymer matrix, as well as the interfacial interaction. This research presents a groundbreaking method for enhancing the surface properties of montmorillonite (Mt) through the use of γ‐(methacryloxy) propyl trimethoxy silane (KH570) coupled with acid treatment, leading to increased grafting efficiency. Confirmed by FT‐IR, TGA, and XRD, the process effectively bonds organo‐silanes to Mt and achieves a high grafting level of 1.59 mequiv/g. Utilizing a latex compounding method, Mt/rubber nanocomposites are synthesized with thoroughly modified clay for peak performance. Dispersion and interfacial properties are evaluated through XRD, TEM, AFM, and DMTA. The findings reveal that the well‐modified Mt is an exceptional filler, ensuring a high level of dispersion and robust interaction with the rubber matrix. This synergy translates to a marked improvement in the mechanical properties of the composite, with notable enhancements observed in both tensile strength and elongation at break of 9.7 MPa and 1141%, respectively. This innovative approach to the graft modification of clays presents a potent method, offering the potential for the industrial‐scale manufacture of high‐performance clay‐based composites.Highlights A processing method for preparing high grafting clay with a silane coupling agent. Functionalized clay presents better nano‐dispersion in the polymeric matrix. Strong covalent interfacial interaction is constructed between clay and rubber. Tensile Strength and elongation at break of the composites are obliviously improved.

Post-polymerization modification of polypropylene with different functional groups utilizing non-catalytic C–H insertion of sulfonyl azide

This study presents a comprehensive investigation into the preparation of functionalized polypropylene (PP) with different functional groups, such as amino-, hydroxyl-, acetamido-, and carboxyl-groups, utilizing efficient C–H insertion capability of sulfonyl azide (SA) compounds with the functional groups. The reactive melt mixing of PP and the SA compounds was performed at temperatures determined by the decomposition temperatures of the SA groups, followed by purification processes to remove unreacted SA compounds, confirming the establishment of stable covalent linkages between the SA compounds and PP chains. Grafting efficiency (GE) values were determined using FT-IR spectroscopy, showcasing efficient grafting of the SA compounds onto PP chains with GE values ranging from 60 % to 70 %. Remarkably, SA compound with carboxyl functional group exhibited an exceptionally high GE value of ∼90 %, likely attributed to its electron-withdrawing carbonyl group. XRD analyses, thermal analyses, morphological analyses of cryogenically fractured modified PPs and mechanical property analyses revealed successful incorporation of SA compounds into PP chains with relatively low sensitivity of the crystal structure of the modified PPs to the incorporated SA compounds. Hydrophilicity assessments revealed improved paint adhesion capabilities of the modified PP surfaces, highlighting the potential for the tailored surface modification strategies to enhance material characteristics.

The Low-Waste Grafting Copolymerization Modification of Chitosan Is a Promising Approach to Obtaining Materials for Food Applications.

Chitosan takes second place of the most abundant polysaccharides naturally produced by living organisms. Due to its abundance and unique properties, such as its polycationic nature, ability to form strong elastic porous films, and antibacterial potential, it is widely used in the food industry and biomedicine. However, its low solubility in both water and organic solvents makes its application difficult. We have developed an environmentally friendly method for producing water-soluble graft copolymers of chitosan and poly (N-vinylpyrrolidone) with high grafting efficiency and a low yield of by-products. By using AFM, SEM, TGA, DSC, and XRD, it has been demonstrated that the products obtained have changed properties compared to the initial chitosan. They possess a smoother surface and lower thermal stability but are sufficient for practical use. The resulting copolymers have a higher viscosity than the original chitosan, making them a promising thickener and stabilizer for food gels. Moreover, the copolymers exhibit an antibacterial effect, suggesting their potential use as a component in smart food packaging.

Preparation and Characterization of Poly(Methyl Methacrylate) Grafted Natural Rubber Latex Films

Poly(methyl methacrylate) (PMMA) grafted natural rubber (NR) latex was successfully prepared and solely exploited even at high MMA concentration (1.5 mol/kg-rubber) to make coherent and uniform vulcanized films without blending with other polymer to achieve excellent physical properties. High ammonia natural rubber (HANR) latex was subjected to graft-copolymerization with methyl methacrylate (MMA) monomer in the presence of tert-butyl hydroperoxide (TBHP) and tetraethylenepentamine (TEPA). High conversion, i.e., 85.12 mol%, and grafting efficiency, i.e., 92.70 mol%, were obtained at 1.5 mol/kg-rubber MMA. The resulting gross PMMA grafted NR (1.5PMMA) latex was then compounded, dipped, and vulcanized to produce thin films. The tensile strength and modulus at 300 percent (M300) of vulcanized 1.5PMMA film were superior to vulcanized HANR film by 1-fold. While elongation at break (EB) was identical to each other due to the high gel content in both vulcanized films. Besides, the vulcanized 1.5PMMA film absorbed less oil compared to HANR film. The thermal stability of vulcanized 1.5PMMA film was found to be higher than that of vulcanized HANR film. Hence, it can be deduced that controlling the graft-copolymerization of PMMA in NR latex is the key to produce coherent thin films with improved properties at higher PMMA content.