Iodine Transfer Polymerization Research Articles

Innovative multifunctional nanocapsules with antibacterial, perfume, and UV-initiated coating properties

Polymer nanocapsules containing fragrance were fabricated for antibacterial, pleasing scent and UV-coating applications. Poly (2-methacryloyloxy dodecyl dimethyl ammonium chloride-4-allyloxy-2-hydroxybenzophenone)-block-polymethyl methacrylate-iodide (P(QAC12-BP)-b-PMMA-I) was first synthesized by solution iodine transfer polymerization (solution ITP) for use as a polymerizable surfactant in miniemulsion polymerization where benzalkonium chloride (BKC) was used as a cosurfactant. The nanocapsules were prepared using poly(methyl methacrylate–divinylbenzene) (P(MMA–DVB)) as a shell, whereas mangosteen oil (MO) was used as a fragrance core model for aroma. High colloidal stability nanocapsules with a size of about 213 nm were obtained. The nanocapsule surface contained QAC12 segments of 15.10 µmol/g-capsule (UV measurement), giving the high positive charge (+70 mV). An essential oil encapsulated inside the nanocapsule had a high encapsulation efficiency (>90%). The nanocapsules effectively inhibited bacterial growth because of QAC12 and BKC on their surface. The nanocapsules are able to coat the substrate via UV-activated covalent bonds of the BP segment.

Preparation of bio-based heat storage microcapsules of cellulose acetate butyrate/ polymethylmethacrylate composite by micro-suspension polymerization

ABSTRACT Because of environmental concerns, the utilization of bio-based, renewable resource materials has attracted great attention for a wide range of applications. In this research, green cellulose-based microcapsules containing capric acid (CA) as a bio-heat storage material were prepared. Cellulose acetate butyrate (CAB)/methacrylate polymer composite particles were produced by microsuspension iodine transfer polymerization to encapsulate CA. The influences of methacrylate polymer type and amount on microcapsule morphology, encapsulation efficiency (EE) and thermal properties were investigated. Using methyl methacrylate (MMA) monomer, the colloidal stable spherical microcapsules with smooth surfaces and core-shell morphology were obtained. Although high percentages of EE, ≥70%, were obtained at all CAB:MMA weight ratios, the latent heats of the encapsulated CA were lower than those of the original ones which may be due to the incomplete phase separation of the CAB/PMMA shell and CA core. The increase of CA content up to 60% provided stable spherical microcapsules with a maximum loading of 59% and 97% EE. After thermal cycling for 100 cycles, stable microcapsules still remained with stable thermal properties. The obtained bio-based microcapsules would be well applied for heat storage and temperature control applications.

Synthesis of PDMS/PEG graft-like and block copolymers via industrially relevant reverse iodine transfer polymerization

Advanced polymer structures are gaining traction in the coatings industry where they may, for instance, give rise to antifouling and anti-icing surfaces. With a focus on industrial feasibility, a series of copolymers from poly(dimethylsiloxane) monomethacrylate (PDMSMA), methoxy poly(ethylene glycol) monomethacrylate (MPEGMA) and methyl methacrylate (MMA) were prepared via reverse iodine transfer polymerization (RITP) and reversible complexation mediated polymerization (RCMP). Using inexpensive materials and synthesis approaches scalable for larger industrial quantities, a variety of (amphiphilic) copolymers and block copolymers were prepared. Compared to semi-batch free-radical polymerization (FRP), the RITP/RCMP approaches resulted in higher conversions of the macromonomers, lower polymer dispersities, allowed synthesis of block copolymers, as well as being simpler than most other common RDRP techniques.

Fabrication of porous polymer particles containing BiVO4 and Fe3O4 nanoparticles using block copolymer as porogen for effective dye removal

Hybrid porous particles (HPPs) of poly(methyl methacrylate-divinylbenzene) P(MMA-DVB) containing a visible light-photocatalyst bismuth vanadate (BiVO4) and magnetite (Fe3O4) nanoparticles (NPs) were synthesized and employed as a reusable material for effective dye removal. The porous structure increasing the surface to volume ratio and high water diffusivity of HPPs, prepared via the microsuspension iodine transfer polymerization, was generated by using poly(methacrylic acid)-block-poly(MMA-3-[trimethoxysilyl] propyl methacrylate) (PMAA-b-P(MMA-MPS)) as porogen. The block copolymer also acting as a surface modifier of BiVO4 NPs allowed the encapsulation of this photocatalyst together with oleic acid coated Fe3O4 NPs in spherical HPPs. The fabricated HPPs could efficiently remove methylene blue (MB) up to 235 mg/g-BiVO4 based on the adsorption and photocatalytic degradation mechanism caused by the particle porosity and BiVO4 NPs, respectively. Moreover, the incorporated Fe3O4 NPs provided the magnetic separation ability of the HPPs for their reusability up to 5 cycles with a high MB removal performance of > 86. These HPPs would be good candidates for effective dye removal in contaminated water

Polyethylene and poly(ethylene-co-vinyl acetate) star polymers by iodine transfer polymerization

Iodine transfer (co)polymerization (ITP) was employed to form polyethylene (PE) and poly(ethylene-co-vinyl acetate) (EVA) stars.

Iodine-influenced morphological evolution of micrometer-sized poly(methyl methacrylate)-block-poly(vinyl acetate) particles upon hydrolysis

Iodine transfer polymerization was used to synthesize micrometer-sized block copolymer particles using methyl methacrylate (MMA) and vinyl acetate (VAc) in a microsuspension system. Three morphologies were obtained after hydrolysis, depending on the block ratio.

Emerging Concepts in Iodine Transfer Polymerization

AbstractControlled radical polymerization corresponds to variety of synthetic strategies that aim the generation of precise macromolecular architectures. Iodine transfer polymerization (ITP) is one of the oldest methods to conduct controlled radical polymerization; however, it seems to have lost visibility compared to other popular techniques. It relies on utilization of iodine species in reversible deactivation kinetics, and it has some significant advantages compared to other methods. Its simplicity, minimized toxicity, metal‐free nature, no coloring on final product, and ease of purification provide widespread applicability, even in industry. In this perspective, the basics of ITP are re‐introduced, and emerging technologies (heterophase polymerization, photoinitiation, and sustainability) in ITP are discussed.

Ultrasonication enhanced photocatalytic solvent-free reversible deactivation radical polymerization up to high conversion with good control

Focusing on energy-saving and environmentally-friendly polymerization engineering, ultrasonication and light were employed as coupled physical stimuli to regulate solvent-free reversible addition fragmentation chain transfer polymerization (RAFT), atom transfer radical polymerization (ATRP) and iodine transfer polymerization (ITP). The solvent-free polymerizations of (meth)acrylate under different conditions were performed with good control even at high monomer conversion (>90%), yielding polymers with low values of dispersity and retention of chain-end functionality. Kinetic experiments and mechanistic insights confirmed that light triggered different photocatalytic pathways (e.g. oxidative quenching cycle for RAFT, reductive quenching cycle for ATRP, photogenerated radical species for ITP) to initiate and mediate the solvent-free polymerizations and ultrasonication was used as an effective process intensification method to improve the diffusive of photocatalysts and their derivatives to alleviate the diffusional limitations for keeping good control up to high monomer conversion. This as-developed strategy is proved to be an efficient technology to produce well-defined polymers without complicated processes of products separation from solvent and residual monomer removal.

Telechelic polyethylene, poly(ethylene-co-vinyl acetate) and triblock copolymers based on ethylene and vinyl acetate by iodine transfer polymerization

Difunctional iodo chain transfer agents (CTAs) were successfully employed in the iodine transfer polymerization (ITP) of ethylene and its copolymerization with vinyl acetate to synthesize telechelic (co)polymers and triblock copolymers.

Expanding monomer scope and enabling post-modification in photocontrolled radical ring-opening polymerization of vinylcyclopropanes by an iodine transfer strategy

Visible light-driven iodine transfer polymerization provides efficient and unique access to novel poly(vinylcyclopropanes) with enhanced material properties.

Synthesis of micrometer-sized poly(vinyl acetate) particles through microsuspension iodine transfer polymerization: effect of iodine species in a water medium

Schematic of the behaviors of iodine species in the microsuspension polymerization of vinyl acetate (VAc) in an aqueous medium.

Tosyl iodide – a new initiator for the photo-controlled iodine transfer polymerization of methacrylates under sunlight irradiation

A very simple photo-controlled iodine transfer polymerization system consisting only of methacrylate monomers, solvent (dimethylacetamide), and initiator (tosyl iodide) under violet and sunlight irradiation is reported.

Emulsion iodine transfer polymerization of nearly uniform submicrometer‐sized polystyrene particles

AbstractEmulsifier‐free emulsion iodine transfer polymerization (emulsion ITP) of styrene was carried out using unpurified and purified poly(methacrylic acid)–iodine (PMAA‐I). PMAA‐I was previously synthesized by solution ITP in dioxane. The solution ITP of methacrylic acid was completed at 40 °C for 24 h. Unexpectedly, 64% of added CHI3 remained in dioxane even after the polymerization. The emulsion ITP was carried out at pH ∼ 9 with unpurified or purified PMAA‐I. The number‐average diameter (dn) of the polymer particles obtained using purified PMAA‐I (148 nm at 93% conversion) was much smaller than that using unpurified PMAA‐I (710 nm at 68% conversion). In both cases, in the early stage of the polymerization, polystyrene (PS) particles stabilized by some PMAA‐b‐PS copolymer chains were formed. This indicates that PMAA‐I worked not only as a macro chain transfer agent but also as a colloidal stabilizer. In the unpurified system, the remaining CHI3 also operated as a chain transfer agent. It resulted in PS‐I homopolymers having controlled molecular weight in the PS particles. On the other hand, many high molecular weight PS homopolymers were formed in the purified system by emulsion conventional radical polymerization in the PS particles. To depress emulsion conventional radical polymerization, the CHI3 was post‐added after 90 min. Nearly uniform submicrometer‐sized (82 nm) PS particles with narrow molecular weight distribution (Mw/Mn = 1.24) were achieved. These polymerization behaviors were reasonably explained from the results obtained by gel permeation chromatography and diffusion ordered spectroscopy 1NMR. © 2021 Society of Industrial Chemistry.

Preparation of Emulsifier-Free Styrene-Acrylic Emulsion via Reverse Iodine Transfer Polymerization.

Styrene–acrylic emulsions containing hydroxyl functional monomer unit’s component are widely used for maintenance coating. In this paper, a stable emulsifier-free styrene–acrylic emulsion with solid content over 43% could be obtained in 210 min via reverse iodine transfer polymerization (RITP). By adding a mixture of methacrylic acid (MAA) and poly(ethylene glycol)methyl ether methacrylate (PEGMA) into a system containing a high content of hydroxyl functional monomer component (19.4 wt.% of the total monomer mass), styrene (St) could be copolymerized with methyl methacrylate (MMA); the modified film exhibited good hardness properties, good adhesive properties, and low water absorption. An increase in the amount of PEGMA decreased the glass transition temperature (Tg). When 1.4 times the reference amount of initiator was added, the highest molecular weight Mn could reach 40,000 g.·mol−1 with 0.25 times the reference amount of iodine in the emulsion. The largest tensile strength of the dried emulsion film over 5.5 MPa endowed the material with good mechanical properties. Living polymerization was proven by the kinetics of RITP emulsion and chain extension reaction. TEM micrographs manifest the emulsification of the seed random copolymer. This paper may provide a potential methodology for preparing polymer materials with excellent mechanical properties.

Aldehyde-Functionalized Polymers from the Reverse Iodine Transfer Polymerization of Lignin-Derivable Compounds

Renewable polymers with reactive functionalities become increasingly attractive as they address some critical global concerns related to sustainability. In this work, vanillin methacrylate (VM), an aldehyde-functionalized monomer synthesized by the methacrylation of vanillin (a possible lignin derivative), was polymerized for the first time via reverse iodine transfer polymerization. The influence of various reaction parameters including the polymerization solvent, the initiator-to-iodine ratio, and the polymerization temperature on the induction (or inhibition) period and the molar mass was investigated by 1H NMR spectroscopy and size exclusion chromatography. The lack of a clear and consistent discoloration of the reaction mixture to indicate the end of the induction period in the solvents investigated, i.e., toluene, methyl ethyl ketone (MEK), and N,N-dimethylformamide (DMF), was an indication that iodine was taking part in a side (complexation) reaction with the solvent. When the monomer conversions were followed by 1H NMR spectroscopy, it was found that the induction periods for the reactions carried out in MEK and DMF were significantly shorter due to the consumption of iodine by VM, leading to the formation of a chain transfer agent (CTA), 4-formyl-2-methoxyphenyl-2-iodo-2-methylpropanoate. The formation of polymer chains derived from this CTA was confirmed by matrix-assisted laser desorption/ionization time-of-flight mass spectrometry. To demonstrate the “livingness” of the polymerization process, PVM was chain-extended with methyl methacrylate, and the formation of block copolymers was confirmed by high-performance liquid chromatography. The application toolbox of these polymers was expanded by the formation of various poly(vanillin methacrylate) Schiff base polymers endowed with additional functional groups.

Multifunctional Polymer Particles Containing Quaternary Ammonium for Antimicrobial Particulate Surfactants and Defoaming

The preparation of multifunctional polymer particles containing quaternary ammonium molecules by emulsion iodine transfer polymerization (emulsion ITP) via polymerization-induced self-assembly was proposed for the first time. Poly(2-methacryloyloxy ethyl trimethyl ammonium chloride-dimethylamino ethyl methacrylate 12 alkyl chain length)-iodide (P(MTMA-QAC12)12-I) was first synthesized by solution iodine transfer polymerization. It was simultaneously used as a macro-chain transfer agent and emulsifier in emulsion ITP. All conditions smoothly proceeded without coagulation, where the polymerization reached high conversion within only 4 h. When the methyl methacrylate-styrene (P(MMA-S)) copolymer was synthesized in the second block as P(MTMA-QAC12)12-b-P(MMA-S)462, the water contact angle of the obtained particles was close to 90°, which was the most appropriate to use as the particulate surfactant. The P(MTMA-QAC12)12-b-P(MMA-S)462 particles represented a good antimicrobial property based on the positive charge quaternary ammonium groups existing on surfaces. Using such P(MTMA-QAC12)12-b-P(MMA-S)462 nanoparticles (∼90 nm) at 1 wt %, the obtained cutting oil emulsion model represented high colloidal stability with approximately 50 μm oil droplet size without any coalescence. Moreover, foam formation was significantly reduced compared to the commercial cutting oil. According to their excellent properties, P(MTMA-QAC12)12-b-P(MMA-S)462 nanoparticles would be effectively used as a particulate surfactant in Pickering emulsion, including defoamers and antimicrobial agents.

Well-Defined Fluorinated Copolymers: Current Status and Future Perspectives

Well-defined fluoropolymers exhibit unique properties such as excellent oil and water repellency, satisfactory thermal stability, a low refractive index, and low surface energy. The origin of these properties is attributed to the presence of a strong electronegative and low polarizable fluorine atom in the backbone of such polymers, which leads to a strong C–F bond (with a high bond dissociation energy of 485 kJ mol–1). Because of these features, these polymers have found applications as functional coatings, thermoplastics, biomedical items, separators, and binders for Li ion batteries, fuel cell membranes, piezoelectric devices, high-quality wires and cables, and so forth. Usually, fluoropolymers are synthesized by the conventional radical (co)polymerization of fluoroalkenes, which leads to the production of (co)polymers with an ill-defined end group, uncontrolled molar mass, and high dispersity values. In the last two decades, significant developments of various reversible deactivation radical polymerization (RDRP) techniques have helped the design of macromolecular architectures (including block, graft, star, and dendrimers) on demand. However, for relevant new applications, well-defined fluoropolymers with controlled macromolecular architectures (e.g., block copolymers as thermoplastic elastomers and electroactive polymers or graft copolymers for fuel cell membranes) are required. Several RDRP methods, developed in the last two decades, have paved the way for the synthesis of (co)polymers with well-defined molar mass, dispersity, chain end-functionality, and macromolecular architectures. Some of these RDRP techniques have been successfully employed for the synthesis of well-defined fluorinated copolymers. These techniques include iodine-transfer polymerization (ITP), reversible addition–fragmentation chain-transfer (RAFT) polymerization, organometallic-mediated radical polymerization (OMRP), and, to a lesser extent, nitroxide-mediated polymerization (NMP). Impressive control of the molar mass parameters of the fluoropolymers synthesized via these techniques also encouraged the researchers to combine these techniques with other postpolymerization strategies, leading to innovative novel polymeric materials. Thus, synthesized well-defined fluoropolymers exhibited a unique combination of properties (such as excellent weather resistance, high thermal/chemical/aging resistance, morphological versatility, and a low dielectric constant/flammability/refractive index). These led to the application of such developed materials in various high-technology applications such as high-performance elastomers, coatings for marine antifouling applications, fluorinated surfactants, fuel cell membranes, and gel polymer electrolytes for Li ion batteries. Newer advances in the field of polymer synthesis techniques are the need of the hour in order to synthesize more advanced fluorinated materials which may change the use of such polymers in engineering and biomedical fields in the current century. However, it should be kept in mind that success in this regard shall heavily depend on a deeper understanding of the polymerization process and structure–activity relationships.

Synthesis of Micrometer-Sized Poly(methyl acrylate) by Temperature-Step Microsuspension Polymerization with Iodoform Based on the "Radical Exit Depression" Effect§.

Previously, we have reported the successful preparation of micrometer-sized poly(methyl methacrylate) particles without submicrometer-sized byproduct particles by microsuspension iodine-transfer polymerization (ms ITP), in which the radical exit depression (RED) effect was expected, with the benzoyl peroxide initiator at 8 wt % relative to the monomer. However, it was difficult to apply it simply under a similar condition for methyl acrylate (MA), which is more hydrophilic than methyl methacrylate (MMA), because the polymerization rate in the water phase (Rpw) arising from the oligomer radicals exiting from the monomer droplets is high, resulting in a lot of submicrometer-sized byproduct particles. In this study, the problem was overcome by utilizing a two-step temperature process in the microsuspension polymerization with iodoform (ms I) of MA, which supports the proposed mechanism in the ms ITP of MMA in the previous paper. Although the control of the molecular weight (Mn) and the molecular weight distribution (Mn/Mw) was restricted, the preparation of micrometer-sized particles without byproduct particles was realized and a high conversion was reached within a practical time that meets the demands of the industry by utilizing the ms I. The optimal conditions for MA were 70 °C for 2 h, followed by 80 °C for 4 h with a high content of initiator (8 wt % relative to a monomer).

Composite polymer particles containing bismuth vanadate particles for self-cleaning fabrics

The aim of this research was to prepare composite polymer particles containing bismuth vanadate (BiVO4) particles through microsuspension iodine transfer polymerization ( ms ITP) for fabric coating as a self-cleaning fabric. To reduce the aggregation of pristine BiVO4 particles during the fabric coating process, composite polymer particles containing the visible-light-driven photocatalyst as BiVO4 particles in self-cleaning fabric applications were investigated in the first time. First, BiVO4 particles were prepared via an aqueous chelating method where the stable precursor solutions of Bi3+ and V5+ with ethylenediaminetetraacetic acid ligand were obtained. After calcination at 500 °C, the BiVO4 particles were obtained. To disperse them well in an oil (monomer) phase in ms ITP, the BiVO4 surface was modified by oleic acid as o-BiVO4 to present a hydrophobic surface. The encapsulation efficiency of the o-BiVO4 (≥60%) in composite poly(methylmethacrylate-divinylbenzene) (P[MMA-DVB]/o-BIVO) particles was significantly higher than that (≈10%) of the pristine BiVO4 particles. Using polyethylene glycol 30 dipolyhydroxystearate (DPHS) as a porogen, porous P(MMA-DVB)/o-BiVO4 particles still maintaining their spherical shape were obtained with an 8% particle of DPHS. Furthermore, increasing the hydrophilic polymer shell by adding 2-hydroxyethyl methacrylate (HEMA) in the oil phase of ms ITP, the P(MMA-DVB-HEMA)/o-BiVO4 particles showed a much higher methylene blue (MB) degradation rate under visible light for 1 h (24 mg MB/g BiVO4 or 96% MB degradation) than that (13 mg MB/g BiVO4 or 52% MB degradation) of the pristine BiVO4. Moreover, the fabric coated with porous P(MMA-DVB-HEMA)/o-BiVO4 particles showed a satisfactory self-cleaning property.

Iodine-Transfer Polymerization (ITP) of Ethylene and Copolymerization with Vinyl Acetate.

Controlled radical polymerization of ethylene using different commercially available, cheap, and non-toxic iodo alkyls is performed by iodine transfer polymerization (ITP) under mild conditions (≤100 °C and ≤200 bar). The formed well-defined iodo end-capped polyethylene (PE-I) species is very stable upon storage. Narrow molar-mass distributions (dispersities around 1.6) were obtained up to number average molar masses of 7300 g mol-1 . The ethylene copolymerization by ITP (ITcoP) with vinyl acetate allowed to form a broad range of poly(ethylene-co-vinyl acetate) (EVA) containing from 0 to 85 mol % of VAc unit. In addition, EVA-b-PE block copolymers or EVA-b-EVA gradient block copolymers with different content of VAc in the blocks were obtained for the first time using ITP. Finally, reactivity trends were explored by a theoretical mechanistic study. This highly versatile synthetic platform provides a straightforward access to a diverse range of well-defined PE based polymer materials.