Use Of Copolymers Research Articles

Exploring the Origins of Low-Temperature Thermochromism in Polydiacetylenes.

This review article delves into the intriguing phenomenon of low-temperature thermochromism, whereby materials change color in response to temperature variations, with a particular focus on its applications in temperature-sensitive fields like medical storage. By closely examining thermochromic materials, this article highlights their potential to offer innovative solutions for monitoring and preserving thermolabile products that require strict temperature control. This leads to a special emphasis on polydiacetylenes (PDAs), a class of conjugated polymers with unique low-temperature thermochromic properties, positioning them as promising candidates for reliable temperature indicators. This article then explores the underlying mechanisms for fine-tuning the thermochromic behavior of PDAs, particularly discussing recent advancements in PDA design, such as structural alterations of monomers to achieve low-temperature thermochromism. These modifications, influenced by factors like side-chain length, hydrogen-bonding interactions, and the use of copolymers, are intended to result in irreversible color transitions at specific low temperatures, which is crucial to maintaining the integrity of thermally sensitive products. Finally, this article discusses the potential applications of PDAs as thermochromic sensors in tissue biobanking, where their ability to provide visual indications of temperature fluctuations could significantly enhance the monitoring and management of biological samples.

S/N/O-Enriched Carbons from Polyacrylonitrile-Based Block Copolymers for Selective Separation of Gas Streams.

A series of polyacrylonitrile (PAN)-based block copolymers with poly(methyl methacrylate) (PMMA) as sacrificial bock were synthesized by atom transfer radical polymerization and used as precursors for the synthesis of porous carbons. The carbons enriched with O- and S-containing groups, introduced by controlled oxidation and sulfuration, respectively, were characterized by Raman spectroscopy, scanning electron microscopy, and X-ray photoelectron spectrometry, and their surface textural properties were measured by a volumetric analyzer. We observed that the presence of sulfur tends to modify the structure of the carbons, from microporous to mesoporous, while the use of copolymers with a range of molar composition PAN/PMMA between 10/90 and 47/53 allows the obtainment of carbons with different degrees of porosity. The amount of sacrificial block only affects the morphology of carbons stabilized in oxygen, inducing their nanostructuration, but has no effect on their chemical composition. We also demonstrated their suitability for separating a typical N2/CO2 post-combustion stream.

‘One-pot’ RAFT polymerization and characterization of quasi-block copolymers; a comparison to traditional block copolymer for use as solid polymer electrolytes

This works reports a novel approach at synthesising ionic quasi-block copolymers derived from a polystyrene-block-poly polyethylacrylate(butylimidazolium)bis(trifluromethanesulfonyl)imide block copolymer using a ‘one-pot’ RAFT polymerization technique. Three different quasi-block copolymer were synthesised following a sequential additional method whereby composition was altered through changing the order of monomer addition and the level of monomer conversion. The new quasi-block copolymers were analysed compositionally, thermally and through phase morphology to assess the impact this new synthesis has on polymer control and to determine whether block behaviour is maintained. The results suggests these new quasi-block behave similarly to block copolymers regarding phase behaviour, while offering potential for increased sustainability in the synthesis.

Synthesis and Comparative Study of Polyether-b-polybutadiene-b-polyether Triblock Copolymers for Use as Polyurethanes.

In this paper, the effects of HTPBs with different main-chain microstructures on their triblock copolymers and polyurethane properties were investigated. Three polyether-modified HTPB triblock copolymers were successfully synthesized via a cationic ring-opening copolymerization reaction using three HTPBs with different microstructures prepared via three different polymerization methods as the macromolecular chain transfer agents and tetrahydrofuran (THF) and propylene oxide (PO) as the copolymerization monomers. Finally, the corresponding polyurethane elastomers were prepared using the three triblock copolymers as soft segments and toluene diisocyanate (TDI) as hard segments. The results of an analysis of the triblock copolymers showed that the triblock copolymers had lower viscosity and glass transition temperature (Tg) values as the HTPB 1,2 structure content decreased, although the effect on the thermal decomposition temperature was not significant. An analysis of the polyurethane elastomers revealed that as the content of the 1,2 structure in HTPB increased, its corresponding polyurethane elastomers showed a gradual increase in breaking strength and a gradual decrease in elongation at break. In addition, PU-1 had stronger crystallization properties compared to PU-2 and PU-3. However, the differences in the microstructures of the HTPBs did not seem to have much effect on the surface properties of the polyurethane elastomers.

Toughening of Bio-Based PA6.19 by Copolymerization with PA 6.6 - Synthesis and Production of Melt-Spun Monofilaments and Knitted Fabrics.

This work reports on the synthesis of statistical copolymers of bio-based PA6.19 and PA6.6 together with the production of melt-spun monofilaments for the production of sustainable textile fibers. The plant oil-based 1.19-nonadecanedioic acid is synthesized from bio-derived oleic acid via isomerizing methoxycarbonylation. The homopolymer PA6.19 with a carbon-based bio-content of 72% showsa good elongation at break of 166%, but lower tensile strength than commercial PA6 (43MPa versus 82MPa). Addition of adipic acid to form statistical PA 6.6/6.19 copolymers improves toughness while maintaining the high elongation at break. Two PA6.6/6.19 copolymers with a carbon-based bio-content of 26% and 33% are successfully synthesized and exhibited comparable toughness (94 ± 6MPa and 92 ± 2MPa) to the commercial PA6 (92 ± 15MPa). The bio-based copolymers also exhibit a much lower water uptake than PA 6 and PA 6.6, resulting in a higher dimensional stability. Melt spinning of the oleic acid-based polyamides is successfully carried out to produce monofilaments with sufficient properties for further processing in a knitting process, demonstrating the capabilities of the bio-based PA6.6/6.19 copolymers for use in the textile industry.

Large Transconductance of Electrochemical Transistors Based on Fluorinated Donor-Acceptor Conjugated Polymers.

Organic electrochemical transistors (OECTs) have enormous potential for use in biosignal amplifiers, analyte sensors, and neuromorphic electronics owing to their exceptionally large transconductance. However, it is challenging to simultaneously achieve high charge carrier mobility and volumetric capacitance, the two most important figures of merit in OECTs. Herein, a method of achieving high-performance OECT with donor-acceptor conjugated copolymers by introducing fluorine units is proposed. A series of cyclopentadithiophene-benzothiadiazole (CDT-BT) copolymers for use in high-performance OECTs with enhanced charge carrier mobility (from 0.65 to 1.73 cm2·V-1·s-1) and extended volumetric capacitance (from 44.8 to 57.6 F·cm-3) by fluorine substitution is achieved. The increase in the volumetric capacitance of the fluorinated polymers is attributed to either an increase in the volume at which ions can enter the film or a decrease in the effective distance between the ions and polymer backbones. The fluorine substitution increases the backbone planarity of the CDT-BT copolymers, enabling more efficient charge carrier transport. The fluorination strategy of this work suggests the more versatile use of conjugated polymers for high-performance OECTs.

Synthesis and characterization of a ruthenium-containing copolymer for use as a photoredox catalyst

We present a [Ru(bpy)2(dmbpy)]2+- and pyrene-based photocatalytic PMMA that enables photoredox-energy transfer to achieve the C–H arylation of electron deficient aryl bromides.

Permeability of a Zinc-Methacrylate-Based Self-Polishing Copolymer for Use in Antifouling Coating Materials by Molecular Dynamics Simulations.

Molecular dynamics simulations were used to investigate the solubility and permeability of H2O in a self-polishing copolymer (SPC) with two zinc methacrylate (ZMA) contents (Z2: 2 mol% ZMA; Z16: 16 mol% ZMA) and ethyl acrylate, methyl methacrylate, 2-methoxyethyl acrylate, and butyl acrylate as antifouling agents. Water was found to be more soluble in hydrated Z16 than Z2 because ZMA interacts strongly with H2O. In contrast, the diffusion coefficient of H2O in Z16 is lower than that of Z2 because H2O molecules are more constrained in the former due to strong ZMA/H2O interactions. Z16 was found to be significantly more permeable than Z2 over time. The SPC hydrated region in Z2 tends to expand toward the SPC region, while the analogous region in Z16 swelled toward both the SPC and H2O regions to leach SPC owing to the higher permeation of H2O into the SPC. These results reveal that H2O permeability can be controlled by adjusting the ZMA content, which provides insight into antifouling performance.

Synthesis and characterization of alkyl-methacrylate-maleic anhydride copolymer for use as a biodiesel flow improver

Methacrylic acid was esterified with four alcohols: 1-decanol, 1-dodecanol, 1-tetradecanol, and 1-cetanol. Afterwards, the obtained monomers were copolymerized with maleic anhydride. The synthesized monomers and copolymers were characterized by 1H-NMR (Nuclear magnetic resonance) and Fourier transform infrared (FTIR) spectroscopy. The ability of the obtained copolymers to reduce the pour point of waste cooking oil-based biodiesel was investigated. The results showed that the polymer additive with the alkyl chain C14H29- demonstrated the best flow improvement performance. At a concentration of 1000 ppm, this polymer additive reduced the pour point of waste cooking oil-based biodiesel from 12 to 5oC.In this study,the effect of alkyl chain length, molecular weight, as well as the concentration of the additives on the pour point of biodiesel was also discussed.

Poly(HPMA-co-NIPAM) copolymer as an alternative to polyethylene glycol-based pharmacokinetic modulation of therapeutic proteins

PEGylation is the standard approach for prolonging the plasma exposure of protein therapeutics but has limitations. We explored whether polymers prepared by Reversible Addition-Fragmentation chain-Transfer (RAFT) may provide better alternatives to polyethylene glycol (PEG). Four RAFT polymers were synthesised with varying compositions, molar mass (Mn), and structures, including a homopolymer of N-(2-hydroxypropyl)methacrylamide, (pHPMA) and statistical copolymers of HPMA with poly(ethylene glycol methyl ether acrylate) p(HPMA-co-PEGA); HPMA and N-acryloylmorpholine, p(HPMA-co-NAM); and HPMA and N-isopropylacrylamide, p(HPMA-co-NIPAM). The intravenous pharmacokinetics of the polymers were then evaluated in rats. The in vitro activity and in vivo pharmacokinetics of p(HPMA-co-NIPAM)-conjugated trastuzumab Fab' and full length mAb were then evaluated. p(HPMA-co-NIPAM) prolonged plasma exposure more avidly compared to the other p(HPMA) polymers or PEG, irrespective of molecular weight. When conjugated to trastuzumab-Fab', p(HPMA-co-NIPAM) prolonged plasma exposure of the Fab' similar to PEG-Fab'. The generation of anti-PEG IgM in rats 7 days after intravenous and subcutaneous dosing of p(HPMA-co-NIPAM) conjugated trastuzumab mAb was also examined and was shown to exhibit lower immunogenicity than the PEGylated construct. These data suggest that p(HPMA-co-NIPAM) has potential as a promising copolymer for use as an alternative conjugation strategy to PEG, to prolong the plasma exposure of therapeutic proteins.

Bottlebrush Copolymer as Surface Neutralizer for Vertical Alignment of Block Copolymer Nanodomains in Thin Films.

Herein we designed bottlebrush copolymers for use as a neutral additive to block copolymer (BCP) thin films in which they are segregated to the interfaces via architectural effects and produce nonpreferential interfaces to induce perpendicular orientation of BCP microdomains. Two BCP systems were employed, a conventional poly(styrene-b-methyl methacrylate) (PS-b-PMMA) with relatively low χ and similar surface energies between blocks, and a high χ poly(styrene-b-methacrylic acid) (PS-b-PMAA) with distinct surface energies. The bottlebrushes, with either short side-chains of PS-r-PMMA or PS-r-PMAA random copolymers, were synthesized via ring-opening metathesis polymerization (ROMP). Remarkably, it was observed that the top and bottom interfaces of both BCP films were enriched with bottlebrush copolymers, regardless of the surface energy difference between blocks, hence, vertically oriented microdomains were achieved for both BCP systems. This can be attributed to the screening of polymer interactions by a good solvent during the spin-casting process, allowing architectural effects to play a role in surface segregation of bottlebrush copolymers, as confirmed by contact angle measurements and time-of-flight secondary ion mass spectroscopy (TOF-SIMS). We believe that this concept can be further extended to various applications that require polymer films with functional surfaces.

Irradiation, thermal and mechanical properties of ethylene-tetrafluoroethylene copolymer for use in wings of unmanned aerial vehicle

To study the properties of ethylene-tetrafluoroethylene (ETFE) copolymer materials in wings of unmanned aerial vehicles, electron beam irradiation was performed to prepare the corresponding irradiated ETFE for air atmosphere. All these irradiated samples were characterized by SEM, FTIR, TGA, DSC, flexural fatigue measurement and tensile test. The results revealed that the logarithm of the flexural fatigue of ETFE decreased with the irradiation dose increased, which could be explained by the growing effect of chain scission. The elongation-at-break decreased with the dose increase, while the tensile strength was kept constant. As shown in FTIR results, the scission of the macromolecular chains induced by irradiation resulted in the relative oxidation of groups, such as carbonyl groups. TGA analysis showed that the initial and maximum decomposition temperatures increased with dose increase due to the inherent cross-linking structures. Besides, the number of the crystalline regions with regular formation (such as crystallization temperature, crystallization degree and crystallization enthalpy) decreased with the dose increase as a result of the formation of unsaturated structures after the elimination of HF from the broken chains, which was confirmed by FTIR. It is expected that our findings can provide important information to promote the development of aircraft materials.

Copolymerization of butyl acrylate with methyl methacrylate in a bubble column reactor and the use of copolymer in corrosion protection

In this paper, copolymerization of methyl methacrylate (MMA) with n-butyl acrylate (BA) in a bubble column reactor using benzoyl peroxide as free radical initiator, at a temperature over 85 °C, is presented. This mode of copolymerization keeps an inert atmosphere throughout the entire reaction and contributes to proper mixing of the monomers. Higher pressure of the bubbling ensures the faster contact of the species, and a higher conversion was obtained in a shorter reaction time. The conversion of monomer at 124 Pa after 210 min is total, which is particularly noteworthy due to the absence of residual monomer that represents hazardous compounds, with negative impact upon employees and end-user safety. Higher conversions are obtained at 96 °C, 124 Pa nitrogen bubble pressure, 60/40% moles monomer ratio BA/MMA and 2% POB. The molar mass Mw, Mn and PDI decrease with the increase in temperature quite linearly. In the absence of nitrogen bubbling, the copolymer composition is approximately the same as in the feeding mixture. The corrosion protection efficiency of steel painted with these acrylic coatings was carried out by means of OCP and potentiodynamic polarization testing and electrochemical impedance spectroscopy (EIS).

π-Extended donor-acceptor conjugated copolymers for use as hole transporting materials in perovskite solar cells

Abstract We introduced 3-octylthiophene (OT) or 3-octylthieno [3,2-b]thiophene (OTT) as π-bridges into PBT (poly(1-(4,8-bis(5- (2-ethylhexyl)selenophen-2-yl)benzo[1,2-b:4,5-b']dithiophen-2-yl)-5-(2-butyloctyl)-4H-thieno[3,4-c]pyrrole-4,6(5H)-dione), which is based on benzodithiophene and thienopyrrolodione units, in order to prepare thiophene-based π-bridging donor-acceptor conjugated copolymers for use as hole-transport layers in perovskite solar cells (PeSCs). The resulting polymers exhibit strengthened intermolecular π-π stacking and increased crystallinity (dominant face-on orientation), which facilitates vertical charge transport and hole mobility. Moreover, the highest occupied molecular orbital level of PBT-OTT is similar to the valence band of the perovskite material. As a result, efficient hole extraction occurs with reduced charge carrier recombination in PBT-OTT-based PeSCs. Therefore, the introduction of π-bridges to extend the π-conjugation length of conjugated polymers is a promising strategy for the development of efficient hole-transporting materials for use in PeSCs.

Functionalization of electrospun PLA fibers using amphiphilic block copolymers for use in carboxy-methyl-cellulose hydrogel composites

Carboxy-methyl-cellulose (CMC) hydrogels, prepared in the presence of a crosslinker and photoinitiator, were reinforced with 3.7 wt% electrospun PLA fibers to create CMC hydrogel composites. To improve fiber-matrix adhesion, electrospun fiber mats based on hybrids of PLA and amphiphilic block copolymer (BCP) poly(D,L-lactide)-block-poly[2-(dimethylamino)ethyl methacrylate] (PLA-b-PDMAEMA) were produced. The presence of PDMAEMA at the fiber surface induced hydrophilic surface properties, which could be controlled by varying the PDMAEMA chain length. PDMAEMA was quaternized and co-electrospun with PLA fibers, which further enhanced the interaction between fibers and hydrogel matrix via ionic interactions. Physicochemical properties of the electrospun fiber mats and their CMC hydrogel based composites were assessed and revealed a nearly two orders of magnitude increase in modulus. Continuous electrospun fiber mats were chopped into discontinuous fibers to create short fiber reinforced CMC hydrogels. Rheological properties of these reinforced hydrogels incorporating 0.5 wt% discontinuous fibers were evaluated and showed potential as injectable composite systems for biomedical applications.

An optical sensor for the detection and quantification of lidocaine in cocaine samples.

An optical sensor (OS) was synthesized by mixing 10,12-pentacosadiinoic acid (PDA) with a triblock copolymer for use in the detection/quantification of lidocaine (LD) in seized cocaine hydrochloride (seized CH) samples. In the presence of LD, the OS presented a chromatic transition from blue to red, while no chromatic transition was observed for other typical cocaine adulterants or cocaine hydrochloride. Isothermal titration calorimetry analysis revealed specific interactions between the PDA molecules of the OS and the LD molecules, with these interactions being enthalpically favorable (-1.20 to -36.7 kJ mol-1). Therefore, the OS color change only occurred when LD was present in the sample, making the OS selective for LD. Consequently, LD was successfully detected in seized CH samples, irrespective of the type of adulteration. The OS was used for the quantification of LD in seized CH samples containing different adulterants, providing a linear range of 0.0959 to 0.225% (w/w), a precision of 7.2%, an accuracy ranging from -10 to 10%, and limits of detection and quantification of 0.0110% (w/w) and 0.0334% (w/w), respectively.

Use of copolymer of vinyl chloride with vinyl acetate as a compatibilizer of polyvinyl chloride with low density polyethylene

The influence of a vinyl chloride – vinyl acetate copolymer on the compatibility of polyvinyl chloride and low density polyethylene in the production of rigid PVC films by the calender method is considered.

Poly(phenylene methylene)-Based Coatings for Corrosion Protection: Replacement of Additives by Use of Copolymers

Poly(phenylene methylene) (PPM) is a thermally stable, hydrophobic, fluorescent hydrocarbon polymer. Recently, blended PPM has been proposed as a valuable anti-corrosion coating material, and, in particular, rheological additives such as external plasticizers resulted crucial to prevent crack formation. Accordingly, to avoid common problems related to the use of external plasticizers, the development of PPM-related copolymer-based coatings containing n-octyloxy side chains and their anti-corrosion behavior were explored in this study. The aluminum alloy AA2024, widely employed for corrosion studies, was selected as a substrate, covered with a thin layer of a polybenzylsiloxane in order to improve adhesion between the underlying hydrophilic substrate and the top hydrophobic coating. Gratifyingly, coatings with those copolymers were free of bubbles and cracks. The n-octyloxy side-chains may be regarded to adopt the role of a bound plasticizer, as the glass transition temperature of the copolymers decreases with increasing content of alkoxy side-chains. Electrochemical corrosion tests on PPM-substituted coatings exhibited good corrosion protection of the metal surface towards a naturally aerated near-neutrally 3.5% wt.% NaCl neutral solution, providing comparable results to blended PPM formulations, previously reported. Hence, the application of rheological additives can be avoided by use of proper design copolymers.

Manufacturing of polypyrrole-FeOOH supercapacitors

ABSTRACTThe low capacitance of charge storage materials for negative electrodes of supercapacitors (SCap) is a bottleneck in the manufacturing of asymmetric SCap with high operation voltage and high power. Polypyrrole (PPR)-FeOOH-carbon nanotube (NT) electrodes with high electrochemically active material mass (AM) of 32 mg cm−2 are manufactured for operation in a negative potential range. The manufacturing method involves the use of copolymer of styrenesulfonic and maleic acids (PSAMA) as a new poly-charged dopant for PPR and pyrocatechol violet (PCV) as a co-dispersant for NT and FeOOH. PPR-FeOOH-NT electrodes show enhanced properties in the negative potential range, compared to PPR-NT electrodes. A capacitance (CS) of 3.8 F cm−2 is obtained for PPR-FeOOH-NT electrodes with PPR:FeOOH mass ratio of 7:2. The electrodes offer advantages of low resistance and high ratio of AM to conductive support mass. The CS of negative PPR-FeOOH-NT electrodes matches the CS of positive MnO2-NT electrodes of the same AM. Asymmetric SCap is fabricated, which shows high capacitance in a voltage range of 0–1.6 V and low resistance, high power, and energy, which make it important for industrial SCap applications.

Understanding the effect of copolymer content on the processability and mechanical properties of polyhydroxyalkanoate (PHA)/wood composites

The present study investigates the effects of copolymer composition on the mechanical properties of extruded mixed culture poly(3-hydroxybutyrate-co-3-hydroxyvalerate) (PHBV) and poly(3-hydroxybutyrate-co-4-hydroxybutyrate) (P3HB4HB) copolymers and their composites with 50 wt% wood flour. The use of copolymers with a higher strain at break (i.e. 24 mol% 3-HV and 15 mol% 4-HB copolymers) for composite production resulted in a slight but promising improvement in strain at break at the cost of lower strength and modulus. The inclusion of 4-HB comonomer was more effective at improving the strain at break of the composites than for the 3-HV comonomer due to the inability of the 4-HB monomer unit to co-crystallise. However, unlike for the tensile properties, the matrix properties did not affect the composite impact strength. It is interpreted that the mechanical properties of the PHA-based WPCs with 50 wt% wood content are dominated by the rigid and brittle wood flour, with the matrix properties having limited influence on the bulk composite properties.