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Solid‐state lithium batteries (SSLBs) offer inherent safety and high energy density for next‐generation energy storage, but the large interfacial resistance and poor physical connection between electrode materials and the solid electrolyte (SE) severely impede their practical applications. This work reports a general strategy to introduce covalent bonds between electrode materials and SE, not only reducing interfacial resistance but also enhancing electrochemical stability and mechanical robustness of SSLBs. The covalent bonding is accomplished by functionalizing electrode surfaces with C═C groups, enabling in situ copolymerization with telechelic polymers in the SE. This approach is applicable to various cathode/anode materials and SEs. Particularly, the SSLBs comprising LiFePO4 cathode, Li6.75La3Zr1.75Ta0.25O12/(polyethylene oxide (PEO)/lithium bis(trifluoromethylsulfonyl)imide (LiTFSI)/silk composite SE and metallic lithium anode exhibit a specific capacity of 158.4 mAh g−1 and can be cycled at 2 C for 2200 times with >80% retention. Additionally, the SSLBs containing the high nickel‐content LiNi0.96Co0.03Mn0.01O2 cathode can afford a high specific capacity of 201.8 mAh g−1. Comprehensive experimental examination and theoretical simulations confirm that the lowered interfacial resistance and intimately contacted electrode materials/electrolyte interfaces facilitate Li+ transport at different stages of charge. Furthermore, the covalently bonded electrode/electrolyte interfaces also endow SSLBs with outstanding mechanical stability, enabling flexible SSLB pouch cells to operate under various bending states without performance decay. [ABSTRACT FROM AUTHOR]

HTPB (hydroxyl‐terminated polybutadiene) is a well‐established binder in the composite solid propellant owing to its excellent compatibility with ammonium perchlorate (AP) and aluminium (Al) particles in giving rise to optimal ballistic and mechanical properties. Efforts are being made to improve the ballistic properties further, such as specific impulse. One way of increasing the specific impulse is to hydrogenate HTPB, which decreases the molecular mass of the combustion product gases. This paper is a summary of efforts in synthesizing hydrogenated HTPB (HHTPB) using copper chromite (CC) as a catalyst. A novel synthesis methodology is developed for HHTPB using a temperature‐programmed batch reactor with a variable speed stirrer and an instrumentation system to maintain the desired liquid reactant temperature. A process cycle is developed that includes addition sequence and reaction time. The product is analyzed using 1H‐NMR and FTIR to estimate the degree of hydrogenation and the geometrical isomers respectively. The estimated apparent equilibrium rate constants from the degree of hydrogenation values are respectively 74 and 2034 L/(mol MPa) for non‐catalyzed and catalyzed systems, indicating the effectiveness of the catalyst. This is also substantiated by the reduction in Gibbs free energy (ΔG), to an extent of 4.48 kJ/mol. Thermogravimetry examination indicates that the decomposition temperature of HHTPB produced by the catalytic method is marginally higher compared to HTPB. DSC curves indicate that the decomposition enthalpy of HHTPB is higher than that of HTPB. In summary, this paper proposed and validated a novel method in the preparation of HHTPB using copper chromite. [ABSTRACT FROM AUTHOR]

This article discusses the synthesis of hydroxyl-terminated polybutadiene (HTPB) using ring-opening metathesis polymerization (ROMP) and different olefin metathesis catalysts. The authors investigated the use of various catalysts, including Grubbs first-generation catalyst (G1), Grubbs second-generation catalyst (G2), Grubbs third-generation catalyst (G3), Hoveyda-Grubbs second-generation catalyst (HG2), and a Z-selective olefin metathesis catalyst (HGZ). They found that G3 produced the most promising results, with rapid monomer conversion and relatively high end-group fidelity. The other catalysts required longer reaction times and produced greater aldehyde formation. The study suggests that rapidly initiating olefin metathesis catalysts like G3 may offer advantages for ROMP with a chain-transfer agent. [Extracted from the article]

Gels made of telechelic polymers connected by reversible cross-linkers are a versatile design platform for biocompatible viscoelastic materials. Their linear response to a step strain displays a fast, near-exponential relaxation when using low-valence cross-linkers, while larger supramolecular cross-linkers bring about much slower dynamics involving a wide distribution of timescales whose physical origin is still debated. Here, we propose a model where the relaxation of polymer gels in the dilute regime originates from elementary events in which the bonds connecting two neighboring cross-linkers all disconnect. Larger cross-linkers allow for a greater average number of bonds connecting them but also generate more heterogeneity. We characterize the resulting distribution of relaxation timescales analytically and accurately reproduce stress relaxation measurements on metal-coordinated hydrogels with a variety of cross-linker sizes including ions, metal-organic cages, and nanoparticles. Our approach is simple enough to be extended to any cross-linker size and could thus be harnessed for the rational design of complex viscoelastic materials. [ABSTRACT FROM AUTHOR]

Blending different types of polymers with traces of a telechelic macromolecule that is end‐functionalized with excimer‐forming chromophores affords materials that display a highly sensitive, reversible, and strain‐dependent mechanochromic response. Confocal microscopy imaging reveals that the additive forms discrete, phase‐separated inclusions in host polymers such as poly(ε‐caprolactone), poly‐isoprene, poly(styrene‐b‐butadiene‐b‐styrene), and different thermoplastic polyurethanes. A comprehensive analysis shows that the mechanochromism of the blends originates from the distortion of the inclusions, which, independent of the additive content and chemical composition of the matrix, deform homogeneously and reversibly in response to the applied macroscopic strain. These findings support the conclusion that such excimer‐forming, telechelic macromolecules can be used as universal additives that allow the straightforward fabrication of a wide range of mechanochromic materials. [ABSTRACT FROM AUTHOR]

Comprehensive Summary: Introducing covalently crosslinked network to telechelic polymers can enable the formation of advanced polymeric materials with enhanced material properties. In this contribution, well‐defined telechelic polymers bearing acetoacetate groups were synthesized via Ru‐catalyzed ring‐opening metathesis polymerization of cyclooctene in the presence of chain transfer agents. Given the unique feature of muti‐site reactive acetoacetate end groups, several crosslinked networks were constructed using different crosslinkers under mild conditions. In the Michael addition reaction system, the introduction of di/trifunctional aliphatic acrylate as crosslinkers significantly enhanced the mechanical properties of the generated crosslinked network (tensile strength up to 27 MPa, elongation at break up to 500%). On the other hand, vitrimers with dynamic covalent crosslinked networks were accessed via transamination of vinylogous urethane reaction using telechelic polymers and tris(2‐aminoethyl)amine. These vitrimers presented great mechanical properties and reprocessing properties. These strategies can be potentially applied to construct other types of high‐performance polymeric materials. [ABSTRACT FROM AUTHOR]

Polyolefins with periodic unsaturation in the backbone chain are sought after for synthesizing chemically recyclable polymers or telechelic polyolefin macromonomers. Here we introduce a bottom‐up synthesis of unsaturated high‐density polyethylene (HDPE) via copolymerization of ethylene with dimethyl 7‐oxabicyclo[2.2.1]hepta‐2,5‐diene‐3,5‐dicarboxylate followed by post‐polymerization retro‐Diels–Alder to unveil hidden double bonds in the polymer backbone. The incorporation of this "Trojan Horse" comonomer was varied and a series of unsaturated HDPE polymers with block lengths of 1.2, 1.9, and 3.5 kDa between double bonds was synthesized. Cross metathesis of unsaturated HDPE samples with 2‐hydroxyethyl acrylate yielded telechelic ester terminated PE macromonomers suitable for the preparation of ester‐linked PE. These materials were depolymerized and repolymerized, making them suitable candidates for chemical recycling. The ester‐linked PE displayed thermal and mechanical properties comparable to commercial HDPE. [ABSTRACT FROM AUTHOR]

Microfluidics is a rapidly advancing technology with expansive applications but has been restricted by slow, laborious fabrication techniques for polydimethylsiloxane (PDMS)-based devices. Currently, 3D printing promises to address this challenge with high-resolution commercial systems but is limited by a lack of material advances in generating high-fidelity parts with micron-scale features. To overcome this limitation, a low-viscosity, photopolymerizable PDMS resin was formulated with a methacrylate-PDMS copolymer, methacrylate-PDMS telechelic polymer, photoabsorber, Sudan I, photosensitizer, 2-isopropylthioxanthone, and a photoinitiator, 2,4,6-trimethyl benzoyl diphenylphosphine oxide. The performance of this resin was validated on a digital light processing (DLP) 3D printer, an Asiga MAX X27 UV. Resin resolution, part fidelity, mechanical properties, gas permeability, optical transparency, and biocompatibility were investigated. This resin produced resolved, unobstructed channels as small as 38.4 (±5.0) µm tall and membranes as thin as 30.9 (±0.5) µm. The printed material had an elongation at break of 58.6% ± 18.8%, Young's modulus of 0.30 ± 0.04 MPa, and was highly permeable to O2 (596 Barrers) and CO2 (3071 Barrers). Following the ethanol extraction of the unreacted components, this material demonstrated optical clarity and transparency (>80% transmission) and viability as a substrate for in vitro tissue culture. This paper presents a high-resolution, PDMS 3D-printing resin for the facile fabrication of microfluidic and biomedical devices. [ABSTRACT FROM AUTHOR]

This work describes a versatile and efficient condensation polymerization route to aliphatic polyesters by organo-catalyzed (4-dimethylaminopyridine) transesterification reactions between an activated pentafluorophenyl-diester of adipic acid and structurally different diols. By introducing "monofunctional impurity" or "stoichiometric imbalance," this methodology can afford well-defined endfunctionalized polyesters with predictable molecular weights and narrow dispersity under mild conditions without any necessity for the removal of the byproducts to accelerate the polymerization reaction, which remains a major challenge in conventional polyester synthesis with non-activated diesters. Wide substrate scope with structurally different monomers and the synthesis of block copolymers by chain extension following either ring-opening polymerization or controlled radical polymerization have been successfully demonstrated. Some of the polyesters synthesized by this newly introduced approach show high thermal stability, crystallinity, and enzymatic degradation in aqueous environments. [ABSTRACT FROM AUTHOR]

[Display omitted] • 4-HBA was used as CINICAT for the ROP catalyst of CL. • The ROP of CL and other cyclic monomers using CINICAT was in a controllable manner. • 4-HBA CINICAT was shown to be entirely a part of resulting polymers. With the increasing demands on healthy and environmental issues in modern society, green chemistry and atomic economics have become the consensus of researchers and manufacturers, forcing us to explore much simpler approaches to producing widely utilized biodegradable and biocompatible polyesters. In this context, 4-(hydroxymethyl) benzoic acid (4-HBA), an organic weak acid involving carboxyl and hydroxyl groups, was selected to proceed the ROP of various cyclic monomers, such as ε -caprolactone (CL), δ -valerolactone (VL), l-lactide (LA) and trimethylene carbonate (TMC), as catalyst and initiator in the same molecule (CINICAT) to give α -carboxyl- ω -hydroxyl polymers with controlled molar mass and narrow dispersity (around 1.15). MALDI-TOF, 2D-NMR and other characterizations were applied to confirm the structure of the produced polymers, while density of functional theory simulation (DFT) calculation was carried out to study the structural influence of CINICAT on the polymerizations as well as the polymerization mechanism. [ABSTRACT FROM AUTHOR]

There is currently intensive research on the development of biobased polymers as potential alternatives to the environmentally hazardous isocyanate-based polyurethanes. In this context, polythioureas (PTUs) form a particularly attractive target because they can be synthesized by using isothiocyanates, a class of molecules that can be found in nature with expected low toxicity. Herein, a series of 16 PTUs with varied chemical structures, mostly being new polymers, have been synthesized and their possible chemical recycling pathways via thermally induced and acid-catalyzed depolymerizations have been investigated. The obtained PTUs showed a varied range of molecular weights (up to M n ∼ 69.5 kDa), intrinsic viscosity (up to ∼6 dL/g), and glass transition temperatures (T g ∼ 59–128 °C). Notably, we observed that the presence of aromatic segments lowered the thermal stability of the polymers, so they were generally easier to depolymerize (compared to those without aromatic groups), forming oligomers with controlled end-groups (i.e. telechelic polymers) that could be repolymerized. The obtained aliphatic PTUs were generally resistant against thermochemical depolymerizations, but they could be effectively depolymerized by sulfuric acid. The repolymerization methods depended on the end groups of the depolymerized products, which in this work included direct repolymerization of polythioureas (if the end groups contain ∼1:1 of isothiocyanates and amines) and copolymerizations with another monomer terephthaldehyde (if the end groups contain only amines). Our results provided a first comprehensive molecular insight into the synthetic and recycling possibilities of using isothiocyanates and polythioureas in the exploration of potential alternatives for isocyanates and polyurethanes. [Display omitted] • 16 potentially biobased polythioureas (PTUs) were synthesized using diisothiocyanates and diamines • Aromatic units in PTUs facilitated thermally induced depolymerizations • Aliphatic PTUs were more thermally stable but could be depolymerized by strong acids • Depolymerizations of PTUs yielded telechelic polymers which could be conveniently re-polymerized [ABSTRACT FROM AUTHOR]

Nano-sized particles functionalised with short single-stranded (ss)DNAs can act as detectors of complementary DNA strands. Here we consider tri-block-copolymer-based, self-assembling DNA-coated nanoparticles. The copolymers are chemically linked to the DNA strands via azide (N 3 ) groups. The micelles aggregate when they are linked with complementary ssDNA. The advantage of such block-copolymer-based systems is that they are easy to make. Here we show that DNA functionalisation results in inter-micellar attraction, but that N 3 -groups that have not reacted with the DNA detector strands also change the phase behaviour of the tri-block polymer solution. We studied the triblock copolymer, Pluronic® F108, which forms spherical micelles in aqueous solutions upon heating. We find that the triblock chains ending with either an N 3 or N 3 -DNA complex show a dramatic change in phase behaviour. In particular, the N 3 -functionalisation causes the chain ends to cluster below the critical micelle temperature (CMT) of pure F108, forming flower-micelles with the N 3 -groups at the core, while the PPO groups are exposed to the solvent. Above the CMT, we see an inversion with the PPO chains forming the micellar core, while the N 3 -groups are now aggregating on the periphery, inducing an attraction between the micelles. Our results demonstrate that, due to the two competing self-assembling mechanisms, the system can form transient hydrogels. [ABSTRACT FROM AUTHOR]

Supramolecular telechelic polymers are intriguing macromolecular systems for the construction of complex supramolecular systems and responsive soft materials. In this work, we report a practical synthetic approach to preparing supramolecular mono-telechelic polymers with high efficiency and modularity. With a combination of in situ catalyst functionalization, ring-opening metathesis polymerization, and post-polymerization modification, a series of supramolecular mono-telechelic polymers with different supramolecular end-groups and sidechains are synthesized. Several selected examples are then discussed in detail to demonstrate their potential in constructing hierarchical supramolecular architectures, adaptive materials, and supramolecular biomaterials. It is highly anticipated that the synthetic approach reported here will provide rapid and controlled access to complex supramolecular polymeric systems with tailored functions.

We present a systematic experimental study of the shear rheology of metallosupramolecular assemblies based on entangled telechelic star polymers comprising one (single dynamic network) or two (double dynamics network) types of physical bonds with the aim to unravel the role of concentration and strength of these bonds on the nonlinear response. Model dynamic networks functionalized with terpyridine ligands were formed by adding different metal ions with increasing bonding strength, zinc, copper, and cobalt. The dynamics are driven by entanglement/disentanglement processes and a ligand exchange mechanism. Steady-state viscosities of single and double dynamics networks collapse onto a universal curve over a wide range of Weissenberg numbers based on terminal time (up to about 300 for single and 1000 for double), exhibiting stronger shear thinning (with an exponent of −0.76) compared to entangled neutral star polymers. Double dynamics networks consisting of two different metal ions (with different lifetimes) exhibit stronger mechanical coherence (rate-dependent fractional viscosity overshoot) and accumulate larger strain at steady-state flow compared to single-ion counterparts. The shear stress growth function signals exhibit weak, albeit unambiguous shear strain hardening, which becomes more pronounced for stronger associations. They also exhibit double overshoot, which reflects the interplay of association strength and chain deformation. Increasing the strength of associations leads to the failure of the Cox–Merz rule, which is more severe for single dynamic networks. The markedly different behavior of double dynamics networks is attributed to the fact that at sufficiently high ion content, the weaker bond acts as a sacrificial component, which provides local energy dissipation and enhances the overall deformability. This bears analogies with their linear viscoelastic response, which has revealed that the arm disentanglement (delayed due to the reversible bonds) effectively interpolates between the two single dynamic network components, depending on composition. Our results suggest ways to tailor the mechanical properties of this class of materials by judicious choice of the type and content of the ion. [ABSTRACT FROM AUTHOR]

Microemulsions are widely employed as drug delivery systems due to their unique solubilization capacity and ability to enhance drug permeability across biological membranes. In this study, we utilize molecular dynamics simulations to investigate the structural and dynamic properties of a decane/water microemulsion system at a low volume fraction ϕ = 2. 8 % , stabilized by cetylpyridinium chloride (CpCl) as the surfactant and octanol as the co-surfactant. To further enhance stability, we graft a telechelic steric polymer, polyethylene oxide PEO − C 12 H 25 , onto the surface of the microemulsion particle. This polymer has been shown to prevent aggregation, increase solubilization, and reduce toxicity. The number of polymers grafted onto each microemulsion particle is denoted as n( PEO − C 12 H 25 ), where n varies from 0 to 32. The potential of this system includes Van der Waals interactions, electrostatic interactions, and steric interactions. The structural properties of the microemulsion particle are analyzed using the pair correlation function g (r) , structure factor S (q) , interaction potential U (r) between particles, and osmotic compressibility χ T. Results indicate that the addition of PEO − C 12 H 25 increases the inter-particle distance between microemulsion particles due to the steric repulsive interactions introduced by the polymer, while an increase in temperature brings the microemulsion particles closer together due to thermal energy. Dynamic properties are examined using the mean square displacement MSD, intermediate scattering function F (q , t) , and viscosity η. From the MSD curves, two diffusion regimes are identified: the ballistic regime (< Δ 2 r > = 3 k B T m t 2 ) and the Fickian regime (< Δ 2 r > = 6 D t). The intermediate scattering function F (q , t) decreases exponentially according to the law F (q , t) ≈ e − t / τ , indicating that diffusion remains normal. We also calculate the diffusion coefficient D from the MSD, relaxation time τ from F (q , t) , and activation energy E a from the Arrhenius equation (η = η ∞ × e x p (E a / R T)). Results show that the diffusion coefficient decreases with the addition of the polymer, while the relaxation time τ , viscosity η , and activation energy E a increase, indicating that PEO − C 12 H 25 inhibits microemulsion particle diffusion. Conversely, increasing the temperature T enhances particle diffusion by increasing the diffusion coefficient and decreasing both the relaxation time τ and viscosity η , indicating a temperature-dependent increase in particle mobility. [Display omitted] [ABSTRACT FROM AUTHOR]

A central question in soft matter is understanding how several individual, weak bonds act together to produce collective interactions. Here, gel-forming telechelic polymers with multiple stickers at each chain end are studied through Brownian dynamics simulations to understand howcollective interaction of the bonds affects mechanical response of the gels. These polymers are modeled as finitely extensible dumbbells using an explicit tau-leap algorithm and the binding energy of these associations was kept constant regardless of the number of stickers. The addition of multiple bonds to the associating ends of telechelic polymers increases or decreases the network relaxation time depending on the relative kinetics of association but increases both shear stress and extensional viscosity. The relationship between the rate of association and the Rouse time of dangling chains results in two different regimes for the equilibrium stress relaxation of associating physical networks. In case I, a dissociated dangling chain is able to fully relax before re-associating to the network, resulting in two characteristic relaxation times and a non-monotonic terminal relaxation time with increasing number of bonds per polymer endgroup. In case II, the dissociated dangling chain is only able to relax a fraction of the way before it re-attaches to the network, and increasing the number of bonds per endgroup monotonically increases the terminal relaxation time. In flow, increasing the number of stickers increases the steady-state shear and extensional viscosities even though the overall bond kinetics and equilibrium constant remain unchanged. Increased dissipation in the simulations is primarily due to higher average chain extension with increasing bond number. These results indicate that toughness and dissipation in physically associating networks can both be increased by breaking single, strong bonds into smaller components. [ABSTRACT FROM AUTHOR]

The high structural anisotropy and colloidal stability of cellulose nanofibrils' enable the creation of self-standing fibrillar hydrogel networks at very low solid contents. Adding methacrylate moieties on the surface of TEMPO oxidized CNFs allows the formation of more robust covalently crosslinked networks by free radical polymerization of acrylic monomers, exploiting the mechanical properties of these networks more efficiently. This technique yields strong and elastic networks but with an undefined network structure. In this work, we use acrylate-capped telechelic polymers derived from the step-growth polymerization of PEG diacrylate and dithiothreitol to crosslink methacrylated TEMPO-oxidized cellulose nanofibrils (MATO CNF). This combination resulted in flexible and strong hydrogels, as observed through rheological studies, compression and tensile loading. The structure and mechanical properties of these hydrogel networks were found to depend on the dimensions of the CNFs and polymer crosslinkers. The structure of the networks and the role of individual components were evaluated with SAXS (Small-Angle X-ray Scattering) and photo-rheology. A thorough understanding of hybrid CNF/polymer networks and how to best exploit the capacity of these networks enable further advancement of cellulose-based materials for applications in packaging, soft robotics, and biomedical engineering. [Display omitted] [ABSTRACT FROM AUTHOR]

In this work, equilibrium molecular dynamics is used to predict the change in the Helmholtz free energy ( Δ A) for solutions of associative polymers of the telechelic type. Δ A is calculated using the thermodynamic integration method, wherein molecular chains are simulated in a coarse-grain scale within an NVT ensemble. Simulations take place in the concentration interval 0.03 ≤ c ≤ 0.25 , such that aggregate formation is possible. The initial configuration is that of dispersed free chains; the increase of interactions among stickers signals the onset of the micelle formation process. The solution with high concentration experiences substantial micelle aggregation despite little conformation changes. Therein, transient networks among micellar flowers are formed. The decrease in free energy is related to the formation of aggregates to achieve stability. When solutions are thermodynamically stable, the free energy and configurational entropy decrease and increase non-linearly with concentration, respectively. Below critical micellar concentration, this behaviour is associated with a step-by-step process along which the sticker groups gather to form the first thermodynamically stable aggregate. Above critical micellar concentration, the most probable distribution increases with concentration, therefore, free energy decreases with increasing aggregates that form the network. [ABSTRACT FROM AUTHOR]

Ruthenium‐mediated olefin metathesis has been widely applied for the synthesis of various organic molecules and polymers. Inspired by the cocatalyst strategy for olefin polymerization, here we demonstrate that the abstraction of a chloride ion from various commercially available ruthenium catalysts significantly enhances their reactivity towards electron‐deficient internal olefins. This cocatalyst strategy can be implemented in ethenolysis and cross‐metathesis reactions of FG‐CH=CH‐FG type substrates bearing electron‐withdrawing groups and the synthesis of telechelic polymers that can be converted to polyethylene‐like materials with closed‐loop recycling properties. The copolymerization of cyclic substrate with cycloolefins followed by hydrogenation afforded polyolefin materials with in‐chain break points. Interestingly, switchable catalysis was achieved in the absence and presence of a cocatalyst, which allowed the polymer microstructure and material properties to be fine‐tuned. [ABSTRACT FROM AUTHOR]

The control of chain‐ends is fundamental in modern macromolecular chemistry for directed one‐to‐one bioconjugation and the synthesis of advanced architectures such as block copolymers or bottlebrush polymers and the preparation of advanced soft materials. Polyphosphazenes are of growing importance as elastomers, biodegradable materials and in biomedical drug delivery due to their synthetic versatility. While controlled polymerization methods have been known for some time, controlling both chain‐ends with high fidelity has proven difficult. We demonstrate a robust synthetic route to hetero and homo α,ω‐chain‐end functionalized polyphosphazenes via end‐capping with easily accessible, functionalized triphenylphosphine‐based phosphoranimines. A versatile thiol‐ene "click"‐reaction approach then allows for subsequent conversion of the end‐capped polymers with various functional groups. Finally, we demonstrate the utility of this system to prepare gels based on homo α,ω‐chain‐end functionalized polyphosphazenes. This development will enhance their progress in various applications, particularly in soft materials and as degradable polymers. [ABSTRACT FROM AUTHOR]

The rheology of emulsions dictates their performance in many scientific and industrial applications. Here, we demonstrate that high-molecular-weight telechelic triblock copolymers composed of polystyrene end blocks with a poly-(ethylene oxide) midblock effectively modify the rheology of a suspension of cyclohexane nanodroplets. Because of their telechelic structure, these polymers bridge between droplets to generate elastic networks with shear moduli on the order of 1000 Pa. The network elasticity increases with polymer concentration and molecular weight as the polymers more effectively form bridges. Furthermore, we tune the nanoscale interactions that control the polymer partitioning by decreasing the temperature below the cloud point of the system. At low temperatures, the polystyrene end blocks no longer preferentially partition into the cyclohexane droplets, and the emulsions begin to exhibit terminal viscous relaxations. These results identify key properties of telechelic block copolymers that can be exploited to significantly enhance nanoemulsion elasticity to improve the processability and transport of complex fluids in applications ranging from 3D printing to functional hydrogels. [ABSTRACT FROM AUTHOR]

The viscoelastic property of vitrimers, which belong to a group of covalent bond adaptable networks, is one of the most critical properties during the applications of these materials. Herein, the significant effect of the network architecture of the cross‐linked polymers, particularly the arrangements of cross‐links and chains, on the viscoelastic property, which is determined directly from the structure of the precursor polymers, is reported. The systematic investigation reveals that vitrimers from telechelic polymers with reactive groups at the chain ends show a sharp elastic modulus decrease. Furthermore, these polymers demonstrate highly fluid‐like behavior at elevated temperature and fast stress relaxation, compared to vitrimers from random copolymers that have similar chain length and number of cross‐linking groups. [ABSTRACT FROM AUTHOR]

We present an analysis of topological constraints of network chains, in particular entanglements, in ABA telechelic associative polymer gels generated by Brownian dynamics technique with a B selective solvent. We find two fundamental types of entanglements formed by bridge chains: first, two or more bridge chains linking different micelles impose topological constraints on each other because they cannot cross, denoted as type-I entanglement; second, two or more bridge chains linking a pair of micelles are twisted together, denoted as type-II entanglement. More complex constraints are composed of both types. There is no difference between type-I and type-II entanglements in polymer melts, but in gels, only type-I entanglement provides extra junctions that can significantly affect the modulus. The dependences of entanglement on chain length and concentration are investigated. The simulations reveal that even at low concentrations where only parts of long chains are entangled, they can provide a considerable number of junctions. [ABSTRACT FROM AUTHOR]

The lattice cluster theory (LCT) for semiflexible linear telechelic melts, developed in Paper I, is applied to examine the influence of chain stiffness on the average degree of self-assembly and the basic thermodynamic properties of linear telechelic polymer melts. Our calculations imply that chain stiffness promotes self-assembly of linear telechelic polymer melts that assemble on cooling when either polymer volume fraction f or temperature T is high, but opposes self-assembly when both f and T are sufficiently low. This allows us to identify a boundary line in the f-T plane that separates two regions of qualitatively different influence of chain stiffness on self-assembly. The enthalpy and entropy of self-assembly are usually treated as adjustable parameters in classical Flory-Huggins type theories for the equilibrium self-assembly of polymers, but they are demonstrated here to strongly depend on chain stiffness. Moreover, illustrative calculations for the dependence of the entropy density of linear telechelic polymer melts on chain stiffness demonstrate the importance of including semiflexibility within the LCT when exploring the nature of glass formation in models of linear telechelic polymer melts. [ABSTRACT FROM AUTHOR]

The lattice cluster theory (LCT) for the thermodynamics of polymer systems has recently been reformulated to treat strongly interacting self-assembling polymers composed of fully flexible linear telechelic chains [J. Dudowicz and K. F. Freed, J. Chem. Phys. 136, 064902 (2012)]. Here, we further extend the LCT for linear telechelic polymer melts to include a description of chain semiflexibility, which is treated by introducing a bending energy penalty whenever a pair of consecutive bonds from a single chain lies along orthogonal directions. An analytical expression for the Helmholtz free energy is derived for the model of semiflexible linear telechelic polymer melts. The extension provides a theoretical tool for investigating the influence of chain stiffness on the thermodynamics of self-assembling telechelic polymers, and for further exploring the influence of self-assembly on glass formation in such systems. [ABSTRACT FROM AUTHOR]

Silicone elastomers are typically thermosets that are difficult to recycle or repurpose. Thermoplastic silicone elastomers formed from Schiff bases utilize crosslinkers based on petroleum. Vanillin is an aromatic phenolic aldehyde recovered from lignin. We demonstrate that its dimer, divanillin, formed by oxidative coupling using an Fe II/III catalytic process, serves as an effective crosslinker for telechelic and pendent aminopropylsilicones. Pendent-derived elastomers swell in solvents and exhibit dynamic adhesion at their interfaces, but are otherwise relatively intractable, essentially thermosets, due to the combination of Schiff base and H-bonding crosslinks. The elastomers derived from telechelic polymers, by contrast, are thermoplastic; chain extension through Schiff bases is accompanied by H-bonding crosslinking that is readily overcome by either solvents or heat. The silicone starting polymers are readily recovered. [ABSTRACT FROM AUTHOR]

Non-equilibrium molecular dynamics are used in a coarse-grained scale to simulate the simple shear flow of telechelic and non-telechelic associative polymer solutions. The work includes the study of inception of flow and stress relaxation in transient flows and the constitutive curve at steady state. The instabilities (plateau stress, stress maxima) and the formation of bands with different velocity gradient and concentration depend on the location of the hydrophobic sites (sticker sites, SS) in the chain. Results allow to shed light on the origin of banded flow within the transient state, related to depletion of bridges between aggregates. This situation induces instabilities in the velocity profiles and concentration inhomogeneities along the velocity gradient during the stress overshoot. As the steady state is reached, instabilities disappear for systems where the SS are in the middle of the chain. The conformation relaxation occurs during a time scale larger than that of the stress, but this is not sufficient condition for the presence of banded flow in telechelic polymer solutions, as it holds in polymer melts. The difference in concentration among the bands suggests the existence of a shear-gradient concentration coupling mechanism under banded flow conditions, such as spatial non-homogeneities in the network density, induces chain diffusivity in the gradient direction and increasing normal stresses, especially in telechelic chains. The role of normal stresses on the flow-concentration coupling instability is analyzed in detail. [ABSTRACT FROM AUTHOR]

Self‐assembly and supramolecular inclusion complexations between telechelic polymers bearing one or double adamantane groups and linear poly(β‐cyclodextrin) (P(β‐CD)) were investigated in water. An adamantane (Ada) attached to poly (acrylic acid) (PAA) was prepared by reversible addition‐fragmentation chain transfer polymerization using s‐1‐dodecyl‐s″ ‐(α,α′‐dimethyl‐α″‐acetic acid) trithio‐carbonate functionalized Ada with tert‐butyl acrylate, followed by functional modification. Additionally, two Ada groups capped triblock copolymer F127 were obtained via an esterification reaction. The dynamic light scattering, transmission electron microscope and 1H 2D NOSEY NMR spectroscopy were conducted to characterize the self‐assembly behaviors. With the inclusion complexation of Ada/CD in 1:1 M ratio in water, the spherical micelles were enlarged at 25°C than that of the adamantyl polymer precursors. Due to the PPO segment of Ada‐F127‐Ada, the micelles aggregation showed temperature dependence from 4 to 37°C for precursor and corresponding inclusion complexation; while in Ada‐PAA/P(β‐CD) system, the hydrodynamic diameters decreased with pH decreasing. [ABSTRACT FROM AUTHOR]

We combine synthesis, physical experiments, and computer simulations to investigate self-assembly patterns of low-functionality telechelic star polymers (TSPs) in dilute solutions. In particular, in this work, we focus on the effect of the arm composition and length on the static and dynamic properties of TSPs, whose terminal blocks are subject to worsening solvent quality upon reducing the temperature. We find two populations, single stars and clusters, that emerge upon worsening the solvent quality of the outer block. For both types of populations, their spatial extent decreases with temperature, with the specific details (such as temperature at which the minimal size is reached) depending on the coupling between inter- and intra-molecular associations as well as their strength. The experimental results are in very good qualitative agreement with coarse-grained simulations, which offer insights into the mechanism of thermoresponsive behavior of this class of materials. [ABSTRACT FROM AUTHOR]

The purpose of this review is to describe the utilisation of natural rubber and its modified form in adhesive applications. Adhesive can be defined as material that capable of joining two or more surfaces permanently by the adhesion process. Recently, natural rubber has gaining great interest in the adhesive application in comparison to its counter parts synthetic rubber due to environmental reason as well as good mechanical and thermal properties. In this review, the adhesive properties along with mechanical and thermal properties of the natural rubber are reviewed. The recent advances in the modified natural rubber such as epoxidized natural rubber, liquid natural rubber, telechelic natural rubber and other modified natural rubber are also included and highlighted. [ABSTRACT FROM AUTHOR]

Catechol‐Fe(III) complexes contain some of the strongest known metal‐chelate coordination bonds. Despite this, they have until now not been utilized in (polymeric linker) linear coordination polymer (LCP) synthesis. With the view of generating catechol end‐functional polymers, a new, symmetrical bis‐catechol functionalized trithiocarbonate reversible addition fragmentation chain transfer (RAFT) agent is synthesized (CatDMAT). Acrylamide (AM) and dimethylacrylamide (DMA) polymerizations are conducted with CatDMAT using direct photoactivation RAFT polymerization to yield bis‐catechol end‐functionalized homo‐ and block‐copolymers of molecular weight 10–15 kDa. Catechol‐Fe(III) LCPs are successfully formed from the telechelic catechol polymers by bis‐complexation to Fe(III). The tetrahedral bis‐complex is detected by UV–vis spectroscopy (λmax = 570 nm), while increases in relative viscosity and Mn,GPC over their respective uncomplexed polymers confirm the occurrence of supramolecular polymerization. The catechol‐LCPs are shown to undergo oxidation and crosslinking in aqueous solution after 24 h. [ABSTRACT FROM AUTHOR]

We show how two-species models, already proposed for the rheology of networks of associative polymer solutions, can be derived from nonequilibrium thermodynamics using the generalized bracket formalism. The two species refer to bridges and (temporary) dangling chains, both of which are represented as dumbbells. Creation and destruction of bridges in our model are accommodated self-consistently by assuming a two-way reaction characterized by a forward and a reverse rate constant. Although the final set of evolution equations for the microstructure of the two species and the expression for the stress tensor are similar to those of earlier models based on network kinetic theory, nonequilibrium thermodynamics sets specific constraints on the form of the attachment/detachment rates appearing in these equations, which, in some cases, deviate significantly from previously reported ones. We also carry out a detailed analysis demonstrating the capability of the new model to describe various sets of rheological data for solutions of associative polymers. [ABSTRACT FROM AUTHOR]

This study reports a step‐growth click‐polymerization of 1,4‐benzenedimethane (BDMT) and diethylene glycol divinyl ether (DEGVE) with 4‐(N,N‐diphenylamino)‐benzaldehyde (DPAB) as a photoredox catalyst under irradiation of visible light. DPAB exhibits a strong UV–vis absorption at 350 nm and a strong fluorescence emission at 480 nm in anisole. There is a strong fluorescence quenching between BDMT and DPAB. The molecular weight of the polythiolether can be controlled by reaction time and monomer feed ratios. More importantly, α,ω‐dithiol and α,ω‐divinyl telechelic polythiolether oligomers are successfully synthesized by simply changing the molar ratios of BDMT to DEGVE. 1H NMR and MALDI‐TOF MS spectra demonstrate that the oligomers have high end group fidelity. In addition, strong fluorescence is observed when the α,ω‐dithiol terminated polythiolether adds with N‐(1‐pyrenyl) maleimide, indicating that the as‐prepared polythiolether bears reactive thiol end groups. Furthermore, high molecular weight polythiolether are prepared by chain extension with reactive polythiolether oligomers as macro‐monomers. For example, α,ω‐divinyl oligomer (Mn = 2000 g mol−1) could further react with α,ω‐dithiol oligomer (Mn = 2400 g mol−1) to form high molecular weight polythiolether (Mn = 6000 g mol−1). [ABSTRACT FROM AUTHOR]

The newly developed lattice cluster theory (in Paper I) for the thermodynamics of solutions of telechelic polymers is used to examine the phase behavior of these complex fluids when effective polymer-solvent interactions are unfavorable. The telechelics are modeled as linear, fully flexible, polymer chains with mono-functional stickers at the two chain ends, and these chains are assumed to self-assemble upon cooling. Phase separation is generated through the interplay of self-assembly and polymer/solvent interactions that leads to an upper critical solution temperature phase separation. The variations of the boundaries for phase stability and the critical temperature and composition are analyzed in detail as functions of the number M of united atom groups in a telechelic chain and the microscopic nearest neighbor interaction energy [variant_greek_epsilon]s driving the self-assembly. The coupling between self-assembly and unfavorable polymer/solvent interactions produces a wide variety of nontrivial patterns of phase behavior, including an enhancement of miscibility accompanying the increase of the molar mass of the telechelics under certain circumstances. Special attention is devoted to understanding this unusual trend in miscibility. [ABSTRACT FROM AUTHOR]

The lattice cluster theory of strongly interacting, structured polymer fluids is applied to determine the thermodynamic properties of solutions of telechelic polymers that may associate through bifunctional end groups. Hence, this model represents a significant albeit natural extension of a diverse array of prior popular equilibrium polymerization models in which structureless 'bead' monomers associate into chain-like clusters under equilibrium conditions. In particular, the thermodynamic description of the self-assembly of linear telechelic chains in small molecule solvents (initiated in Paper II) is systematically extended through calculations of the order parameter [uppercase_phi_synonym] and average degree of self-assembly, the self-assembly transition temperature Tp, and the specific heat CV of solutions of telechelic molecules. Special focus is placed on examining how molecular and thermodynamic parameters, such as the solution composition [lowercase_phi_synonym], temperature T, microscopic interaction energies ([variant_greek_epsilon]s and [variant_greek_epsilon]), and length M of individual telechelic chains, influence the computed thermodynamic quantities that are commonly used to characterize self-assembling systems. [ABSTRACT FROM AUTHOR]

The lattice cluster theory (LCT) for the thermodynamics of a wide array of polymer systems has been developed by using an analogy to Mayer's virial expansions for non-ideal gases. However, the high-temperature expansion inherent to the LCT has heretofore precluded its application to systems exhibiting strong, specific 'sticky' interactions. The present paper describes a reformulation of the LCT necessary to treat systems with both weak and strong, 'sticky' interactions. This initial study concerns solutions of linear telechelic chains (with stickers at the chain ends) as the self-assembling system. The main idea behind this extension of the LCT lies in the extraction of terms associated with the strong interactions from the cluster expansion. The generalized LCT for sticky systems reduces to the quasi-chemical theory of hydrogen bonding of Panyioutou and Sanchez when correlation corrections are neglected in the LCT. A diagrammatic representation is employed to facilitate the evaluation of the corrections to the zeroth-order approximation from short range correlations. [ABSTRACT FROM AUTHOR]

Telechelic polyelectrolytes, bearing short hydrophobic blocks at both ends, will ionize into polyions and their counterions when dissolved in water. With the variation of concentration, the interplay between short range attraction and the long range electrostatic interaction as well as the counterion distribution exerts a major influence on the chain conformations (two basic conformations: loop and nonloop, the latter can be subdivided into three association types: free, dangling, and bridge), the cluster structure and the forming of a physical gel. For weak hydrophobic interaction, the relative strong electrostatic interaction dominates the gelation progress; sol-gel transition occurs at higher concentrations due to electrostatic screening and mainly involves the forming of stretched nonloop conformations such as dangling and bridge. While for strong hydrophobic interaction, the hydrophobic interaction dominates and the electrostatic interaction provides a contribution to the formation of gels by maintaining a spatial swelling structure, resulting in a much lower concentration region of sol-gel transition; besides, the sol-gel transition is characterized by the competition of the forming of loop and bridge chains. [ABSTRACT FROM AUTHOR]

Equilibrium, supramolecular assembly in melt blends of two species of telechelic polymers with reversible bonding sites at both ends is theoretically investigated. The bonding between polymers, whether between like or dislike chains, is controlled by affinities of chain bonding set by specified bond energies. Low affinities, or low overall bond strength, results in a monodisperse population of unlinked chains while larger affinities cause longer chains to assemble, forming a polydisperse blend. We investigate sequentially blends with only homobonding (like chain), only heterobonding (dislike chain), and finally a mixed homo- and heterobonding melt. In the first case, the effects of longer chain assembly and polydispersity in a homogeneous melt and its bulk demixing transition are explored. In contrast with the homobonding case, large heterobonding affinities cause alternating blocks to assemble into multiblock copolymers, which can lead to mesophases. The weak bonding region between bulk phase separation and mesophase stability is investigated and a novel Lifshitz point is found indicating a region prone to emulsify. Mixed homo- and heterobonding systems are also examined. Polymeric segments of both species are modeled as flexible Gaussian threads and nonspecific interactions between dissimilar blocks are contactlike Flory–Huggins repulsions. The melts are assumed to be incompressible and all calculations are carried out within mean-field theory. A new integral equation formalism is developed for enumerating all linear species in these complex supramolecular systems, and the random phase approximation and numerical self-consistent field theory are invoked in this context to map out a variety of phase diagrams. [ABSTRACT FROM AUTHOR]

We theoretically study the viscoelastic and thermodynamic properties of transient gels comprised of telechelic associating polymers. We extend classical theories of transient networks so that correlations among polymer chains through the network junctions are taken into account. This extension enables us to investigate how rheological quantities such as elastic modulus, viscosity, and relaxation time are affected by the association equilibrium, and how these quantities are related to the aggregation number (or multiplicity) of the junctions. In this paper, we assume, in the conventional manner, that chains are elastically effective if both their ends are connected with other chains. It is shown that the dynamic shear moduli are well described in terms of the Maxwell model. As a result of the correlation, the reduced moduli (moduli divided by the polymer concentration) increase with the concentration, but become independent of the concentration in the high-concentration range. The fraction of pairwise junctions is larger at lower concentrations, indicating the presence of concatenated chains in the system, which decreases as the concentration increases. This leads to a network relaxation time that increases with the concentration. [ABSTRACT FROM AUTHOR]

The authors present a model describing the coexistence of hydrophobic association and phase separation with lower critical solution temperature (LCST) in aqueous solutions of polymers carrying short hydrophobic chains at both chain ends (telechelic associating polymers). The LCST of these solutions is found to decrease along the sol/gel transition curve as a result of both end-chain association (association-induced phase separation) and direct hydrophobic interaction of the end chains with water. The authors relate the magnitude of the LCST decrease to a hydration cooperativity parameter σ. The LCST decreases substantially (∼100 K) in the case of random hydration (σ=1), whereas only a small shift (∼5–10 K) occurs in the case of cooperative hydration (σ=0.3). The molecular weight dependence of the LCST drop is studied in detail in each case. The results are compared with experimental observations of the cloud points of telechelic poly(ethylene oxide) solutions, in which random hydration predominates, and of telechelic poly(N-isopropylacrylamide) solutions, in which cooperative hydration prevails. [ABSTRACT FROM AUTHOR]

The kinetics of conformational fluctuations of a telechelic chain with two binding sites at both ends is studied by Monte Carlo simulations. The site-to-site binding energy is -[variant_greek_epsilon]. An example of the telechelic biopolymer is RNA or ssDNA made of a homogeneous sequence such as poly(T) with complementary bases at both ends. The conformation of such a chain fluctuate from loop (closed) to coil (open) state and the probability of the coil state depends on the temperature. An all-or-none transition between open and closed states is often adopted to depict the melting curves. It is found that the two-state model fails due to the existence of the intermediate state. A three-state model including open, intermediate, and closed states is proposed. The melting curves obtained from such a scenario agree quite well with the simulation results and there are two characteristic temperatures. The rate constants from closed to intermediate states k[sub c,i] and from intermediate to open states k[sub i,o] are independent of chain length but proportional to e[sup -[variant_greek_epsilon]/kT]. In contrast, the rate constants from open to intermediate states k[sub o,i] is independent of temperature and that from intermediate to closed states k[sub i,c] is essentially constant. © 2003 American Institute of Physics. [ABSTRACT FROM AUTHOR]

Studies the molecular dynamics of the solution of semiflexible telechelic polymer chains with strongly associating end-groups. Model and simulation technique used in the study; Equilibrium of association; System morphology; Comparative analysis of theoretical and computer simulation data.

A versatile strategy for the preparation of end‐functional polymers and block copolymers by radical exchange reactions is described. For this purpose, first polystyrene with 2,2,6,6‐tetramethylpiperidine‐1‐oxyl end group (PS‐TEMPO) is prepared by nitroxide‐mediated radical polymerization (NMRP). In the subsequent step, these polymers are heated to 130 °C in the presence of independently prepared TEMPO derivatives bearing hydroxyl, azide and carboxylic acid functionalities, and polymers such as poly(ethylene glycol) (TEMPO‐PEG) and poly(ε‐caprolactone) (TEMPO‐PCL). Due to the simultaneous radical generation and reversible termination of the polymer radical, TEMPO moiety on polystyrene is replaced to form the corresponding end‐functional polymers and block copolymers. The intermediates and final polymers are characterized by 1H NMR, UV, IR, and GPC measurements. © 2019 Wiley Periodicals, Inc. J. Polym. Sci., Part A: Polym. Chem. 2019, 57, 2387–2395 [ABSTRACT FROM AUTHOR]

A new near‐infrared (NIR) photosensitization system for the activation of a copper‐catalyzed azide‐alkyne cycloaddition click reaction (CuAAC) is reported. Selected cyanines comprising either a cationic or zwitterionic structural pattern were tested for their photosensitization activity to generate Cu(I) by photoreduction of Cu(II) to trigger CuAAC under NIR light at ambient temperature. The photosensitization system described also facilitates chemical modification of UV‐sensitive materials by CuAAC. Upon exposure to light of wavelength 790 nm under anaerobic conditions, the cyanine with a zwitterionic structure comprising a barbiturate group; that is 5‐(6‐(2‐(3‐ethyl‐1,1‐dimethyl‐1H‐benzo[e]indol‐2(3H)‐ylidene)ethylidene)‐2‐(2‐(3‐ethyl‐1,1‐dimethyl‐1H‐benzo[e]‐indol‐3‐ium‐2‐yl)vinyl)cyclohex‐1‐en‐1‐yl)‐1,3‐dimethyl‐2,6‐dioxo‐1,2,3,6‐tetrahydropyrimidin‐4‐olate in combination with Cu(II)‐N,N,N′,N′′,N′′‐pentamethyldiethylene‐triamine complex, exhibited excellent activity with high yields. The possibility to synthesise different macromolecular structures such as telechelic polymers and block copolymers by NIR‐sensitized CuAAC is demonstrated. The structural and molecular characteristics of the intermediates and final products were evaluated by spectral and chromatographic analyses. This new photochemical reaction opens up new pathways for the macromolecular synthesis of complex macromolecular structures and applications requiring light as an activation tool. [ABSTRACT FROM AUTHOR]

Describes a statistical treatment of the system of associating telechelics with due regard for formation of complicated many-chains clusters for the case when the active telechelic ends associate only in two and threefold aggregates. General approach to the description of associating telechelics; Scattering properties; Diagram technique.