Poly(hydroxyisobutyrate) by ring‐opening polymerizations of 5,5‐dimethyl‐1,3,2‐dioxithiolan‐4‐one‐2‐oxide

α‐Hydroxyisobutyric acid anhydrosulfate HiBAS (5,5‐dimethyl‐1,3,2‐dioxithiolan‐4‐one‐2‐oxide) was polymerized under various reaction conditions and the solid reaction products were characterized by ¹H NMR spectroscopy, MALDI‐TOF mass spectrometry (MT m.s.), fast atom bombardment mass spectrometry (FAB m.s.), viscosity, and SEC measurements. Thermal polymerizations at 100 °C mainly yielded cyclic oligo polyesters presumably resulting from a zwitterionic polymerization. Cycles were also detected when pyridine was used as catalyst at 20 °C. When triethylamine was used as catalyst traces of H₂O played the role of initiators. Benzyl alcohol initiated the polymerization of HiBAS at 100 °C and yielded a polyester terminated by one benzylester and one OH endgroup. The SEC measurements indicated that all samples possess relatively low molar masses with number–average molecular weights ≤ 10,000 Da (in contrast to the literature data). © 2008 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 46: 6229–6237, 2008     

Behavior of 3‐vinylpyridine in nitroxide‐mediated radical polymerization: The influence of nitroxide concentration,solvent, and temperature

The influence of nitroxide concentration, solvent, and temperature on the nitroxide‐mediated radical polymerization of 3‐vinylpyridine (3VP) was examined. Long‐chain poly(3‐vinylpyridine)s with low polydispersities were synthesized. The initial 2,2,6,6‐tetramethylpiperidin‐1‐oxyl concentration had no influence on the kinetics of the polymerization but was responsible for the obtained molar weights. Compared with the polymerization of styrene, the polymerization of 3VP proved quite fast. The influence of temperature on the reaction rate was also demonstrated, and the polymerization could be controlled even at 110 °C. Some polymerizations were also performed in solution to test the influence of a solvent such as ethylene–glycol, whose effect on the polymerization of 3VP was dependent on temperature. © 2000 John Wiley & Sons, Inc. J Polym Sci A: Polym Chem 38: 3067–3073, 2000     

Incubation period in the 2,2,4,4‐tetramethyl‐1‐piperidinyloxy‐mediated thermal autopolymerization of styrene: Kinetics and simulations

Mechanisms and simulations of the induction period and the initial polymerization stages in the nitroxide‐mediated autopolymerization of styrene are discussed. At 120–125 °C and moderate 2,2,4,4‐tetramethyl‐1‐piperidinyloxy (TEMPO) concentrations (0.02–0.08 M), the main source of radicals is the hydrogen abstraction of the Mayo dimer by TEMPO [with the kinetic constant of hydrogen abstraction (k_h)]. At higher TEMPO concentrations ([N?] > 0.1 M), this reaction is still dominant, but radical generation by the direct attack against styrene by TEMPO, with kinetic constant of addition k_ad, also becomes relevant. From previous experimental data and simulations, initial estimates of k_h ≈ 1 and k_ad ≈ 6 × 10^?7 L mol^?1 s^?1 are obtained at 125 °C. From the induction period to the polymerization regime, there is an abrupt change in the dominant mechanism generating radicals because of the sudden decrease in the nitroxide radicals. Under induction‐period conditions, the simulations confirm the validity of the quasi‐steady‐state assumption (QSSA) for the Mayo dimer in this regime; however, after the induction period, the QSSA for the dimer is not valid, and this brings into question the scientific basis of the well‐known expression k_th[M]³ (where [M] is the monomer concentration and k_th is the kinetic constant of autoinitiation) for the autoinitiation rate in styrene polymerization. © 2006 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 44: 6962‐6979, 2006     

Kinetics of the ring‐opening metathesis polymerization of a 7‐oxanorbornene derivative by Grubbs' catalyst

The kinetics of the initiation and propagation of the ring‐opening metathesis polymerization of exo,exo‐5,6‐bis(methoxycarbonyl)‐7‐oxabicyclo[2.2.1]hept‐2‐ene catalyzed by Grubbs' catalyst (Cl₂(PCy₃)₂Ru?CHPh) were measured by ultraviolet–visible and ¹H NMR spectroscopy, respectively. Activation parameters for these processes were also determined. Although the ratio of the rate constant of initiation to the rate constant of propagation was determined to be less than 1 for this system, this polymerization showed many of the characteristics of a living system, including low polydispersities. © 2003 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 41: 2125–2131, 2003     

Kinetics of free‐radical graft polymerization of 1‐vinyl‐2‐pyrrolidone onto silica

The kinetics of aqueous free‐radical graft polymerization of 1‐vinyl‐2‐pyrrolidone onto silica activated with vinyltrimethoxysilane was studied with a mechanistic polymerization model and experimental data for a temperature range of 70–90 °C. The polymerization was initiated with hydrogen peroxide with initial monomer concentrations ranging from 10 to 40 vol %. The kinetic model, which incorporates the hybrid cage–complex initiation mechanism, describes the experimental polymerization data for which the kinetic order, with respect to the monomer concentration, varies from 1 to . Surface chain growth occurs by both monomer addition and homopolymer grafting, although the latter contribution to the total polymer graft yield is less significant. Increasing the initial monomer concentration enhances both surface polymer density and average grafted chain length. Increasing reaction temperature, however, produces a denser surface layer of shorter polymer chains. © 2001 John Wiley & Sons, Inc. J Polym Sci Part A: Polym Chem 40: 26–42, 2002     

Single‐electron transfer‐living radical copolymerization of butyl methacrylate and divinylbenzene for preparation of oil‐absorbing gel

Crosslinking copolymerization of butyl methacrylate with a small amount of divinylbenzene (DVB) was carried out using single‐electron transfer‐living radical polymerization initiated with carbon tetrachloride (CCl₄) and catalyzed by Cu(0)/N‐ligand in N,N‐dimethylformamide to produce a highly oil‐absorbing gel. The polymerization, gelation process, and oil‐absorbing properties were studied in detail. Analysis of monomer conversion with reaction time showed that the polymerization followed first‐order kinetics for both linear and crosslinking polymerization before gelation. Higher levels of DVB led to earlier gelation and the influence of N‐ligand on gelation was also significant. Under optimal conditions, oil absorption of the prepared gel to chloroform could reach 42.1 g·g^?1. © 2013 Wiley Periodicals, Inc. J. Polym. Sci., Part A: Polym. Chem. 2013, 51, 3233–3239     

Kinetics of self‐condensing vinyl hyperbranched polymerization in three‐dimensional space

Self‐condensing vinyl hyperbranched polymerization (SCVP) with A‐B* type monomer is simulated applying Monte Carlo method using 3d bond fluctuation lattice model in three‐dimensional space. The kinetics of SCVP with zero active energy of reaction is studied in detail. It is found that the maximal number–average and weight–average polymerization degrees and the maximal molecular weight distribution, at varying the initial monomer concentration and double bond conversion, are about 52, 190, and 3.93, respectively, which are much lower than theoretical values. The maximal average fraction of branching points is about 0.27, obtained at full conversion at the initial monomer concentration of 0.75. The simulation demonstrated the importance of steric effects and intramolecular cyclization in self‐condensing vinyl hyperbranched polymerization. The results are also compared with experiments qualitatively and a good agreement is achieved. © 2008 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 46: 4486–4494, 2008     

Cationic addition polymerization of 1,4‐dioxene using gacl3 as lewis acid catalyst: Long‐lived species‐mediated polymerization

Effective cationic addition polymerization of 1,4‐dioxene, a six‐membered cyclic olefin with two oxygen atoms adjacent to the double bond, was performed using a simple metal halide catalyst system in dichloromethane. The polymerization was controlled when the reaction was conducted using GaCl₃ in conjunction with an isobutyl vinyl ether–HCl adduct as a cationogen at –78°C to give polymers with predetermined molecular weights and relatively narrow molecular weight distributions. The long‐lived properties of the propagating species were further confirmed by a monomer addition experiment and the analyses of the product polymers by ¹H NMR and MALDI–TOF–MS. Although highly clean propagation proceeded, the apparent rate constant changed during the controlled cationic polymerization of 1,4‐dioxene. The reason for the change was discussed based on polymerization results under various conditions. The obtained poly(1,4‐dioxene) exhibited a very high glass transition temperature (T_g) of 217°C and unique solubility. © 2012 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem, 2012     

Deactivation reactions in the modeled 2,2,6,6‐tetramethyl‐1‐piperidinyloxy‐mediated free‐radical polymerization of styrene: A comparative study with the 2,2,6,6‐tetramethyl‐1‐piperidinyloxy/acrylonitrile system

The competitiveness of the combination and disproportionation reactions between a 1‐phenylpropyl radical, standing for a growing polystyryl macroradical, and a 2,2,6,6‐tetramethyl‐1‐piperidinyloxy (TEMPO) radical in the nitroxide‐mediated free‐radical polymerization of styrene was quantitatively evaluated by the study of the transition geometry and the potential energy profiles for the competing reactions with the use of quantum‐mechanical calculations at the density functional theory (DFT) UB3‐LYP/6‐311+G(3df, 2p)//(unrestricted) Austin Model 1 level of theory. The search for transition geometries resulted in six and two transition structures for the radical combination and disproportionation reactions, respectively. The former transition structures, mainly differing in the out‐of‐plane angle of the N? O bond in the transition structure TEMPO molecule, were correlated with the activation energy, which was determined to be in the range of 8.4–19.4 kcal mol^?1 from a single‐point calculation at the DFT UB3‐LYP/6‐311+G(3df, 2p)//unrestricted Austin Model 1 level. The calculated activation energy for the disproportionation reaction was less favorable by a value of more than 30 kcal mol^?1 in comparison with that for the combination reaction. The approximate barrier difference for the TEMPO addition and disproportionation reaction was slightly smaller for the styrene polymerization system than for the acrylonitrile polymerization system, thus indicating that a β‐proton abstraction through a TEMPO radical from the polymer backbone could diminish control over the radical polymerization of styrene with the nitroxide even more than in the latter system. © 2006 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 45: 232–241, 2007     

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

4′‐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 (k_p²/k_t) in ITP conditions (36.2·10^?2 l·mol^?2·sec^?2 at 80 °C) from the Tobolsky's kinetic law. Polydispersity index (?) 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 ? values' influence onto surface properties of the synthesized polymers. © 2013 Wiley Periodicals, Inc. J. Polym. Sci., Part A: Polym. Chem. 2013, 51, 3202–3212     

Emulsion and controlled miniemulsion polymerization of the renewable monomer γ‐methyl‐α‐methylene‐γ‐butyrolactone

The kinetics of free‐radical emulsion polymerization of γ‐methyl‐α‐methylene‐γ‐butyrolactone (MeMBL), a renewable monomer related to methyl methacrylate, are presented in detail for the first time, and stable polymer latices are prepared. The effects of different reaction parameters on free‐radical emulsion polymerization of MeMBL are presented. Homogeneous nucleation is asserted to be the dominant path for particle formation. Miniemulsion copolymerization of MeMBL and styrene is also reported. In this case, the homogeneous nucleation process appears limited when using an oil soluble initiator. Both the RAFT miniemulsion polymerizations and RAFT bulk polymerizations are well controlled and narrow polydispersity copolymers are produced. Rate retardation is observed in the RAFT miniemulsion polymerizations compared with the free‐radical polymerization and RAFT bulk polymerizations and the possible causes of the retardation are discussed. The reactivity ratios of MeMBL and styrene in RAFT bulk copolymerization are also determined. © 2008 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 46: 5929–5944, 2008     

Stereospecific and molecular weight‐controlled polymerization of 1,3‐butadiene with Co(acac)3‐MAO catalyst

The polymerization of butadiene (Bd) with Co(acac)₃ in combination with methylaluminoxane (MAO) was investigated. The polymerization of Bd with Co(acac)₃‐MAO catalysts proceeded to give cis‐1,4 polymers (94 – 97%) bearing high molecular weights (40 × 10⁴) with relatively narrow molecular weight distributions (M_w's/M_n's). The molecular weight of the polymers increased linearly with the polymer yield, and the line passed through an original point. The polydispersities of the polymers kept almost constant during reaction time. This indicates that the microstructure and molecular weight of the polymers can be controlled in the polymerization of Bd with the Co(acac)₃‐MAO catalyst. The effects of reaction temperature, Bd concentration, and the MAO/Co molar ratio on the cis‐1,4 microstructure and high molecular weight polymer in the polymerization of Bd with Co(acac)₃‐MAO catalyst were observed. © 2001 John Wiley & Sons, Inc. J Polym Sci Part A: Polym Chem 39: 2793–2798, 2001     

Kinetic model of reversible addition‐fragmentation chain transfer polymerization in microemulsions

A simplified kinetic model for RAFT microemulsion polymerization has been developed to facilitate the investigation of the effects of slow fragmentation of the intermediate macro‐RAFT radical, termination reactions, and diffusion rate of the chain transfer agent to the locus of polymerization on the control of the polymerization and the rate of monomer conversion. This simplified model captures the experimentally observed decrease in the rate of polymerization, and the shift of the rate maximum to conversions less than the 39% conversion predicted by the Morgan model for uncontrolled microemulsion polymerizations. The model shows that the short, but finite, lifetime of the intermediate macro‐RAFT radical (1.3 × 10^?4–1.3 × 10^?2 s) causes the observed rate retardation in RAFT microemulsion polymerizations of butyl acrylate with the chain transfer agent methyl‐2‐(O‐ethylxanthyl)propionate. The calculated magnitude of the fragmentation rate constant (k_f = 4.0 × 10¹–4.0 × 10³ s^?1) is greater than the literature values for bulk RAFT polymerizations that only consider slow fragmentation of the macro‐RAFT radical and not termination (k_f = 10^?2 s^?1). This is consistent with the finding that slow fragmentation promotes biradical termination in RAFT microemulsion polymerizations. © 2009 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 48: 604–613, 2010     

H‐transfer reaction during decomposition of N‐(2‐methylpropyl)‐ N‐(1‐diethylphosphono‐2,2‐dimethylpropyl)‐N‐oxyl (SG1)‐based alkoxyamines

Thermal decomposition of four tertiary N‐(2‐methylpropyl)‐N‐(1‐diethylphosphono‐2,2‐dimethylpropyl)‐N‐oxyl (SG1)‐based alkoxyamines (SG1‐C(Me)₂‐C(O)‐OR, R = Me, tBu, Et, H) has been studied at different experimental conditions using ¹H and ³¹P NMR spectroscopies. This experiment represents the initiating step of methyl methacrylate polymerization. It has been shown that H‐transfer reaction occurs during the decomposition of three alkoxyamines in highly degassed solution, whereas no products of H‐transfer are detected during decomposition of SG1‐MAMA alkoxyamine. The value of the rate constant of H‐transfer for alkoxyamines 1 (SG1‐C(Me)₂‐C(O)‐OMe) and 2 ( SG1‐C(Me)₂‐C(O)‐OtBu) has been estimated as 1.7 × 10³ M^?1s^?1. The high influence of oxygen on decomposition mechanism is found. In particular, in poorly degassed solutions, nearly quantitative formation of oxidation product has been observed, whereas at residual pressure of 10^?5 mbar, the main products originate from H‐atom transfer reaction. The acidity of the reaction medium affects the decomposition mechanism suppressing the H‐atom transfer. © 2012 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem, 2013     

Infrared thermography analysis of the thermally latent polymerization of 3‐ethyl‐3‐phenoxymethyloxetane

Infrared thermography was employed to analyze multiple batches of the thermally latent polymerization of 3‐ethyl‐3‐phenoxymethyloxetane at once. The temperature changes in the polymerization depended on the polymerization rates. That is, a fast polymerization was exothermic, increasing the temporal temperature of the polymerization by approximately 130 °C within a few minutes. Infrared thermography, which can analyze multiple samples instantaneously, proved effective as a screening method for thermally latent curing systems. Exothermicity in the crosslinking polymerization of 1,4‐bis(3‐ethyloxetanylmethoxy)benzene was also analyzed by infrared thermography. © 2006 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 44: 5519–5524, 2006     

Role of sodium dodecylbenzenesulfonate in 2,2,6,6‐tetramethy‐1‐piperidinyloxy‐mediated styrene miniemulsion polymerization

In studying 2,2,6,6‐tetramethy‐1‐piperidinyloxy (TEMPO)‐mediated styrene miniemulsions, we have observed that the surfactant sodium dodecylbenzenesulfonate (SDBS) not only provides colloidal stability but also influences the rate of polymerization. Increasing the SDBS concentration results in higher polymerization rates, although the molecular weight distribution and particle size distribution are not significantly impacted. We have also examined another common sulfonate surfactant, DOWFAX 8390. In contrast to SDBS, DOWFAX 8390 does not affect the polymerization rate. Furthermore, DOWFAX‐stabilized polymerizations are slower than SDBS‐stabilized polymerizations. TEMPO‐mediated bulk styrene polymerizations are also accelerated significantly in the presence of SDBS. Although the mechanism for the rate acceleration is unknown, the experimental evidence suggests that SDBS is participating in the generation of radicals capable of propagating, thereby reducing the TEMPO concentration within the particles. © 2006 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 44: 5974–5986, 2006     

Atom transfer radical polymerization of ionic liquid 2‐(1‐butylimidazolium‐3‐yl)ethyl methacrylate tetrafluoroborate

Polymeric forms of ionic liquids may have many potential applications because of their high thermal stability and ionic nature. They are generally synthesized by conventional free‐radical polymerization. Here we report a living/controlled free‐radical polymerization of an ionic liquid monomer, 2‐(1‐butylimidazolium‐3‐yl)ethyl methacrylate tetrafluoroborate (BIMT), via atom transfer radical polymerization. Copper bromide/bromide based initiator systems polymerized BIMT very quickly with little control because of fast activation but slow deactivation. With copper chloride as the catalyst and trichloroacetate, CCl₄, or ethyl α‐chlorophenylacetate as the initiator, BIMT was polymerized at 60 °C in acetonitrile with first‐order kinetics with respect to the monomer concentration. The molecular weight was linearly dependent on the conversion. The monomer concentration strongly affected the polymerization: a low monomer concentration caused the polymerization to be incomplete, probably because of catalyst disproportionation in polar solvents. The addition of a small amount of pyridine suppressed such disproportionation, but a further increase in the amount of pyridine greatly slowed the polymerization. © 2004 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 42: 5794–5801, 2004     

Fluorescent probes for monitoring the pulsed‐laser‐induced photocuring of poly(urethane acrylate)‐based adhesives

Fluorescence spectroscopy was used to study the kinetics of polymerization of acrylic adhesive formulations exposed to a 355‐nm pulsed emission from an Nd‐YAG laser. Nine fluorescent probes were used for monitoring the laser curing, showing different sensitivities. In general, the fluorescence intensity emission increased as crosslinking occurred. In addition, solvatochromic fluorescent probes showed a blueshift in their emission. A relative method was applied for the evaluation of the polymerization rates in three different acrylic systems. Special features of pulsed‐laser‐induced polymerization were treated in detail, such as the influence of the laser pulse frequency and the incident laser beam intensity. The polymerization rate slowed down as the pulse repetition rate decreased. An inhibition period due to oxygen quenching was observed, and it was highly dependent on the laser repetition rate and the nature of the photoinitiator. The effect of the laser beam intensity on the kinetics of such fast reactions was studied. In general, increasing the laser energy improved the rate of polymerization. The degree of cure improved as the polymerization rate increased as a result of faster crosslinking, rather than relaxation volume kinetics. Moreover, a saturation rate effect occurred that depended on the photoinitiator. The different behaviors of the two photoinitiators in the curing of the same acrylic formulation was explained on the basis of primary radical termination. © 2004 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 42: 1227–1238, 2004     

Ring‐opening polymerization of 1,4‐dioxan‐2‐one initiated by lanthanum isopropoxide in bulk

Lanthanum isopropoxide (La(OiPr)₃) has been synthesized and employed for ring‐opening polymerization of 1,4‐dioxan‐2‐one in bulk as a single‐component initiator. The influences of reaction conditions such as initiator concentration, reaction time, and reaction temperature on the polymerization were investigated. The kinetics indicated that the polymerization is first‐order with respect to the monomer concentration. The Mechanistic investigations according to ¹H NMR spectrum analysis demonstrated that the polymerization of PDO proceeded through a coordination‐insertion mechanism with a rupture of the acyl‐oxygen bond of the monomer rather than the alkyl‐oxygen bond cleavage. © 2008 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 46: 5214–5222, 2008