On the Critical Role of RAFT Agent Design in Reversible Addition-Fragmentation Chain Transfer (RAFT) Polymerization

Reversible Addition-Fragmentation Chain-Transfer Polymerization in Supercritical CO2: A Review

The development of cleaner, more environmentally friendly processes in polymerization technology is crucial due to the prevalent use of volatile organic solvents (VOCs), which are harmful and toxic. Future regulations are likely to limit or ban VOCs. This review explores the use of supercritical solvents, specifically supercritical CO2 (scCO2), in polymerization processes. The study focuses on reversible addition-fragmentation chain-transfer (RAFT) induced homo-polymerization of various monomers using specific chain transfer agents (CTAs) in scCO2. RAFT polymerization, a reversible deactivation radical polymerization (RDRP) polymerization, relies heavily on the choice of CTA, which significantly influences the dispersity and molar mass of the resulting polymers. Stabilizers are also crucial in controlling product specifications for polymerizations in supercritical CO2, except for fluor-based polymers, although they must be removed and preferably recycled to ensure product purity and sustainability. The review notes that achieving high molar mass through RAFT polymerization in scCO2 is challenging due to solubility limits, which lead to polymer precipitation. Despite this, RAFT polymerization in scCO2 shows promise for sustainable, circular production of low molar mass polymers, although these cannot yet be fully considered green products.

2-Cyanopropan-2-yl versus 1-Cyanocyclohex-1-yl Leaving Group: Comparing Reactivities of Symmetrical Trithiocarbonates in RAFT Polymerization

This study introduces bis(1-cyanocyclohex-1-yl)trithiocarbonate (TTC-bCCH) as a novel trithiocarbonate chain transfer agent and compares its reactivity with the previously described bis(2-cyanopropan-2-yl)trithiocarbonate (TTC-bCP) for the reversible addition-fragmentation chain transfer (RAFT) polymerization of styrene (St), n-butyl acrylate (nBA), and methyl methacrylate (MMA). Significant findings include the effective control of Mn and low dispersities from the onset of polymerization of St and nBA showing swift addition-fragmentation kinetics, leading to similar behaviors between the two RAFT agents. In contrast, a fourfold decrease of the chain transfer constant to MMA is established for TTC-bCCH over TTC-bCP. This trend is confirmed through density functional theory (DFT) calculations. Finally, the study compares thermoplastic elastomer properties of all-(meth)acrylic ABA block copolymers produced with both RAFT agents. The impact of dispersity of PMMA blocks on thermomechanical properties evaluated via rheological analysis reveals a more pronounced temperature dependence of the storage modulus (G') for the triblock copolymer synthesized with TTC-bCCH, indicating potential alteration of the phase separation.

Azobenzene-Containing Liquid Crystalline Twisted Ribbons via Polymerization-Induced Hierarchical Self-Assembly

Polymerization-induced self-assembly incorporating liquid crystallization, as a polymerization-induced hierarchical self-assembly (PIHSA) method to produce polymeric particles with anisotropic morphologies facilely and efficiently, has drawn wide attention recently. However, the means of regulating the morphologies of liquid crystalline (LC) polymer assemblies still need to be explored. Herein, a route is presented to fabricate the twisted ribbons via PIHSA containing azobenzene based on poor reversible addition-fragmentation chain transfer (RAFT) control, called poorly controlled PIHSA. Cyano-4-(dodecylsulfanylthiocarbonyl)sulfanyl pentanoic acid-2-(2-pyridyldithio) ethyl ester is used as the RAFT agent with poor controllability, and the morphological evolution from ribbons to twisted ribbons can be observed in the corresponding PIHSA system. The formation mechanism of the twisted ribbons is studied systematically and the broad molecular weight distribution is considered to be the decisive factor. Moreover, the supramolecular chirality induced by symmetry breaking is also related to the twist of the ribbons. This study enriches the methods of controlling the morphologies of LC polymer particles and is helpful for further clarifying the mechanism of PIHSA.

Self-assembled block copolymer biomaterials for oral delivery of protein therapeutics

Protein therapeutics have guided a transformation in disease treatment for various clinical conditions. They have been successful in numerous applications, but administration of protein therapeutics has been limited to parenteral routes which can decrease patient compliance as they are invasive and painful. In recent years, the synergistic relationship of novel biomaterials with modern protein therapeutics has been crucial in the treatment of diseases that were once thought of as incurable. This has guided the development of a variety of alternative administration routes, but the oral delivery of therapeutics remains one of the most desirable due to its ease of administration. This review addresses important aspects of micellar structures prepared by self-assembled processes with applications for oral delivery. These two characteristics have not been placed together in previous literature within the field. Therefore, we describe the barriers for delivery of protein therapeutics, and we concentrate in the oral/transmucosal pathway where drug carriers must overcome several chemical, physical, and biological barriers to achieve a successful therapeutic effect. We critically discuss recent research on biomaterials systems for delivering such therapeutics with an emphasis on self-assembled synthetic block copolymers. Polymerization methods and nanoparticle preparation techniques are similarly analyzed as well as relevant work in this area. Based on our own and others' research, we analyze the use of block copolymers as therapeutic carriers and their promise in treating a variety of diseases, with emphasis on self-assembled micelles for the next generation of oral protein therapeutic systems.

Renewable Polymers Derived from Limonene

Renewable natural and synthetic basic substances can be used to produce biodegradable polymers. Several methods of the polymerization of terpene limonene have been evaluated. The polymerization methods evaluated are radical polymerization, cationic polymerization and thiol-ene polymerization. The free-radical polymerization of limonene with azobisisobutyronitrile (AIBN) as an initiator was carried out. The cationic polymerization of limonene was carried out using AlCl3 as a catalyst. The copolymerization of limonene with mercaptoethanol, 2-mercaptoethyl ether without an initiator and with an AIBN initiator was studied and it was also shown that polymerization can proceed spontaneously. The resulting compounds were investigated by NMR and FTIR spectroscopy. The values of the molecular weight characteristics of the samples obtained are presented, such as: number-average molecular weight, hydrodynamic radius and characteristic viscosity, depending on the method of production. The coefficients α (molecular shape) in the Mark–Kuhn–Houwink equation are determined according to the established values of the characteristic viscosity. According to the values obtained, the AC molecules in solution have parameters α 0.14 to 0.26, which corresponds to a good solvent and the molecular shape-dense coil.

Dual Function of β-hydroxy Dithiocinnamic Esters: RAFT Agent and Ligand for Metal Complexation

The reversible addition-fragmentation chain-transfer (RAFT) process has become a versatile tool for the preparation of defined polymers tolerating a large variety of functional groups. Several dithioesters, trithiocarbonates, xanthates, or dithiocarbamates have been developed as effective chain transfer agents (CTA), but only few examples have been reported, where the resulting end groups are directly considered for a secondary use besides controlling the polymerization. We here demonstrate that β-hydroxy dithiocinnamic esters represent a hitherto overlooked class of materials, which were originally designed for the complexation of transition metals but might as well act as reversible CTA. Modified with a suitable leaving group (R-group), these vinyl conjugated dithioesters indeed provide reasonable control over the polymerization of acrylates, acrylamides, or styrene via the RAFT process. Kinetic studies revealed linear evolutions of molar mass with conversion, while different substituents on the aromatic unit had only a minor influence. Block extensions prove the livingness of the polymer chains, although extended polymerization times may lead to side reactions. The resulting dithiocinnamic ester end groups are still able to form complexes with platinum, which verifies that the structural integrity of the end group is maintained. These findings open a versatile new route to tailor-made polymer bound metal complexes. This article is protected by copyright. All rights reserved.

Biomedical Applications of polymeric micelles in the treatment of diabetes mellitus: Current success and future approaches

INTRODUCTION

Diabetes mellitus (DM) is the most common metabolic disease and multifactorial, harming patients worldwide. Extensive research has been carried out in the search for novel drug delivery systems offering reliable control of glucose levels for diabetics, aiming at efficient management of DM.

AREAS COVERED

Polymeric micelles (PMs) as smart drug delivery nanocarriers are discussed, focusing on oral drug delivery applications for the management of hyperglycemia. The most recent approaches used for the preparation of smart PMs employ molecular features of amphiphilic block copolymers (ABCs), such as stimulus sensitivity, ligand conjugation, and as a more specific example the ability to inhibit islet amyloidosis.

EXPERT OPINION

PMs provide a unique platform for self-regulated or spatiotemporal drug delivery, mimicking the working mode of pancreatic islets to maintain glucose homeostasis for prolonged periods. This unique characteristic is achieved by tailoring the functional chemistry of ABCs considering the physicochemical traits of PMs, including sensing capabilities, hydrophobicity, etc. In addition, the application of ABCs for the inhibition of conformational changes in islet amyloid polypeptide garnered attention as one of the root causes of DM. However, research in this field is limited and further studies at the clinical level are required.

Oxygen-demanding Photocontrolled RAFT Polymerization under Ambient Conditions

A photocontrolled reversible addition-fragmentation chain transfer (RAFT) process is developed by initiating polymerization through a 1,3-diaminopropane-triethylborane (DAPTB)-diphenyl iodonium salt (Ph₂ I⁺ ) complex (DAPTB/Ph₂ I⁺ ) under ambient temperature and atmosphere. Upon demand, this air-stable DAPTB/Ph₂ I⁺ complex is photolyzed to liberate a reactive triethylborane that consumes atmospheric oxygen and generates ethyl radicals, which initiate and mediate RAFT polymerization. Controlled RAFT polymerization is thus achieved without any prior deoxygenation using a novel RAFT chain transfer agent, BP-FSBC, which contains both benzophenone and sulfonyl fluoride moieties. Furthermore, the kinetics of polymerization reveal that the reaction process is rapid, and well-defined polymers are produced by a 61% conversion of 2-hydroxyethyl acrylate (HEA) within 7 minutes and 77% conversion of N,N-dimethylacrylamide (DMA) within 10.5 minutes. The temporal and spatial control of this photopolymerization is also demonstrated by an "on/off" switch of UV irradiation and a painting-on-a-surface approach, respectively. In addition, active chain ends are demonstrated by preparing block copolymers by chain extension and click sulfur(VI)-fluoride exchange (SuFEx) postreaction using RAFT-derived macrochain transfer agents. This article is protected by copyright. All rights reserved.

Self-Assembled Nanoparticles Based on Block-Copolymers of Poly(2-Deoxy-2-methacrylamido-d-glucose)/Poly(N-Vinyl Succinamic Acid) with Poly(O-Cholesteryl Methacrylate) for Delivery of Hydrophobic Drugs

The self-assembly of amphiphilic block-copolymers is a convenient way to obtain soft nanomaterials of different morphology and scale. In turn, the use of a biomimetic approach makes it possible to synthesize polymers with fragments similar to natural macromolecules but more resistant to biodegradation. In this study, we synthesized the novel bio-inspired amphiphilic block-copolymers consisting of poly(N-methacrylamido-d-glucose) or poly(N-vinyl succinamic acid) as a hydrophilic fragment and poly(O-cholesteryl methacrylate) as a hydrophobic fragment. Block-copolymers were synthesized by radical addition-fragmentation chain-transfer (RAFT) polymerization using dithiobenzoate or trithiocarbonate chain-transfer agent depending on the first monomer, further forming the hydrophilic block. Both homopolymers and copolymers were characterized by ¹H NMR and Fourier transform infrared spectroscopy, as well as thermogravimetric analysis. The obtained copolymers had low dispersity (1.05-1.37) and molecular weights in the range of ~13,000-32,000. The amphiphilic copolymers demonstrated enhanced thermal stability in comparison with hydrophilic precursors. According to dynamic light scattering and nanoparticle tracking analysis, the obtained amphiphilic copolymers were able to self-assemble in aqueous media into nanoparticles with a hydrodynamic diameter of approximately 200 nm. An investigation of nanoparticles by transmission electron microscopy revealed their spherical shape. The obtained nanoparticles did not demonstrate cytotoxicity against human embryonic kidney (HEK293) and bronchial epithelial (BEAS-2B) cells, and they were characterized by a low uptake by macrophages in vitro. Paclitaxel loaded into the developed polymer nanoparticles retained biological activity against lung adenocarcinoma epithelial cells (A549).

Experimental Design in Polymer Chemistry-A Guide towards True Optimization of a RAFT Polymerization Using Design of Experiments (DoE)

Despite the great potential of design of experiments (DoE) for efficiency and plannability in academic research, it remains a method predominantly used in industrial processes. From our perspective though, DoE additionally provides greater information gain than conventional experimentation approaches, even for more complex systems such as chemical reactions. Hence, this work presents a comprehensive DoE investigation on thermally initiated reversible addition–fragmentation chain transfer (RAFT) polymerization of methacrylamide (MAAm). To facilitate the adaptation of DoE for virtually every other polymerization, this work provides a step-by-step application guide emphasizing the biggest challenges along the way. Optimization of the RAFT system was achieved via response surface methodology utilizing a face-centered central composite design (FC-CCD). Highly accurate prediction models for the responses of monomer conversion, theoretical and apparent number averaged molecular weights, and dispersity are presented. The obtained equations not only facilitate thorough understanding of the observed system but also allow selection of synthetic targets for each individual response by prediction of the respective optimal factor settings. This work successfully demonstrates the great capability of DoE in academic research and aims to encourage fellow scientists to incorporate the technique into their repertoire of experimental strategies.

EFFECT OF EMULSION SBR PREPARED BY ASYMMETRIC REVERSIBLE ADDITION-FRAGMENTATION TRANSFER AGENT ON PROPERTIES OF SILICA-FILLED COMPOUNDS

The development of ultra-high-performance tires that satisfy fuel efficiency, traction, handling performance, and abrasion resistance has gained significant importance in the tire industry. Solution SBR has been used as a raw material, owing to its useful characteristics (e.g., narrow dispersity controllable microstructure and chain-end functionalization). In a recent improvement, emulsion SBR (ESBR), a high-molecular-weight compound with narrow dispersity, has been reported for application in the tire tread compounds. In particular, S,S-dibenzyl trithiocarbonate (DBTC) reversible addition-fragmentation transfer (RAFT) ESBR has exhibited excellent abrasion resistance and fuel efficiency in unfilled and carbon black–filled vulcanizates. However, owing to the symmetrical structure of DBTC RAFT ESBR, the polymer chain was shortened by the reaction of a silane coupling agent with trithiocarbonate, leading to poor abrasion resistance and fuel efficiency in the case of silica-filled vulcanizates. In this study, benzyl (4-methoxyphenyl) trithiocarbonate (BMPTC), an asymmetric RAFT agent that promotes unilateral polymer growth, was synthesized and used in the polymerization of BMPTC RAFT ESBR. Chain cleavage was not observed. Upon application to silica-filled vulcanizates, BMPTC RAFT ESBR exhibited improved abrasion resistance (by 9%), improved fuel efficiency (by 20%), and improved wet traction performance (by 10%) compared with the DBTC RAFT ESBR.

Harnessing amphiphilic polymeric micelles for diagnostic and therapeutic applications: Breakthroughs and bottlenecks

Amphiphilic block copolymers are widely utilized in the design of formulations owing to their unique physicochemical properties, flexible structures and functional chemistry. Amphiphilic polymeric micelles (APMs) formed from such copolymers have gained attention of the drug delivery scientists in past few decades for enhancing the bioavailability of lipophilic drugs, molecular targeting, sustained release, stimuli-responsive properties, enhanced therapeutic efficacy and reducing drug associated toxicity. Their properties including ease of surface modification, high surface area, small size, and enhanced permeation as well as retention (EPR) effect are mainly responsible for their utilization in the diagnosis and therapy of various diseases. However, some of the challenges associated with their use are premature drug release, low drug loading capacity, scale-up issues and their poor stability that need to be addressed for their wider clinical utility and commercialization. This review describes comprehensively their physicochemical properties, various methods of preparation, limitations followed by approaches employed for the development of optimized APMs, the impact of each preparation technique on the physicochemical properties of the resulting APMs as well as various biomedical applications of APMs. Based on the current scenario of their use in treatment and diagnosis of diseases, the directions in which future studies need to be carried out to explore their full potential are also discussed.

Redox-Initiated Reversible Addition-Fragmentation Chain Transfer (RAFT) Miniemulsion Polymerization of Styrene using PPEGMA-Based Macro-RAFT Agent

Redox-initiated reversible addition-fragmentation chain transfer (RAFT) miniemulsion polymerizations are successfully conducted with an employment of trithiocarbonate-based macro-RAFT agents and surfactant. Two macro-RAFT agents-hydrophilic poly(poly(ethylene glycol) methyl ether methacrylate) (PPEGMA₂₇ ) and amphiphilic poly(poly(ethylene glycol) methyl ether methacrylate)-b-polystyrene (PPEGMA₂₇ -b-PS₃₃ )- are examined for the miniemulsion polymerization of styrene. The use of PPEGMA₂₇ (in the presence of sodium dodecyl sulfate (SDS)) results in a slow polymerization rate with a broad particle size. In the absence of SDS, the use of PPEGMA₂₇ -b-PS₃₃ results in a broad particle size distribution due to its inability to form uniform initial droplets whereas the same amphiphilic block copolymer in the presence of SDS yields resulting products with a uniform particle size distribution. The latter exhibits a fashion of controlled polymerization with a high consumption of monomer (98% in 100 min) and a narrow molecular weight distribution throughout the polymerization. This is attributed to the formation of uniform droplets facilitated by SDS in a miniemulsion. The amphiphilic macro-RAFT agent is able to anchor efficiently on the monomer droplet or particle/water interface and form stabilized particles of well-defined PPEGMA₂₇ -b-PS block copolymer, confirmed using dynamic light scattering and transmission electron micrographs.

Effect of Reversible Addition-Fragmentation Transfer Emulsion Styrene Butadiene Rubber (RAFT ESBR) on the Properties of Carbon Black-Filled Compounds

Tread is an important component that directly affects the performance of passenger car radial (PCR) tires. Styrene-butadiene rubber (SBR) is mainly used for tire tread and it includes solution styrene-butadiene rubber (SSBR) and emulsion styrene-butadiene rubber (ESBR). Although SSBR is mainly used, the manufacturing process for SSBR is more challenging than ESBR, which is environmentally friendly, but has the disadvantage of a broad molecular weight distribution. To overcome this, a reversible addition-fragmentation radical transfer (RAFT) polymerization technique is used in ESBR polymerization. An environmentally friendly RAFT ESBR with a narrow dispersity can be polymerized. Here, carbon black-filled compounds were manufactured while using RAFT ESBR, and their properties were compared to ESBR. The analysis showed a low crosslink density of RAFT ESBR, due to the high polysulfide crosslink structure. We manufactured a carbon black-filled compound with the same crosslink density and structure as the ESBR carbon black-filled compound, and the effect of the dispersity of the base polymer was investigated. RAFT ESBR showed 9% better abrasion resistance and 29% better fuel efficiency than ESBR, according to the analysis of the data. The narrow dispersity can reduce energy loss and positively influence the abrasion resistance and fuel efficiency.

Electrochemical Behavior of Thiocarbonylthio Chain Transfer Agents for RAFT Polymerization

Electrochemical activation of thiocarbonylthio reversible addition-fragmentation chain transfer (RAFT) agents (S=C(Z)S-R) is explored as a potential method for initiating RAFT polymerization under mild conditions without producing initiator-derived byproducts. Herein we apply cyclic voltammetry to establish a predominant reduction mechanism, where electrochemical reduction is coupled to an irreversible first-order chemical reaction. Structure-dependent trends in cyclic voltammograms (CVs), and comparison to absorption spectra, clarify the role of R- and Z-groups in determining reduction processes. The major reduction peak moves to more cathodic potentials in the series dithiobenzoates > trithiocarbonates > heteroaromatic dithiocarbamates > xanthates ∼ N-alkyl-N-aryldithiocarbamates, due to the Z-group influence on thiocarbonyl bond reactivity. More active (electron-withdrawing, radical stabilizing) R-groups shift the reduction peak anodically, in part due to their influence on the rate of the coupled chemical reaction. Analysis of CVs across a range of scan rates revealed that kinetic control over the reduction mechanism is influenced by both the charge transfer rate and chemical reaction rate.

Synthesis of S-Alkyl Phosphinocarbodithioates with Switch between P(III) and P(V) Derivatives

Simple and effective synthetic pathways are described to prepare compounds R₂P(X)C(S)SCH(Me)Ph with the P atom either in the oxidation state V [R/X = t-Bu/O (6), Ph/S, (7), t-Bu/S (8), t-Bu/Se (9)] or III [R/X = Ph/BH₃ (4), t-Bu/BH₃ (5), t-Bu/lone pair (10)]. Compound 9 is the first example of carbodithioate ester with a P = Se group, and for the first time, a phosphinocarboditioate with a free phosphine function (compound 10) is described. Stabilization of the latter crucially depends on the steric protection by the t-Bu groups since an analogous derivative with R = Ph is observable but too unstable for isolation. Compound 10 can be reversibly protonated to yield the [t-Bu₂PHC(S)SCH(Me)Ph]⁺ cation (10-H⁺), which was isolated as a BF₄^- salt. A few interconversion processes resulting in the facile addition/removal or exchange of the X group in this family of compounds are also described. The oxidation state of the phosphorus atom and the nature of an electron-withdrawing group have a significant impact on the spectral properties.

Manganese phosphinocarbodithioate for RAFT polymerisation with sunlight-induced chain end post-treatment

A new manganese complex of the formula Cp(CO)₂MnP(Ph)₂C(S)SCH(CH₃)Ph is an efficient RAFT agent for the preparation of SH-terminated polymers by simple visible light photocleavage of the organometallic end-group.

Exploiting Wavelength Orthogonality for Successive Photoinduced Polymerization-Induced Self-Assembly and Photo-Crosslinking

We report a facile benchtop process for the synthesis of cross-linked polymeric nanoparticles by exploiting wavelength-selective photochemistry to perform orthogonal photoinduced polymerization-induced self-assembly (Photo-PISA) and photo-crosslinking processes. We first established that the water-soluble photocatalyst, zinc meso-tetra(N-methyl-4-pyridyl) porphine tetrachloride (ZnTMPyP) could activate the aqueous PET-RAFT dispersion polymerization of hydroxypropyl methacrylate (HPMA). This photo-PISA process could be conducted under low energy red light (λ_max = 595 nm, 10.2 mW/cm²) and without deoxygenation due to the action of the singlet oxygen quencher, biotin (vitamin B₇), which allowed for the synthesis of a range of nanoparticle morphologies (spheres, worms, and vesicles) directly in 96-well plates. To perform wavelength selective nanoparticle cross-linking, we added the photoresponsive monomer, 7-[4-(trifluoromethyl)coumarin] methacrylamide (TCMAm) as a comonomer without inhibiting the evolution of the nanoparticle morphology. Importantly, under red light, exclusive activation of the photo-PISA process occurs, with no evidence of TCMAm dimerization under these conditions. Subsequent switching to a UV source (λ_max = 365 nm, 10.2 mW/cm²) resulted in rapid cross-linking of the polymer chains, allowing for retention of the nanoparticle morphology in organic solvents. This facile synthesis of cross-linked spheres, worms, and vesicles demonstrates the utility of orthogonal light-mediated chemistry for performing decoupled wavelength selective chemical processes.

Opportunities for dual RDRP agents in synthesizing novel polymeric materials

Dual RDRP agents provide access to new polymeric materials by combining ATRP, NMP, and RAFT polymerization without end group transformations.

Functional multisite copolymer by one-pot sequential RAFT copolymerization of styrene and maleic anhydride

Functional multisite copolymers with a controlled number and position of side chains were synthesized by a one-pot RAFT polymerization process and post-functionalization.

Determination and correlation of regioselectivity and dead dormant species from head addition in acrylate RAFT polymerization

The dead dormant species from head addition in a RAFT process can be separated and quantified by combining chain-extension and GPEC.

One-shot controlled/living copolymerization for various comonomer sequence distributions via dual radical and cationic active species from RAFT terminals

One-shot control of comonomer sequence distributions was demonstrated by dual radical and cationic copolymerization using RAFT mediator.

A detailed mechanistic study of bulk MADIX of styrene and its chain extension

By combining experimental and modeling tools, a detailed characterization study of MADIX properties becomes possible.

A facile route to well-defined imidazolium-based poly(ionic liquid)s of enhanced conductivity via RAFT

Examining the relationship between the glass transition temperature, conductivity and molecular weight of tailored imidazolium-based PILs synthesized via RAFT.

Diverse approaches to star polymers via cationic and radical RAFT cross-linking reactions using mechanistic transformation

Core cross-linked star polymers were synthesizedviacationic RAFT polymerization and three different approaches in combination with a radical RAFT mechanism.

A phosphonium intermediate for cationic RAFT polymerization

Phosphates and phosphinates mediate cationic RAFT polymerization of vinyl ethers with a small amount of triflic acid via a phosphonium intermediate.

A novel method for the measurement of degenerative chain transfer coefficients: proof of concept and experimental validation

A novel method is presented to determine transfer coefficients in degenerative reversible addition fragmentation chain transfer (RAFT) polymerization from experimental dispersity data.