Structure Of Copolymers Research Articles

Toward the production of block copolymers in microbial cells: achievements and perspectives.

The microbial production of polyhydroxyalkanoate (PHA) block copolymers has attracted research interests because they can be expected to exhibit excellent physical properties. Although post-polymerization conjugation and/or extension have been used for PHA block copolymer synthesis, the discovery of the first sequence-regulating PHA synthase, PhaCAR, enabled the direct synthesis of PHA-PHA type block copolymers in microbial cells. PhaCAR spontaneously synthesizes block copolymers from a mixture of substrates. To date, Escherichia coli and Ralstonia eutropha have been used as host strains, and therefore, sequence regulation is not a host-specific phenomenon. The monomer sequence greatly influences the physical properties of the polymer. For example, a random copolymer of 3-hydroxybutyrate and 2-hydroxybutyrate deforms plastically, while a block copolymer of approximately the same composition exhibits elastic deformation. The structure of the PHA block copolymer can be expanded by in vitro evolution of the sequence-regulating PHA synthase. An engineered variant of PhaCAR can synthesize poly(D-lactate) as a block copolymer component, which allows for greater flexibility in the molecular design of block copolymers. Therefore, creating sequence-regulating PHA synthases with a further broadened substrate range will expand the variety of properties of PHA materials. This review summarizes and discusses the sequence-regulating PHA synthase, analytical methods for verifying block sequence, properties of block copolymers, and mechanisms of sequence regulation. KEY POINTS: • Spontaneous monomer sequence regulation generates block copolymers • Poly(D-lactate) segment can be synthesized using a block copolymerization system • Block copolymers exhibit characteristic properties.

Functional copolymer coatings on electrospun fibers via photo‐initiated chemical vapor deposition

AbstractWith the increasing use of implantable patches in biomedical applications, the significance of surface modification techniques in improving biocompatibility, enhancing adhesion, and regulating drug release has grown. A significant challenge that these methods must address is ensuring that the process does not harm the delicate fibers or therapeutic agents they contain. Here, we report surface functionalization of implantable, curcumin loaded Polycaprolactone (PCL) patches with pH‐responsive poly(2‐hydroxyethyl methacrylate‐co‐4‐vinylpyridine), p(HEMA‐co‐4VP) polymer thin film. The polymer was coated on the patch surface via photo‐initiated chemical vapor deposition (piCVD) where the polymerization was initiated by the UV degradation of the initiator tert‐butyl peroxide (TBPO) and the monomer HEMA. Additionally, the piCVD method was utilized to crosslink the HEMA without the use of additional crosslinkers. The pH‐responsiveness of the coating was achieved by incorporating 4VP into the copolymer structure. The effect of the coating was demonstrated through degradation and drug release studies. The presence of the polymer coating decelerated the fiber degradation and the pH‐dependent swelling of the coating allowed for the control of drug release rates from the patches. The innovative use of piCVD as a coating method provides a platform for advancing tailored surface modifications in various biomedical applications.

Hierarchical structure of poly(ε-caprolactone) crystals on its copolymer poly(l-lactide-co-ε-caprolactone) fibers

In crystallization, heterogeneous structures of copolymers are employed to establish a hierarchical architecture comprising two polymers, this typically occurs on the surface of block copolymers or blended polymers. While hierarchical structures in block copolymer fibers are well-established and widely utilized, achieving a regular hierarchical structure on random copolymer fibers is both meaningful and challenging. Here, we present a case of forming a hierarchical structure on the surface of the random copolymer poly(L-lactide-co-caprolactone) (PLCL)fibers. The (ε-caprolactone)(CL) polymer chain segments of the random copolymer are released on the surface of the modified copolymer fiber using sodium hydroxide. Subsequently, poly(ε-caprolactone)(PCL) forms a shish kebab-like crystalline structure under the guidance of the CL segments. The CL segments act as crystalline precursors to induce the formation of heterogeneous PLCL/PCL shish kebab structures. The variation of CL segments on the fiber changes with modification time, leading to the formation of crystalline lamellae of different sizes, which had been confirmed by characterization techniques such as scanning electron microscope (SEM), 1H NMR, X-ray photoelectron spectra (XPS), differential scanning calorimetry (DSC), etc. The implementation of this heterogeneous structure provides possibilities for the implementation of hierarchical structure in random copolymers.

Controlling the wax crystallization behaviors via the ratio of phenyl to aliphatic branches in block copolymer synthesized by RAFT copolymerization

AbstractThe precipitation and deposition of waxes in high waxy crude oil often result in the low throughput and clogging of pipeline. Adding polymers is a practical approach to solve these problems. In this study, poly(styrene‐co‐docosyl maleate)s (PSDMs) were synthesized by reversible addition‐fragmentation chain transfer polymerization. The chemical structure and molecular weight of copolymers were characterized using Fourier infrared spectroscopy, 1H nuclear magnetic resonance spectroscopy, and gel permeation chromatography. The ratio of phenyl to aliphatic branches varies from 10:8 to 25:8. The crystallization and morphology of waxes in model oil were investigated by x‐ray diffraction, differential scanning calorimetry, and polarized light microscopy. The cold flow behaviors of crude oil were evaluated by rheological methods. With the increase of the ratio of phenyl to aliphatic branches, the crystallinity, viscosity, and yield stress of crude oil first increase and then decrease. In the presence of PSDM‐2, the crystallinity and enthalpy of phase transition (ΔH) are reduced by 44.2% and 48.9%. Thus, the pour point, viscosity, and yield stress of crude oil are reduced by 6.0°C, 76.8% and 77.4%, respectively. Therefore, well‐defined PSDMs are promising to be remarkable flow improvers for waxy crude oils.

Encounter between Gyroid and Lamellae in Janus Colloidal Particles Self-Assembled by a Rod-Coil Block Copolymer.

Controlling the internal structure of block copolymer (BCP) particles has a significant influence on its functionalities. Here, a structure-controlling method is proposed to regulate the internal structure of BCP Janus colloidal particles using different surfactants. Different microphase separation processes take place in two connected halves of the Janus particles. An order-order transition between gyroid and lamellar phases is observed in polymeric colloids. The epitaxial growth during the structural transformation from gyroid to lamellar phase undergoes a two-layered rearrangement to accommodate the interdomain spacing mismatch between these two phases. This self-assembly behavior can be ascribed to the preferential wetting of BCP chains at the interface, which can change the chain conformation of different blocks. The Janus colloidal particles can further experience a reversible phase transition by restructuring the polymer particles under solvent vapor. It is anticipated that the new phase behavior found in Janus particles can not only enrich the self-assembly study of BCPs but also provide opportunities for various applications based on Janus particles with ordered structures.

Thermodynamically stable plumber's nightmare structures in block copolymers.

Block copolymer self-assembly affords diverse nanostructures, spanning from spheres and cylinders to networks, offering meticulous control over properties and functionalities at the nanoscale. However, creating thermodynamically stable network structures with high packing frustration remains a challenge. In this study, we report a methodology to access diverse network structures such as gyroid, diamond, and primitive phases from diblock copolymers using end group and linker chemistry. The stability of the medial packing of polymer chain ends (plumber's nightmare structure) over skeletal aggregation (gyroid) is attributed to the interplay between the strength of the end-end interactions and the initial shape of the curvature. Our study establishes an approach to develop tailored network structures from block copolymers, providing an important platform for using block copolymers in nanotechnology applications.

Exploiting controlled transesterification as a “top down” approach to tailor poly(ε-caprolactone)-poly(lactic acid) copolymer structures with bis-Zn catalysts

Mediated by a bis-Zn catalyst, poly(lactic acid)-block-poly(ε-caprolactone) diblock copolymers can be modified via controlled transesterification, leading to diverse copolymer structures.

Quantitative comparison of the copolymerisation kinetics in catalyst-transfer copolymerisation to synthesise polythiophenes.

Polythiophenes are one of the most widely studied conjugated polymers. With the discovery of the chain mechanism of Kumada catalyst-transfer polymerisation (KCTP), various polythiophene copolymer structures, such as random, block, and gradient copolymers, have been synthesized via batch or semi-batch (sequential addition) methods. However, the lack of quantitative kinetic data for thiophene monomers brings challenges to experimental design and structure prediction when synthesizing the copolymers. In this study, the reactivity ratios and the polymerisation rate constants of 3-hexylthiophene with 4 thiophene comonomers in KCTP are measured by adapting the Mayo-Lewis equation and the first-order kinetic behaviour of chain polymerisation. The obtained kinetic information highlights the impact of the monomer structure on the reactivity in the copolymerisations. The kinetic data are used to predict the copolymer structure of equimolar batch copolymerisations of the 4 thiophene derivatives with 3-hexylthiophene, with the experimental data agreeing well with the predictions. 3-Dodecylthiophene and 3-(6-bromo)hexylthiophene, which have higher structural similarity to 3-hexylthiophene, show nearly equivalent reactivity to 3-hexylthiophene and give random copolymers in the batch copolymerisation. 3-(2-Ethylhexyl)thiophene with a branched side chain is less reactive compared to 3-hexylthiophene and failed to homopolymerize at room temperature, but produced gradient copolymers with 3-hexylthiophene. Finally, the bulkiest 3-(4-octylphenyl)thiophene, despite its ability to homopolymerize, failed to maintain chain polymerisation in the copolymerisation with 3-hexylthiophene, possibly due to the large steric hindrance caused by the phenyl ring directly attached to the thiophene center. This study highlights the importance of monomer structures in copolymerisations and the need for accurate kinetic data.

Investigating the effect of the micelle structures of block and random copolymers on dye solubilization.

To elucidate the correlation between dye solubilization into micelles and their core-shell aggregated structure, the structures of block and random copolymer micelles were characterized. The block copolymer micelles exhibited a higher dye solubilization capacity which correlated with their core volume, clear core-shell contrast and slow solubilization rate.

Effect of hydrostatic pressure on charge carriers in a conducting pyrrole-co-poly(pyrrole-3-carboxylic) copolymer.

The charge carriers in conducting pyrrole-co-poly(pyrrole-3-carboxylic) were examined using high-pressure Raman spectroscopy. The molecular structure of the new copolymer was investigated using high-resolution 13C ssNMR, 1H-13C 2D NMR correlation spectroscopy, and density functional theory (DFT) calculations. Bands in Raman spectra that showed the presence of polarons and bipolarons were studied. It was observed that the quantity of polarons and bipolarons correlated with the hydrostatic pressure. At a pressure of 4 GPa, an anomaly in the correlation between pressure and the position of the Raman band was identified.

One-pot single-step copolymerization of aromatic trifluorovinyl ethers toward perfluorocyclobutyl (PFCB) segmented copolymers

A segmented PFCB aryl ether copolymer was synthesized directly from two aryl TFVE monomers having different reactivities and the blocky copolymer structure was confirmed by 19F NMR spectroscopic data.

Unveiling the reverse reactivity and composition profile of copolymers from synthesized and separated 3-/7-(prop-2-ynyl)oxepan-2-one isomers: implications for precise polymer structure prediction

The gradient copolymer structure of 3- and 7-(prop-2-ynyl)oxepan-2-one was clearly revealed, rationalized and visualized using the Skeist model.

Polyether-based polyurethane electrolyte for lithium metal battery: a perspective.

Polyurethane (PU)-based electrolyte has become one of the most important research directions because of its unique repeating 'soft-hard' segment co-polymer structure. Its 'soft segment' composition includes polyethylene oxide, polysiloxane, polycarbonate, cellulose and polyether. Among them, polyether-based polyurethane electrolytes (PPES) have the advantages of simple synthesis, molecular structure optimization and functional group modification, which can greatly improve the ionic conductivity of the system and form a good ion transport interface. To date, a few separate and detailed reviews of advances in PPES have been reported. In this paper, the research progress of PPES is reviewed from the aspects of structural design strategy, molecular synthesis, conductivity modification methods, specific functions and interfacial ion transport behavior in lithium metal batteries (LMBs). In addition, the synthetic route of PPES and the development prospect of PPES are discussed. We also provide guidance for developing high-performance PPES for next-generation LMBs.

Synthesizing a Water-Soluble Polymeric Nitrification Inhibitor with Novel Soil-Loosening Ability.

Nitrification inhibitor is essential for increasing the nitrogen utilization efficiency of agricultural plants, thus reducing environmental pollution and increasing crop yield. However, the easy volatilization and limited functional property is still the bottleneck of nitrification inhibitors. Herein, a novel water-soluble polymeric nitrification inhibitor was synthesized through the copolymerization of acrylamide and bio-based acrylic acid, which was synthesized from biomass-derived furfural, and the complexation of carboxyl groups and 3,4-dimethylpyrazole. The results showed that the nitrification inhibitor was an amorphous polymer product with a glass transition temperature of 146 °C and a thermal decomposition temperature of 176 °C, and the content of 3,4-dimethylpyrazole reached 2.81 wt%, which was 115% higher than our earlier product (1.31 wt%). The polymeric nitrification inhibitor can inhibit the activity of ammonia-oxidizing bacteria effectively, thus inhibiting the conversion of ammonium nitrogen to nitrate nitrogen and converting the insoluble phosphate into soluble and absorbable phosphate. By introducing a copolymer structure with a strong flocculation capacity, the polymeric nitrification inhibitor is further endowed with a soil-loosening function, which can increase the porosity of soil to improve the soil environment. Therefore, the nitrification inhibitor can be used in water-soluble and liquid fertilizers, as well as in high tower melting granulated compound fertilizers.

Copolymerization of Industrial Organochlorine Waste with Wood Pyrolysis Products for Bitumen Compositions

The work presents a new approach to the copolymerization and co-processing of industrial organochlorine waste (OCW) resulted in the production of vinyl chloride at Karpatnaftochim LLC, Kalush, Ukraine, and liquid wood pyrolysis products (LWPP) generated by the activated charcoal production at Perechyn Forestry and Chemical Plant, LLC. Kalush, Ukraine. This article highlights studies of the composition of the raw materials and the properties of the resulting products. Through the use of infrared spectroscopy and DTA analysis, the primary structure and properties of copolymers, oligomers, asphalt and bitumen products obtained from OCW and LWPP were determined. It describes the trial of the liquid products of wood pyrolysis in bitumen compositions with OCW.

Improving the properties of polylactic acid/polypropylene carbonate blends through cardanol-induced compatibility enhancement

Cardanol (CD) is used as a reactive compatibilizer, and blended with polylactic acid (PLA) and polypropylene carbonate (PPC) resin (70/30(w/w)) to obtain a series of PLA/PPC/CD blends. The systematic study was conducted on the thermal properties, optical properties, rheological properties, mechanical properties, and microscopic morphology of the blend, by varying amounts of CD added to the blends. A detailed explanation and comprehensive analysis of the reaction mechanism between CD and PLA/PPC have been made. The study found that CD acts as a “bridge” between the PLA and PPC, forming the structure of a block copolymer (PLA-b-CD-b-PPC), and the copolymer can greatly improve the compatibility of PLA and PPC. When the amount of CD reaches 8 wt%, only one Tg is observed in the blend, simultaneously, PLA/PPC has already transitioned from a partially compatible system to a completely compatible system. At the same time, the addition of CD does not have any negative impact on the thermal stability of the PLA/PPC blend under processing temperature conditions, and the thermal stability of the PLA/PPC/CD blends can even be improved under extreme conditions. In addition, the addition of CD allows the PLA/PPC/CD blends to maintain a high light transmittance while reducing the opacity of the blend (the light transmittance remains above 92 %, and the opacity is reduced from 37 % to about 24 %), demonstrating excellent optical properties. Moreover, the elongation at break and impact strength of the PLA/PPC/CD blend both show a trend of first increasing and then decreasing with the increase of CD amount. When the CD amount varies within the range of 6– 8 wt%, the blends undergoes a brittle-ductile transition, and its toughness is greatly improved while the rigidity can also meet practical needs. When the amount of CD in the system increases to 12 wt%, the toughness of the blend reaches its peak, and its elongation at break and impact strength reach 513.24 % and 9211.5 J/m2 respectively (increased to 2442.84 % and 270.73 % of the PLA/PPC blend). Concurrently, the fracture surface of the blend exhibits large-scale plastic flow in the direction of the applied force, with marked shear yield phenomena, showing obvious characteristics of tough fracture.

Synthesis and Properties of Modified Biodegradable Polymers Based on Caprolactone.

In this paper, the synthesis and characterization of two polycaprolactone-polydimethylsiloxane (PDMS-CL) copolymers with biodegradable properties are reported. A comparative study was carried out using an aminopropyl-terminated polydimethylsiloxane macro-initiator (APDMS) with two different molecular weights. The copolymers (PDMS-CL-1 and PDMS-CL-2) were obtained by ring-opening polymerization of ɛ-caprolactone using APDMS as initiators and stannous 2-ethylhexanoate as a catalyst. The copolymer's structures were confirmed by Fourier transform infrared spectroscopy (FT-IR), nuclear magnetic resonance (1H-NMR) spectra, and energy dispersion spectroscopy (EDX). Surface morphology was investigated using scanning electron microscopy (SEM) and atomic force microscopy (AFM). The hydrophobic properties of the copolymers were demonstrated by the water contact angle and water vapor sorption capacity. Additionally, biological tests were conducted on San Marzano type tomato plants (Lypercosium esculentum) to assess the synthesized copolymers' susceptibility to the environment in terms of biological stability and metabolic activity. The biodegradation of PDMS-CL-1 and PDMS-CL-2 copolymers does not have a dangerous effect on the metabolic activity of plants, which makes it a convenient product in interaction with the environment.

In-situ regulation of solid electrolyte interface formation by molecular designing of polymer binders for high-performance silicon/graphite anode

A new acrylic acid copolymer is prepared by free radical copolymerization with acrylic acid (AA) and hexafluoro butyl acrylate (HFA). The product is used as a polymer binder for Silicon/Graphite (Si/Gr) anode in a lithium-ion battery. The molecular structure of the copolymer and the electrochemical performance of binders are carefully investigated. The results show that the Si/Gr anode based on AA-HFA copolymers binders has good rate performance and excellent cycle stability after adjusting the amount of HFA. The initial charge/discharge capacity reachs about 771/914 mAh g−1 during the first charge-discharge cycle. Its Initial Coulomb Efficiencie (ICE) is higher than 84 %. The reversible specific capacity can be maintained to 504 mAh g−1 with in 350 cycles at 1 C, while it can reach 220 mAh g−1 at 5 C. The in-depth analysis further show that this kind of AA-HFA copolymer binder can effectively inhibit electrolyte decomposition since solid electrolyte interphases (SEI) can be constructed at a molecular level. This stable interphases can be attributed to the successful combination of the flexible molecular structure of AA-HFA copolymer with the rigid SEI layer formed between the active material and electrolyte. The success of this work provides a promising way to pursue lithium-ion batteries with long cycle life by molecular designing with polymer binders.

Thermoresponsive Property of Poly(N,N-bis(2-methoxyethyl)acrylamide) and Its Copolymers with Water-Soluble Poly(N,N-disubstituted acrylamide) Prepared Using Hydrosilylation-Promoted Group Transfer Polymerization.

The group-transfer polymerization (GTP) of N,N-bis(2-methoxyethyl)acrylamide (MOEAm) initiated by Me2EtSiH in the hydrosilylation-promoted method and by silylketene acetal (SKA) in the conventional method proceeded in a controlled/living manner to provide poly(N,N-bis(2-methoxyethyl)acrylamide) (PMOEAm) and PMOEAm with the SKA residue at the α-chain end (MCIP-PMOEAm), respectively. PMOEAm-b-poly(N,N-dimethylacrylamide) (PDMAm) and PMOEAm-s-PDMAm and PMOEAm-b-poly(N,N-bis(2-ethoxyethyl)acrylamide) (PEOEAm) and PMOEAm-s-PEOEAm were synthesized by the block and random group-transfer copolymerization of MOEAm and N,N-dimethylacrylamide or N,N-bis(2-ethoxyethyl)acrylamide. The homo- and copolymer structures affected the thermoresponsive properties; the cloud point temperature (Tcp) increasing by decreasing the degree of polymerization (x). The chain-end group in PMOEAm affected the Tcp with PMOEAmx > MCIP-PMOEAmx. The Tcp of statistical copolymers was higher than that of block copolymers, with PMOEAmx-s-PDMAmy > PMOEAmx-b-PDMAmy and PMOEAmx-s-PEOEAmy > PMOEAmx-b-PEOEAmy.

Multifunctional Poly(2-ethyl-2-oxazoline) Copolymers Containing Dithiolane and Pentafluorophenyl Esters as Effective Reactive Linkers for Gold Surface Coatings.

Surface functionalization with biological macromolecules is an important task for the development of sensor materials, whereby the interaction with other biological materials should be suppressed. In this work, we developed a novel multifunctional poly(2-ethyl-2-oxazoline)-dithiolane conjugate as a versatile linker for gold surface immobilization of amine-containing biomolecules, containing poly(2-ethyl-2-oxazoline) as antifouling polymer, dithiolane for surface immobilization, and activated esters for protein conjugation. First, a well-defined carboxylic acid containing copoly(2-ethyl-2-oxazoline) was synthesized by cationic ring-opening copolymerization of 2-ethyl-2-oxazoline with a methyl ester-containing 2-oxazoline monomer, followed by postpolymerization modifications. The side-chain carboxylic groups were then converted to amine-reactive pentafluorophenyl (PFP) ester groups. Part of the PFP groups was used for the attachment of the dithiolane moiety, which can efficiently bind to gold surfaces. The final copolymer contained 1.4 mol% of dithiolane groups and 4.5 mol% of PFP groups. The copolymer structure was confirmed by several analytical techniques, including NMR spectroscopy and size-exclusion chromatography. The kinetics of the PFP ester aminolysis and hydrolysis demonstrated significantly faster amidation compared to hydrolysis, which is essential for subsequent protein conjugation. Successful coating of gold surfaces with the polymer was confirmed by spectroscopic ellipsometry, showing a polymer brush thickness of 4.77 nm. Subsequent modification of the coated surfaces was achieved using bovine serum albumin as a model protein. This study introduces a novel reactive polymer linker for gold surface functionalization and offers a versatile polymer platform for various applications including biosensing and surface functionalization.