Design,preparation and properties of novel renewable UV-curable copolymers based on cardanol and dimer fatty acids

A cardanol-based UV-curable vinyl ester (VE) monomer was prepared via simple esterification, and its successful synthesis was demonstrated by FTIR and ¹H-NMR. In order to improve its rigidity, it was mixed with certain proportions of another reactive bio-based VE monomer, maleic anhydride modified dimer fatty acids polymerized glycidyl methacrylate (MA-m-DA-p-GMA) which had rigid and strong polar groups, and then a series of UV-cured copolymers were prepared from the two VE monomers. The UV curing process was monitored by FTIR analysis. The tensile and thermal properties of the cured copolymer films were also investigated. UV curing analysis demonstrated that the double bonds in the mixed VE could be converted to ultimate curing level within 40 s. Tensile tests showed the prepared copolymers had a tensile strength of 8.86 MPa. Dynamic mechanical analysis (DMA) revealed the copolymers had relatively high glass transition temperature (T_g) from 40 to 60 °C. Thermogravimetric analysis (TGA) showed the copolymers containing higher content of CDMA had higher thermal stability, and all copolymers’ main thermal initial decomposition temperatures were above 410 °C, indicating the copolymers had certain thermal stability. These copolymer films can be used as eco-friendly materials in coatings and other applications to replace the currently used petroleum-based polymers.     

Novel carbazole phenoxy-based methacrylates to produce high-refractive index polymers

A novel, high-refractive index homopolymer was produced by incorporating carbazole and phenol into the methacrylate monomer structure. The reaction of phenol with 9-(2,3-epoxypropyl)-carbazole, followed by the reaction of the carbazole phenoxy-based intermediate with methacryloyl chloride or methacrylic anhydride, and recrystallization from methanol, produced a good yield of highly pure carbazole phenoxy functionalized methacrylate monomer. Subsequent free radical polymerization or UV photopolymerization of the functionalized methacrylate monomer, in addition to copolymerizations with methyl methacrylate, provided for high-refractive index materials well suited for lightweight optical applications. Unlike N-vinyl carbazole, the novel carbazole phenoxy-based methacrylate readily copolymerized with methyl methacrylate. Statistical copolymers of carbazole based methacrylates with methyl methacrylate were produced by free radical solution polymerization in DMAC or by photopolymerization in DMF. The carbazole phenoxy-based methacrylate monomer was characterized for molecular weight using gel permeation chromatography (GPC), for melting point and glass transition temperature using differential scanning calorimetry (DSC), for decomposition using thermal gravimetric analysis (TGA), and for chemical composition by one- and two-dimensional ¹H nuclear magnetic resonance (NMR) spectroscopy and by elemental analysis. The AIBN initiated carbazole phenoxy-based methacrylate polymerization was followed using in situ FTIR, which showed the reaction to be complete within 40 min in DMAC at 90 °C. Refractive indices of the carbazole based methacrylate homopolymers and copolymers ranged from 1.52 to 1.63. PhotoDSC was used to determine the heat of polymerization (ΔH_p) for the carbazole phenoxy-based methacrylate (ΔH_p=−39.4 kJ/mol). The carbazole phenoxy-based methacrylate homopolymer had a surprisingly high onset of decomposition temperature (T_onset=316 °C). ¹³C NMR spectroscopy experiments and molecular modeling were used to explore the configuration of the polymerized carbazole phenoxy-based methacrylate. The lack of head-to-head linkages due to steric considerations reasonably explains the high thermal stability observed for the carbazole phenoxy-based methacrylate polymer.     

Synthesis and characterization of carboxyl group-containing acrylic resin for powder coatings

The carboxyl group-containing acrylic resin for powder coatings can be obtained by succinic anhydride reacting with hydroxyl group-containing acrylic resin, which was prepared by radical copolymerization of methyl methacrylate (MMA), n-butyl methacrylate (BMA) and β-hydroxypropyl methacrylate (HPMA) using 2,2′-azobisisobutyronitrile (AIBN) as initiator in toluene solution. The influence of synthesis method, weight ratio of monomers, and the amount of succinic anhydride on carboxyl group-containing acrylic resin was investigated. The ¹H NMR results reveal that carboxyl group was successfully attached to acrylic resins. The optimum monomer weight ratio is MMA:BMA:HPMA = 65:20:15. The acid value of resin increases with the increasing of the amount of succinic anhydride, while the T_g of resin decreases.     

Synthesis and aqueous solution characterization of amphiphilic diblock copolymers containing carbazole

A series of near-monodisperse diblock copolymers of 2-(N-carbazolyl)ethyl methacrylate and 2-(dimethylamino)ethyl methacrylate (DMAEMA) of relatively low molecular weights (2600-24,000 g mol⁻¹) were synthesized by group transfer polymerization using tetrahydrofuran (THF) as a solvent. The molecular weight distributions and compositions of all the copolymers were obtained using gel permeation chromatography (GPC) in THF and proton nuclear magnetic resonance (¹H NMR) spectroscopy, respectively. Differential scanning calorimetry and thermal gravimetric analysis provided low glass transition temperatures (T_gs) of about 60 °C and decomposition temperatures between 320 and 450 °C for the copolymers, respectively. The three copolymers with the highest DMAEMA content were water-soluble below pH 7. Aqueous GPC at pH 3 showed that the water-soluble block copolymers formed micelles with apparent number average molecular weights above 100,000 g mol⁻¹.     

Synthesis and characterization of itaconic anhydride and stearyl methacrylate copolymers

The free-radical copolymerization and the properties of comb-like copolymers derived from renewable resources, itaconic anhydride (ITA) and stearyl methacrylate (SM), are described. The ITA-SM copolymers were nearly random with a slight alternating tendency. The copolymers exhibited a nanophase-separated morphology, with the stearate side-chains forming a bilayer, semi-crystalline structure. The melting point (T_m) of the side-chains and the crystallinity decreased with increasing ITA concentration. The crystalline side-chains suppressed molecular motion of the main chain, so that a glass transition temperature (T_g) was not resolved unless the ITA concentration was sufficiently high so that T_g > T_m. The softening point and modulus of the copolymers increased with the increasing ITA concentration, but the thermal stability decreased.     

UV-curing and characterization of polymer–clay nanocoatings by dispersion of acrylate-funtionalized organoclays

Nanocoatings have been prepared by dispersing two different surfmer-modified nanosilicate platelets into acrylic resins. UV-induced polymerization gave rise to highly crosslinked networks. The UV-curing kinetics was not affected by the presence of the nanofiller. XRD and TEM investigations showed that, during the dispersion of the organoclays in the UV-curable resins, the surfmer treatment promotes an important lamellae intercalation which is maintained after UV curing. An increase of the T_g values and of the thermal stability was achieved in the samples containing 5 wt% of modified clay.     

Synthesis and characterization of new polymethacrylates bearing perfluorocyclobutyl and sulfonyl units

A new methacrylate monomer containing perfluorocyclobutyl and sulfonyl units, p-(2-(p-(benzenesulfonyl)phenoxy)perfluorocyclobutoxy)phenyl methacrylate, was synthesized from commercially available reagents in good yield and this kind of methacrylate can be homopolymerized by free radical polymerization using 2,2′-azobis(isobutyronitrile) as initiator or atom transfer radical polymerization using methyl 2-bromopropionate as initiator and CuBr/PMDETA as catalytic system. The reactivity ratios for BSPPFCBPMA and MMA were found to be r₁ = 1.2436 and r₂ = 0.8171 determined by Fineman-Ross method, and r₁ = 1.2279 and r₂ = 0.8023 by Kelen-Tudos method respectively. The resultant polymethacrylates bearing perfluorocyclobutyl and sulfonyl functionalities exhibit excellent thermal stability as evidenced from thermogravimetric analysis and the decomposition temperature rose dramatically with the increasing of molecular weights. Random copolymers of BSPPFCBPMA and methyl methacrylate were obtained by free radical copolymerization and their thermo-stabilities increase while raising the contents of BSPPFCBPMA.     

Fast physical drying,high water and salt resistant coatings from non-drying vegetable oil

This paper reports fast physical drying, high water and salt resistances of coating materials from non-drying palm oleic acid. Short oil-length alkyd was synthesized and copolymerized with methyl methacrylate. Three copolymers of the alkyd and methyl methacrylate with different alkyd/MMA ratios were prepared via free radical polymerization. The copolymers were characterized by FTIR and H NMR spectroscopy, and glass transition temperatures (T_g) were measured by DSC. The decreasing amount of alkyd was noticed to increasing conversion and T_g. The overall thermal stability has increased with higher amount of alkyd in the copolymer. Moreover, incorporation of alkyd has improved the adhesion and film hardness of the coatings.     

Effect of oxirane groups on curing behavior and thermal stability of vinyl ester resins

The effects of oxirane groups in vinyl ester (VE) resin and reactive diluent on curing characteristics and thermal behavior of cured resins are described. Stoichiometric (0.5:1, sample A) as well as nonstoichiometric (0.5:0.85, sample B) ratios of the diglycidyl ether of bisphenol-A (DGEBA) and methacrylic acid (MA) were used for the synthesis of VE resins. Resin sample B had more residual epoxy groups because of the stoichiometric imbalance of the reactants. VE resins thus obtained were diluted with methyl methacrylate (MMA; 1:1, w/w), and controlled quantities of epoxy groups were introduced by partial replacement of MMA with glycidyl methacrylate (GMA), keeping the overall ratio of resin and reactive diluent constant. Increase of GMA content in resin A or B resulted in a decrease in gel time, indicating that the curing reaction is facilitated by the presence of epoxy groups. An increase in initiator content also reduced the gel time. In the differential scanning calorimetry (DSC) scans, a sharp curing exotherm was observed in the temperature range 107 ± 3–150 ± 1 °C. The onset temperature (T_onset) and peak exotherm temperature (T_exo) decreased with increase in GMA content. Heat of curing (ΔH) also increased with increase in GMA content. A broad exotherm was observed after the initial sharp exotherm that was attributed to the etherification reaction. Cured VE resins were stable up to 250–260 °C, and started losing weight above this temperature. Rapid decomposition was observed in the temperature range 400–500 °C. © 2001 John Wiley & Sons, Inc. J Appl Polym Sci 82: 416–423, 2001     

Synthesis of novel phosphorus-containing cyanate esters and their curing reaction with epoxy resin

Novel phosphorus-containing cyanate esters with phosphorus contents between 1-4% (badcyp_x, x=1-4) were synthesized from the addition reaction of 9,10-dihydro-9-oxa-10-phosphaphenanthrene 10-oxide (dopo) and bisphenol A dicyanate (badcy). The structures of synthesized cyanate ester resins were confirmed by NMR and IR spectra. The modified cyanate esters were either self-curing (badcy and badcyp_x series) or curing with epoxy (badcye and badcyp_xe series). Thermal properties of cured cyanate ester were evaluated by differential scanning calorimetry (DSC), dynamic mechanical analysis (DMA), thermal gravimetric analysis (TGA), dielectric analyzer (DEA) and UL-94 vertical test. It was found that T_g and T_d (5%) decrease markedly with the phosphorus content for the self-curing system, while T_g and T_d (5%) decrease slightly with the increase of cyanate equivalent weight for the cyanate-epoxy curing system. The flame retardancy increases with the phosphorus content and a UL-94 V-0 rating can be achieved for cured badcyp₂-badcyp₄ and badcyp₃e-badcyp₄e. These flame retardant thermosets exhibit low moisture absorption as well as low dielectric constants and dissipation factors. Experimental results indicate that introducing the flame retardant phosphorus element into cyanate ester will not sacrifice its low dielectric characteristic.     

Phase segregation of poly(3-dodecylthiophene)-block-poly(methyl methacrylate) copolymers

We investigated, via small angle X-ray scattering (SAXS), the ordered-to-disordered transition temperature (T_ODT) of symmetric poly(3-dodecylthiophene)-block-poly(methyl methacrylate) copolymers (P3DDT-b-PMMA) with different molecular weights synthesized by anionic coupling reaction. When the molecular weight of P3DDT-b-PMMA was properly chosen, the T_ODT was observed within experimentally accessible temperature range (higher than the glass transition and melting temperature for PMMA and P3DDT, respectively, but lower than the thermal degradation temperature). We also measured the temperature dependence of Flory–Huggins interaction parameter (χ) between P3DDT and PMMA as χ = 0.1109 + 76.63/T, in which T is the absolute temperature.     

Synthesis and characterization of siloxane-modified epoxy resin

Epoxy resins of the EBS, a bis-p-phenol S modified diglycidyl ether of bis-p-phenol A and the ESBS, a siloxane modified EBS epoxy resin were prepared. Both structures of EBS and ESBS were elucidated with IR,¹H NMR, and¹³C NMR. The near perpendicular comformation of two phenyl rings of sulfone has been introduced into the epoxy resins of EBS und ESBS for Me increase of Me T_g. Some curing and thermal characteristics of these modified EBS and ESBS epoxy resins were studied. The curing patterns of ESBS and ESBS indicated the similarity with that of the DGEBA epoxy resins. T_g measurements resulted an increasing order of We ESBS (T_g of 141 °C), EBS (T_g of 135 °C) and then followed by Epons 1004 (T_g of 104 °C), 1001 (T_g of 101 °C) and 828 (T_g of 100 °C) in samples tested under the same conditions. Thus the substantial improvement of the thermal stability of the modified epoxy resins was indicated. Compatibility characteristics of the EBS and ESBS as indicated by the SEM/EDS is that an ESBS up to 30 % of the siloxane content was found to be compatible but not miscible with the Epon, a phenolic epoxy resin of DGEBA.     

Synthesis of poly(methyl methacrylate)-silica nanocomposites using methacrylate-functionalized silica nanoparticles and RAFT polymerization

Well-defined poly(methyl methacrylate)-silica nanocomposites were produced by “grafting through” using reversible addition-fragmentation chain transfer (RAFT) polymerization. The surface of silica nanoparticle was modified covalently by attaching methacryl group to the surface using 3-methacryloxypropyldimethylchlorosilane. Polymerization of methyl methacrylate (MMA) using the 4-cyano-4-(dodecylsulfanylthiocarbonyl)sulfanyl pentanoic acid RAFT agent, produced the PMMA-SiO₂ nanocomposites. Characterization of these well-defined nanocomposites included FT-IR, gel permeation chromatography (GPC), thermogravimetric analysis (TGA), differential scanning calorimeter (DSC), transmission electron microscopy (TEM) and dynamic mechanical analysis. These results show that the T_g values are higher and the mechanical strength of the PMMA-SiO₂ nanocomposites is slightly improved when compared to bulk PMMA. Further, the molecular weight of the PMMA (up to M_n = 100,000) is controlled and the SiO₂ are well dispersed in the PMMA matrix.     

Poly(methyl methacrylate-co-acrylonitrile)

Stable macroradicals of methyl methacrylate were prepared by the azobisisobutyronitrile-initiated polymerization of methyl methacrylate in hexane whose solubility parameter value (δ) differed from that of the macroradical by more than 1.8 hildebrand units and in 1-propanol at temperatures below its theta temperature (84.5°C). The rates of heterogeneous polymerization in hexane and 1-propanol were much faster than that of the homogeneous polymerization in benzene. Stable macroradicals were not obtained in benzene which was a good solvent nor at temperatures above the glass transition temperature (T_t) of the macroradicals. Thus, stable macroradicals of butyl methacrylate (T_g20°C) and and methyl acrylate (T_g3°C) were not obtained at a polymerization temperature of 50°C. Good yields of block copolymers of methyl methacrylate and acrylonitrile were obtained by the addition of acrylonitrile to the methyl methacrylate macroradical in methanol, ethanol, 1-propanol and hexane at 50°C. The rate of formation of the block copolymer decreased in these poor solvents as the differences between the solubility parameter of the solvent and macroradical increased.The block copolymer samples prepared at temperatures of 50°C and above were dissolved in benzene which is a non-solvent for acrylonitrile homopolymer, but is a good solvent for poly(methyl methacrylate) and the block copolymer. The presence of acrylonitrile and methyl methacrylate in the benzene-soluble macromolecule was demonstrated by pyrolysis gas chromatography, infra-red spectroscopy and differential thermal analysis.     

Solvent induced morphologies of poly(methyl methacrylate-b-ethylene oxide-b-methyl methacrylate) triblock copolymers synthesized by atom transfer radical polymerization

Poly(methyl methacrylate-b-ethylene oxide-b-methyl methacrylate) (PMMA-PEO-PMMA) triblock copolymers were synthesized using atom transfer radical polymerization (ATRP) and halogen exchange ATRP. PEO-based macroinitiators with molecular weight from M_n = 2000 to 35,800 g/mol were used to initiate the polymerization of MMA to obtain copolymers with molecular weight up to M_n = 82,000 g/mol and polydispersity index (PDI) less than 1.2. The macroinitiators and copolymers were characterized by gel permeation chromatography (GPC) and nuclear magnetic resonance (NMR) spectroscopy. The melting temperature and glass transition temperature of the copolymers were measured by differential scanning calorimetry (DSC). Crystallinities of the PEO blocks were determined from the WAXS patterns of both homopolymers and block copolymers, which revealed the fragmentation of PEO blocks due to the folding of the PMMA chains. Interestingly, the fragmentation was less pronounced when cast on surfaces compared to that in bulk, as measured by GISAXS. Solvent casting was used to control the morphology of the copolymers, permitting the formation of various states including amorphous, induced micellar with a PMMA core and flower-like PEO arms, and a cross-linked gel. Atomic force microscopy (AFM) was used to visualize the different copolymer morphologies, showing micellar and amorphous states.     

Silicone-acrylic hybrid aqueous dispersions of core–shell particle structure and corresponding silicone-acrylic nanopowders designed for modification of powder coatings and plastics. Part I – Effect of silicone resin composition on properties of dispersions and corresponding nanopowders

Aqueous silicone-acrylic dispersions with core–shell particle structure can be obtained in the process of emulsion polymerization of acrylic or methacrylic monomers in previously synthesized silicone resin dispersions. If the glass transition temperature (T_g) of the shell is around +120 °C or higher, drying of such dispersions leads to “nanopowders” which can be applied as impact modifiers for powder coatings and plastics due to the presence of low T_g silicone resin contained in the hybrid nanoparticles. The aim of our study was to investigate the effect of silicone resin composition on the properties of dispersions and the corresponding nanopowders what, in turn, was expected to influence the properties of powder coatings modified with such nanopowders. Silicone resin dispersions (DSI) were synthesized by emulsion polymerization of three silicone monomers: octamethylcyclotetrasiloxane (D4), methyltrimethoxysilane (METMS) and methacryloyltrimethoxysilane (MATMS) in the presence of dodecylbenzenesulphonic acid playing the role of both surfactant and polymerization catalyst. Silicone-acrylic hybrid dispersions (DASI) having core–shell particle structure confirmed by TEM were further obtained by emulsion polymerization of methyl methacrylate in DSI, and eventually nanopowders (NP-DASI) were produced by spray-drying of DASI. A designed experiment was conducted where the different proportions of D4, METMS and MATMS were used in DSI synthesis and a range of properties of DSI, DASI and NP-DASI were tested. A significant effect of starting silicone monomers composition (reflected in silicone resin structure) on dispersion particle size was observed what could be explained by differences in their hydrophobicity. SEM investigations revealed that NP-DASI were produced in the form of 1–10 μm agglomerates of round-shaped nanoparticles of ca. 120 nm in size. Two clear glass transition temperatures (T_g) of NP-DASI were identified by DSC: one attributed to silicone part – around −120 °C – and the other attributed to poly(methyl methacrylate) (PMM) part – around +120 °C. T_g attributed to silicone part decreased with increased share of D4 and MATMS in the silicone monomers composition while T_g of PMM part showed a minimum for specific composition of silicone monomers.     

Star‐shaped POSS–methacrylate copolymers with phenyl–triazole as terminal groups,synthesis, and the pyrolysis analysis

Star‐shaped polyhedral oligomeric silsesquioxane (POSS)–methacrylate hybrid copolymers with phenyl–triazole as terminal groups had been designed and synthesized via sequential atom transfer radical polymerization (ATRP), azidation, and phenylacetylene‐terminated procedures, and the hybrid copolymers here could be denoted as POSS–(PXMA‐Pytl)₈, where X can be M, B, L, and S, represented four different methacrylate monomers, such as methacrylate (MMA), butyl methacrylate (BMA), lauryl methacrylate (LMA), and stearyl methacrylate (SMA), respectively. Thermal gravimetric analysis (TGA) and in situ Fourier transform infrared spectroscopy (FTIR) were applied for studying the thermal stability and degradation mechanism, and it was found that all of the POSS–(PXMA‐Cl)₈ and POSS–(PXMA‐Pytl)₈ copolymers exhibited excellent thermal stabilities, which had great potential in heat‐resistant material application. Different tendencies of decomposition temperatures at 5% and 10% weight loss (T₅ and T₁₀) dependent on the side‐chain length and terminal group species were investigated respectively. The longer alkyl side chains of the monomers, the lower thermal stabilities, and enhanced T₅ and T₁₀ were also shown with the introduction of phenyl–triazole groups instead of chlorine groups. © 2014 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2014 , 131, 40652.     

Thermal behavior and specific interaction in high glass transition temperature PMMA copolymer

A series of high glass transition temperature copolymers based on poly(methyl methacrylate) (PMMA) were prepared by free radical copolymerization of methacrylamide and methyl methacrylate monomers in dioxane solvent. The thermal properties and hydrogen-bonding interactions of these poly(methacrylamide-co-methyl methacrylate) (PMAAM-co-PMMA) copolymers with various compositions were investigated by differential scanning calorimetry (DSC), Fourier transform infrared (FTIR) spectroscopy, and solid-state nuclear magnetic resonance (NMR) spectroscopy. A large positive deviation in the behavior of T_g, based on the Kwei equation from DSC analyses, indicates that strong hydrogen bonding exists between these two monomer segments. The FTIR and solid-state NMR spectroscopic analyses give positive evidence for the hydrogen-bonding interaction between the carbonyl group of PMMA and the amide group of PMAAM (e.g. by displaying significant changes in chemical shifts). Furthermore, the proton spin-lattice relaxation time in the rotating frame (T_1ρ(H)) has one single value over the entire range of compositions of copolymers, and gives a value shorter than the average predicted. The proton relaxation behavior indicates the rigid nature of the copolymer.     

Synthesis, preparation and properties of novel high-performance allyl-maleimide resins

Three novel allyl-maleimide monomers (i.e., A₂B, AB and AB₂) were designed, synthesized and thermally cured to yield a series of high-performance allyl-maleimide resins. All the monomers obtained are readily soluble in common organic solvents enabling an easy solution processing. The thermal properties of the three monomers were studied by the differential scanning calorimetry (DSC). A₂B and AB showed fairly low melting temperature (T_m < 90 °C) and wide processing window ranging from 90 °C to 260 °C. The thermal stability of the cured allyl-maleimide resins (i.e., PA₂B, PAB and PAB₂) was studied by the thermogravimetric analysis (TGA). Dynamic mechanical analysis (DMA) was used to investigate the dynamic mechanical properties of the composites based on the cured allyl-maleimide resins. PA₂B and PAB₂ showed good glass transition temperatures (T_g > 270 °C) and their corresponding composites showed high bending modulus (E′ > 1900 MPa). Allyl-compound-modified BMI resins based on AB monomer were prepared. Rheometer revealed that the processability of the prepolymer (BR-AB-pre) was improved by the addition of AB monomer. The cured BMI resins (BR and BR-AB) showed good thermal stability (T_d > 400 °C, both in nitrogen and in the air), high glass transition temperature (T_g > 320 °C), and good mechanical properties and low water uptake (<2.6%, 120 h).     

Synthesis of novel random and block copolymers of tert-butyldimethylsilyl methacrylate and methyl methacrylate by RAFT polymerization

Hydrophobic-hydrolysable copolymers consisting of methyl methacrylate (MMA) and tert-butyldimethylsilyl methacrylate (TBDMSMA) have been synthesized for the first time by Reversible Addition-Fragmentation chain Transfer (RAFT) polymerization technique using cumyl dithiobenzoate (CDB) and cyanoisopropyl dithiobenzoate (CPDB) as chain transfer agents (CTAs). The monomer reactivity ratios for TBDMSMA (r₁ = 1.40 ± 0.03) and MMA (r₂ = 1.08 ± 0.03) have been determined using a non-linear least-squares fitting method. Well-defined random copolymers PMMA-co-PTBDMSMA have been prepared. Then, the versatility of the RAFT process to synthesize silylated block copolymers with controlled molecular weights and low polydispersities has been demonstrated using two strategies: the synthesis of PMMA-SC(S)Ph or PTBDMSMA-SC(S)Ph as macro-chain transfer agent (macro-CTA) for use in a two step method or an one-pot method which consists in the successive addition of the two monomers. Diblock copolymers with narrow molecular weight distributions (PDI < 1.2) were obtained from the one-pot method with number-average molecular weight values within the range 10,000-22,000 g mol⁻¹.