Rate coefficients of free-radical polymerization deduced from pulsed laser experiments

Fluorinated Organic Polymers for Cancer Drug Delivery

In the realm of cancer therapy, the spotlight is on nanoscale pharmaceutical delivery systems, especially polymer-based nanoparticles, for their enhanced drug dissolution, extended presence in the bloodstream, and precision targeting achieved via surface engineering. Leveraging the amplified permeation and retention phenomenon, these systems concentrate therapeutic agents within tumor tissues. Nonetheless, the hurdles of systemic toxicity, biological barriers, and compatibility with living systems persist. Fluorinated polymers, distinguished by their chemical idiosyncrasies, are poised for extensive biomedical applications, notably in stabilizing drug metabolism, augmenting lipophilicity, and optimizing bioavailability. Material science heralds the advent of fluorinated polymers that, by integrating fluorine atoms, unveil a suite of drug delivery merits: the hydrophobic traits of fluorinated alkyl chains ward off lipid or protein disruption, the carbon-fluorine bond's stability extends the drug's lifecycle in the system, and a lower alkalinity coupled with a diminished ionic charge bolsters the drug's ability to traverse cellular membranes. This comprehensive review delves into the utilization of fluorinated polymers for oncological pharmacotherapy, elucidating their molecular architecture, synthetic pathways, and functional attributes, alongside an exploration of their empirical strengths and the quandaries they encounter in both experimental and clinical settings.

Monomer Equilibrium and Transport in Emulsion and Miniemulsion Polymerization

The dual concepts of monomer equilibrium and monomer transport in emulsion and miniemulsion polymerization are discussed in depth. The concepts must be considered together since, first, dispersed-phase polymerizations (in this case emulsion and miniemulsion polymerizations) are by their nature multiphase systems that function only due to interphase mass transfer; and second, because phase equilibrium determines the driving force for monomer transport in these (and all heterophase reaction) systems. Concepts of polymer particle swelling are reviewed, and the question first addressed by Paul Flory in the 1950s: Are emulsion polymerizations transport or reaction limited? is revisited in detail.

Temperature Dependence of the Number of Defect-Structures in Poly(vinylidene fluoride)

Poly(vinylidene fluoride) (PVDF) is predominantly characterized by alternating CH2 and CF2 units in a polymer backbone, originating from the head-to-tail addition of monomers or regular propagation. Due, to a small extent, to inverse monomer addition, so-called defect structures occur which influence the macroscopic properties of PVDF significantly. The amount of defect structures in the material is determined by the polymerization conditions. Here, the temperature dependence of the fraction of defect structures in PVDF obtained from polymerizations between 45 and 90 °C is reported. We utilized 19F-NMR spectroscopy to determine the fraction of defect structures as a function of temperature. To derive kinetic data, the polymerization of VDF is considered a quasi-copolymerization described by the Terminal Model involving four different propagation reactions. Based on the experimentally determined temperature-dependent fractions of defect structures, the known overall propagation rate coefficient, and taking into account the self-healing behavior of the macroradical, the Arrhenius parameters of the individual propagation rate coefficients were determined using the Monte Carlo methods.

The thermodynamics and kinetics of depolymerization: what makes vinyl monomer regeneration feasible?

Depolymerization is potentially a highly advantageous method of recycling plastic waste which could move the world closer towards a truly circular polymer economy. However, depolymerization remains challenging for many polymers with all-carbon backbones. Fundamental understanding and consideration of both the kinetics and thermodynamics are essential in order to develop effective new depolymerization systems that could overcome this problem, as the feasibility of monomer generation can be drastically altered by tuning the reaction conditions. This perspective explores the underlying thermodynamics and kinetics governing radical depolymerization of addition polymers by revisiting pioneering work started in the mid-20th century and demonstrates its connection to exciting recent advances which report depolymerization reaching near-quantitative monomer regeneration at much lower temperatures than seen previously. Recent catalytic approaches to monomer regeneration are also explored, highlighting that this nascent chemistry could potentially revolutionize depolymerization-based polymer recycling in the future.

Preparation and Characterization of Acrylic and Methacrylic Phospholipid-Mimetic Polymer Hydrogels and Their Applications in Optical Tissue Clearing

The 2-methacryloyloxyethyl phosphorylcholine (MPC) polymers are mimetic to phospholipids, being widely used as biocompatible polymers. In our previous study, MPC polymer hydrogels proved more effective for optical tissue clearing compared to acrylamide (AAm) polymer hydrogels. In the present study, 2-acryloyloxyethyl phosphorylcholine (APC) was synthesized and employed to create hydrogels for a comparative analysis with methacrylic MPC-based hydrogels. APC, an acrylic monomer, was copolymerized with AAm in a similar reactivity. In contrast, MPC, as a methacrylic monomer, demonstrated higher copolymerization reactivity than AAm, leading to a spontaneously delayed two-step polymerization behavior. This suggests that the polymer sequences and network structures became heterogeneous when both methacrylic and acrylic monomers, as well as crosslinkers, were present in the copolymerization system. The molecular weight of the APC polymers was considerably smaller than that of the MPC polymers due to the formation of mid-chain radicals and subsequent β-scission during polymerization. The swelling ratios in water and strain sweep profiles of hydrogels prepared using acrylic and methacrylic compounds differed from those of hydrogels prepared using only acrylic compounds. This implies that copolymerization reactivity influences the polymer network structures and crosslinking density in addition to the copolymer composition. APC-based hydrogels are effective for the optical clearing of tumor tissues and are applicable to both passive and electrophoretic methods.

Controlled Radical Copolymerization toward Well-Defined Fluoropolymers

In the past 80 years, fluoropolymers have found broad applications in both industrial and academic settings, owing to their unique physicochemical properties. Copolymerizations of fluoroalkene feedstocks present an important avenue to obtain high-performance materials by merging intrinsic attributes of fluorocarbons and great versatility of comonomers. Recently, while massive investigations have disclosed the great potentials of precisely synthesized polymers, researchers have made considerable efforts to approach well-defined fluorinated copolymers. This minireview discusses challenges in controlled radical copolymerizations (CRCPs) of fluoroalkenes and provides a concise perspective on recent progress in CRCPs of fluoroalkenes (e.g., tetrafluoroethylene, chlorotrifluoroethylene, hexafluoropropene, perfluoroalkyl vinyl ethers) with non-fluorinated vinyl comonomers, which have enabled on-demand preparations of various main-chain fluoropolymers with predefined molar masses, low dispersities, as well as regulable chemical compositions and sequences. The synthetic advantages of CRCPs will promote controlled and facile access to customized fluoropolymers for high-tech applications such as batteries, coatings and so on.

Precise Modeling of the Particle Size Distribution in Emulsion Polymerization: Numerical and Experimental Studies for Model Validation under Ab Initio Conditions

The particle size distribution (PSD) in emulsion polymerization (EP) has been modeled in the past using either the pseudo bulk (PB) or the 0-1/0-1-2 approaches. There is some controversy on the proper type of model to be used to simulate the experimental PSDs, which are apparently broader than the theoretical ones. Additionally, the numerical technique employed to solve the model equations, involving hyperbolic partial differential equations (PDEs) with moving and possibly steep fronts, has to be precise and robust, which is not a trivial matter. A deterministic kinetic model for the PSD evolution of ab initio EP of vinyl monomers was developed to investigate these issues. The model considers three phases, micellar nucleation, and particles that can contain n≥0 radicals. Finite volume (FV) and weighted-residual methods are used to solve the system of PDEs and compared; their limitations are also identified. The model was validated by comparing predictions with data of monomer conversion and PSD for the batch emulsion homopolymerization of styrene (Sty) and methyl methacrylate (MMA) using sodium dodecyl sulfate (SDS)/potassium persulfate (KPS) at 60 °C, as well as the copolymerization of Sty-MMA (50/50; mol/mol) at 50 and 60 °C. It is concluded that the PB model has a structural problem when attempting to adequately represent PSDs with steep fronts, so its use is discouraged. On the other hand, there is no generalized evidence of the need to add a stochastic term to enhance the PSD prediction of EP deterministic models.

Gelatin acrylamide with improved UV crosslinking and mechanical properties for 3D biofabrication

Photocrosslinkable gelatin has attracted increasing interest in the field of biofabrication, with the most studied and widely used photocrosslinkable gelatin being gelatin methacrylate (GelMa). However, the 3D fabrication of GelMa has presented several limitations and challenges, primarily due to its slow crosslinking speed. It is generally known that acryl-based functional groups have faster reaction kinetics than methacryl-base groups. However, gelatin acrylamide (GelAc) has not been widely investigated, largely due to its increased complexity of synthesis relative to GelMA. In this study, we developed a novel synthesis method for GelAc. By varying the reaction ratio of reagents, GelAc with a degree of substitution from 20% to 95% was produced. The UV crosslinking properties of GelAc was studied, demonstrating significantly faster crosslinking kinetics than GelMa, especially at lower concentrations and low photoinitiator concentrations. The swelling ratio and mechanical properties of the crosslinked GelAc hydrogel were also characterized, and biocompatibility experiments conducted via both surface seeding and hydrogel encapsulation of cells, with good cell viability observed. The application of GelAc for 3D biofabrication was demonstrated by 3D printing. GelAc can be a useful material for the fabrication of 3D conduits for tissue engineering applications.

Using Excimer Laser for Manufacturing Stimuli Responsive Membranes

A 248 nm KrF excimer laser can be used to manufacture temperature and pH-responsive polymer-based membranes for controlled transport applications. This is done by a two-step approach. In the first step, well-defined/shaped and orderly pores are created on commercially available polymer films by ablation by using an excimer laser. The same laser is used subsequently for energetic grafting and polymerization of a responsive hydrogel polymer inside the pores fabricated during the first step. Thus, these smart membranes allow controllable solute transport. In this paper, determination of appropriate laser parameters and grafting solution characteristics are illustrated to obtain the desired membrane performance. Fabrication of membranes with 600 nm to 25 μm pore sizes by using the laser through different metal mesh templates is discussed first. Laser fluence and the number of pulses need to be optimized to obtain the desired pore size. Mesh size and film thickness primarily control the pore sizes. Typically, pore size increases with increasing fluence and the number of pulses. Larger pores can be created by using higher fluence at a given laser energy. The vertical cross-section of the pores turns out to be inherently tapered due to the ablative action of the laser beam. The pores created by laser ablation can be grafted with PNIPAM hydrogel by using the same laser to perform a bottom-up grafting-from type pulsed laser polymerization (PLP) in order to achieve the desired transport function controlled by temperature. For this purpose, a set of laser frequencies and pulse numbers need to be determined to obtain the desired hydrogel grafting density and the extent of cross-linking, which ultimately provide controlled transport by smart gating. In other words, on-demand switchable solute release rates can be achieved by controlling the cross-linking level of the microporous PNIPAM network. The PLP process is extremely fast (few seconds) and provides higher water permeability above the lower critical solution temperature (LCST) of the hydrogel. Experiments have shown high mechanical integrity for these pore-filled membranes, which can sustain pressures up to 0.31 MPa. The monomer (NIPAM) and cross-linker (mBAAm) concentrations in the grafting solution need to be optimized in order to control the network growth inside the support membrane pores. The cross-linker concentration typically has a stronger effect on the temperature responsiveness. The pulsed laser polymerization process described can be extended to different unsaturated monomers, which can be polymerized by the free radical process. For example, poly(acrylic acid) can be the grafted to provide pH responsiveness to membranes. As for the effects of thickness, a decreasing trend is observed in the permeability coefficient with increasing thickness. Furthermore, the film thickness has little or no effect on PLP kinetics. The experimental results have shown that membranes manufactured by excimer laser are excellent choices for applications where flow uniformity is the prime requirement, as they possess uniform pore sizes and distribution.

Frontal Polymerizations: From Chemical Perspectives to Macroscopic Properties and Applications

The synthesis and processing of most thermoplastics and thermoset polymeric materials rely on energy-inefficient and environmentally burdensome manufacturing methods. Frontal polymerization is an attractive, scalable alternative due to its exploitation of polymerization heat that is generally wasted and unutilized. The only external energy needed for frontal polymerization is an initial thermal (or photo) stimulus that locally ignites the reaction. The subsequent reaction exothermicity provides local heating; the transport of this thermal energy to neighboring monomers in either a liquid or gel-like state results in a self-perpetuating reaction zone that provides fully cured thermosets and thermoplastics. Propagation of this polymerization front continues through the unreacted monomer media until either all reactants are consumed or sufficient heat loss stalls further reaction. Several different polymerization mechanisms support frontal processes, including free-radical, cat- or anionic, amine-cure epoxides, and ring-opening metathesis polymerization. The choice of monomer, initiator/catalyst, and additives dictates how fast the polymer front traverses the reactant medium, as well as the maximum temperature achievable. Numerous applications of frontally generated materials exist, ranging from porous substrate reinforcement to fabrication of patterned composites. In this review, we examine in detail the physical and chemical phenomena that govern frontal polymerization, as well as outline the existing applications.

Free-Radical Propagation Rate Coefficients of Diethyl Itaconate and Di-n-Propyl Itaconate Obtained via PLP–SEC

The propagation step is one of the key reactions in radical polymerization and knowledge about its kinetics is often vital for understanding and designing polymerization processes leading to new materials or optimizing technical processes. Arrhenius expressions for the propagation step in free-radical polymerization of diethyl itaconate (DEI) as well as di-n-propyl itaconate (DnPI) in bulk, for which propagation kinetics was yet unexplored, were thus determined via pulsed-laser polymerization in conjunction with size-exclusion chromatography (PLP-SEC) experiments in the temperature range of 20 to 70 °C. For DEI, the experimental data was complemented by quantum chemical calculation. The obtained Arrhenius parameters are A = 1.1 L·mol–1·s–1 and Ea = 17.5 kJ·mol−1 for DEI and A = 1.0 L·mol–1·s–1 and Ea = 17.5 kJ·mol−1 for DnPI.

Eosin Y-Catalyzed Visible-Light-Induced Hydroperfluoroalkylation of Electron-Deficient Alkenes

The eosin Y-catalyzed hydroperfluoroalkylation of electron-deficient alkenes is described herein. The reaction proceeded smoothly under visible light irradiation and selectively afforded a hydroperfluoroalkylated product. Various perfluoroalkyl bromides and electron-deficient olefins can be used in this reaction, and all chemicals required for this reaction are safe and readily available.

Simple and Rapid Adhesion of Commodity Polymer Substrates under Ambient Conditions Using Complexed Alkylboranes

Adhesives are ubiquitous in manufacturing spanning nearly all sectors from healthcare and photovoltaics to aerospace and electronics. Yet many commercial polymers remain challenging to adhere, necessitating either pretreatment, mechanical fastening, or adhesive processes that involve specialized equipment, high temperature/vacuum, and long cure times. Thus, rapid-cure adhesives for polymers that can set under ambient conditions using simple procedures are desirous because they offer cost savings, faster production, and greater design freedom to producers. Herein, we report a powerful adhesive platform that bonds a wide scope of commodity polymers via (hydrogen) atom transfer and free-radical (graft) polymerization initiated with a trialkylborane-ligand complex and isocyanate decomplexing agent. The developed adhesive formulation is air-stable, bulk, and operates in air at room temperature using a high-glass-transition temperature polyacrylate, i.e., poly(isobornyl acrylate). The alkylborane-initiated bonding process is rapid (∼30 min), requires minimal surface preparation (cleaning and mild roughening), and successfully bonds seven diverse substrates including polytetrafluoroethylene, polyethylene, polypropylene, polycarbonate, nylon, polymethylmethacrylate, and polyvinylchloride. This contribution uniquely investigates the process-property relationships for the adhesive formulation, lap-shear performance, mechanism of failure, and a reactive additive for enhancing the adhesive's glass-transition temperature to ∼120 °C (polyhedral oligomeric silsesquioxane or POSS) to widen its operation temperature. We envision that the reported alkylborane-initiated adhesion platform could hold promise in the automotive, aerospace, and marine sectors as means for rapid manufacturing and structural adhesion.

Effect of side-group structure and temperature on chain transfer to polymer and branching in acrylate homopolymerizations

The paper reports studies of the effects of ester side-group size and structure on chain transfer to polymer (CTP) and mol% branches (%br) in the final polymers from monomer-starved semi-batch emulsion homopolymerizations of a series of alkyl acrylates with different numbers of ester OR side-group carbon atoms (NsgC) in the range 1–10. Although the high instantaneous conversions and high gel contents in the final polymers show that intermolecular CTP is significant, the kinetics have been analysed principally in terms of intramolecular CTP (intraCTP) because this is expected to be numerically the dominant CTP process. For linear OR side groups, there is a small, continuous increase in %br (from ~ 3.4 to ~ 5.0 mol%) as NsgC increases from 1 to 8, which arises predominantly from the acrylate molar mass (Macrylate) reducing the molar monomer concentration and from the small increase in rate coefficient for propagation (kp) as NsgC increases; no discernible effects of NsgC on the rate coefficient for intraCTP ($${k}_{\mathrm{trP}}^{\mathrm{intra}}$$ k trP intra ) are evident. For isomeric butyl acrylates, there is no measurable effect of isomer structure on %br (4.3–4.4 mol%), indicating that butyl groups are too small for changes in side-group bulkiness to influence $${k}_{\mathrm{trP}}^{\mathrm{intra}}$$ k trP intra and kp. A similar observation was made for n-hexyl acrylate (nHA) and 2-ethylbutyl acrylate (%br 4.7–4.8 mol%). However, cyclohexyl acrylate (cHA) gives a much higher %br (~ 7.2 mol%), which has been assigned to steric effects increasing $${k}_{\mathrm{trP}}^{\mathrm{intra}}$$ k trP intra because kp values for nHA and cHA are very similar. For OR side-groups with NsgC of 8 and10, there is a strong effect of side-group non-linearity (2-ethylhexyl, iso-octyl and iso-decyl) increasing %br, with polymers from n-alkyl acrylates having much lower %br (~ 4.5–5.0 mol%) than those from the equivalent non-linear acrylates (~ 6.7–7.1 mol%); since the kp values are expected to be similar for these acrylates, it is evident that the much bulkier non-linear OR groups cause a significant increase in $${k}_{\mathrm{trP}}^{\mathrm{intra}}$$ k trP intra compared to the linear equivalents. Tentative hypotheses for these steric effects have been postulated. Studies of the effect of temperature (0–80 °C) on CTP and %br for methyl acrylate solution homopolymerization (in which intraCTP should be completely dominant) show the expected reduction in %br as temperature reduces, such that CTP is negligible at 0 °C; Arrhenius analysis gives an activation energy of 40.7 kJ mol−1 for intraCTP, which is within the range of values reported for n-butyl acrylate.

Photoinduced Organocatalyzed Atom Transfer Radical Polymerization (O-ATRP): Precision Polymer Synthesis Using Organic Photoredox Catalysis

The development of photoinduced organocatalyzed atom transfer radical polymerization (O-ATRP) has received considerable attention since its introduction in 2014. Expanding on many of the advantages of traditional ATRP, O-ATRP allows well-defined polymers to be produced under mild reaction conditions using organic photoredox catalysts. As a result, O-ATRP has opened access to a range of sensitive applications where the use of a metal catalyst could be of concern, such as electronics, certain biological applications, and the polymerization of coordinating monomers. However, key limitations of this method remain and necessitate further investigation to continue the development of this field. As such, this review details the achievements made to-date as well as future research directions that will continue to expand the capabilities and application landscape of O-ATRP.

Chain-Length Dependence of Propagation Rate Coefficient for Methyl Acrylate Polymerization at 25 °C Investigated by PLP-SEC Method

When applying the pulsed laser polymerization–size exclusion chromatography (PLP-SEC) method to determine the propagation rate coefficient (kp) for bulk methyl acrylate at 25 °C, the characteristic ratio L1/L2 of chain...

Connecting Gas-Phase Computational Chemistry to Condensed Phase Kinetic Modeling: The State-of-the-Art

In recent decades, quantum chemical calculations (QCC) have increased in accuracy, not only providing the ranking of chemical reactivities and energy barriers (e.g., for optimal selectivities) but also delivering more reliable equilibrium and (intrinsic/chemical) rate coefficients. This increased reliability of kinetic parameters is relevant to support the predictive character of kinetic modeling studies that are addressing actual concentration changes during chemical processes, taking into account competitive reactions and mixing heterogeneities. In the present contribution, guidelines are formulated on how to bridge the fields of computational chemistry and chemical kinetics. It is explained how condensed phase systems can be described based on conventional gas phase computational chemistry calculations. Case studies are included on polymerization kinetics, considering free and controlled radical polymerization, ionic polymerization, and polymer degradation. It is also illustrated how QCC can be directly linked to material properties.

Porous Polymers from High Internal Phase Emulsions as Scaffolds for Biological Applications

High internal phase emulsions (HIPEs), with densely packed droplets of internal phase and monomers dispersed in the continuous phase, are now an established medium for porous polymer preparation (polyHIPEs). The ability to influence the pore size and interconnectivity, together with the process scalability and a wide spectrum of possible chemistries are important advantages of polyHIPEs. In this review, the focus on the biomedical applications of polyHIPEs is emphasised, in particular the applications of polyHIPEs as scaffolds/supports for biological cell growth, proliferation and tissue (re)generation. An overview of the polyHIPE preparation methodology is given and possibilities of morphology tuning are outlined. In the continuation, polyHIPEs with different chemistries and their interaction with biological systems are described. A further focus is given to combined techniques and advanced applications.

Radical Cations of Phenoxazine and Dihydrophenazine Photoredox Catalysts and Their Role as Deactivators in Organocatalyzed Atom Transfer Radical Polymerization

Radical cations of photoredox catalysts used in organocatalyzed atom transfer radical polymerization (O-ATRP) have been synthesized and investigated to gain insight into deactivation in O-ATRP. The stability and reactivity of these compounds were studied in two solvents, N,N-dimethylacetamide and ethyl acetate, to identify possible side reactions in O-ATRP and to investigate the ability of these radical cations to deactivate alkyl radicals. A number of other factors that could influence deactivation in O-ATRP were also probed, such as ion pairing with the radical cations, radical cation oxidation potential, and halide oxidation potential. Ultimately, these studies enabled radical cations to be employed as reagents during O-ATRP to demonstrate improvements in polymerization control with increasing radical cation concentrations. In the polymerization of acrylates, this approach enabled superior molecular weight control, a decrease in polymer dispersity from 1.90 to 1.44, and an increase in initiator efficiency from 78 to 102%. This work highlights the importance of understanding the mechanism and side reactions of O-ATRP, as well as the importance of catalyst radical cations for successful O-ATRP.

Solvent-Free Synthesis of the Polymer Electrolyte via Photo-Controlled Radical Polymerization: Toward Ultrafast In-Built Fabrication of Solid-State Batteries under Visible Light

Thin solid polymer electrolytes (SPEs) with good processability, improved room-temperature ionic conductivity, and better interfacial compatibility are urgently needed to develop solid-state batteries without safety and leakage issues. In-built electrolyte polymerization has emerged as a novel and effective platform to obtain such electrolytes. However, existing in-built methods usually involve heat, UV, γ irradiation, and so forth to initiate the polymerization and often require the addition of solvents to avoid the concentrated active propagating species, which inevitably afford solvent residues that persist in the electrolyte matrix, leading to complex SPE preparation processes, safety hazards, and side reactions with the electrodes. Herein, a simple solvent-free preparation of the poly(mPEGAA)-based electrolyte film was achieved via the photo-controlled radical polymerization under visible light irradiation via an in-built manner, which resulted in 99% monomer conversion within 5 min to obtain the polymer electrolytes with a controlled molecular weight distribution. Thanks to the mild and green conditions, a thin, solvent-free, and cross-linked SPE electrolyte film was obtained efficiently yet in a well-regulated manner, which gave rise to good interfacial compatibility and an improved room-temperature ionic conductivity of 1.5 × 10^-4 S cm^-1 at 25 °C. As-prepared solid-state LiFePO₄|Li batteries based on the in-built thin SPE exhibited a high discharge areal capacity of 1.7 mA h cm^-2 (164.6 mA h g^-1) at an ambient temperature. Furthermore, the system displayed lithium dendrite suppression behavior and good long-term charge-discharge cycling in the Li symmetric battery for over 270 h, representing enhanced stability and capacities compared with ex-built systems.

Determination of Photoinduced Radical Generation Quantum Efficiencies by Combining Chemical Actinometry and 19F NMR Spectroscopy

We introduce a general and relatively straightforward protocol aimed at determining the absolute photoinduced radical generation efficiency via NMR monitoring. This approach relies on the use of a radical scavenger probe that combines a nitroxide moiety that specifically reacts with radicals and a trifluoromethyl group used as a ¹⁹F NMR signaling unit. Using an LED source, whose fluence is precisely determined by a chemical actinometry procedure also described herein, the method is used to determine the radical photogeneration quantum yields of three well-known polymerization initiators: azobisisobutyronitrile (AIBN), 4,4'-bis(N,N-diethylamino)benzophenone (BDEBP, a derivative of Michler's ethyl ketone), and 2,4,6-trimethylbenzoyl diphenylphosphine oxide (MAPO). The overall good agreement with values previously reported in the literature proves the robustness of this new method. We then extended the study to the precise measurement of the quantum yield of free-radical photogeneration on a newly synthesized photoinitiator used for two-photon direct laser writing. This study highlights the potential of this methodology for the quantitative determination of photoinduced radical generation efficiency used in many fields of applications.

Screening RAFT agents and photocatalysts to mediate PET-RAFT polymerization using a high throughput approach

We report a high throughput approach for the screening of RAFT agents and photocatalysts to mediate photoinduced electron/energy transfer-reversible addition–fragmentation chain transfer (PET-RAFT) polymerization.

Impact of side reactions on molar mass distribution, unsaturation level and branching density in solution free radical polymerization of n-butyl acrylate under well-defined lab-scale reactor conditions

The paper describes the influence of side reactions in isothermal solution free-radical polymerization of n-butyl acrylate accounting for chain-length dependent diffusional limitations on termination.