Effect Of Polymer Structure Research Articles

Efficient Polymeric Nanoparticle Gene Delivery Enabled Via Tri- and Tetrafunctional Branching.

Poly(β-amino ester) (PBAE) nanoparticles (NPs) show great promise for nonviral gene delivery. Recent studies suggest branched PBAEs (BPBAEs) offer advantages over linear counterparts, but the effect of polymer structure has not been well investigated across many chemical constituents. Here, a library of BPBAEs was synthesized with tri- and tetrafunctional branching. These polymers self-assemble with DNA to form highly cationic, monodisperse NPs with notably small size (∼50 nm). Optimal transfection occurred with polymer structures that featured moderate PBAE branching, enabling complete DNA encapsulation, rapid NP uptake, and robust expression at low DNA doses and polymer amounts. Optimized NPs enabled efficient DNA delivery to diverse cell types in vitro while maintaining high cellular viability, demonstrating significant improvements over a well-performing linear PBAE counterpart. BPBAEs also facilitated efficient mRNA and siRNA delivery, highlighting the versatility of these structures and demonstrating the broad utility of BPBAE NPs as vectors for nucleic acid delivery.

A survey of recent publications on polymers employing reactive, halogen‐free flame‐retardant functionalities

AbstractModern society relies heavily on producing commercial and industrial plastics to improve the quality and quantity of our lives. However, increased fire risks threaten commercial operations and the potential impact of high‐performance electronic and transportation technologies that utilize polymeric materials. Despite significant monitoring and reduction of commonly used halogenated flame retardants, their worldwide usage still poses environmental hazards. Many non‐halogenated flame‐retardant compounds are viable additives for synthetic polymers; however, their incorporation often results in reduced composite homogeneity and mechanical strength. This review focuses on reactive flame retardants and the effect of polymer structure on inherent flame retardance in recent studies. The synthesis and characterization of polymeric systems (e.g. polyurethanes, polyamides, polyimides, polyesters and epoxy resins) are discussed in terms of structure–flame‐retardant performance using a complement of analytical tools, including thermogravimetric analysis, cone calorimetry, limiting oxygen index and UL 94 testing. These commercially important polymeric systems represent a broad compositional space for future adaptation and the discovery of increasingly modular polymeric materials with, while also contributing to the fundamental understanding of unique combinations of gas‐ and condensed‐phase mechanisms of flame retardance. © 2024 Society of Chemical Industry.

Recent Advances of Imide‐Functionalized Polymer Donors for Non‐fullerene Solar Cells†

Comprehensive SummaryIn recent years, there has been a shift towards using non‐fullerene electron acceptors in organic solar cells (OSCs) as a replacement for fullerene derivatives. This change requires polymer donors that possess compatible physical properties, such as absorption range, HOMO energy level, miscibility, and crystallinity. Moreover, the high cost and poor batch‐to‐batch reproducibility of polymer donors also hinder future large‐scale manufacturing. These emphasize the need to explore alternative types of polymer donors. The imide‐functionalized building units possess several key attributes that make their polymers highly promising for non‐fullerene OSCs. These attributes include ease of synthesis, strong electron‐withdrawing ability, rigid and co‐planar structure, and the ability to easily tune solubility through imide side chains. In this review, we summarized the synthetic routes of imide building units, and the structural evolution of imide‐functionalized polymer donors by focusing on the effects of polymer structure on their physical, optoelectronic, and photovoltaic properties. We hope that this mini‐review will serve as a catalyst for future research on imide‐functionalized polymers toward high‐performance, cost‐effective, and durable organic solar cells (OSCs).

Cu-immobilized cellulose filter paper: effect of polymer structure and functionality on catalytic activity and reusability for 4-nitrophenol reduction

ABSTRACT Cellulose filter paper (CFP) was modified with poly(acrylic acid) (PAA) and/or poly(ethylene glycol)methacrylate (PEGMA), followed by Cu immobilization for 4-nitrophenol (4NP) reduction. Among these samples, Cu-immobilized CFP modified with PEGMA polymer (CFP@PEGMA-Cu) exhibited the highest Cu incorporation of 2.21%. Those having the copolymer (CFP@PAA-co-PEGMA-Cu) demonstrated the highest efficiency, completing 4NP reduction in 3 min with an impressive 99.45% conversion, a high-rate constant (k) of 27.5 × 10−3 s−1, and turnover frequency (TOF) of 18.36 h−1. Notably, the catalysts containing PAA maintained good reusability, preserving 97% conversion upon 9 cycles. These results suggest their promising applications in sustainable catalysis, offering the catalytic potential with simple preparation and low cost required.

WITHDRAWN: Investigating the Polymer Structure Effects on SBS-Modified Asphalt Binders under Short-Term Aging through the Artificial Neural Networks, Genetic Algorithms, and Fuzzy Logic

SBS-modified asphalt (SBSMA) exhibits complicated aging behavior in the weathering environment due to oxidation of the matrix asphalt, degradation of the SBS, and disruption of the SBS-asphalt relationship. The weathering process of SBS-modified asphalt has been studied extensively. However, most of this research has taken a broad, environmental approach. This research delved into the nuanced effects of aging on low polymer-modified asphalt (LPMA) compositions integrated with a rejuvenating agent (RA), leveraging advanced computational intelligence methodologies. The study uniquely employed fuzzy logic, Artificial Neural Networks (ANN), and genetic algorithms to forecast and analyze the performance dynamics of distinct asphalt mixtures. Five asphalt mixtures were examined: a PG 58-28 binder served as the foundational benchmark, while the subsequent four used modified PG 58-28 with different ratios of Ethylene Vinyl Acetate (EVA) and sesame oil (RA). Assessment methodologies comprised the Resilient Modulus Test, Wheel Track Test, Flow Time, Direct Tension, and Quarter-Circle Bend tests. The ANN framework was instrumental in predicting rutting and crack trajectories, while fuzzy logic facilitated understanding the intricate interplays between component ratios and resultant performance metrics. Genetic algorithms optimized the EVA and RA ratios for enhanced efficacy. Initial results demonstrated that the amalgamation of EVA and RA strengthened the overall lifespan and rutting resilience of the asphalt composites. Enhanced blends, optimized using the genetic algorithm, exhibited improved resistance to initial crack formations relative to the baseline. As the aging process advanced, the modified blend's resilience to recurrent stress-induced cracks experienced minor reductions but paralleled the foundational benchmark. A harmonized combination, pinpointed via the genetic algorithm containing 6.5% EVA and 6% RA, emerged as the most proficient in amplifying durability, resistance against deformations, and immediate crack resistance.

Water-soluble and Water-dispersible Polymers Used in Commercial Agricultural Formulations: Inventory of Polymers and Perspective on their Environmental Fate.

Agricultural formulations contain water-soluble and water-dispersible polymers (WSPs and WDPs) to increase the application efficiency of the active ingredients (e.g. pesticides and fertilizers). Despite their direct release to soils and crops, there is currently no inventory of used polymers and their fate in soils is poorly studied and understood. Herein, we identify WSPs and WDPs used in agricultural formulations on the German and Swiss markets. By searching the scientific literature, patents, and manufacturer websites, we tentatively identified that 233 of the 1815 listed trade names of formulation additives contained polymers, the majority of which belonged to three main chemical classes: polyethylene glycol (PEG)-based (co)polymers, functionalized polysaccharides (PSacs), and vinylic (co)polymers (VCPs). We report information on their functionalization, molecular weights, and market significance. In 2015, their estimated combined annual application volume in Switzerland surpassed 100 tonnes. Low molecular weight PEGs and natural, unfunctionalized PSacs reportedly biodegrade, suggesting no accumulation in soils associated with their use as formulation additives. Conversely, high molecular weight functionalized PEGs, functionalized PSacs, and the majority of the VCPs have been reported to undergo only slow or no soil biodegradation. These polymers may thus persist and accumulate in agricultural soils, requiring more detailed investigations of their environmental fate and resulting exposure scenarios. There is a need for systematic studies on the effects of polymer structure, molecular weight, and functionalization on soil biodegradability.

Effect of polymer structure on the functional properties of alginate for film or coating applications

This study aimed to characterize the effect of molecular weight (MW) and mannuronic/guluronic acids ratio (M/G) on the functional properties of four different alginate types, considering both the aqueous film-forming solutions (rheological and interfacial properties) and the self-standing films (mechanical and barrier properties). Regarding the film-forming solutions, a structure-dependent effect was clearly disclosed with respect to the flow properties. The high MW alginates showed greater values of apparent viscosity and a more pronounced shear-thinning behavior than low MW alginates. Surprisingly, the corresponding alginate films did not exhibit any significant difference in terms of Young modulus (≈1.9 GPa), elongation at break (≈8.4 %) and tensile strength (≈42.5 MPa), as well as oxygen and water vapor permeances (PO2 ≈ 7.0 ∙ 10−15 mol. m−2.s−1.Pa−1, and PH2O ≈ 1.0 ∙ 10−7 mol. m−2.s−1.Pa−1 at semi-dry condition and 25 °C). In addition, the best oxygen barrier performance was obtained for a film thickness of ∼20 μm, above which no significant increase in the oxygen barrier performance was noticeable. The outcome of this study suggests the potential of sodium alginate for specific food packaging applications, such as the manufacturing of edible films or functional coatings for packaging materials (e.g., plastics, paper, etc.), thus possibly meeting the increasing demand for more sustainable products and processes.

Simulations predict water uptake and transport in nanostructured ion exchange membranes

Ion exchange membranes are made up of polymers with charged groups randomly tethered to the backbone. In humid conditions, these membranes absorb water to form nanostructures: the polymers reside in a hydrophobic domain, while the charged groups and counterions reside in interconnected water-filled paths that facilitate ion and water transport. Consequently, these membranes find their application in energy storage and water filtration. Molecular dynamics simulations can be used to investigate the effect of polymer structure and hydration level on the nanostructured pore space and transport within it. Here, we investigate polystyrene-polymethylbutylene (PS-PMB) block copolymer membranes, with the PS block randomly sulfonated to an experimentally relevant level of 25 mole percent. The counterion distribution in the pore space is not uniform; counterions are mainly found near the polymer-water interface, which is decorated with negative sulfonate groups. We vary the water content in the membrane, and predict an equilibrium water uptake consistent with experiments. Surprisingly, even at a water content 8 times smaller than equilibrium, the aqueous paths remain connected; however, the pores shrink down to narrow ribbons. We measure both short-time and long-time diffusivity of counterions and water, and find that diffusivity increases with water content and is impacted by pore tortuosity.

Porous thin films with hierarchical structures formed by self-assembly of zwitterionic comb copolymers

Zwitterions exhibit high dipole moments and strong intra- and inter-molecular interactions. As a result, amphiphilic copolymers with zwitterionic repeat units easily self-assemble. Here, we explore the wide range of self-assembled morphologies formed by zwitterionic comb-shaped copolymers (ZCCs) comprising a hydrophobic backbone and zwitterionic side-chains. We study the effect of polymer structure, architecture, and film preparation method on self-assembled morphology. We synthesized ZCCs with varying zwitterionic side chain density and length, and applied each ZCC as a thin film on glass substrates using different methods. We compared the morphology of these films with ZCCs films coated on a porous substrate by non-solvent induced phase separation, creating mechanically supported thin films (MSTFs) and comparing them with films on non-porous substrates. The porous support led to distinct changes in film morphology, creating hierarchical features including ∼17 nm spherical micelles along with larger nanopores (∼85 nm). This feature size could be tuned using a zwitterionic homopolymer additive. MSTFs exhibited significant changes in water permeance and morphology upon exposure to saline solutions, known to stimulate expansion of the zwitterionic side-chains. These results demonstrate the wide range of morphologies accessible by this comb copolymer family and document the significant effect of a porous support on the film formation process.

Random versus Block Glycopolymers Bearing Betulin and Porphyrin for Enhanced Photodynamic Therapy.

Porphyrins and their derivatives, representing the second-generation photosensitizers, can generate reactive oxygen species (ROS) and kill tumors upon light irradiation. To compensate for the fluorescence quenching and reduced ROS production caused by aggregation and rigid inherent hydrophobicity of porphyrins, a series of comparable random and block glycopolymers bearing betulin and porphyrin were prepared via RAFT polymerization. Betulin was introduced into the copolymers to decrease aggregation-induced quenching of porphyrins and to improve the photodynamic therapy (PDT) efficiency of copolymers. The characteristics, self-assembly, and photophysical chemistry properties of these copolymers were systemically studied. The effect of polymer structure on photophysical chemistry properties and cellular interaction was investigated as well to demonstrate their potential targeting for PDT applications.

The suspending appearance of poly(acrylic acid)‐based rheology modifier in high‐content surfactant: The effect of polymer structure and molecular weight on the rheological properties of the complex systems

AbstractThe “all in one” multifunctional and concentrated daily chemical products are required by the market, such as the long‐term release of anti‐bacterial, medical, or perfume agents. These functions mainly rely on the microcapsules, which could encapsulate these functional and unstable molecules, and then release them in the long term. To stabilize these functional solid particles in a high‐content surfactant, it is necessary to add a suspending rheological modifier. The poly(acrylic acid) (PAA)‐based rheology modifier is one of the most common additives in the industry of daily chemicals, for thickening or suspending. In this paper, linear PAA, and branched PAA polymers (Carbomer 941 and Carbomer 940) were selected to study the suspending ability of PAA‐based rheology modifier in high‐content surfactant and to investigate the effect of PAA polymer structure and Mw on the complex solution's rheological properties. The yield and viscosity test of the complex solutions of linear PAA and high‐content surfactant revealed that the addition of linear PAA could lead to lower yield stress and viscosity, and failed to suspend the polystyrene (PS) model microspheres due to its smaller mean square radius of gyration. The branched PAA polymer, Carbomer 940 and Carbomer 941 were more stable than the linear PAA in these two kinds of surfactant. More specifically, Carbomer 940 with a higher Mw, would exhibit higher yield stress and viscosity than Carbomer 941 with a lower Mw in nonionic surfactant alcohol polyoxyethylene ether (AEO) solvent with content less than 5 wt%. When the content was higher than 5 wt%, Carbomer 941 presented higher yield stress and viscosity than Carbomer 940, and successfully suspended PS microspheres in the 20 wt% AEO solution. This could depend on the polymer chain's elongation state of these two PAA‐based branched rheology modifiers. The same trend happened in the appearance of Carbomer 940 and Carbomer 941 in alcohol ether sulphate (AES) solution. However, the electrostatic repulsive force between the AES and PAA‐based rheology modifier could further make the polymer chain curl up and restrain the suspending ability in a lower content surfactant solution. Therefore, this fundamental research could guide the application of the anionic polyelectrolytes in the concentrated daily chemical product for stable suspending particles.

Effect of Polymer Structure on the Size and Shape of Metal and Metal Oxide Nanopowder: An HR-TEM Approach

A metal and metal oxide quantum dot (QD) was synthesized by a simultaneous oxidative reduction method. Aniline was polymerized both in the presence and absence of o-toluidine (OT) as a co-monomer and in the presence of peroxomonosulfate (PMS) as a free radical initiator in N-methyl pyrrolidone (NMP) medium at 0–5∘C for 3 h under vigorous stirring condition. The metal or metal oxide bulk powder was used as source material for the generation of QD. At the end of the reaction a dark green colored polymer was formed, filtered and dried at 110∘C for overnight. The dried polymer was subjected to HR-TEM analysis. The size and shape of the crystals formed were noted and compared with the literature reports.

Interlocking degradation of vinyl polymers via main‐chain CC bonds scission by introducing pendant‐responsive comonomers

AbstractDegradation of vinyl polymers remains a challenge because of the robust main‐chain CC bonds. In this study, we designed novel pendant‐responsive comonomers with a carbon–halogen bond, which can be copolymerized with vinyl monomers to enable facile degradation of the CC backbone upon triggering stimulus. The comonomer unit was designed to induce interlocking degradation, that is, it first generates side‐chain radical upon trigger, subsequently provides a main‐chain radical via intramolecular 1,5‐shift, and then finally causes the main‐chain cleavage via β‐scission. A remarkable decrease in molecular weight was observed when the obtained copolymer was treated with a copper catalyst, and the effect of polymer structure was assessed on the interlocking degradation behavior.

Accelerated Post-Polymerization Amidation of Polymers with Side-Chain Ester Groups by Intramolecular Activation.

The catalytic conversion of esters to amides represents new opportunities in the synthetic diversification and upcycling of polymers, as esters are commonly featured in various polymer structures. Yet, direct amidation is typically hampered by poor reaction kinetics and the effects of polymer structure on the reactivity remain poorly understood. We report the accelerated amidation for amines with additional hydrogen bond donating or accepting groups. These amines facilitate the expeditious (co)amidation of polymers with pendant ester groups, displaying at least a 400-fold higher reactivity relative to polyesters with esters in the main chain. Furthermore, a positive correlation between the reactivity and degree of polymerization for poly(methyl acrylate) suggests a hydrogen-bond mediated intramolecular activation of the esters, which was confirmed by FT-IR spectroscopy and basic molecular mechanics modeling. The reported method paves the way to synthesize diverse (co)polymers with amide side chains from readily available polymeric precursors.

Accelerated Post‐Polymerization Amidation of Polymers with Side‐Chain Ester Groups by Intramolecular Activation

AbstractThe catalytic conversion of esters to amides represents new opportunities in the synthetic diversification and upcycling of polymers, as esters are commonly featured in various polymer structures. Yet, direct amidation is typically hampered by poor reaction kinetics and the effects of polymer structure on the reactivity remain poorly understood. We report the accelerated amidation for amines with additional hydrogen bond donating or accepting groups. These amines facilitate the expeditious (co)amidation of polymers with pendant ester groups, displaying at least a 400‐fold higher reactivity relative to polyesters with esters in the main chain. Furthermore, a positive correlation between the reactivity and degree of polymerization for poly(methyl acrylate) suggests a hydrogen‐bond mediated intramolecular activation of the esters, which was confirmed by FT‐IR spectroscopy and basic molecular mechanics modeling. The reported method paves the way to synthesize diverse (co)polymers with amide side chains from readily available polymeric precursors.

Effect of polymer structure and chemistry on viscosity index, thickening efficiency, and traction coefficient of lubricants

The chemistry and structure of base oil and polymer additive molecules in lubricants directly affect key performance metrics such as viscosity index, thickening efficiency, and traction coefficient. However, the relationship between molecular properties and these metrics is still not fully understood, inhibiting the design of new fluids with potentially improved performance. This study used molecular dynamics simulations to identify structure–property-function relationships for model lubricants consisting of branched and linear polymers with chemistries consistent with commercially available products. First, fluids with similar kinematic viscosities at 100 °C were formulated with five different polymers. Then, the simulation-calculated Newtonian viscosities at 40 and 100 °C, viscosity index, thickening efficiency, and traction coefficient in full film lubrication at 40 °C were validated by direct comparison to experimental data. Next, the molecular origins of differences in the viscosity index, thickening efficiency, and traction coefficient between the fluids were investigated by calculating multiple structural properties of the simulated polymers. Finally, the simulations were used to develop simple empirical models using the best subset linear regression analysis to rapidly predict viscosity index, thickening efficiency, and traction coefficient. The atomistic simulations and empirical models developed in this work can ultimately guide the design of new lubricants or additives.

Preparation of Smart Surfaces Based on PNaSS@PEDOT Microspheres: Testing of E. coli Detection.

The main task of the research is to acquire fundamental knowledge about the effect of polymer structure on the physicochemical properties of films. A novel meta-material that can be used in manufacturing sensor layers was developed as a model. At the first stage, poly(sodium 4-styrenesulfonate) (PNaSS) cross-linked microspheres are synthesized (which are based on strong polyelectrolytes containing sulfo groups in each monomer unit), and at the second stage, PNaSS@PEDOT microspheres are formed. The poly(3,4-ethylenedioxythiophene) (PEDOT) shell was obtained by the acid-assisted self-polymerization of the monomer; this process is biologically safe and thus suitable for biomedical applications. The suitability of electrochemical impedance spectroscopy for E. coli detection was tested; it was revealed that the attached bacterial wall was destroyed upon application of constant oxidation potential (higher than 0.5 V), which makes the PNaSS@PEDOT microsphere particles promising materials for the development of antifouling coatings. Furthermore, under open-circuit conditions, the walls of E. coli bacteria were not destroyed, which opens up the possibility of employing such meta-materials as sensor films. Scanning electron microscopy, X-ray photoelectron spectroscopy, water contact angle, and wide-angle X-ray diffraction methods were applied in order to characterize the PNaSS@PEDOT films.

Effects of polyimide sequence and monomer structures on CO2 permeation and mechanical properties of sulfonated polyimide/ionic liquid composite membranes

The effects of polymer structure on CO2 separation and mechanical properties of ion gel membranes composed of ionic liquids (ILs) and sulfonated polyimides (SPIs) were investigated. SPIs with different sequential distributions of ionic groups (multiblock and random) were synthesized. The multiblock copolymer exhibited higher IL uptake (∼80 wt.%) than the random copolymer, resulting in higher CO2 permeability (∼480 Barrer). The multiblock copolymer exhibited a clearer phase-separated structure than the random copolymer. However, the strain at the break of the multiblock copolymer was lower owing to the brittleness of the non-ionic phase. To improve the mechanical properties, an SPI containing fluorinated groups as a non-ionic part was also synthesized. Compared with the random SPI ion gel membranes, the multiblock SPI ion gel membranes containing fluorinated groups exhibited good CO2 permeability (∼500 Barrer) and simultaneously ductile properties with higher strain at the break due to the plasticization of the non-ionic phase, enabling a thin and tough membrane with excellent CO2 separation properties. These results indicate that the polyimide sequence in addition to the chemical structure of monomers affects CO2 permeation and mechanical properties of the sulfonated polyimide/ionic liquid composite membranes.

Catalytic degradation of waste rubbers and plastics over zeolites to produce aromatic hydrocarbons

Catalytic conversion of waste rubbers and plastics into aromatic hydrocarbons is a promising approach to waste management and energy recovery. In the present study, acidic HY zeolites were supported by cobalt, iron, and zirconium, and the catalysts were characterized by powder X-ray diffraction, nitrogen adsorption-desorption, ammonia temperature programmed desorption, X-ray photoelectron spectroscopy, and pyridine-Fourier transform infrared spectroscopy. The catalytic degradation of waste polybutadiene rubbers (BR) was conducted to investigate the degradation mechanism and evaluate the catalytic activity of supported zeolites. Experimental results indicated that HY loaded by zirconium and iron led to a higher content of Lewis acid sites as opposed to cobalt supported one. Compared with the non-catalytic pyrolysis of BR, the zirconium supported HY (Zr/HY) led to a 10-fold increase in aromatic hydrocarbons production with a distinctively high selectivity of 97.9%. A series of waste polymers including waste tires (WT), polyethylene (PE), polycarbonate (PC), and BR, were subjected to catalytic pyrolysis to explore the effects of polymer type on aromatic hydrocarbons generation, and BR was the most effective substrate, with yield enhancement reaching 2.4 over Zr/HY. Catalytic co-pyrolysis of waste rubbers and plastics was conducted to probe the effect of polymer structure on aromatic hydrocarbons formation, where a significant synergistic effect was observed in the PE co-fed with PC run.

Effect of Host-Guest Complexation on the Thermoresponsive Behavior of Poly(oligo ethylene glycol acrylate)s Functionalized with Dialkoxynapththalene Guest Side Chains.

The combination of thermoresponsive polymers with supramolecular host-guest interactions enables accurate tuning of the phase transition temperature, while also providing additional response mechanisms based on host-guest complexation. Most studies focused on a single thermoresponsive polymer to demonstrate the effect of host-guest complexation on the responsive behavior. In this work, the effect of the polymer structure on the host-guest complexation and thermoresponsive behavior is reported. Therefore, different poly(oligoethylene glycol acrylate)s, namely, poly(2-hydroxyethylacrylate) (PHEA), poly(methoxy diethylene glycol acrylate), poly(methoxy triethylene glycol acrylate), and poly(methoxy tetraethylene glycol acrylate), are synthesized functionalized with 1,5-dialkoxynaphthalene guest molecules in the side chain. Their complexation with the cyclobis(paraquat-p-phenylene) tetrachloride host is studied to understand the effect of polymer structure on the supramolecular association and the polymer phase transition, revealing that the oligoethylene glycol side chains lead to weaker host-guest complexation and also have a smaller increase in the cloud point temperature compared to PHEA.