ACS Macro Letters最新文献

A polymerization-induced self-stabilization strategyis reportedfor the fabrication of degradable polymer foams without external surfactantsor particulate stabilizers. Specifically, interfacial polycondensationbetween glyoxal and 1,6-hexanedithiol generates amphiphilic oligomersin situ, which spontaneously adsorb at the oil–water interfaceand stabilize high internal phase emulsions (HIPEs). Subsequent curingand cross-linking afford interconnected hydrophobic foams with tunableporous structures and mechanical properties. The resulting materialsexhibit efficient separation of organic solvents from water, facilitatingrecovery and reuse. Moreover, incorporation of glyoxylic acid as acomonomer tailors surface wettability, enabling effective adsorptionof Cu²⁺ from aqueous solutions. Notably, the foams exhibitoxidative degradability under mild H₂O₂ treatment,underscoring their environmental benignity. This work establishes“polymerization-induced self-stabilization” as a newstrategy for constructing surfactant-free, degradable foams templatedby HIPEs with demonstrated applications in the fields of separationand adsorption.

Diels–Alderreaction has been widely employedto accesshighly strained cyclic olefin monomers for efficient ring-openingmetathesis polymerization (ROMP). However, the high ring strain energies(RSEs > 15 kcal/mol) of these traditional Diels–Alder monomers,while promoting efficient polymerization, compromise the depolymerizabilityof the resulting polymers, thereby limiting their chemical recyclability.Herein, we report a class of low-strain Diels–Alder monomersbased on trans-succinimide-fused cyclohexenes (tSICHs), synthesized from readily available feedstocks,fumaric acid and 3-sulfolene. The relatively low RSEs of the tSICH monomers (6.1–6.2 kcal/mol) enable both efficientROMP and ring-closing metathesis depolymerization (RCMD) through concentration-controlledmetathesis equilibrium. All tSICH monomers achievedhigh conversions (>91%) during ROMP at an initial monomer concentrationof 5 M, yielding polymers with high molecular weights (>100 kDa).Moreover, near-quantitative monomer regeneration (>95%) was achievedvia RCMD at room temperature with an olefin concentration of 0.2 M.Critically, the resulting polymers exhibit highly tunable thermomechanicalproperties, affording a broad range of glass transition temperatures(30–78 °C) and tensile strains at break (3–550%).Overall, this work provides a new monomer design strategy that unlocksaccess to chemically recyclable polymers from Diels–Alder-derivedROMP monomers.

Chemically recyclable and/or biobased polymers are promisingalternativesto conventional petroleum-derived plastics, yet strategies that simultaneouslyimprove their performance and recyclability remain scarce. Here, wereport that the combined use of thermal denaturation and dynamic covalentchemistry can transform protein materials into strong, chemicallyrecyclable bioplastics with enhanced hydrolytic stability. Cross-linking a priori brittle bovine serum albumin (BSA)with dynamic vinylogous urethane (VU) linkages producesrobust plastics with tensile strengths of up to 35 MPa. Simultaneously,thermal denaturation at 80 °C restructures BSA fromα-helices into more hydrophobic β-sheet-rich domains,reducing water absorption and thereby stabilizing the otherwise hydrolyzable VU cross-links. The resulting protein networks are chemicallyrecyclable in acidic water, allowing the recovery of both BSA and cross-linkers. Overall, by exploiting the reciprocal interplaybetween dynamic covalent cross-linking and protein thermal denaturation,this work offers a fresh perspective to overcome the trade-off betweenpolymer stability and recyclability.

Photodynamic therapy (PDT) is a noninvasive, spatiotemporallyselectivemodality that affords rapid healing with negligible scarring, butits clinical efficacy is severely limited by tumor hypoxia and aggregation-inducedquenching of photosensitizers. Perfluorocarbons possess excellentoxygen dissolution and transport capacities and have been widely employedto construct oxygen-enriched microenvironments. In addition, the heavy-atomeffect enhances intersystem crossing by promoting spin-orbit coupling,thereby increasing singlet oxygen generation. Herein, we synthesizeda series of amphiphilic bottlebrush polymers (BBPs) covalently graftedwith porphyrin photosensitizers, featuring tunable fluorine-containingside chains and iodine functionalization. Distinct from conventionalpolymeric PDT systems that primarily serve as photosensitizer carriers,the BBP architecture provides a confined multifunctional microenvironmentthat simultaneously regulates photosensitizer aggregation, oxygenavailability, and intersystem crossing. The strong steric repulsionbetween neighboring side chains prevents undesired photosensitizeraggregation and preserves their photoactivity, while the fluorine-richdomains and iodine substituents cooperatively promote singlet oxygengeneration through oxygen enrichment and external heavy-atom effects,respectively. Consequently, polymer vesicles assembled from thesefluorinated and iodinated BBPs exhibit significantly enhanced PDTefficacy. This work establishes a cooperative molecular-design strategythat integrates aggregation suppression, oxygen regulation, and heavy-atom-enhancedintersystem crossing within a single bottlebrush polymer platformfor improved PDT.

Diblock copolymer melts with roughly symmetric compositionproducea fluctuating, network-like morphology in the disordered state thatconverts to lamellae upon cooling through the order–disordertransition. Using dissipative particle dynamics simulations, we documentthe long-time trapping of a single bicontinuous, disordered networkphase for a semiflexible diblock copolymer with a persistence lengthcommensurate with the block contour length. The equilibrium lamellarphase is recovered upon subsequent thermal cycling near the equilibriumorder–disorder condition. These insights suggest that a disorderednetwork phase could be realized via the controlled cooling of a bottlebrushdiblock copolymer melt possessing a modest backbone degree of polymerization.

Conventional radicalultraviolet (UV) curing requires opticallytransparent substrates owing to the rapid termination of propagatingradicals, limiting its use in opaque or geometrically complex assemblycases. We report a photoinduced redox initiation system for delayed-onsetradical UV-curable adhesives combining a coumarin-based photobasegenerator (Cou-TMG) with dilauroyl peroxide (LP). Upon UV irradiation,Cou-TMG releases 1,1,3,3-tetramethylguanidine, which reacts with LPthrough a redox process that continuously generates radicals, sustainingpolymerization after irradiation stops. Optimized photobase generatorloading and irradiation dose provide an open time sufficient for substratelamination (low C═C conversion immediately after UV irradiation)and endow substantial postpolymerization capability (higher C═Cconversion after 1 h), contrasting conventional radical UV curingsystems. The delayed-onset, radical UV-curable adhesives are applicableto various multifunctional acrylates. Specifically, trimethylolpropanetriacrylate-based adhesives achieve a high lap-shear strength of 4.4MPa on aluminum, and the present system further bonds Cu, Fe, polycarbonate,and glass substrates.

A block copolymercontaining a chiral block is referredto as achiral block copolymer, which can form a helical phase (H*) in diblockcopolymers and an alternating gyroid phase (G^A) in triblockterpolymers with controlled chirality from self-assembly, as evidencedby electron tomography. Polylactide-containing chiral block copolymerscan be used as a representative system for the investigation of homochiralevolution from molecular chirality examined by electronic circulardichroism (ECD) to conformational chirality examined by C═Ovibrational circular dichroism (VCD), and finally to phase chiralitycharacterized by electron tomography, with C–O–C VCDproviding insight into interchain chiral interactions. The intra-and interchain contributions should be evaluated in the context ofthe specific molecular structure and sample conditions. By takingadvantage of noncovalent chirality induction, it is feasible to introducea chiral bias by associating a chiral dopant with an achiral block,giving H* with controlled chirality from an achiral block copolymer.This Viewpoint highlights the fundamental principles, providing perspectiveson the design of chiral soft materials for device applications.

Poly(ε-caprolactone) (PCL)-based dynamic polymersare promisingadaptive biomaterials due to their biocompatibility, biodegradability,and high chain mobility; however, the onset temperature for bond-exchangereactions, often referred to as topology-freezing temperature, T_v, remains difficult to control and is typicallytreated as a bulk property governed by catalyst selection and networkstructure. Consequently, many reported dynamic polymers operate attemperatures well above the biomedical operating window, limitingtheir biomedical applicability. Here, we propose an interfacial kineticengineering strategy in which nanoparticle–polymer interfacesact as localized kinetic regulators of dynamic covalent bond exchange.By tailoring nanoparticle (NP) surface chemistry, including functionalgroup density, polarity, and catalytic activity, the activation energy(E_a) can be modulated at the nanoscale,enabling programmable control of T_v. Exchangekinetics in PCL-based dynamic polymers are expected to be highly sensitiveto the local chemical environment, indicating that interfacial effectscan decouple dynamic behavior from bulk composition. This perspectiveestablishes NP–dynamic polymer interfaces as a programmablekinetic design parameter for controlling bond-exchange reactions indynamic polymer networks, opening a pathway toward spatially definedcovalent adaptable materials with application-specific and programmabledynamic behavior.

Low-temperature depolymerization of ATRP polymers hasbeen successfullydemonstrated both in bulk and solution. However, all reported examplesnecessitate a metal catalyst for chain-end activation, require extensivemodifications and transformations prior to depolymerization, or usespecialized initiators. Herein, a catalyst-free bulk depolymerizationmethod for poly(O-aryl methacrylates) is realized,whereby the elimination of lactonization lowers the temperature bymore than 100 °C and enables up to 92% depolymerization efficiencyat temperatures as low as 230 °C. Key to the approach is thein-situ thermal transformation of halogen chain-ends into macromonomer,resulting in monomer yields comparable to those obtained in the presenceof a catalyst. The method can be expanded from various poly(O-aryl methacrylates) to conventional polymethacrylates,for example, poly(methyl methacrylate) and poly(benzyl methacrylate),after a short block addition of an O-aryl methacrylate.This work provides a straightforward, high-yielding, catalyst-freebulk method for chemical recycling and offers mechanistic insightsinto the thermal stability and depolymerization of ATRP polymers.

Accessto smaller phase domain dimensionsrequires reducingthedegree of polymerization, which weakens segregation and increasesthe importance of strong segmental incompatibility; however, the samechemical contrast can impede direct sequential block copolymerizationthrough differences in solvent affinity. Here, we synthesized poly(hexafluorobutylacrylate)-block-poly(acrylamide) (PHFBA-b-PAAm) in one pot from 2,2,3,4,4,4-hexafluorobutyl acrylate (HFBA)and acrylamide (AAm) using organotellurium-mediated radical polymerization(TERP), without intermediate purification or solvent exchange. AlthoughAAm addition induced micron-scale aggregation at room temperature,the system reorganized into a nanoscale dispersion under polymerizationconditions, supporting high-conversion chain extension with low dispersity.Well-defined block copolymers with molecular weights of 15–100kDa and varied compositions were obtained at high monomer conversions.Small-angle X-ray scattering and atomic force microscopy revealedmicrophase separation throughout the series, including the 15 kDasample. Overall, direct synthetic access and low-molecular-weightphase separation can be reconciled in block copolymers with stronglyincompatible segments.