Gradient copolymers, which feature a gradual transition in monomer composition along the polymer backbone, uniquely combine tunable material properties with inherent stochasticity at the molecular level, bridging the structure-property landscape between block and random copolymers. Their broad glass transition temperature range, self-assembly potential, and amphiphilic behavior, if they consist of hydrophilic and hydrophobic comonomer units, enable applications in damping materials, drug delivery, and cosmetics. Moreover, they are interesting potential substitutes for block copolymers based on their much simpler and cheaper production process. However, gradient copolymers are not as simple as often presumed because they emerge from less trivial monomer inclusion probability profiles that are determined by monomer reactivity ratios and/or feeding profiles. As a result, gradient copolymers exhibit significant compositional heterogeneity, even under idealized conditions (fast chain initiation; no side reactions; and no diffusional limitations). This perspective highlights the critical importance of compositional control and structural evaluation in gradient (tapered) copolymer synthesis, highlighting the relevance of calculating a set of structural deviation (SD) metrics using coupled matrix-based Monte Carlo (CMMC) simulations to assess structural quality. In parallel to experimental protocol development and design, SD metrics such as the average SD (⟨SD⟩), SD standard deviation (σSD), SD skewness ( ), and coefficient of variation (CVSD) can be used to assess whether improved synthesis protocols are worthwhile or not. For a given synthesis recipe, a simultaneous SD evaluation with respect to block, gradient, block-gradient, and block-gradient-block targets is recommended based on a framework calibrated on the individual chain level. This facilitates the identification of the application scope of both exploratory and systematic research on gradient copolymer synthesis approaches.

Aiming for renewable polymers with potential recyclability and biodegradability, polyesters are very promising due to an increasing number of available biobased monomers and ester bonds that can be hydrolyzed under specific conditions. Citric acid, for example, is a biobased, nontoxic, cheap, and easily available resource. Its multifunctionality enables the synthesis of polyesters with free carboxy groups, thus providing possibilities for further functionalization and cross-linking. Citric acid and dimethylolpropionic acid were used to synthesize water-soluble polyesters via melt polycondensation at 150 °C without the need for potentially hazardous catalysts. The resulting polyesters displayed a significant amount of free carboxylic acid groups (8 mmol gpolyester -1), and reasonable number-average molar masses up to 5200 g mol-1. Via postsynthetical (partial) neutralization procedures using KOH, charged moieties could be successfully incorporated to further increase hydrophilicity. The degree of neutralization proved to be well controllable. This enables tunability of the final properties, as remaining free carboxy groups can be used for further modifications. Alternative to carboxylate moieties, the introduction of sulfonate groups promotes hydrophilicity. For this purpose, unsaturated polyesters were synthesized that contained varying amounts of maleic anhydride as a third monomer. Postsynthetical sulfonation was performed via the Michael addition of sodium sulfite, introducing a significant number of sulfonate groups. Neutralization and sulfonation were performed in aqueous solution, leading to slight decreases in molar mass due to hydrolysis. The extent of the reduction was successfully reduced by optimizing both procedures. The synthesized water-soluble polyesters carry a substantial number of functional groups. They have high potential as precondensates for cross-linked, water-absorbing materials to be used in agriculture and biomedicine, for which biodegradability is a crucial property.

Covalently cross-linked rubbers face persistent sustainability challenges due to their irreversible networks hindering recycling, while polarity mismatch complicates the incorporation of additional self-healing materials into vulcanization-free cis-1,4-polyisoprene (PI). To advance the sustainable development of functionalized PI with additional new features while promoting the elasticity and mechanical properties, our group proposes a straightforward one-step free radical-mediated thiol-ene reaction using l-cysteine (LC) as a biodegradable compound that bears three main functional groups consisting of thiol, carboxylic acid, and amine. The thiol group is covalently attached to the PI double bonds via free radical thiol-ene chemistry, while the carboxylic acid and amine groups facilitate noncovalent cross-linking through dynamic hydrogen bonds. As the LC content increases, the functionalized PI-LC-X (with X = 10, 30, and 50 denoting the percentage of LC units attached to the PI double bonds) exhibits a synergistic enhancement in the mechanical strength and elasticity. Among them, PI-LC-30 represents the optimal performance in self-healing ability, achieving 100% recovery of toughness at room temperature along with excellent recyclability through acid hydrolysis. This outstanding behavior is attributed to the well-controlled ideal radical thiol-ene reaction (anti-Markovnikov addition), which prevents unwanted chain extension or interchain cross-linking and preserves the linear structure of PI. Maintaining this structural integrity is vital for recyclability, as acid hydrolysis selectively disrupts the reversible hydrogen bonds while keeping the covalent thioether linkages intact, enabling the regeneration of PI-LC-X films with properties closely matching the original material. This strategy effectively addresses polarity mismatch and recyclability challenges, offering a sustainable pathway for functionalizing diene rubbers.

Stimulus-responsive hydrogels have emerged as promising candidates for next-generation biomedical materials, yet the direct influence of copolymer architecture on their gelation kinetics, mechanical performance, and adaptive properties remains underexplored. Here, we systematically compare random (poly-(HEMA-co-NIPAM)) and block (poly-(HEMA-b-NIPAM)) copolymer architectures, synthesized via RAFT polymerization and cross-linked with disulfide-containing DTPA, to engineer redox-responsive hydrogels. Notably, random copolymer hydrogels achieve ultrafast gelation within 30 s and display superior elasticity, with a fracture strain of 295.9% at 40 wt % solid content-substantially higher than the 99.0% observed in block copolymer hydrogels. Thermal analysis reveals that random copolymer hydrogels exhibit a maximum degradation temperature of 380 °C, surpassing the 340 °C of block counterparts, while DSC shows a higher glass transition temperature (135 °C vs 125 °C). SEM imaging further demonstrates that random hydrogels possess uniform, interconnected pores (∼20-25 μm), whereas block architectures yield irregular and larger pores (∼35-40 μm). All hydrogels display robust self-healing and reversible gel-sol-gel transitions upon redox cycling, attributable to dynamic disulfide linkages. These results underscore the pivotal role of macromolecular architecture in tuning hydrogel performance, and establish random copolymer networks as promising platforms for smart wound dressings and responsive drug delivery.

Poly-(styrene-co-maleic anhydride) (SMAnh) and its hydrolyzed derivative, poly-(styrene-co-maleic acid) (SMA), have been widely utilized in applications such as adhesives, drug delivery systems, and hydrogels. Despite the copolymer's versatility, there is a growing need for bioderived alternatives that retain comparable performance while reducing environmental impact. Here, we investigate how polymer backbone rigidity governs the thermal and solution properties of two bioderived analogues of SMAnh: poly-(styrene-co-itaconic anhydride) (SIAnh) and poly-(indene-co-maleic anhydride) (IMAnh). Using asymmetrical flow field flow fractionation with light scattering detection (AF4-LS), we present a comprehensive comparison of how different media and protonation states affect the conformation and flexibility of the corresponding hydrolyzed copolymers SMA, poly-(styrene-co-itaconic acid) (SIA), and poly-(indene-co-maleic acid) (IMA), thereby revealing how their chemical nature dictates their structural response in solution. Data from AF4-LS, size exclusion chromatography with light scattering (SEC-LS), and thermal analysis highlight how subtle changes in monomer substitution (itaconic, indene vs styrene/maleic) alter backbone rigidity. It was determined that SIA is the most flexible copolymer derivative, SMA exhibits intermediate rigidity, and IMA is the most rigid. Each copolymer substitution pattern results in a distinct copolymer coil conformation in solution and ionization behavior. Collectively, these data indicate that the bioderived SIAnh and IMAnh are viable alternatives to SMAnh, but with distinct rigidity-dependent properties, which may result in slightly different performance in applications.

Dynamic ion gels (DIGs) obtained via complex coacervation of oppositely charged poly(ionic liquid)s (PILs) address the inherent trade-off between ionic conductivity (σDC) and mechanical strength (G′) of PILs by providing both enhanced ion transport and robust viscoelastic properties. In order to tune the strength of ionic cross-links through charge delocalization of ion pairs, we study a series of four DIGs obtained from the combination of a cationic PIL (PIL+) containing pendant imidazolium groups and free bis(trifluoromethylsulfonyl)imide (TFSI) counteranions with four anionic PILs (PIL–) bearing pendant sulfonate anions and various free counter cations (i.e., 1-methyl-3-butylimidazolium, trimethylpropylammonium, tetrabutylammonium, and tetrabutylphosphonium). These new DIGs are produced via the formation of ionic cross-links with ion pairs having more localized charges (i.e., cations paired with sulfonate instead of TFSI). This results in stronger electrostatic interactions with counterions, reducing their mobility and significantly increasing the enthalpic driving force for ion exchange-induced coacervation. As a consequence, the four resulting DIGs release different free ionic liquids (ILs) consisting of TFSI anions associated with imidazolium, ammonium or phosphonium cations. The physical, ion-conducting, and viscoelastic properties of the resulting DIGs are systematically investigated by differential scanning calorimetry, broadband dielectric spectroscopy and rheology. The DIG having sulfonate-imidazolium ionic cross-links and releasing EMIM-TFSI ILs exhibits the best compromise between G′ = 62 kPa (at 25 °C, 1 rad s–1) and σDC = 6.5 × 10–6 S cm–1 (at 25 °C), significantly outperforming the parent PILs. These results highlight DIGs as a highly promising class of materials with enhanced processability and mechanical integrity, making them ideal candidates for electrochemical applications such as supercapacitors, soft robotics, electrochromic devices, sensors, and solar cells.

The increasing concern over plastic pollution mostly due to extensive use of petroleum-based poly-(ethylene terephthalate) (PET) has intensified the search for sustainable biobased alternatives. Poly-(ethylene furanoate) (PEF), a fully biobased polyester derived from renewable feedstocks, has emerged as one of the most promising candidates. With superior gas-barrier performance, strong mechanical properties, and the potential for lower carbon emissions, PEF has attracted significant attention as a viable material to replace PET in several applications. This perspective presents an up-to-date and comprehensive overview of scientific and technological developments in PEF, tracing progress from its early discovery to its current industrial relevance. Particular emphasis is placed on the chemistry of PEF synthesis, including recent advances in greener pathways, as well as the structure-property relationships that refer to its superior thermal, mechanical, and barrier properties compared to PET. Performance characteristics arising from chemical structure and molecular modifications are also discussed. The review further examines the present landscape of PEF recycling, covering mechanical, chemical, and emerging enzymatic methods and integrates findings from recent life cycle assessment and techno-economic analysis studies to evaluate its environmental and economic viability. Industrial applications and associated challenges are explored, with a focus on packaging, where PEF's barrier and mechanical advantages offer clear benefits over PET and multilayer systems. The paper concludes by outlining key research gaps that must be addressed to enable scalable, circular, and industrial deployment of the PEF.

In the pursuit of more sustainable tire technologies, the replacement of petroleum-derived additives with bio-based alternatives has become a key research focus. Tackifying resins, which contribute significantly to tread performance and viscoelastic behavior, are among the additives under evaluation for substitution. In this study, several complementary techniques were applied to styrene–butadiene rubber (SBR) compounds, containing either a natural rosin-based resin (Dertoline) or a petroleum-derived resin (Kristalex) at concentrations ranging from 15 to 45 phr, to investigate the effect of resin on the curing process and on compound properties before and after curing. Solid-state NMR spectroscopy and differential scanning calorimetry revealed intimate mixing between polymer and resin at all concentrations and a slowdown in dynamics with increasing resin content that was more pronounced for Kristalex. Dertoline appeared to hinder effective interactions between carbon black, used as a filler, and SBR, leading to a strong suppression of bound rubber, as evidenced by swelling experiments. Vulcanization kinetics, monitored by moving die rheometer experiments, was affected by the two resins in different manners: Kristalex slowed down curing, while Dertoline accelerated it. Moreover, a marching phenomenon was observed at long curing time for high Dertoline concentrations. Cross-link density, determined by equilibrium swelling, decreased with increasing resin loading. Final mechanical and viscoelastic properties of vulcanized compounds, evaluated by dynamic mechanical analysis and tensile tests, were influenced by both resin type and concentration, showing mechanical plasticization effects and changes in both the elastic and anelastic response. Importantly, the two resins appeared to influence wet grip and rolling resistance differently, highlighting their distinct impact on key performance parameters. These results support the tailored use of bio-based tackifiers in sustainable SBR formulations.