Polyether Segments Research Articles

Block Copoly (Ester-Carbonate) Electrolytes for LiFePO4|Li Batteries with Stable Cycling Performance.

To address the challenges posed by the narrow oxidation decomposition potential window and the characteristic of low ionic conductivity at room temperature of solid polymer electrolytes (SPEs), carbon dioxide (CO2), epichlorohydrin (PO), caprolactone (CL), and phthalic anhydride (PA) were employed in synthesizing di-block copolymer PCL-b-PPC and PCL-b-PPCP. The carbonate and ester bonds in PPC and PCL provide high electrochemical stability, while the polyether segments in PPC contribute to the high ion conductivity. To further improve the ion conductivity, we added succinonitrile as a plasticizer to the copolymer and used the copolymer to assemble lithium metal batteries (LMBs) with LiFePO4 as the cathode. The LiFePO4/SPE/Li battery assembled with PCL-b-PPC electrolyte exhibited an initial discharge-specific capacity of 155.5 mAh·g-1 at 0.5 C and 60 °C. After 270 cycles, the discharge-specific capacity was 140.8 mAh·g-1, with a capacity retention of 90.5% and an average coulombic efficiency of 99%, exhibiting excellent electrochemical performance. The study establishes the design strategies of di-block polymer electrolytes and provides a new strategy for the application of LMBs.

Synthesis of soy-protein adhesives with excellent cohesion and cold-pressing bonding strength through multiple noncovalent crosslinking network of waterborne epoxy resin

In order to achieve the purpose of reducing cost and increasing efficiency of plywood fabrication, development of high-temperature soy meal (HSM)-based adhesives with high cold-pressing bonding strength without compromising its internal cohesion and interfacial adhesion is a meaningful goal in production. However, due to the agglomerated intrinsic structure, weak intermolecular interactions and strong hydrophilicity, the application of HSM adhesive was limited by its poor cohesion and unstable bonding performances. Taking consideration of the abundant hydrogen bonds sites and toughened microphase separation structure, in this work, polyurethane (PU) fragments served to provide bonding strength during prepressing stage. Sulfonate groups were grafted to prepare a stable waterborne epoxy emulsion (WEU) and then used as a crosslinker for HSM adhesives. Besides the introduced carbamate and polyether segments that provided regular hydrogen bonding platforms within HSM matrix, the soft polymer long-chain coils overlapped to increase the initial viscosity of the adhesives. This enhanced cohesive network strengthened the cold-pressing bonding strength of HSM-WPA2–15, reaching 0.76 MPa, which is enough for actual factory requirements. Pressure and thermal condition can stimulate resin penetrating into wood voids and cure it, opening active epoxy groups to covalent bonding within HSM chains. The secondary crosslinking network optimized the water resistance of cured adhesives, achieving 1.00 MPa of the adhesives under wet shear strength testing. This novel and feasible method demonstrates a foundational design, being able to be utilized for developing other plant-based wood adhesives with improved performances.

Material Design Concepts and Gas Separation Mechanism of CO2 Selective Polyether-Based Multiblock Copolymers.

Aliphatic polyethers have been widely explored as membrane materials for the separation of CO2 from other gases, e.g., N2 , H2 , CH4, O2 etc. The polymeric membranes having aliphatic polyether segments, especially poly(ethylene oxide) segments, allow faster permeation of CO2 compared to the light gases due to the affinity of the polar ether oxygen and quadrupolar CO2 . Rational macromolecular design is the key to control the permeation of gases through these membrane materials. In this regard, multiblock copolymers having short amorphous polyether segments have been extensively investigated. A large number of tailor made polymers have been reported to get the best combination of permeability and selectivity. Material design concepts and structure-property relationships of these membrane materials in terms of CO2 separation performance are thoroughly discussed in this review.

Preparation of CO2‐based poly(carbonate‐co‐lactide) with different porphyrin aluminum (III) catalysts

AbstractTwo‐component catalysts composed of tetra (para‐X substituted) phenylporphyrin aluminum (III) chloride, T (p‐X‐P)PAlCl, (where X = H, F, Cl, Br, CH3, OCH3, tert‐butyl), and cocatalyst bis(triphenylphosphine)imminium chloride (PPN+Cl−), could initiate the polymerization of propylene oxide (PO). And they could react with rac‐lactide, (rac‐LA), in the presence of propylene oxide (PO), to yield chains of enriched isotactic polylactide (PLA) with trace polyether segment. Also, these catalysts displayed different catalytic activity in the copolymerization of CO2 and PO, resulting in poly(carbonate‐co‐ether) copolymer with different carbonate unit content (CU%). Further, these catalysts could initiate one‐pot regio‐ and stereo‐ selective terpolymerization of rac‐LA, CO2 and rac‐PO, resulting in multi‐blocky poly(carbonate‐co‐lactide) with trace polyether segment. The structure of the products was verified by 1H NMR, 13C NMR, GPC, and DSC analysis, and it was found that variation of substitution groups in the periphery of porphyrin ligand would affect on the catalytic efficiency of ter‐polymerization, and the relative polymerization reaction ratio of the ring‐opening polymerization of LA (ROP) to the ring‐opening copolymerization of PO and CO2 (ROCOP), resulting in ter‐polymer with different contents of PLA segment and PPC segment. However, H‐T% in polycarbonate unit and Pi% in polylactide unit did not vary much with the change of catalysts.

Preparation, Characterization, and Properties of Alkali-Resistant and Hydrolysis-Resistant Silicone Surfactant

It is a challenge to research and develop silicon surfactants with good acid and alkali stability. In the present paper, methylpropenyl polyether modified nonionic silicone surfactant (MPNTS), an alkali-resistant and hydrolysis-resistant silicone surfactant, was synthesized by hydrosilylation of 1,1,1,3,5,5,5-heptamethyl trisiloxane (MDHM) and methylpropenyl polyether (EO(7)). The polyether segments are grafted onto the main chain of organosilicon heptamethyl trisiloxane at a molar ratio of 1:1.05 (n(Si-H):n(C=C)). To evidence product formation, the MPNTS were analyzed by FT-IR and 1H NMR spectroscopy. The surface tension of NPNTS is 18.68 mN/m, and the CMC value is 78 mg/L by a contact angle tester. MPTNS shows hydrolytic stability and maintains that it could keep surface activity after standing for 60 days at pH = 7–10. The compatibility performance analysis shows that MPNTS has good compatibility and synergy with cationic, anionic, and nonionic surfactants, and it reveals the application prospects in daily chemicals, agricultural adjuvants, and other products.

Adding Polypeptides to the Toolbox for Redox-Switchable Polymerization and Copolymerization Catalysis

Bis(imino)pyridine (BIP) iron alkoxide complexes act as catalysts to efficiently polymerize N-carboxyanhydrides (NCAs), including γ-benzyl-l-glutamate NCA (BLG-NCA) and sarcosine NCA (Sar-NCA), at room temperature. Reaction rates were greatly enhanced with the addition of mild Lewis acids, such as [CoCp2][BArF24], which work cooperatively with the iron-based catalysts to facilitate NCA polymerization. The reactivity of (2,6MeBIP)FeOCH2C(CH3)3 with Sar-NCA was combined with its known reactivity for ε-caprolactone polymerization to form diblock and triblock copoly(ester-b-peptides) through sequential addition of lactone and NCA monomers. Redox-switchable polymerization reactions were developed by iteratively exposing the catalyst to redox reagents and Sar-NCA or cyclohexene oxide. The orthogonal reactivity demonstrated by the catalyst in its oxidized and reduced states led to the synthesis of diblock and triblock copoly(ether-b-peptides). Polyether segments were synthesized with the catalyst in its oxidized state, while the polyamide segments were synthesized with the catalyst in its reduced state. Both copolymerization reactions developed here are rare examples where NCA polymerization reactions can be combined with other ring-opening polymerization reactions to make copolymers containing polypeptides and other functional monomers.

Boronic Ester Transesterification Accelerates Ion Conduction for Comb-like Solid Polymer Electrolytes

Polyether is a kind of ideal polymer matrix for solid polymer electrolytes (SPEs), but its inherent drawbacks (such as the semi-crystalline nature and strong complexation of lithium ions) still hinder their commercial application. The construction of comb-like SPEs effectively increases their functionalities and improves the comprehensive performance. Herein, we apply a dynamic boronic ester exchange strategy to simultaneously enhance the lithium-ion conduction and self-healing ability of the SPEs, thus effectively solving the current problems of polyether. The copolymer (GPA) containing side chains with poly(ethylene glycol) (PEG) and diol groups was obtained through reversible addition–fragmentation chain-transfer (RAFT) polymerization and hydrolysis, and PBA-M2070 containing the boronic acid group and flexible polyether segments was obtained via Schiff base reaction. Boronic ester bonds were formed by dehydration of the diol groups of GPA and the boronic acid groups of PBA-M2070. Dynamic exchange of the boronic ester bonds at the branched sites enhanced the side-chain motion, thus increasing the self-healing ability and electrochemical performance of the SPEs, as well as the cycling stability of assembled batteries. Benefiting from the dynamic boronic ester exchange and enhanced side-chain mobility, the SPEs exhibited self-healing within 10 min and an ionic conductivity of 1.58 × 10–5 S cm–1 at 30 °C. The assembled lithium metal batteries (LMBs) were operated stably at 0.5C for 300 cycles. The dynamic boronic ester exchange strategy used to enhance the LMBs properties provides new insight into the design of comb-like polymer electrolytes.

Multiblock poly(ether-b-amide) copolymers comprised of PA1212 and PPO-PEO-PPO with specific moisture-responsive and antistatic properties

Functional multiblock poly(ether-b-amide) (PEBA) copolymers, comprised of PA1212 (polyamide 1212) as hard segments and Jeffamine ED-2003 as soft segments, were successfully prepared via two-step melt polycondensation without any amidation catalyst. Here, using diamino-terminated poly(propylene oxide)-poly(ethylene oxide)-poly(propylene oxide) (PPO-PEO-PPO), Jeffamine ED-2003, enhances the compatibility between polyamide oligomer and polyether, which is better than the traditional route using hydroxyl-terminated polyether. The chemical structure of multiblock PEBAs, as well as the microphase separated structure with crystalline phase of polyamide and polyether, were confirmed by heteronuclear multiple-bond correlation spectrum, heteronuclear multiple quantum correlation spectrum, Fourier transform infrared spectroscopy (FT-IR), differential scanning calorimetry and dynamic mechanical analysis. The hydrophilic PEBA copolymers showed water adsorption ranging from 87.3% to 17.1% depending on the polyether content, and specially showed moisture responsive behavior within seconds when exposed to moisture. The corresponding mechanism was studied using time-resolved attenuated total reflectance FT-IR spectroscopy in the molecular level and the water diffusion coefficient was estimated to be 1.07 × 10–8 cm2∙s–1. Two-dimensional correlation FT-IR spectra analysis was performed to confirm that the interaction between water and polyether phase was in preference to that between water and polyamide matrix, and water molecule only forms hydrogen bond with the polyether segment. Due to the incorporation of PEO segments, the PEBAs have the surface resistivity varying from 5.6 × 109 to 6.5× 1010 Ω, which makes PEBA potential candidate as permanent antistatic agent.

Multiblock copolymers containing polyether segments for separation of C4 hydrocarbons

Separation of C4 paraffins and C4 olefins from each other is an underdeveloped sector of membrane gas separation. Permeabilitieis, diffusivities and solubilities of C4 paraffins (i.e. n-butane and isobutane) and C4 olefins (i.e. cis-2-butene, trans 2-butene, 1-butene, isobutylene and 1,3-butadiene) in three commercial polymers- PEBAX 2533, PolyActive1500PEGT77PBT23 and PolyActive4000PEGT77PBT23 are reported in this study for the first time. The aim of this study is to thoroughly understand the single gas permeation mechanism of the C4 paraffins and C4 olefins through the multiblock copolymers. The cohesive energy density of the polyether segments plays a vital role to determine the permeabilities through the polymer. The selectivity of the olefin/paraffin gas pairs are largely dependent on the content of the ether oxygen of the polyether segments. But the selectivity of the paraffin gas pair and the olefin isomer gas pairs are not influenced by the ether oxygen content of the polyether segments of the multiblock copolymers.

Stretchable Self-Healing Plastic Polyurethane with Super-High Modulus by Local Phase-Lock Strategy.

In this work, a multiblock polyurethane (PU-Im) consisting of polyether and polyurethane segments with imidazole dangling groups is demonstrated, which can further coordinate with Ni2+ . By controlling the ligand content and metal-ligand stoichiometry ratio, PU-Im-Ni complex with vastly different mechanical behavior can be obtained. The elastomer PU-2Im-Ni has extraordinary mechanical strength (61MPa)andexcellenttoughness(420 MJ m-3 ), but the plastic PU-4Im-Ni exhibits super-high modulus (515 MPa),strength(63 MPa),andgoodstretchability(≈800%). The metal-ligand interaction between polyurethane segments and Ni2+ is proved by Raman spectra, dynamic mechanical analysis (DMA), and transmission electron microscopy (TEM). The polyurethane segments domain formed by microphase separation is dynamically "locked" by Ni2+ coordinated with imidazole, revealing a local phase-lock effect. The phase-locking hard domains reinforce the PU-Im-Ni complex and maintain stimuli-responsive self-healing ability, while the free polyether segments provide stretchability. Primarily, the water environment with plasticization effect serves as an effective and eco-friendly self-healing approach for PU-Im-Ni plastic. With the excellent mechanical performance, thermal/aquatic self-healing ability, and unique damping properties, the PU-Im-Ni complexes show potential applications in self-healing engineering plastic and cushion protection fields.

Dielectric Properties in Oriented and Unoriented Membranes Based on Poly(Epichlorohydrin-co-Ethylene Oxide) Copolymers: Part III.

The dielectric spectra and conductivity properties of neat poly(epichlorohydrin-co-ethylene oxide)(PECH-co-EO) copolymer and two modified copolymers with a 20% or 40% of dendron 3,4,5-tris[4-(n-dodecan-1-yloxy)benzyloxy] benzoate units were analysed. A process of thermal orientation was applied to the copolymers to fine-tune the molecular motion of the side chains and determine their validity for cation transport materials. The study was conducted using Dielectric Thermal Analysis (DETA). The spectra of the modified unoriented and oriented copolymers consisted of five dielectric relaxations (δ, γ, β, αTg, and αmelting). The analysis of the relaxations processes shows that as the grafting with the dendron units increases, both the lateral and main chains have a greater difficulty moving. The thermal orientation induces in the main chain partial crystallization, including the polyether segments, and modifies the cooperative motion of the main chain associated with the glass transition (αTg). A deep analysis of the electrical loss modulus revealed that the degree of modification only modifies the temperature peak of each relaxation, and this effect is more perceived if the dendron unit content is higher (40%). The thermal orientation process seems equal to the spectra of CP20-O and CP40-O to the point that the degree of modification does not matter. Nevertheless, the fragility index denotes the differences in the molecular motion between both copolymers (40% and 20%) due to the thermal orientation. The study of the electric conductivity showed that the ideal long-range pathways were being altered by neither the thermal orientation process nor the addition of dendrimers. The analysis of the through-plane proton conductivity confirmed that the oriented copolymer with the highest concentration of dendrimers was the best performer and the most suitable copolymer for proton transport materials.

Improved gas separation performance of Pebax®1657 membrane modified by poly-alcoholic compounds

Poly (ether-block-amide) or Pebax is one of the most promising copolymers employed for CO2 separation. The existence of polyamide and polyether segments within the total matrix gives superior properties to Pebax, providing it significant CO2 permeation compared to the other light gases such as CH4 and N2. However, improving the separation performance of Pebax is one of the major concerns in developing new membranes. Compounds with hydroxyl and carboxyl groups are listed as appropriate candidates to be embedded within the Pebax matrix, finally enhancing the CO2 separation. Such compounds with oxygen atoms (negatively charged) can interact with the central carbon (positively charged) of CO2 via Lewis acid-base interactions, which contributes to further CO2 permeation. In this study, Pebax®1657, which has a good performance in CO2 separation, was blended with maltitol and mannitol as multi-hydroxyl compounds. Pebax/mannitol and Pebax/maltitol blend membranes were prepared by solution casting/solvent evaporation method, and their CO2 separation performance from N2 and CH4 was studied. Changes in chemical bonds, thermal properties, and cross-sectional morphology of the membranes were investigated using FTIR, DSC, TGA, FESEM and XRD analysis. The gas permeability results showed that the highest permeability of CO2 was 341.27 barrer and 228.64 barrer, which are related to Pebax/maltitol (20 wt%), and Pebax/mannitol (20 wt%) at a temperature of 30 °C and feed pressure of 10 bar, respectively. In addition, the highest selectivity of 66.65 (CO2/N2) and 23.95 (CO2/CH4) was obtained for Pebax/maltitol (20 wt%). Likewise, selectivity values of 67.84 for CO2/N2 and 25.49 for CO2/CH4 were obtained with Pebax/mannitol (20 wt%), at a pressure of 10 bar.

On the toughening of unsaturated polyester resins using nadimide end‐functionalized polyether telechelics

AbstractCopoly‐propylene glycol (terephthalate–maleate) based unsaturated polyester resin (UPER) was modified with nadimide end‐capped polyether telechelics namely, polypropylene glycol (PPG with molecular weight 2000, 1000, 400 g/mol), polytetramethylene oxide (PTMO with molecular weight 2000 g/mol) and polyethylene glycol (PEG with molecular weight 2000 g/mol) (NPPG/NPTMO/NPEG). The telechelic NPPG/NPTMO/NPEG were synthesized from the corresponding polyols (hydroxy telechelics) by reaction with 4‐nadimido benzoyl chloride. These derivatives were characterized by chemical and spectral methods. Blends of UPER with varying amounts of NPPG/NPTMO/NPEG were prepared. Blending boosted the cohesive energy through enhanced crosslinking as reflected in the gel content of the cured matrices done in separate studies. It increased the fracture characteristics tremendously. The addition of 2.5 phr of the nadimide end functional polyether gave the maximum toughness. The crosslink density showed an initial increase on blending, but further addition of the telechelics did not make any change. The properties of the prepared blends were compared with maleimide end‐capped polyether toughened UPE resins. It was concluded that the toughening effect of the polyether additive depends not only on its concentration but also on its distribution in the matrix as dictated by its reactivity ratio with styrene. The high reactivity of the nadimide groups did not create an ambiance good enough to get an acceptable distribution of the polyether segments conducive for a tough matrix. Whereas the maleimide end‐capped polyether provides better toughening efficiency.

Poly(ether-block-amide) Copolymer Membranes in CO2 Separation Applications

Poly(ether-block-amide) (PEBA, commercialized as Pebax) copolymer membranes show a highly promising platform for preparing high-performance membranes for CO2 capture from process streams containing CH4 and N2. Pebax combines high CO2 affinity with the desired mechanical strength for polymeric membranes thanks to its flexible polyether segment and hard polyamide block, respectively. Furthermore, researchers have been improving the performance of these membranes by preparing a thin Pebax selective layer on top of porous supports and by incorporating inorganic and organic nanofillers into the Pebax matrix to overcome the permeance-selectivity limit. The chemical and structural characteristics of Pebax membranes according to the different fabrication techniques and parameters are discussed first. Then, the recent developments in terms of both Pebax-based thin film composite and mixed matrix membranes are summarized. Finally, thermal and water stabilities of these membranes are addressed.

Improved curing performances of epoxy resin by a structure-controllable self-emulsifying curing agent

Curing agent is one of the indispensable components in waterborne epoxy resin system. However, its applications are seriously limited by the inferior emulsifying performances. By introducing hydrophilic segment, the curing agent can well emulsify the epoxy resin latex and thus improves the mechanical strength of cured film. In the present work, a structure-controllable self-emulsifying epoxy curing agent containing polyether segments was synthesized and characterized by FTIR and 1H NMR spectra. Then, effect of synthesis conditions on the performances of curing agent was studied, including the reactant ratio, reaction temperature and time. To improve the heat stability of curing agent and dispersion ability of epoxy resin latex, 5 wt% of HAc (to -NH) was applied as a neutralization agent. From the size of curing agent and epoxy resin latex measured by dynamic light scattering (DLS), it is found that the polyether segment in the curing agent remarkably affects the self-emulsifying and emulsifying abilities. The curing kinetics of liquid epoxy resin (E-51) in the presence of curing agent was studied by differential scanning calorimetry (DSC), and the curing process of cured film was observed by light microscope. Compared with the commercial one, the curing agent exhibits better construction and mechanical properties, which indicates that it possesses great potentials in the application of architectural and industrial coatings.

Non-isocyanate Polyurethanes from 1,1'-Carbonyldiimidazole: A Polycondensation Approach.

1,1'-Carbonyldiimidazole (CDI) provides a platform to generate high molecular weight polyurethanes from industrially relevant diols and diamines. CDI, which is described in the literature for its use in amidation and functionalization reactions, enables the production of well-defined and stable polyurethane precursors, thus eliminating the need for isocyanates. Herein, the functionalization of 1,4-butanediol with CDI yields an electrophilic biscarbamate, bis-carbonylimidazolide (BCI), which is suitable for further step-growth polymerization in the presence of amines. Elevated reaction temperatures enable the solvent-, catalyst-, and isocyanate-free polycondensation reaction between the BCI monomer and various diamines. The thermoplastic polyurethanes produced from this reaction demonstrate high thermal stability, tunable glass transition temperatures based on incorporation of flexible polyether segments, and mechanically ductile thin films. CDI functionalized diols will allow the preparation of diverse polyurethanes without the use of isocyanate-containing monomers.

Real‐time Raman spectroscopy measurements to monitor the effect of polypropylene crosslinking on its true mechanical behaviour

AbstractIn‐situ Raman spectroscopy analysis to mechanical tests were performed to investigate the deformation micromechanisms of an isotactic polypropylene‐grafted maleic anhydride (PP‐g‐MAH) depending on the crosslinking degree provided by functional polyether amine molecules. The switch from brittle to highly ductile mechanical behaviours was focused in terms of microstructure modifications in real time during stretching. From the Raman spectral analysis, crystallinity index and macromolecular chains orientation factors for both crystalline and amorphous phases were determined. A new orientation factor relative to the polyether segments was proposed. The results shown allow a more complete understanding of the proper micromechanisms of deformation involved in each phase and their interaction between one another. These results also highlight the impact of the crosslinking reaction on the material resilience improvement.

Effects of Heterogeneous Linear Polyether Segments on the Membrane Breathability of Nonionic Polyurethane

Characterizing the relationships between the water repellency and moisture permeability (breathability) of hydrophilic polyurethane and its supramolecular structure, including the phase inversion temperature in the soft phase, is unavoidable when developing intelligent, breathable textile products. In this study, a two-step technique was employed to prepare hydrophilic nonionic polyurethanes (PU) with various polyether (PE) soft segments. The hard segments of the samples were composed of 4,4′-diphenylmethane diisocyanate (MDI) and 1,4-butanediol (BDO), while the soft segments consisted of polyethylene glycol 1000 (PEG), polytetramethylene glycol 1000 (PTMG), or their mixture. The relationships between the chemical and physical structure and the breathability were studied. The results showed that the samples with better separated structure between the soft and hard domains had a special microstructure of partial compatibility and simultaneously partial separation between the polyether soft and hard domains. In addition, the distribution of the mixed polyethers in the soft domains was homogeneous. The microphase structure, especially the hydrophilic ether bond content, exhibited a specific corresponding relevancy to the water resistance, moisture permeability and hydrophilicity of the PU membrane. The moisture permeability and water resistance were also directly related to their film-forming properties. Enhanced microphase separation intensified the positive effects of ether bonds on the moisture permeability, while worsened microphase separation weakened their negative influence on the water resistance/hydrophobicity.

Self-assembly and rheological behavior of chloramphenicol-based poly(ester ether)urethanes

New poly(ester ether)urethanes containing biocide chloramphenicol in the hard segments are presented. SEM microphotographs evidence highly porous morphologies which depend on the nature of polyether segments. The self-assembly ability in micellar aggregates was evidenced by TEM and DLS analyses. Critical micelle concentration values determined by steady-state fluorescence measurements tend to increase with more solvophilic poly(ethylene oxide) and β-cyclodextrin segments. The flow curves reveal shear thinning (pseudoplastic behavior) followed by Newtonian plateaus for all studied polyurethane solutions. The complex viscosity reveals shear thinning behavior at low values of angular frequency followed by shear thickening behavior at higher values of angular frequency. The rheological temperature test evidences an Arrhenius thermothinning behavior at low temperatures followed by thermothickening behavior at higher temperatures. The studied polyurethanes have thermoresponsive and thermoassociative properties.

Itaconimide telechelics of polyethers, synthesis, and their impact on mechanical properties of unsaturated polyester resins

AbstractThe present work focuses on the evolution in the mechanical properties of an unsaturated polyester resin (UPR) on blending with itaconimide‐end terminated polyethers, namely, polypropylene glycol (I‐PPG), polyethylene glycol (I‐PEG), and polytetra methylene oxide (I‐PTMO). Blends of an unsaturated polyester (UPR, based on propylene glycol, terephthalic, and maleic acids) resin with different loading of itaconimide end‐capped telechelics were investigated for their mechanical and thermal properties. Blending with these additives enhanced the mechanical and thermal properties of the crosslinked UPR. The impact strength and fracture toughness values were improved by more than 100% by small quantities of the additives. The improvement in fracture properties was correlatable primarily to a decrease in overall crosslink density. The distribution of the polyether chains in the cured matrix as dictated by the reactivity ratios of styrene and polyether macromer was found to have a role in deciding the properties. The properties were found to be the best for the blend toughened with I‐PPG with a molecular weight 2000 g/mole at a loading of 2.5 parts per hundred parts. On comparison with the resin blended with a maleimide‐encapped polyether of same molecular weight, the itaconimide end‐capped polyether was found to provide a better toughening of the UPR matrix. This could a priori be explained based on a difference in distribution of the end‐capped polyether as a consequence of the difference in the copolymerization behavior of itaconimide and maleimide functionalized telechelics toward UPR. The itaconimide enters into a random copolymerization with styrene and the probability for formation of the continuous sequences of the itaconic group is about 60%. This will permit polyether segments to come close enough to form micro or even sub‐micron clusters of the polyether which eventually forms the micro crystallites of poly ether that act as a crack stopper. This possibility cannot be envisaged in maleimides which forms invariably an alternating sequence with styrene. The morphological features as reflected in scanning electron microscopic analyses tallied with these observations. This work could help identify the ways for obviating the inherent brittleness of the UPR systems.