Conventional Radical Polymerization Research Articles

Radical polymerization of trifluoromethyl-substituted methyl methacrylates and their application for use in pressure-sensitive paint

Three CF3-substituted methyl methacrylates (MMAs), 2,2,2-trifluoroethyl methacrylate (TFEMA), 1,1,1,3,3,3-hexafluoroisopropyl methacrylate (HFIPMA) and nonafluoro-tert-butyl methacrylate (NFTBMA), were polymerized by conventional radical polymerization to give oxygen-permeable polymers for application in pressure-sensitive paint (PSP). The radical copolymerizations of styrene with TFEMA, HFIPMA, or NFTBMA were carried out to examine the effect of CF3 groups on the polymerizability. The e values increased in the order of MMA (0.40) < TFEMA (0.76) < HFIPMA (1.19) < NFTBMA (1.31). The homopolymers of TFEMA, HFIPMA and NFTBMA (PTFEMA, PHFIPMA, and PNFTBM, respectively) were examined as polymers for use in PSP using 5,10,15,20-tetrakis(pentafluorophenyl)porphinato platinum(II) (PtTFPP). The PSP consisting of PNFTBMA and PtTFPP exerted very high pressure sensitivity and very low temperature sensitivity. In the absence of oxygen, the temperature sensitivity decreased in the order of PTFEMA > PHFIPMA > PNFTBMA = PMMA, which corresponds to the order of glass transition temperatures (Tg). However, the activation energies of the overall process of the luminescence quenching by oxygen were found to be 16.8 (PMMA), 13.0 (PTFEMA), 6.8 (PHFIPMA), and 4.3 kJ mol−1 (PNFTBMA). Therefore, the low temperature sensitivity of PNFTBMA was attributed to its high degree of substitution with CF3 groups and to its relatively high Tg value. © 2013 Wiley Periodicals, Inc. J. Polym. Sci., Part A: Polym. Chem. 2014, 52, 963–972

Preparation and characterization of an IPN type chelating resin containing amino and carboxyl groups for removal of Cu(II) from aqueous solutions

A novel IPN type chelating resin, amino-functionalized poly (glycidyl methacrylate)/poly (acrylic acid), (pGMA/pAA), was synthesized by a combination of serial reactions including, conventional radical polymerization, amination and photopolymerization. To assess the efficacy and characteristics of the resin in removal of Cu (II), batch adsorption experiments were carried out, and the effects of different parameters such as contact time, adsorbent dosage, initial metal ion concentration, temperature, and pH on the adsorption process were investigated. The results showed that 0.5g/L dosage and pH 5 are the optimum values to achieve the maximum adsorption capacity and the adsorption kinetic of Cu (II) was well represented by pseudo-second-order kinetic model. In addition, it was found that the adsorption was mainly controlled by the film diffusion mechanism, along with a considerable contribution of the intra-particle diffusion mechanism, and Langmuir, Freundlich and Dubinin–Radushkevich (D–R) isotherm models can be used for interpreting the adsorption process. Moreover, FT-IR analysis results and the mean free energies of adsorption clearly indicate that the ion exchange and chelation mechanisms took place as dominating mechanisms simultaneously during the adsorption process. It was also found to be that IPN resin could be used at least four times without losing its original activity.

Synthesis and polymerization of styrene monomer carrying isothiocyanate moiety and its copolymerization with HEMA based on chemo-selectivity to nucleophiles

Isothiocyanate is a very useful functional group for post-polymerization modification by the reaction with amine or alcohol. An isothiocyanate monomer, 4-vinylbenzyl isothiocyanate, was synthesized from 4-vinylbenzyl chloride without using any harmful reagents such as thiophosgene and CS2. The obtained monomer was successively polymerized by the conventional radical polymerization (AIBN, 1,4-dioxane, 60 °C) to afford the corresponding polymer. The obtained polymer was characterized by 1H NMR, FTIR, thermogravimetric analysis (TGA), and differential scanning calorimetry. In contrast to the isocyanate group, the isothiocyanate group was relatively tolerant to alcohols, and this character enabled us to synthesize a copolymer of 4-vinyl benzylisothiocyanate and (2-hydroxyethyl methacrylate). The copolymer is transformed into networked polymer by 1,8-diazabicyclo[5.4.0]undec-7-ene as a promoter of the reaction between isothiocyanate and alcohol to afford thiocarbamate. The formation of networked polymer was characterized by FTIR and TGA. © 2013 Wiley Periodicals, Inc. J. Polym. Sci., Part A: Polym. Chem. 2013, 51, 5215–5220

Conformations of Alternating Partially Fluorinated Copolymers in Dilute Ethanol Solutions

Equimolar copolymers of N-vinyl pyrrolidone with 1,1,1-3,3,3-hexafluoroisopropyl-α-fluoroacrylate were obtained by reversible addition-fragmentation chain transfer radical (RAFT) polymerization and by conventional radical polymerization (RAD). The copolymer conformation and compositional heterogeneity were analyzed by dynamic and static light scattering. RAFT copolymers of 41,000 ≤ M w ≤ 68,000 g/mol were shown to adopt cylindrical all-trans conformation. RAD copolymer of higher molecular mass (Mw = 390,000 g/mol) exhibited less extended conformation, thus indicating that the statistical Kuhn segment is less than RAD copolymer length.

Thermoresponsive/low‐fouling Zwitterionic hydrogel for controlled drug release

ABSTRACTA controlled/ living free‐radical polymerization technique was introduced to prepared a homogeneous poly(N‐isopropylacrylamide)‐g‐poly(sulfobetaine methacrylate) hydrogel (RG) possessing a highly porous architecture via two steps. Compared to a poly(N‐isopropylacrylamide)‐co‐poly(sulfobetaine methacrylate) hydrogel (CG) prepared by conventional radical polymerization, RG exhibited a much faster shrinking rate (it lost over 72% of the water in 15 min) in response to the temperature changes. The release behaviors of tetracycline hydrochloride (TCHC) of the hydrogels indicated the TCHC release from the RG could be prolonged to 48 h at 37°C; this was much longer than that for CG (5 h at 37°C). Bovine serum albumin (BSA) was chosen as the model protein to examine the low‐fouling properties of the RG. The BSA adsorption data showed that improved antifouling properties could be achieved by the RG at both 25 and 37°C. © 2013 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2014, 131, 39816.

Synthesis and Properties of Sulfonium Polyelectrolytes for Biological Applications.

Sulfonium macromolecules displayed for the first time nucleic acid binding and transfection in vitro. Conventional and controlled radical polymerization techniques coupled with subsequent alkylation generated a sulfonium homopolymer, poly(DMSEMA), and a sulfonium diblock copolymer, poly(OEG-b-DMSEMA). DNA gel shift assays probed the ability of sulfonium macromolecules to complex nucleic acids, and luciferase assays examined the transfection efficiency and cytotoxicity of both sulfonium macromolecules. Poly(DMSEMA) and poly(OEG-b-DMSEMA) bound pDNA at a charge ratio of 1, and both induced significant luciferase expression in HeLa cells under serum-free conditions. Colloidal stability studies using dynamic light scattering highlighted the excellent colloidal stability of poly(OEG-b-DMSEMA) under salt and serum conditions due to the sterically stabilizing OEG block. Sulfonium macromolecules offer an alternate route to design cationic macromolecules for nonviral nucleic acid delivery, and future work will aim to add functionality to create more efficient delivery vehicles.

Controlled Radical Polymerization Vs Conventional Radical Polymerization: Differences in Surface Properties of 4'-nonafluorobutyl Styrene Polymers

Controlled Radical Polymerization vs Conventional Radical Polymerization: Differences in Surface Properties of 4’Nonafluorobutyl Styrene Polymers Falvio Ceretta, Alessandro Zaggia*, Lino Conte, Bruno Ameduri Dipartimento di Ingegneria Industriale Universita degli Studi di Padova, Via Marzolo 9 35131 Padova, Italy b Ingenierie & Architectures Macromoleculaires, Institut Charles Gherardt, UMR 5253, 8, Rue Ecole Normale 34296 Montpellier , France alessandro.zaggia@unipd.it

Conventional radical polymerization and iodine‐transfer polymerization of 4′‐nonafluorobutyl styrene: Surface and thermal characterizations of the resulting poly(fluorostyrene)s

ABSTRACT4′‐Nonafluorobutylstyrene (3) was synthesized and polymerized by conventional and controlled radical polymerization (iodine transfer polymerization (ITP)). Such an aromatic fluoromonomer was prepared from Ullmann coupling between 1‐iodoperfluorobutane and 4‐bromoacetophenone followed by a reduction and a dehydration in 50% overall yield. Two radical polymerizations of (3) were initiated by AIBN either under conventional or controlled conditions, with 1‐iodoperfluorohexane in 84% monomer conversion and in 50% yield. ITP of (3) featured a fast monomer conversion and a linear evolution of the ln([M]0/[M]) versus time. The kinetics of radical homopolymerization of (3) enabled one to assess its square of the propagation rate to the termination rate (kp2/kt) in ITP conditions (36.2·10−2 l·mol−2·sec−2 at 80 °C) from the Tobolsky's kinetic law. Polydispersity index (Đ) of the fluoropolymer achieved by conventional polymerization was 1.30 while it worthed 1.15 when synthesized by ITP. Thermal stabilities of these oligomers were satisfactory (10% weight loss under air occurred from 305 °C) whereas the melting point was 47 °C. Contact angles and surface energies assessed from spin‐coated poly(3) films obtained by conventional (hysteresis = 18°, surface energy 18 mN.m−1) and ITP (hysteresis = 47°, surface energy 15 mN.m−1) evidenced Đ values' influence onto surface properties of the synthesized polymers. © 2013 Wiley Periodicals, Inc. J. Polym. Sci., Part A: Polym. Chem. 2013, 51, 3202–3212

Design of Polymer-Brush-Grafted Magnetic Nanoparticles for Highly Efficient Water Remediation

Highly efficient removal of mercury(II) ions (Hg(II)) from water has been reported by employing polymer-brush-functionalized magnetic nanoparticles (MNPs). Surface-initiated conventional radical polymerization (SI-cRP) was used to grow poly(2-aminoethyl methacrylate hydrochloride) (poly-AEMA·HCl) polymer chains on magnetite nanoparticles (Fe3O4), followed by the transformation of pendant amino groups into dithiocarbamate (DTC) groups, which showed high chelating affinity toward Hg(II) ions. This polymer-brush-based DTC-functionalized MNP (MNPs-polyAEMA·DTC) platform showed the complete removal of Hg(II) from aqueous solutions. The Hg(II) ion removal capacity and efficiency of MNPs-polyAEMA·DTC were compared with its monolayer analogue, which was derived from the direct transformation of amino groups of (3-aminopropyl) triethoxysilane (APTES)-functionalized MNPs (MNPs-APTES) to DTC functional groups (MNPs-DTC). The surface chemical modifications and higher chelating functional group density, in the case of MNPs-polyAEMA·DTC, were ascertained by transmission electron microscopy (TEM), thermogravimetric analysis (TGA), physical property measurement system (PPMS), attenuated total reflectance infrared (ATR-IR) spectroscopy, and X-ray photoelectron spectroscopy (XPS). The Hg(II) ion removal capacity and efficiency of monolayer and polymer-brush-based DTC-functionalized MNPs (MNPs-DTC and MNPs-polyAEMA·DTC, respectively) were evaluated and compared by studying the effect of various factors on the percentage removal of Hg(II) such as adsorbent amount, temperature, and contact time. Furthermore, the adsorption behavior of MNPs-DTC and MNPs-polyAEMA·DTC was analyzed by applying Langmuir and Freundlich adsorption isotherm models. In addition, the adsorption thermodynamics, as well as the adsorption kinetics, were also evaluated in detail. The higher surface functional group density of MNPs-polyAEMA·DTC led to superior remediation characteristics toward Hg(II) ions than its monolayer analogue.

RAFT miniemulsion polymerization using dioctyl sodium sulfosuccinate

The anionic surfactant dioctyl sodium sulfosuccinate (AOT) has been shown to operate well as a surfactant in aqueous miniemulsion polymerization of styrene both for conventional radical polymerization and RAFT polymerization. AOT is generally more soluble in hydrophobic monomers than in water, and is as such rather unique for an aqueous miniemulsion system. The particle size obtained was smaller than what is customary for both conventional radical polymerization and RAFT polymerization in miniemulsion.

Photocleavable glycopolymer aggregates

We present here a water soluble diblock glycopolymer, poly(spiropyran methacrylate)-block-poly(3-O-4-vinylbenzoyl-D-glucopyranose) (PSP-b-PBG), synthesized by the conventional atom transfer radical polymerization (ATRP) technique. Irradiation with UV light results in switching of the hydrophobic colorless spiropyran (SP) form to zwitterionic purple coloured merocyanine (MC) increasing the overall polarity of the glycopolymer, resulting in its enhanced affinity towards water. The MC form reverts back to the SP form in the dark or under visible light irradiation, restoring the amphiphilic nature of the polymer. Vesicular aggregates formed by this diblock copolymer in water could be dissociated and reconstructed by alternate UV and visible light irradiation. The ability of these polymersomes to efficiently encapsulate, release and re-encapsulate a hydrophobic dye was also explored.

Controlled polymer monolayer synthesis by radical transfer to surface immobilized transfer agents

Radical chain transfer from solution-generated free radicals to thiol transfer agents bound to the surfaces of planar silicon and silica particles was investigated as a method to generate surface-bound polymer brushes. Both conventional radical and reversible addition–fragmentation chain transfer (RAFT) polymerizations created polymer films with molecular weights dependent on the details of the reaction. In the presence of high free radical concentrations or RAFT agent modifiers, the surface had minimal influence on the growth of grafted polymer chains following the initial radical transfer to the surface. Notably, excellent control of film thickness was achieved in the absence of surface-bound initiators or RAFT agents, thereby simplifying the synthesis of immobilized brush architectures. On the other hand, low concentrations of solution free radicals in conventional radical polymerization generated grafted polymers with lengths varying considerably from polymers in solution. Despite the simplicity and versatility of this technique for creating polymer-modified surfaces by surface initiated polymerization (SIP), it has been under-utilized; likely due to the absence of a framework for the rational design of the brush. The details of this investigation should allow surface modification by polymer films to become accessible to researchers without the need to create complex precursor surface chemistries.

Simultaneous control over the molecular weight and tacticity of poly(vinyl acetate) using a low-temperature photoinitiated RAFT process in fluoroalcohols

A photoinitiated RAFT process in fluoroalcohols (FAs) was successfully applied to the preparation of poly(vinyl acetate) and its hydrolyzed polymer, poly(vinyl alcohol), permitting the simultaneous control over the molecular weight (MW) and tacticity. The polymerization reaction displayed living polymerization characteristics, evidenced with linear relationships between ln([M]0/[M]) and time, and between the MW and the conversion. Polymers of higher syndiotacticity could be prepared by using the FA solvent, achieving a 62.4% racemic diad at −20 °C. The syndiotacticity of the polymer increased with increasing concentrations of FAs or with decreasing polymerization temperatures, and the dependence was stronger than the one observed in conventional radical polymerization reactions due to the slower RAFT process. Furthermore, by performing a sequential polymerization reaction involving the high-temperature reaction in the bulk state and the low-temperature reaction in the FAs, stereoblock copolymers of poly(vinyl alcohol) could be obtained.

Direct Transformation of N,N′‐Methylene Bisacrylamide Self‐Assembled Fibers Into Polymer Microtubes via RAFT Polymerization

A novel fabrication method of polymer tubes with simple operation process and high yield is presented. N,N'-methylene bisacrylamide (MBA) polymer microtubes are fabricated via reversible addition-fragmentation chain transfer (RAFT) polymerization using MBA self-assembled fibers as both the template and monomer source. The resulting products are characterized by SEM, TEM, FTIR, and element analysis. The mechanical properties of the gel-like product and the MBA organogel are measured by rheometer. The morphology of the polymer tubes obtained via RAFT polymerization is compared with the sample obtained via conventional radical polymerization. Based on the current investigations, the fabrication mechanism of this method is initially proposed.

Preparation of glycopolymer‐coated magnetite nanoparticles for hyperthermia treatment

AbstractIn this article, magnetite nanoparticles (MNPs) coated with glycopolymer bearing glucose moieties were designed with optimal structural, colloidal, and magnetic properties for biomedical applications. MNPs with an average size of 17 ± 2 nm were synthesized by thermal decomposition process and then their surfaces were modified with active vinyl groups. Two different monomers were immobilized onto the surfaces: dopamine methacrylamide, a monomer with properties inspired on mussels adhesive capacity, or unprotected glycomonomer, 2‐{[(D‐glucosamin‐2N‐yl)carbonyl]‐oxy}ethyl methacrylate. Afterward, the glycomonomer were polymerized at the interface of both vinyl functionalized MNPs by conventional radical polymerization. The resultant hybrid NPs were water dispersible presenting good stability in aqueous solution for long time periods. Moreover, the high density of carbohydrates at the surface of the magnetic NPs could confer targeting properties to the system as demonstrated by studies of their binding interactions with lectins, where the binding activity is higher as the glycopolymer content augments. The magnetic and magneto‐thermal properties of the synthesized hybrid NPs were evaluated. The magnetization curves reveal superparamagnetic features at 300 K, with high values of saturation magnetization. Furthermore, the hybrid glycoparticles show suitable heat dissipation power when exposed to alternating magnetic field conditions. © 2012 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem, 2012

Atom-Transfer Cyclization with CuSO4/KBH4: A Formal “Activators Generated by Electron Transfer” Process Also Applicable to Atom-Transfer Polymerization

The 4-exo and 5-exo-trig atom-transfer cyclizations of 1, 8a-e, 9, 12, and 13 can be mediated with as little as 0.05 mol % of Cu(TPMA)SO(4)·5H(2)O in the presence of 2.5 mol % of borohydride salts in 10 min at room temperature in air. This formal "activators generated by electron transfer" (AGET) procedure utilizes a cheap and oxidatively stable copper source (CuSO(4)·5H(2)O) and can be carried out in environmentally benign solvents (EtOH). It is possible to alter the product distribution in the 5-endo radical-polar crossover reactions of 10a,b and 11 by tailoring the amount of borohydride. Cyclization onto alkynes 14 and 15 is also possible in only 20 min. Controlled radical polymerization of styrene, with increased rates over conventional atom-transfer radical polymerization (ATRP), can be carried out in a controlled fashion (Mn, PDI) using either CuBr or CuSO(4)·5H(2)O and Bu(4)NBH(4).

Aqueous RAFT Polymerization ofN‐Acryloylmorpholine, Synthesis of an ABA Triblock Glycopolymer and Study of its Self‐Association Behavior

AbstractThe RAFT polymerization ofN‐acryloylmorpholine with a symmetric trithiocarbonate was investigated in homogeneous aqueous solution. The effects of temperature and of a high magnetic field were examined and RAFT experiments were compared with the corresponding conventional radical polymerizations. For all temperatures tested, the molar mass of the polymer increased linearly with conversion and closely matched the theoretical value. Molar mass dispersities were in the range 1.05–1.16 and the presence of a magnetic field had little effect on the rate of RAFT polymerizations, although the latter were systematically slower than the corresponding conventional processes. A uniform ABA triblock glycopolymer was prepared, which formed unilamellar polymersomes with a diameter of 380 nm in 91% (v/v) THF/water mixture.

Synthesis and properties of novel functional polymers from tetrachlorinated perylene bisimide

AbstractAsymmetric tetrachlorinated perylene‐3,4,9,10‐tetracarboxylic acid bisimides (4Cl‐PBI) were prepared in one‐pot by a reaction of tetrachlorinated perylene‐3,4,9,10‐tetracarboxylic acid dianhydride with a mixture of 2‐aminoethanol and dodecanamine or 2‐decyltetradecan‐1‐amine. Then, two 4Cl‐PBI methacrylates bearing one (M1) and two (M2) long alkyl tails were prepared, and a series of functional homopolymers were obtained by subjecting conventional radical polymerization and atom transfer radical polymerization. Furthermore, amphiphilic block copolymers pendent with 4Cl‐PBI units, PEO‐PM1 and PEO‐PM2, were prepared using monomethoxyl PEO bromoisobutyrate as a macroinitiator. Size exclusion chromatography, UV–vis spectroscopy, fluorescence spectroscopy, and cyclic voltammetry have been applied to characterize the polymers obtained. Moreover, the Ullmann reactions between the grafted 4Cl‐PBI units were conducted to form large π units, and the PEO‐PM2 block copolymers gave di‐ or tri‐PBI units in about 30%. Also, self‐assembly of the amphiphilic block copolymers PEO‐PM1 and PEO‐PM2 in water was applied to generate spherical nanoparticles of 4Cl‐PBI. © 2012 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem, 2012

Unique UV absorbance for triphenylimidazole‐based polymer

AbstractIn this study, a novel vinyl polymer containing 2,4,5‐triphenylimidazole side groups was synthesized through conventional radical polymerization, which possesses the characteristic of temperature‐dependent absorbance in the near‐ultraviolet (UV) spectral region. The linear dependence of UV absorbance on temperature was confirmed for the polymer both in solid state and in solution by experiment and also supported by the results of theoretical investigation. © 2012 Wiley Periodicals, Inc. J Appl Polym Sci, 2012

Amphiphilic mesogen‐jacketed liquid crystalline polymers: Design, synthesis, and self‐assembly behaviors

AbstractWe synthesized a series of amphiphilic mesogen‐jacketed liquid crystalline (LC) polymers with a biphenyl side‐chain mesogen containing a carboxylic acid group on one side and an octyloxy group on the other, and the number of methylene units between the biphenyl core and the exterior carboxylic acid group was varied to adjust the mesophases and the amphiphilic nature. The polymers were obtained through conventional radical polymerizations and characterized by a combination of different techniques such as thermogravimetric analysis, differential scanning calorimetry, polarized light microscopy, and X‐ray scattering. The results revealed that the polymer without any methylene spacer, POBP‐0C, did not exhibit LC properties while POBP‐1C (n = 1) and POBP‐7C (n = 7) formed double layer smectic A (SA) phases. The hydrogen bonding among the carboxylic acid groups and the segregation between the carboxylic acid groups and the alky chains played important roles in forming the mesophases. In addition, the solution self‐assembly behaviors were also preliminarily investigated through the fluorescent probe technique and transmission electron microscopy, and vesicles with uniform sizes were observed. The weak hydrophilicity and large degree of freedom of the carboxylic acid group and the relative rigidity of the polymer chain due to the “jacketing” effect were responsible for the formation of the structures. © 2012 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem, 2012