Physical Properties Of Polymers Research Articles

Correction to “Lower Critical Solution Temperature in Polyelectrolyte Complex Coacervates”

ADVERTISEMENT RETURN TO ISSUEPREVCorrectionNEXTORIGINAL ARTICLEThis notice is a correctionCorrection to “Lower Critical Solution Temperature in Polyelectrolyte Complex Coacervates”Samim AliSamim AliMore by Samim Alihttps://orcid.org/0000-0002-4607-0210, Markus BleuelMarkus BleuelMore by Markus Bleuel, and Vivek M. Prabhu*Vivek M. PrabhuMore by Vivek M. Prabhuhttps://orcid.org/0000-0001-8790-9521Cite this: ACS Macro Lett. 2021, 10, 12, 1636Publication Date (Web):December 6, 2021Publication History Received22 November 2021Published online6 December 2021Published inissue 21 December 2021https://doi.org/10.1021/acsmacrolett.1c00727Copyright © 2021 American Chemical SocietyRIGHTS & PERMISSIONSArticle Views531Altmetric-Citations1LEARN ABOUT THESE METRICSArticle Views are the COUNTER-compliant sum of full text article downloads since November 2008 (both PDF and HTML) across all institutions and individuals. These metrics are regularly updated to reflect usage leading up to the last few days.Citations are the number of other articles citing this article, calculated by Crossref and updated daily. Find more information about Crossref citation counts.The Altmetric Attention Score is a quantitative measure of the attention that a research article has received online. Clicking on the donut icon will load a page at altmetric.com with additional details about the score and the social media presence for the given article. Find more information on the Altmetric Attention Score and how the score is calculated. Share Add toView InAdd Full Text with ReferenceAdd Description ExportRISCitationCitation and abstractCitation and referencesMore Options Share onFacebookTwitterWechatLinked InReddit PDF (453 KB) Get e-AlertsSUBJECTS:Polymer solutions,Anions,Physical and chemical properties,Polyelectrolytes,Polymers Get e-Alerts

Erratum to: Possibilities of Combining Water Permeability with Various Physical Properties of Polymers

Erratum to: Possibilities of Combining Water Permeability with Various Physical Properties of Polymers

Light‐Fueled Climbing of Monolithic Torsional Soft Robots via Molecular Engineering

Azobenzene‐functionalized liquid crystalline polymer networks (azo‐LCNs) are promising candidates for light‐fueled contactless manipulation of miniaturized soft robots through embedding photoactive molecular switches into alignment‐programmable LCNs. In particular, the 3D helical geometry of azo‐LCNs is reported to achieve rapid photomotility by introducing rolling resistance. However, the maximum height of the obstacle that soft robot can overcome is limited by the helix diameter and the stress–strain responsivity. Herein, the helical diameter per unit length and photogenerated stress through molecular engineering of photoactive molecular switches are maximized. The carbon number of aliphatic spacers in the photoactive molecular switches is varied from two to eight to systematically investigate the structure–property–performance relations by studying the molecular geometry, physical properties of polymers, and photomotility of polymers. Furthermore, a finite‐element analysis simulation is presented to understand the rolling locomotion of helical torsional soft robots. Through molecular engineering, the helix diameter per unit length of 0.2 mg soft robots is maximized, demonstrating high Young's modulus (≈2 GPa) and photogenerated stress (>1 MPa), as well as large velocity per body length, compared with the previously reported soft robots. Finally, the molecularly engineered soft robots successfully climb stairs, which is a key task in robotic systems.

Balancing Degradability and Physical Properties of Amorphous Poly(d,l‐lactide) by Making Blends

AbstractThe problem in using the existing biodegradable polymers for day‐to‐day commodity and specialty applications (non‐physiological) is the trade‐off between the degradability and physical properties of polymers. Therefore, the authors study the properties of polyester films made by solution blending of amorphous poly(d,l‐lactide) and semi‐crystalline poly(l,l‐lactide) (PLLA) with an aim to achieve a good balance of mechanical properties and degradability under environmental conditions. The degradation test using proteinase K enzyme shows faster degradation of blends in comparison to homopolymers by weight loss. Faster fragmentation of blends and fragments of lower masses in comparison to PLLA is also seen in immature compost with bulk degradation as the main mechanism of degradation. A detailed investigation shows increased crystallinity and the formation of crystalline stereo‐complex in fragmented samples that may limit degradation after a stage causing microplastics persisting for a longer period. Therefore, further degradation studies in compost for at least 8–10 weeks are recommended. Other environmental sinks, such as activated sludge water, fresh, and seawater, provide either extremely slow or no degradation excluding the use of such blends for applications intended for these sinks. In future, smart solutions are required to enhance the degradation of polylactide in different environmental sinks.

How rigid are conjugated non‐ladder and ladder polymers?

AbstractPersistence length is commonly used to quantitatively describe the chain rigidity of macromolecules, which represents an important structural parameter governing many physical properties of polymers. Although the mathematical models and experimental measurements on the chain rigidity of conventional single stranded polymers have been well explored and documented, those of the more rigid yet highly intriguing multiple stranded polymers, especially conjugated ladder polymers, are yet not well established. This article introduces the fundamental concepts on macromolecular chain rigidity, as well as the corresponding experimental methods, models, and simulations. Subsequently, representative examples of works done on the chain rigidity of nonladder conjugated polymers and conjugated ladder polymers are reviewed. Last but not least, it provides outlooks on the challenges with respect to the less‐investigated chain rigidity of conjugated ladder polymers, including new models to describe and predict chain conformation, synthetic control on structural defects, and insights into the correlation of rigidity and applications.

An effect of crystallographic distortion on carrier mobility in poly(3-hexylthiophene) thin films

The aggregation states and physical properties of polymers in thin films deviate from those found in the bulk. Although an effect of the thickness on the carrier mobility for thin films of poly(3-hexylthiophene) (P3HT) has been widely studied, there is a lack of discussion in terms of crystallographic distortion. Here, we demonstrate how the out-of-plane hole mobility in P3HT, which is a typical semiconducting polymer, changes with decreasing film thickness. Time-of-flight measurements with an analysis using the Gaussian disorder model revealed that the zero-field out-of-plane hole mobility decreased with decreasing thickness because of an increase in the energetical and spatial distribution of hopping sites. Grazing incidence wide-angle x-ray diffraction measurements revealed that such distributions of charge carriers were induced by the crystallographic distortion of P3HT in the thin films.

Connection of water permeability with a number of physical properties of polymers

Currently, methods for predicting the properties of polymers are very popular, since they simplify the work of synthetic chemists. Instead of lengthy and time-consuming experiments, many properties of polymers can be predicted in advance based on their chemical structure. Naturally, such tasks must be computerized so that the properties are predicted after the chemical structure of the repeating polymer unit is displayed on the display screen. This is the so-called direct task. The inverse problem is more complex and interesting. It consists in entering the intervals of the desired characteristics into the computer. Then computer synthesis of polymers possessing these characteristics are realized. The work consists in writing a computer program that allows the computer synthesis of polymers of different classes with specified intervals of water permeability. These classes include polyurethanes, polysulfones, polysulfides, polyethers and polyesters, polyamides, polyketones and polyethyrketones, polycarbonates, polyolefins, vinyl polymers, polystyrene, acrylic and methacrylic polymers. On the basis of this program, water permeability compatibility diagrams are constructed with various physical characteristics of polymers – glass transition temperature, temperature of the onset of intensive thermal degradation, cohesion energy, density, solubility parameter (Hildebrand parameter).

Impact of Nanosized CuO Insertion on Structural and Mechanical Properties of PVA: HPMC Based Polymer Blend Nanocomposites

Insertion of metal-oxide nanoparticles to polymers stipulate the modification of physical properties of polymers over and above the accomplishment of new features in the polymer matrix. In the current study, an attempt was made to disperse the CuO nanoparticles in the polyvinyl alcohol and hydroxypropyl methylcellulose (HPMC) blend to investigate the structural, mechanical and optical properties of the nanocomposite. Blend was prepared in different ratios using PVA and HPMC, viz. 25:50, 50:50 and 75:25 wt%. The CuO nanoparticles were added to the 75:25 PVA:HPMC blend in different percentage like 0.5,1 and 1.5%. The polymer with and without CuO incorporation were subjected to X-ray diffraction, Fourier transform infrared spectroscopy, scanning electron microscopy, UV-visible spectral analyses and mechanical strength, etc. The results revealed that the incorporation of the CuO nanoparticles enhanced the structural and mechanical properties of the polymer by forming successful nanocomposite.

An unusually stable solid state Ag|AgCl reference electrode for long term continuous measurements based on a crosslinked poly(vinyl acetate)/KCl composite

Electrochemical measurements are attractive for continuous or long-term monitoring of chemical species in a range of analytical applications including health, environmental and agricultural monitoring, as well as food analysis and industrial process control. A significant barrier to long-term electrochemical measurements in continuous online monitoring applications is the requirement for stable and durable reference electrodes. Most reference electrodes require regular maintenance in such situations to maintain the concentration of the internal electrolyte reservoir and prevent fouling of the electrode. Solid state reference electrodes (SSREs) are well suited to these long-term monitoring applications, but most only have their short-term performance reported or are designed for disposable applications. Additionally, polymer crosslinking has been demonstrated as an effective way to slow leakage of suspended solutes, improve chemical resistance, and control a polymer's physical properties; but application of this technique in SSRE materials is yet to be reported. This work describes the construction and performance of a novel SSRE with exceptional long-term stability, using an ethylene glycol dimethacrylate (EGDMA) crosslinked PVAc/KCl composite material. Open circuit potentiometry and electrochemical impedance spectroscopy were used to study the electrochemical performance. Conductivity measurements and micro X-ray fluorescence mapping were used to examine the effect of EGDMA crosslinking on electrolyte leakage and electrode lifetime. A SSRE with a 1% molar ratio of EGDMA/vinyl acetate proved to be exceptionally stable and provided a reliable reference potential for at least 175 days in a 1 M Na2SO4 solution. PVAc/KCl composites without crosslinker were found to leak electrolyte ca. 30% faster than those with 1% EGDMA. EGDMA crosslinking also was shown to improve electrochemical performance and SSRE lifetime in both highly acidic and strongly alkaline solutions, suggesting a broad range of applications. Additionally, a 1% crosslinked SSRE demonstrated comparable performance to a commercial reference electrode in potentiometric and voltammetric measurements. The results demonstrate that crosslinked polymer-electrolyte composites provide a promising new approach for improving reference electrode performance in electrochemical measurements, particularly in continuous long-term online monitoring applications.

Synthesis and characterization of substrates for grafting polymers used in medical plastics

Abstract This synthetic overview describes the formation and characterization of branched substrates for future use in obtaining graft copolymers with characteristics appropriate for medical plastics. Due to the critical necessity of medical devices, optimization of materials used in their production is of substantial interest. The substrate synthesis was varied by utilizing reactants with different heteroatoms (e.g., diols, dithiols) and chain lengths. Although sixteen new molecules were synthesized and confirmed by high resolution mass spectrometry (HRMS), the reaction conditions and purification methodology require further optimization before subsequent use. The objective of this research was to synthesize novel substrates for altering the physical properties of polymers used for clinical applications. Experimental results and crude spectral data analysis are provided herein for newly synthesized compounds.

Direct observation of morphological transition for an adsorbed single polymer chain

A better understanding of the structure of polymers at solid interfaces is crucial for designing various polymer nano-composite materials from structural materials to nanomaterials for use in industry. To this end, the first step is to obtain information on how synthetic polymer chains adsorb onto a solid surface. We closely followed the trajectory of a single polymer chain on the surface as a function of temperature using atomic force microscopy. Combining the results with a full-atomistic molecular dynamics simulation revealed that the chain became more rigid on the way to reaching a pseudo-equilibrium state, accompanied by a change in its local conformation from mainly loops to trains. This information will be useful for regulating the physical properties of polymers at the interface.

ChemEscape, Polymer Chemistry: Solving Interactive Puzzles Featuring Scaffolded Learning to Promote Student Understanding of Polymers and Structure–Property Relationships

The introduction of polymer chemistry in undergraduate science courses is becoming more popular in recent years, introducing content into the relationships between polymer structure and physical properties in a variety of contexts. However, active learning techniques, outside of laboratory experience, for teaching polymer chemistry are extremely limited. The ChemEscape project has successfully integrated escape-room type puzzle design and course specific learning objectives into an interactive learning experience. The novel battle box design, a self-contained puzzle unit, allows for puzzles to be easily transported and applied as a teaching tool in large postsecondary classrooms as well as an outreach tool. Herein, we describe the design and application of a series of new polymer puzzles, focusing on tacticity, elasticity, and hydrophobicity, into the battle box design as well as an all-in-one backdrop design. Puzzles are scaffolded to allow for all learning to be combined in the final puzzle solution as well as a workbook provided for participants to record observations and learning during the puzzles’ solutions.

Highly active and thermo‐stable iminopyridyl vanadium oxychloride catalyzed isoprene polymerization

AbstractStereoregular polymerizations are of high importance, which disclosing the relationships between microstructures and physical properties of polymers. In this contribution, a series of iminopyridyl vanadium oxychloride complexes V1–V8 (R = H, R1 = CH2Ph for V1; R = H, R1 = CHPh2 for V2; R = H, R1 = octamyl for V3; R = H, R1 = Ph for V4; R = H, R1 = 4‐OMe‐C6H4 for V5; R = H, R1 = 4‐CF3C6H4 for V6; R = H, R1 = 2,4,6‐Ph3C6H2 for V7 and R = Me, R1 = Ph for V8) have been prepared, and were investigated for their catalytic capacity of isoprene polymerization. A single crystal structure of V7′ was reported, which was reduced from V(v) to V(iv) in the oxidation state of vanadium central atom. The catalytic activity was up to 408 kg (mol V)−1 hr−1, when V4 was used. The catalyst V6 was found to be highly thermo‐stable with excellent activity even at 100°C. Most importantly, resultant polymers mainly possessed cis‐1,4 units (up to 75%) with 25% side‐chain 3,4 functional group, which is particularly important component to enhance the application of these synthetic rubbers.

Modeling temporal and spatial changes during hydrolytic degradation and erosion in biodegradable polymers

This paper presents a computational model in describing the spatial and temporal changes in the chemical and physical characteristics of biodegradable polymer solids during hydrolytic degradation and erosion processes. A set of coupled governing differential equations are formulated to account for the diffusion of water molecules into the polymers, scission kinetics from a hydrolytic process, formation of monomers, and diffusion of the soluble monomers out of the polymer body. A multi-network model is adopted for capturing the hydrolytic scission, in which a long polymeric chain is being converted to monomers and byproducts. As the monomers leave the polymer body, surface and bulk erosion mechanisms are described and changes in the shape and size of the polymer body also take place. The governing differential equations are solved using a finite difference approach. It is noted that hydrolytic degradation induces temporal and spatial changes in the chemical and physical properties of polymers; and thus, the polymers that are initially homogeneous with regards to the above properties become heterogeneous due to the spatial changes in their macromolecular networks during biodegradation. The responses obtained from the model are compared with available experimental data of PLGA biodegradable polymer.

NMR relaxometry of oil paint binders.

Mobile nuclear magnetic resonance (NMR) is a flexible technique for nondestructive characterization of water in plants, the physical properties of polymers, moisture in porous walls, or the binder in paintings by relaxation measurements. NMR relaxation data report material properties and therefore can also help to characterize the state of tangible cultural heritage. In this work, we discuss the relaxation behavior in two series of naturally aged paint mock-up samples. First, paints with different pigment concentrations were prepared and investigated in terms of the longitudinal and transverse relaxation-time distributions. We document the evolution of both relaxation-time distributions during the initial drying stage and demonstrate the heightened importance of transverse over longitudinal relaxation measurements. Second, we observe nonlinear dependences of the relaxation times on the pigment concentration in a typical oil binder. Third, in a study of naturally aged paint samples prepared in the years between 1914 and 1951 and subsequently aged under controlled conditions, we explore the possibility of determining the age of paintings using partial least square regression (PLS) by fitting T1 -T2 data with the sample age. Our results suggest some correlation, albeit with significant scatter. Estimating the age of a painting stored under unknown conditions from NMR relaxation data is therefore not feasible, as the cumulative effects of light irradiation, humidity, and biological degradation further obfuscate the chemical and physical impact of aging on the relaxation times in addition to the impact of pigment concentration.

Physical Properties of Polymers Under Soft and Hard Nanoconfinement: A Review

Polymeric materials under nanoconfinements have substantially deviated physical properties with respect to the bulk, especially glass transition temperature, physical aging, and crystallization behavior. Here we highlight the leading methods for creating various confinement systems. Upon these systems, recent advances on hard and soft confinement effect for glass transition, physical aging, mechanical properties and crystallization of polymers are reviewed in details. Furthermore, as nanoconfined systems in extreme conditions are experimentally inaccessible, simulation results describing confinement effect on such systems are also discussed.

Controlling polymer properties through the shape of the molecular-weight distribution

The manipulation of a polymer’s properties without altering its chemical composition is a major challenge in polymer chemistry, materials science and engineering. Although variables such as chemical structure, branching, molecular weight and dispersity are routinely used to control the architecture and physical properties of polymers, little attention is given to the often profound effect of the breadth and shape of the molecular-weight distribution (MWD) on the properties of polymers. Synthetic strategies now make it possible to explore the importance of parameters such as skew and the higher moments of the MWD function beyond the average and standard deviation. In this Review, we describe early accounts of the effect of MWD shape on polymer properties; discuss synthetic strategies for controlling MWD shape; describe current endeavours to understand the influence of MWD shape on rheological and mechanical properties and phase behaviour; and provide insight into the future of using MWDs in the design of polymeric materials. Controlling polymerization is required to fully understand and tune the function of a polymer. Alongside variables such as dispersity, molecular weight and chemical composition, the shape of the molecular-weight distribution has substantial influence on polymer properties. In this Review, we discuss methods to systematically control the shape of a polymer’s molecular-weight distribution, as well as explore the profound effects of shape on polymer properties.

Online simulation powered learning modules for materials science

Simulation tools are playing an increasingly important role in materials science and engineering and beyond their well established importance in research and development, these tools have a significant pedagogical potential. We describe a set of online simulation tools and learning modules designed to help students explore important concepts in materials science where hands-on activities with high-fidelity simulations can provide insight not easily acquired otherwise. The online tools, which involve density functional theory and molecular dynamics simulations, have been designed with non-expert end-users in mind and only a few clicks are required to perform most simulations, yet they are powered by research-grade codes and expert users can access advanced options. All tools and modules are available for online simulation in nanoHUB.org and access is open and free of charge. Importantly, instructors and students do not need to download or install any software. The learning modules cover a range of topics from electronic structure of crystals and doping, plastic deformation in metals, and physical properties of polymers. These modules have been used in several core undergraduate courses at Purdue’s School of Materials Engineering, they are self contained, and are easy to incorporate into existing classes.

Conjugated Carbon Cyclic Nanorings as Additives for Intrinsically Stretchable Semiconducting Polymers.

Molecular additives are often used to enhance dynamic motion of polymeric chains, which subsequently alter the functional and physical properties of polymers. However, controlling the chain dynamics of semiconducting polymer thin films and understanding the fundamental mechanisms of such changes is a new area of research. Here, cycloparaphenylenes (CPPs) are used as conjugated molecular additives to tune the dynamic behaviors of diketopyrrolopyrrole-based (DPP-based) semiconducting polymers. It is observed that the addition of CPPs results in significant improvement in the stretchability of the DPP-based polymers without adversely affecting their mobility, which arises from the enhanced polymer dynamic motion and reduced long-range crystalline order. The polymer films retain their fiber-like morphology and short-range ordered aggregates, which leads to high mobility. Fully stretchable transistors are subsequently fabricated using CPP/semiconductor composites as active layers. These composites are observed to maintain high mobilities when strained and after repeated applied strains. Interestingly, CPPs are also observed to improve the contact resistance and charge transport of the fully stretchable transistors. ln summary, these results collectively indicate that controlling the dynamic motion of polymer semiconductors is proved to be an effective way to improve their stretchability.

Direct estimation of polymer crystallinity with Raman spectroscopy using ratio of scattering cross-sections estimated from variable temperature measurements.

Physical properties of polymers (e.g. crystallinity, lamella thickness, thermodynamic properties etc.) can in principle be reliably estimated from their Raman spectral intensities by converting intensities to corresponding concentrations of conformers. However, such conversions are not straightforward due to the unknown scattering cross-sections. The study demonstrates that for several practical applications of Raman spectroscopy, a ratio of cross-sections can be used instead of the absolute values. A straight forwards method for accurately estimating ratio of scattering cross-section from variable temperature measurements is described here. In order to demonstrate its applicability, percent crystallinity (PC) of polyethylene has been directly estimated from Raman intensities without external calibration with other techniques. This general method can be applied to any polymer when there is a continuous change in composition of conformers over a range of temperatures.