Reverse Iodine Transfer Polymerization Research Articles

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.

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.

Emulsifier-Free Acrylate-Based Emulsion Prepared by Reverse Iodine Transfer Polymerization.

The self-emulsifying acrylate-based emulsions with solid content 45 wt.% were prepared in 3.5 h by reverse iodine transfer polymerization (RITP), and the polymer molecular weight (Mn) could be 30,000 g·mol−1. The influences of methacrylic acid (MAA) amount, soft/hard monomer mass ratio, and iodine amount on polymerization and latex were investigated. A moderate amount of ionized MAA was needed to stabilize the emulsion. Glass transition temperature (Tg) was decreased with the increasing mass ratio of soft/hard monomer. A higher iodine amount resulted in lower Mn. The increased Mn after chain extension of the polymer with water-insoluble monomers in iterative one-pot method proved the living of polymer. Compared with conventional emulsion polymerization, molecular weight (Mn) could be controlled, and Mn of polymer synthesized in RITP emulsion polymerization is higher; emulsion of polyacrylate-containing hydroxyl monomer units prepared by RITP emulsifier-free radical polymerization is more stable. Good properties, such as hardness, water resistance, adhesion, and increased value of maximum tensile of films modified by reaction of polyacrylate with melamine–formaldehyde (MF) resin, indicated potential application in baking coating.

Synthesis and Characterization of Amphiphilic Diblock Copolymer by Reverse Iodine Transfer Polymerization (RITP)

Abstract Iodine transfer radical homo- and diblock copolymerization of N-[3-(dimethylamino)propyl] methacrylamide (DMAPMA) with methyl methacrylate (MMA) were carried out in the presence of iodine I2 and 2,2′-azobis(isobutyronitrile) (AIBN) as chain transfer agent and initiator, respectively. Using reverse iodine transfer polymerization (RITP) method based on the in situ generation of transfer agents using molecular iodine I2. The homopolymer and copolymer were characterized by FT-IR and 1H NMR. The self-assembly behaviours of diblock copolymer in water are studied by viscosity and tensiometry techniques. The water-soluble fraction of P(DMAPMA-b-MMA) block copolymer formed micelles which were investigated at 25°C in water at 0.2 mg.mL−1 concentration using a tensiometry device. Dynamic light scattering technique (DLS) was performed over a wide range of concentration to determine hydrodynamic size of the aggregates.

Aqueous reverse iodine transfer polymerization of acrylic acid

The utilization of sodium iodide, potassium persulfate, and a thermal radical initiator enables facile access to PAA via the direct reverse iodine transfer polymerization of acrylic acid. This polymerization proceeds rapidly in aqueous media using inexpensive and commercially available reagents.

2,5-Di-(2-ethylhexanoylperoxy)-2,5-dimethylhexane as difunctional radical initiator in reverse iodine transfer polymerization (RITP) of styrene, methyl methacrylate and butyl acrylate

The use of 2,5-di-(2-ethylhexanoylperoxy)-2,5-dimethylhexane (T141) as difunctional radical initiator in Reverse Iodine Transfer Polymerization (RITP) was studied at 80 °C (k d,T141 = 9.6 × 10−5 s−1) for styrene (St), methyl methacrylate (MMA) and butyl acrylate (BuA). Firstly, the apparent efficiency coefficients α and β were determined by RITP of St, MMA and BuA using monofunctional initiators such as dilaurylperoxide (LYP) at 73 °C (k d,LYP = 9.6 × 10−5 s−1) and bis(4-tert-butylcyclohexyl)peroxydicarbonate (P16S) at 59 °C (k d,P16S = 9.6 × 10−5 s−1). The decomposition of the monofunctional initiators LYP and P16S generates free radicals with similar structures as those produced during the homolysis of T141. Once the polymerization reactions were performed, monomer conversions were determined by proton nuclear magnetic resonance and the molecular weights Mn,exp were obtained by size exclusion chromatography. Thus, the following apparent efficiency coefficients were calculated: α = 0.41 and β = 1.00 for St, α = 0.14 and β = 0.75 for MMA and α = 0.07 and β = 0.14 for BuA. Afterwards, these values were successfully tested in RITP using an asymmetric initiator such as tert-amyl peroxy-2-ethylhexanoate (T121). In addition, the RITPs were performed for all three monomers using T141 as difunctional initiator. The results prove that the calculated values for α and β were consistent, since the theoretical molecular weights in all polymeric samples match well with the Mn,exp.

Reverse iodine transfer polymerization of vinyl acetate and vinyl benzoate: synthesis and characterization of homo- and copolymers

Reverse iodine transfer polymerization of vinyl acetate and vinyl benzoate: synthesis and characterization of homo- and copolymers

懸濁重合系への逆ヨウ素移動重合（RITP）の適用

懸濁重合系への逆ヨウ素移動重合（RITP）の適用

Fabrication of honeycomb-patterned porous films from PS-b-PNIPAM amphiphilic diblock copolymers synthesized via RITP

Poly(styrene)-b-poly(N-isopropylacrylamide) (PS-b-PNIPAM) amphiphilic diblock copolymers were synthesized via reverse iodine transfer polymerization (RITP) firstly. And then the honeycomb structured porous films were fabricated by drop the amphiphilic diblock copolymer solutions on glass substrates. The porous films were characterized using field emission scanning electron microscopy (FESEM) and atomic force microscopy (AFM), respectively. The results showed that the regular honeycomb patterned porous film was achieved successfully by employing the block copolymer with a significantly larger polystyrene block proportion into the solution and the pore diameter of the film decreases obviously with the polymer concentration increased. The effects of airflow speed and Ag particles on porous films are also discussed in this study.

Molecular iodine in monomer and polymer designing

Not only does the molecular iodine play a leading role in organic synthesis but also in the polymer synthesis. Different kinds of polymerization initiated by molecular iodine are herein screened: cationic polymerization, radical polymerization, living/controlled radical polymerization (LCRP) such as reverse iodine transfer polymerization, polycondensation, and ring-opening polymerization (ROP). Also, the functionalization of polymers using molecular iodine, such as the acetylation of polysaccharides (cellulose, starch), and the use of iodine–polymer complex in organic synthesis are also discussed. Numerous natural and synthetic polymers are prone to make complexes with molecular iodine, and one feature of such complexes is their propensity as polymer-supported reagent and catalysts in many organic syntheses.

Reverse Iodine Transfer Polymerization (RITP) of 1,1,2,2‐Tetrahydroperfluorodecyl Acrylate in Supercritical Carbon Dioxide

Reverse iodine transfer polymerization (RITP) of 1,1,2,2‐tetrahydroperfluorodecyl acrylate (FDA) is successfully performed in supercritical carbon dioxide (scCO2) at 70 °C under a CO2 pressure of 300 bar. PolyFDA (PFDA) of increasing molecular weights (from 10 000 to 100 000 g mol−1) is synthesized with good agreement between theoretical, 1H NMR spectroscopy and and size exclusion chromatography/refractive index/right‐angle laser‐light scattering/differential viscometer (SEC/RI/RALLS/DV)‐estimated molecular weights (). Furthermore, the increase of goes with a decrease of the dispersity of the polymers (Đ from 2.06 to 1.33), which is consistent with a controlled radical polymerization (CRP). Lastly, the structure of final PFDA and therefore the RITP process are confirmed by matrix‐assisted laser desorption ionization time‐of‐flight mass spectrometry (MALDI‐TOF MS) analyses. image

Synthesis of anionic amphiphilic diblock copolymers of poly(styrene) and poly(acrylic acid) by reverse iodine transfer polymerization (RITP) in solution and emulsion

offer the appealing prospect of synthesizing these amphiphilic block copolymers. However, there are numerous drawbacks arising from the use of each technique in terms of the high cost of the control agents as in NMP and RAFT, the cumbersome removal of the catalyst in the ATRP catalytic system and the instability problems of the transfer agents requiring thereby special precautions during storage. In the respect of overcoming the problems posed by the common CRP techniques, great interest is involved in adopting and developing the innovative CRP method called Reverse Iodine Transfer Polymerization (RITP) 7-8 which was developed by our group. This method comprises a degenerative chain transfer mechanism and its simplicity rests on the use of molecular iodine (or its precursors such as sodium iodide, NaI) 9-10 for the in situ generation of transfer agents. Herein, we report the synthesis of amphiphilic diblock copolymers of poly(styrene), (PS) and poly(acrylic acid) (PAA) from the easy cleavable tert-butyl acrylate precursor, by reverse iodine transfer polymerisation (RITP) in solution and emulsion. Experimental Materials. Tert-butyl acrylate (tBA, Aldrich, 98%) was extracted three times with 5% aqueous NaOH and then washed with distilled water. After drying over CaCl2 and filtering off the drying agent, the monomer was distilled under reduced pressure. Styrene (Acros, 99%) and toluene (BDH, 99%) were distilled under reduced pressure before use. 2,2'- Azobis(isobutyronitrile) (AIBN, Fluka, 98 %) was purified by recrystallization in methanol. Iodine (I2, Aldrich, 99.8%), trifluroacetic acid (TFA, Aldrich, 99%), dichloromethane (DCM) (Fluka), potassium persulfate (KPS, Aldrich, 99%), sodium 1-hexadecanesulfonate (M= 328.49 g.mol -1 , Lancaster, 99%), and Mersolat H40 (Lanxess, 40% aqueous solution) were used as received. Water was deionized by passing it through columns packed with ion exchange resins. Instrumentation. The samples were characterized by 1

Fabrication of poly(methyl methacrylate)‐block‐poly(N‐isopropylacrylamide) amphiphilic diblock copolymer on silicon substrates via surface‐initiated reverse iodine transfer polymerization

Amphiphilic diblock copolymer on silicon substrates were synthesized via surface‐initiated reverse iodine transfer polymerization (RITP) technique. The silicon substrates (Si (111) surface) were modified with the azo groups, which were introduced by the treatment of Si (111) surface with 4,4′‐azobis (4‐cyanopentanoic acid). The poly(methyl methacrylate) (PMMA) were then prepared under RITP conditions from the Si (111) wafer. The synthesis of amphiphilic diblock copolymer was carried out on Si‐g‐PMMA substrate by sequential addition of monomer N‐isopropylacrylamide (NIPAM). The observed narrow molecular weight distributions (Mw/Mn), linear kinetic plots, and linear plots of molecular weight (Mn) versus monomer conversion indicate that the chain growth from the silicon substrates is a controlled process with a “living” characteristic. The ellipsometry and contact angle results indicated that the MMA had grafted from the surface of the silicon substrates successfully and the graft layer was well defined. The structure of the polymer and the ability to extend the chains were characterized and confirmed with the surface sensitive techniques such as X‐ray photoelectron spectroscopy and atomic force microscope. POLYM. ENG. SCI., 54:925–931, 2014. © 2013 Society of Plastics Engineers

Controlled radical polymerization of 1,1,2,2-tetrahydroperfluorodecyl acrylate by reverse iodine transfer polymerization (RITP)

Solution polymerization of 1,1,2,2-tetrahydroperfluorodecyl acrylate initiated by 2,2′-azobis(isobutyronitrile) (AIBN) at 65°C in the presence of molecular iodine I2 has been studied. The process, called reverse iodine transfer polymerization (RITP), efficiently controls the molecular weight (determined by 1H NMR) and the structure of the polymer. For instance, a poly(1,1,2,2-tetrahydroperfluorodecyl acrylate) sample of Mn,NMR=5200gmol−1 (Mn,theoretical=5000gmol−1), with a monomer conversion of 97% was successfully prepared. The iodine end-capped structure of the polymers (A–Mn–I, where n is the mean number degree of polymerization) was further demonstrated by mass-assisted laser desorption ionization time-of-flight (MALDI-TOF). When targeting very low degrees of polymerization (e.g. DPn=5), monomer conversion reached its maximum before the end of the induction period (incomplete consumption of iodine and of the A–I adduct) leading to higher than expected molecular weights. This could be a limitation for RITP when targeting very low molecular weight oligomers (DPn<10). Finally, an efficient functionalization method was used to end-cap the PFDA polymer chains with a hydroxyl or a carboxylic acid function. The iodine atom at the chain end was displaced by 2-mercaptoethanol or 2-mercaptoacetic acid in basic media to yield the corresponding alcohol or acid.

Trithiocarbonates prepared from iodo-functionalized RITP-polymers

Iodo-terminated polymers (polystyrene, polybutyl acrylate and polyvinyl acetate) were synthesized by reverse iodine transfer polymerization (RITP) and then used to form homopolymeric trithiocarbonates through a coupling reaction induced by Cs2CO3/CS2. The resulting polymeric trithiocarbonates were subsequently used in RAFT polymerization to form ABA block copolymers. This coupling reaction was extended to some iodo-terminated AB diblock copolymers prepared entirely by RITP to form ABA triblock copolymers.

One‐pot synthesis of amphiphilic diblock copolymers of poly(styrene) and poly(2‐methyl‐2‐oxazoline) by the direct combination of reverse iodine transfer polymerization (RITP) and cationic ring‐opening polymerization (CROP) processes

A iodo-terminated polystyrene (PS-I) synthesized by reverse iodine transfer polymerization (RITP) was directly used as macroinitiator in the cationic ring-opening polymerization of 2-methyl-2-oxazoline to afford a water-soluble diblock copolymer. This is the first example of combination of RITP and CROP in macromolecular engineering.

Molecular control of polystyrene in the reverse iodine transfer polymerization (RITP) – Suspension process

The reverse iodine transfer polymerization (RITP)-suspension polymerization of styrene was carried out in the presence of molecular iodine (I2) using AIBN as an initiator and polyvinylalcohol (PVA) as a stabilizer under argon atmospheres at 70 °C for 10 h in the absence of light. The effect of iodine and styrene contents on the molecular characteristics was investigated. The result was summarized into three categories; (1) the two different polymerizations, the emulsion and suspension, simultaneously occurred in the RITP-suspension polymerization. (2) The emulsion fraction decreased, whereas the suspension fraction increased with the I2 content from 0 to 0.25 mmol, resulting in the decreased molecular weight of the resultant polymer from 320,000 to 59,000 g/mol, respectively. This was arisen from the higher reaction rate of the RITP-suspension polymerization due to the better solubility of AIBN in the monomer droplet in the suspension phase than in the micelle in the emulsion phase upon the increased I2 content. (3) As the styrene content increased up to 40 wt% under fixed I2 content, the suspension fraction dominated, resulting in the reduced molecular weight from 59,000 to 38,000 g/mol, respectively. This was rationalized that the temperature increment upon the relatively small amount of solvent, which means due to the large amount of monomer, induced the rapid polymerization in the monomer droplets where the suspension polymerization was favorable. Thus, the RITP-suspension process dramatically decreased the molecular weight of PS not only by the presence of I2, but also by the dominated suspension fraction.

Preparation of poly(styrene‐b‐2‐hydroxyethyl acrylate) block copolymer using reverse iodine transfer polymerization

AbstractReverse iodine transfer polymerizations (RITP) of 2‐h‐ydroxyethyl acrylate (HEA) were performed in N,N‐dimethylformamide at 75°C using AIBN as initiator. Poly(2‐hydroxyethyl acrylate) (PHEA) with Mn = 3300 g mol−1 and Mw/Mn &lt;1.5 were obtained. Homopolymerization of styrene in RITP was also carried out under similar conditions using toluene as solvent. The resulting iodo‐polystyrene (PS‐I) with (Mn, SEC = 607 g mol−1, polydispersity index (PDI) = 1.31) was used as a macroinitiator for the synthesis of amphiphilic block copolymers based on HEA with controlled well‐defined structure. Poly(styrene‐b‐2‐hydroxyethyl acrylate) (PS‐b‐PHEA) with Mn = 13,000 g mol−1 and polydispersity index (Mw/Mn) = 1.4 was obtained, copolymer composition was characterized using 1H‐NMR and FTIR, whereas SEC and gradient HPLC were used to confirm the formation of block copolymer and the living character of polymer chains. © 2012 Wiley Periodicals, Inc. J Appl Polym Sci, 2012

NMR Studies on the Mechanism of Reverse Iodine Transfer Polymerization of Styrene

The evolution of chain transfer agents (CTAs) was studied for the polymerization of styrene by reverse iodine transfer polymerization (RITP). CTAs are formed during an inhibition period where the radical initiator reacts with molecular iondine. These compounds were studied using in situ1H nuclear magnetic resonance (NMR) experiments. The molecular weight of polystyrene was evaluated with size exclusion chromatography (SEC) and 1H NMR. Structural analysis of the resulting polymers was done using 1H NMR spectroscopy and matrix-assisted laser desorption/ionization time-of-flight (MALDI–ToF) mass spectrometry. The inhibition period of styrene polymerized by RITP was much shorter than expected. This is due to the consumption of iodine in the reaction between styrene and iodine which reversibly forms 1,2-diiodoethylbenzene leading to the subsequent formation of 1-phenylethyl iodide (1-PEI). For the first time the formation of 1,2-diiodoethylbenzene as an intermediate structure in RITP of styrene has been proven experimentally. The active role of 1-PEI in the polymerization process is documented through the detection of phenylethyl end groups by MALDI–ToF and 1H NMR.