This document provides recommendations addressing the long-standing dilemma of the wide variety of terms that are used to describe the two common classes of polymerization mechanisms in the scientific literature, which includes chemistry and polymer science textbooks. It is an update of a 1994 IUPAC document on this topic and provides clarification and hierarchical structure regarding the basic classification and terminology describing polymerization reactions. The term step polymerization describes polymerizations in which growth occurs by reactions between monomer, oligomer, or polymer molecules of any length. We clearly denote here the two subclasses of step polymerization: additive step polymerization (synonym: polyaddition) and condensative step polymerization (synonym: polycondensation). The term chain polymerization describes polymerizations that proceed via a chain reaction with monomer molecules adding to active sites on polymer chains. Subclasses of chain polymerization include additive chain polymerization and condensative chain polymerization. The terms provide a logical and straightforward structure for describing the two common classes of polymerization mechanisms. Previously defined terms relevant to these two classes of polymerization reactions are also repli-cated in this Recommendation document.

The transmission of viral pathogens via contaminated surfaces remains a critical public health concern, particularly in shared environments. Conventional antiviral coatings incorporating biocidal compounds face limitations due to cytotoxicity, environmental persistence, degradation, and the risk of promoting antiviral resistance. Nanostructured mechano-bactericidal surfaces have proven effective in preventing bacterial colonization, motivating exploration of their antiviral potential. In this study, flexible nanostructured acrylic films with nanopillar arrays are fabricated using anodized aluminum oxide (AAO) molds and ultraviolet nanoimprint lithography (UV-NIL), providing a scalable mechano-virucidal platform, capable of physically rupturing viral particles. Systematic variation of nanopillar pitch and height reveals that interpillar spacing is the dominant determinant of antiviral efficacy. Dense arrays with a 60 nm pitch reduce human parainfluenza virus type 3 (hPIV-3) infectivity by up to 1.2-log (∼94%) within 1 h. Finite element method (FEM) simulations demonstrate that these arrays generate localized stresses exceeding the estimated ∼10 MPa rupture threshold of the viral envelope. In contrast, increasing the pitch to 100 nm results in diminished antiviral activity that is influenced by nanopillar height, while a 200 nm pitch abolishes antiviral activity. These findings offer a chemical-free, mechano-virucidal strategy for scalable antiviral surface protection across healthcare, consumer, and environmental applications.

The correct use of IUPAC terminology can facilitate clarity in scientific publications, litigation, and education. This document summarizes IUPAC's recommendations for polymer terminology. In the version attached in the Supplementary Information, hyperlinks lead to the original source material, and screen-tips give the definitions as published by IUPAC.

This report provides a summary of recommended or suggested values of the rate coefficients for thermal decomposition (k d) and of the efficiencies for radical generation (f g) and initiation of polymerization (f i) for some commercially available dialkyldiazene (also known as azo-compound) initiators. These initiators are one of the most important classes of initiators used in both conventional radical polymerization and reversible-deactivation radical polymerization (RDRP). Although values of k d can be cited with confidence for many initiators, it must also be stated that for most initiators there is insufficient quality data in the open literature to allow a rigorous statistical analysis. The situation is complicated by some initiators existing as a mixture of diastereomers and decomposition rates being subject to small, yet experimentally significant, solvent dependence. Efficiencies for radical generation (f g) are available for some initiators. Efficiencies for initiation of polymerization (f i) are less common and have been demonstrated to be strongly dependent on the initiator, the complexity of the mechanisms for radical generation and for initiation of polymerization, the reaction medium, the monomers being polymerized and their concentration as determined by the amount of solvent, and the conversion of monomer to polymer. Consequently, only general recommendations for initiator efficiency are possible at this stage.

The growing drive for sustainable materials has pushed the development of degradable polymers. This work explores the incorporation of alpha-lipoic acid (LA), a commercially available monomer capable of radical ring-opening polymerization (rROP), into polymer backbones using macroRAFT-mediated emulsion polymerization. A series of poly(butyl acrylate) (PBA) seed latexes with increasing LA content (up to 40 mol%) were synthesized and subsequently chain extended with tert-butyl acrylate (tBA) with up to 40 mol% LA and styrene (St) with up to 10 mol% LA to form diblock copolymers. Degradation studies revealed that thermolysis in DMF to cleave the C-S and S-S bonds was significantly more effective than using tris(2-carboxyethyl)phosphine (TCEP) to selectively target the S-S bonds. Substantial molecular weight reduction was observed from low LA mol% incorporation (<10 mol% LA), with minimal additional reduction with increasing mol% LA. Mechanical testing of PBA-b-PSt films demonstrated that at 5 mol% LA incorporation, minimal impact on mechanical properties was observed, while still enabling effective degradation. These findings highlight the potential of LA-based emulsion polymerization systems for producing scalable, degradable polymeric materials suitable for industrial applications such as coatings and adhesives.

Radical ring-opening copolymerization of lipoic acid derivatives with vinyl monomers (VMs) is a versatile route to create degradable copolymers and enables tuning of vinyl polymer properties. Although thermally initiated systems with acrylates, styrene, and acrylamide are well established, photoinduced polymerization remains comparatively underexplored. In this work, we investigate the photopolymerization of ethyl lipoate (ELp) with diverse VMs, including butyl acrylate (BA), N,N-dimethylacrylamide (DMA), methyl methacrylate (MMA), N-vinylpyrrolidone (NVP), vinyl acetate (VAc), isobutyl vinyl ether (IBVE), and norbornene (NB) under 405 nm light. We show that efficient copolymerization is obtained with the use of the photoinitiator (diphenylphosphoryl)(mesityl)methanone (TPO). In its absence, ELp undergoes photolysis to produce only low-molecular-weight oligomers (M-n = 1-2 kg mol(-1)) with limited monomer conversion (<= 20%). In contrast, with TPO, all comonomers, except for styrene and allyl alcohol, achieve efficient polymerization, yielding high molecular weight copolymers (M-n > 19 kg mol(-1)). In addition, we compared the TPO initiated photopolymerization at ambient temperature with AIBN-initiated conventional thermal polymerization at 70 degrees C. We found that ELp exhibits significantly higher conversion under photopolymerization. Monomers such as VAc, IBVE, and NB show much better incorporation when using photoinitiated polymerization conditions, whereas methyl methacrylate and styrene are more suitable for thermal polymerization. Using VAc as a representative case, we further examine how the ELp: VAc feed ratio influences copolymerization kinetics and final copolymer composition. Finally, the resulting VM-ELp copolymers undergo thiolate-promoted disulfide exchange, with M-n values decreasing significantly from 19-82 kg mol(-1) to 1-2 kg mol(-1). Finally, we evaluated the thermal properties of the copolymers. The VAc-co-ELp copolymer containing 15 mol % ELp shows comparable thermal stability to the corresponding VAc homopolymer. However, TGA analysis reveals that the copolymer undergoes a more complete thermal decomposition at lower temperatures. Collectively, this work highlights a substantial, untapped potential of photoinduced lipoate-vinyl copolymerization for creating degradable and functional polymeric materials.

Synthetic polymers are of paramount importance in modern life - an incredibly wide range of polymeric materials possessing an impressive variety of properties have been developed to date. The recent emergence of artificial intelligence and automation presents a great opportunity to significantly speed up discovery and development of the next generation of advanced polymeric materials. We have focused on the high-throughput automated synthesis of multiblock copolymers that comprise three or more distinct polymer segments of different monomer composition bonded in linear sequence. The present work has exploited automation to prepare high molar mass multiblock copolymers (typically>100,000 g mol −1 ) using reversible addition-fragmentation chain transfer (RAFT) polymerization in aqueous emulsion. A variety of original multiblock copolymers have been synthesised via a Chemspeed robot, exemplified by a multiblock copolymer comprising thirteen constituent blocks. Moreover, libraries of copolymers of randomized monomer compositions (acrylates, acrylamides, methacrylates, and styrenes), block orders, and block lengths were also generated, thereby demonstrating the robustness of our synthetic approach. One multiblock copolymer contained all four monomer families listed in the pool, which is unprecedented in the literature. The present work demonstrates that automation has the power to render complex and laborious syntheses of such unprecedented materials not just possible, but facile and straightforward, thus representing the way forward to the next generation of complex macromolecular architectures.

The ability to revert polymers to their original monomers represents a crucial chemical recycling technique, promoting sustainability and offering the chance to convert used materials into valuable products. In recent years, numerous studies have explored the use of polymers synthesized via reversible deactivation radical polymerization (RDRP) techniques to facilitate efficient depolymerization reactions. Herein, we report the use of a photocatalyst, zinc tetraphenylporphyrin (ZnTPP), along with light irradiation to accelerate depolymerization of polymers prepared by reversible addition-fragmentation chain transfer (RAFT) polymerization. We explore various parameters affecting depolymerization efficiency, including solvents, reaction temperature (80, 100, and 120 degrees C), the presence of photocatalysts (ZnTPP and Eosin Y), and the type of RAFT end-groups, namely trithiocarbonate, dithiobenzoate, and 1H-pyrazole-1-carbodithioate. For instance, when PMMA was diluted to 25 mM in 1,4-dioxane and heated to 120 degrees C under green light irradiation in the presence of ZnTPP (200 ppm), rapid depolymerization exceeding 70% occurred within 1 h. Without ZnTPP, under similar conditions, the reaction required over 8 h to achieve a slightly lower yield. Furthermore, this method confers moderate oxygen tolerance to the system, enabling depolymerization to proceed without the need of deoxygenation, albeit at a lower rate and consequently lesser monomer recovery (31%). image

Transitioning towards a circular economy, extensive research has focused on dynamic covalent bonds (DCBs) to pave the way for more sustainable materials. These bonds enable debonding and rebonding on demand, as well as facilitating end-of-life recycling. Acylhydrazone/hydrazone chemistry offers a material with high stability under neutral and basic conditions making it a promising candidate for materials research, though the material is susceptible to acid degradation. However, this degradation under acidic conditions can be exploited, making it widely applicable in self-healing and biomedical fields, with potential for reprocessing and recycling. This review highlights studies exploring the reversibility of acylhydrazone/hydrazone bonds in various polymers, altering their properties, and utilizing them in applications such as self-healing, reprocessing, and recycling. The review also focuses on how the mechanical properties are affected by the presence of dynamic linkages, and methods to improve the mechanical performance.

Abstract During the 49th World Polymer Congress held 17–21 July 2022 in Winnipeg, Canada, Graeme Moad presented the Stepto Lecture Award [1], describing the mechanism and terminological evolution of reversible deactivation radical polymerization (RDRP) [2, 3, 4], including more recent intricate designs through the use of light and electrical propulsion.

Due to the high density of human populations within enclosed spaces, respiratory viruses are mainly transmitted via airborne aerosols; however, they can also be transmitted via indirect contact when a respiratory droplet containing a viral load contaminates a smooth surface, on which some viruses have long survivability. In this perspective, we outline recent developments of antiviral surfaces to combat the surface transmission of viruses. Numerous technologies already exist for the development of antibacterial surfaces that have the potential to be extended toward the development of antiviral surfaces. We overview the potential to utilise nanostructured surfaces for the physical inactivation of virus particles. However, there remains a limited number of suitable nanofabrication approaches and a lack of understanding of the nature of efficient virucidal surfaces.

Reversible addition-fragmentation chain transfer polymerization (RAFT) is a popular method for the synthesis of well-defined macromolecules, but its sensitivity to oxygen is a major limitation for many industrial applications. Recent research has focused on developing strategies to confer oxygen tolerance onto RAFT polymerization, eliminating the need for deoxygenation steps and allowing for simpler reaction conditions. This minireview highlights several promising approaches to achieve oxygen tolerance in RAFT polymerization, including enzyme-mediated, alkylborane-initiated, and photomediated methods. The potential applications of oxygen-tolerant RAFT polymerization are also discussed, demonstrating the promise for significant advances in large-scale industrial polymer synthesis.

This paper presents a comprehensive experimental and theoretical investigation into the antiviral properties of nanostructured surfaces and explains the underlying virucidal mechanism. We used reactive ion etching to fabricate silicon (Si) surfaces featuring an array of sharp nanospikes with an approximate tip diameter of 2 nm and a height of 290 nm. The nanospike surfaces exhibited a 1.5 log reduction in infectivity of human parainfluenza virus type 3 (hPIV-3) after 6 h, a substantially enhanced efficiency, compared to that of smooth Si. Theoretical modeling of the virus-nanospike interactions determined the virucidal action of the nanostructured substrata to be associated with the ability of the sharp nanofeatures to effectively penetrate the viral envelope, resulting in the loss of viral infectivity. Our research highlights the significance of the potential application of nanostructured surfaces in combating the spread of viruses and bacteria. Notably, our study provides valuable insights into the design and optimization of antiviral surfaces with a particular emphasis on the crucial role played by sharp nanofeatures in maximizing their effectiveness.

An oxygen-tolerant SI-PhotoRAFT technique has been developed for the efficient synthesis of surface-tethered polymer brushes under low-energy near-infrared (NIR) light. This technique takes advantage of the unique properties of NIR light, in particular enhanced penetration, to effectively prepare polymeric coatings, even through barriers that are opaque to visible light. The NIR-mediated SI-PhotoRAFT polymerization technique was utilized to precisely modulate brush height in direct correlation with the irradiation time. Additionally, this technique facilitated sequential chain extension, enabling the fabrication of block copolymer brushes. Moreover, the incorporation of a photoresponsive monomer, 7-[4-(trifluoromethyl)coumarin]acrylamide [2-(2-oxo-4-(trifluoromethyl)-2H-chromen-7-yl)acrylamide, TCAm], within the poly(N,N-dimethylacrylamide) brushes enables orthogonal control over polymerization and cross-linking processes through the use of two different wavelengths (NIR and UV light). When exposed to a UV source (? = 365 nm, 18.2 mW/cm2), the TCAm undergoes dimerization triggering cross-linking of the grafted brush "arms". Furthermore, by utilizing the enhanced penetration of NIR light, a polymeric coating was prepared on the inner walls of a tube that was opaque to visible light. Finally, this process is successfully applied to the synthesis of antifouling surfaces on poly(dimethylsiloxane)-coated silicon wafers, leading to inhibition of biofouling.

A multiblock copolymer is a polymer of a specific structure that consists of multiple covalently linked segments, each comprising a different monomer type. The control of the monomer sequence has often been described as the "holy grail" of synthetic polymer chemistry, with the ultimate goal being synthetic access to polymers of a "perfect" structure, where each monomeric building block is placed at a desired position along the polymer chain. Given that polymer properties are intimately linked to the microstructure and monomer distribution along the constituent chains, it goes without saying that there exist seemingly endless opportunities in terms of fine-tuning the properties of such materials by careful consideration of the length of each block, the number and order of blocks, and the inclusion of monomers with specific functional groups. The area of multiblock copolymer synthesis remains relatively unexplored, in particular with regard to structure-property relationships, and there are currently significant opportunities for the design and synthesis of advanced materials. The present review focuses on the synthesis of multiblock copolymers via reversible addition-fragmentation chain transfer (RAFT) polymerization implemented as aqueous emulsion polymerization. RAFT emulsion polymerization offers intriguing opportunities not only for the advanced synthesis of multiblock copolymers, but also provides access to polymeric nanoparticles of specific morphologies. Precise multiblock copolymer synthesis coupled with self-assembly offers material morphology control on length scales ranging from a few nanometers to a micrometer. It is imperative that polymer chemists interact with physicists and material scientists to maximize the impact of these materials of the future.

In this work we use RAFT crosslinking polymerisation coupled with a Chemspeed robotic synthesis platform to optimise conditions to produce PDMS-arm star polymers by an arm-first strategy.

Chain polymerizations are defined as chain reactions where the propagation steps occur by reaction between monomer(s) and active site(s) on the polymer chains with regeneration of the active site(s) at each step. Many forms of chain polymerization can be distinguished according to the mechanism of the propagation step (e.g., cyclopolymerization – when rings are formed, condensative chain polymerization – when propagation is a condensation reaction, group-transfer polymerization, polyinsertion, ring-opening polymerization – when rings are opened), whether they involve a termination step or not (e.g., living polymerization – when termination is absent, reversible-deactivation polymerization), whether a transfer step is involved (e.g., degenerative-transfer polymerization), and the type of chain carrier or active site (e.g., radical, ion, electrophile, nucleophile, coordination complex). The objective of this document is to provide a language for describing chain polymerizations that is both readily understandable and self-consistent, and which covers recent developments in this rapidly evolving field.

We describe electrochemically initiated emulsion polymerization with reversible addition-fragmentation chain transfer (eRAFT) to form well-defined multiblock copolymers with low molar mass dispersity. We demonstrate the utility of our emulsion eRAFT process with the synthesis of low dispersity multiblock copolymers by seeded RAFT emulsion polymerization at ambient temperature (∼30 °C). Thus, a triblock, poly(butyl methacrylate)-block-polystyrene-block-poly(4-methylstyrene) [PBMA-b-PSt-b-PMS], and a tetrablock, poly(butyl methacrylate)-block-polystyrene-block-poly(styrene-stat-butyl acrylate)-block-polystyrene [PBMA-b-PSt-b-P(BA-stat-St)-b-PSt], were synthesized as free-flowing, colloidally stable latexes commencing with a surfactant-free poly(butyl methacrylate) macroRAFT agent seed latex. A straightforward sequential addition strategy with no intermediate purification steps was able to be employed due to the high monomer conversions achieved in each step. The method takes full advantage of compartmentalization phenomena and the nanoreactor concept described in previous work to achieve the predicted molar mass, low molar mass dispersity (Đ ∼ 1.1-1.2), incrementing particle size (Zav = 100-115 nm), and low particle size dispersity (PDI ∼ 0.02) for each generation of the multiblocks.