Preparation of ureido group bearing polymers and their upper critical solution temperature in water

Poly(2‐ureidoethylmethacrylate) (PUEM_n) was synthesized via reversible addition‐fragmentation chain transfer (RAFT) radical polymerization and following polymer reaction. We prepared two PUEM_n samples with different degrees of polymerization (n = 100 and 49). The polymers exhibited upper critical solution temperature (UCST) in phosphate‐buffered saline (PBS) solution. The phase separation temperature (T_p) in PBS can be controlled ranging from 17 to 55 °C by changing molecular weight of the polymer, polymer concentration, and adding NaCl concentration. The polymers in PBS formed coacervate drops by liquid–liquid phase separations below T_p. Results of the dielectric relaxation measurement, the hydration number per monomeric unit was 5 above T_p. Based on a fluorescence study, the polymer formed slightly hydrophobic environments below T_p. The liquid–liquid phase separation was occurred presumably because of weak hydrophobic interactions and intermolecularly hydrogen bonding interactions between the pendant ureido groups. © 2016 Wiley Periodicals, Inc. J. Polym. Sci., Part A: Polym. Chem. 2016 , 54, 2845–2854     

Kinetic and ESR studies on radical polymerization of methyl methacrylate in the presence of fullerene

The effect of fullerene (C₆₀) on the radical polymerization of methyl methacrylate (MMA) in benzene was studied kinetically and by means of ESR, where dimethyl 2,2′-azobis(isobutyrate) (MAIB) was used as initiator. The polymerization rate (R_p) and the molecular weight of resulting poly(MMA) decreased with increasing C₆₀ concentration ((0–2.11) × 10⁻⁴ mol/L). The molecular weight of polymer tended to increase with time at higher C₆₀ concentrations. R_p at 50°C in the presence of C₆₀ (7.0 × 10⁻⁵ mol/L) was expressed by R_p = k[MAIB]^0.5[MMA]^1.25. The overall activation energy of polymerization at 7.0 × 10⁻⁵ mol/L of C₆₀ concentration was calculated to be 23.2 kcal/mol. Persistent fullerene radicals were observed by ESR in the polymerization system. The concentration of fullerene radicals was found to increase linearly with time and then be saturated. The rate of fullerene radical formation increased with MAIB concentration. Thermal polymerization of styrene (St) in the presence of resulting poly(MMA) seemed to yield a starlike copolymer carrying poly(MMA) and poly(St) arms. The results (r₁ = 0.53, r₂ = 0.56) of copolymerization of MMA and St with MAIB at 60°C in the presence of C₆₀ (7.15 × 10⁻⁵ mol/L) were similar to those (r₁ = 0.46, r₂ = 0.52) in the absence of C₆₀. © 1998 John Wiley & Sons, Inc. J Polym Sci A: Polym Chem 36: 2905–2912, 1998     

Kinetics of dispersion polymerization: Effect of medium composition

The effect of the medium composition (monomer and solvent) on the kinetics of dispersion polymerization of methyl methacrylate (MMA) was studied via reaction calorimetry. It was found that increasing the monomer concentration increased the reaction rate; the exponent of the dependency of the initial reaction rate on the MMA concentration was found to be 0.93. Narrow particle size distributions were achieved at the lower monomer concentrations (0.24–0.81 mol/L) and a minimum size (2.45 μm) was found at an intermediate concentration (0.44 mol/L). The average molecular weight of the PMMA increased and the molecular weight distribution broadened with increasing monomer concentration. During a dispersion polymerization, the MMA concentration was found to decrease linearly with conversion in both phases, whereas the ratio of concentrations in the particles and continuous phase ([M]_p/[M]_c) remained constant (0.47) with partitioning favoring the continuous phase. The average number of free radicals per particle in MMA dispersion polymerization was estimated to be high from the nucleation stage onward (>5000). The increasing rate during the first ～ 40% conversion was primarily caused by the increasing volume of the polymer particle phase. © 2008 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 46: 3638–3647, 2008     

Living carbocationic polymerization. LXII. Living polymerization of styrene,p-methylstyrene and p-chlorostyrene induced by the common ion effect

The effect of common anion producing salt, tetrabutylammonium chloride (n-Bu₄NCl), on the livingness and kinetics of styrene (St), p-chlorostyrene (pClSt), and p-methylstyrene (pMeSt) polymerization initiated by the 2-chloro-2,4,4-trimethylpentane (TMPCl)/TiCl₄ system has been investigated. Uncontrolled (conventional) carbocationic polymerization of St and p MeSt can be converted to living polymerization by the use of n-Bu₄NCl. Under similar conditions the polymerization of p ClSt is living even in the absence of n-Bu₄NCl, although the molecular weight distribution (MWD) of the polymer becomes narrower in the presence of this salt. The apparent rates of polymerizations decrease in the presence of n-Bu₄NCl in proportion with the concentration of the salt. The rate of living polymerization of p ClSt is noticeably lower than that of St, while that of p MeSt is higher. The apparent rate constants, k_p^A, of these polymerizations have been determined, and the effects of the electron donating p Me- and electron withdrawing p Cl-substituents relative to the rate of St polymerization have been analyzed. [For part LXI, see J. Si and J. P. Kennedy, Polym. Bull., 33 , 651 (1994)]. © 1997 John Wiley & Sons, Inc. J Polym Sci A: Polym Chem 35 : 3341–3347, 1997     

Atom transfer radical polymerization of methyl methacrylate catalyzed by ion exchange resin immobilized Co(II) hybrid catalyst

Ion exchange resin immobilized Co(II) catalyst with a small amount of soluble CuCl₂/Me₆TREN catalyst was successfully applied to atom transfer radical polymerization (ATRP) of methyl methacrylate (MMA) in DMF. Using this catalyst, a high conversion of MMA (>90%) was achieved. And poly(methyl methacrylate) (PMMA) with predicted molecular weight and narrow molecular weight distribution (M_w/M_n = 1.09–1.42) was obtained. The immobilized catalyst can be easily separated from the polymerization system by simple centrifugation after polymerization, resulting in the concentration of transition metal residues in polymer product was as low as 10 ppm. Both main catalytic activity and good controllability over the polymerization were retained by the recycled catalyst without any regeneration process. © 2008 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 46: 1416–1426, 2008     

Photoinitiated,inverse emulsion polymerization of acrylamide: Some mechanistic and kinetic aspects

The kinetics of photoinitiated, inverse emulsion polymerization of acrylamide with 2,2‐dimethoxy‐2‐phenylacetophenone (DMPA) as a photoinitiator was investigated under three different cases. First, in a quartz reactor transparent to full UV light, the polymerization rate (R_p) increased and then decreased with the change of initiator order from 0.27 to a negative value when the DMPA concentration was increased, and it was particularly unusual that monomer orders at different DMPA concentrations were lower than the first. Second, for polymerization without DMPA in a quartz reactor, the dependence of R_p on monomer concentration was similar to that of R_p on initiator concentration in the aforementioned case. Third, when polymerization was carried out in a Pyrex reactor where the far UV light was filtered, a peak rate was also observed, and initiator orders varied from 0.24 to a negative value; however, under this case monomer orders at different initiator concentrations were greater than the first. These results indicated that the effect of absorbance often observed in bulk or solution photopolymerization also existed in this system, and the self‐initiation of monomer had some influence on polymerization, and the role of primary radical termination could not be neglected, as evidenced by kinetic analysis. © 2004 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 42: 846–852, 2004     

Synthesis of novel blue‐light‐emitting polypyridine

A new regioregular head‐to‐tail (HT)‐type polypyridine with methoxyethoxyethoxy (MEEO) side chains, HT‐PMEEOPy, was synthesized by means of Kumada‐Tamao coupling polymerization of a Grignard monomer with a Ni catalyst. Although the polymer was precipitated in THF during polymerization, multiangle laser light scattering (MALLS) analysis indicated that the weight‐average molecular weight (M_w) was about 25,000. The HT content in the polymer was 95%. A solution of HT‐PMEEOPy in CHCl₃ was found to emit a strong blue light when the solution was irradiated with UV light; the UV‐vis absorption maximum (λ_max) and photoluminescence maximum (λ_{max em}) were at 392 and 460 nm, respectively. To clarify the effect of regioregularity of PMEEOPy on the photoluminescence, head‐to‐head (HH) PMEEOPy was synthesized by means of Yamamoto coupling polymerization. The photoluminescence of HH‐PMEEOPy (λ_max = 330 nm, λ_{max em} = 414 nm) was weaker than that of HT‐PMEEOPy. © 2012 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem, 2012     

Cationic photopolymerization of liquid fullerene derivative under visible light

We describe the synthesis and cationic photopolymerization of a C₆₀ derivative bearing a 2,4,6‐tris(epoxynonyloxy)phenyl moiety (FB9ox). Rheological analysis of monomer indicates that temperature of 130 °C yields sufficiently low viscosity for polymerization. A thin film of the liquid monomer has been cationically photopolymerized with a photoinitiator system of curcumin and p‐(octyloxyphenyl)phenyliodonium hexafluoroantimonate, which harvests 424 nm light instead of commonly used ultraviolet light. The degree of polymerization was determined with ATR‐IR. The reaction is the first recorded photopolymerization of a fullerene derivative thin film. The polymer exhibits good mechanical and chemical stabilities. The polymerization can also be achieved by annealing at 150 °C without illumination, but with a smaller degree of polymerization. © 2008 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 46: 5194–5201, 2008     

Kinetics of the microemulsion polymerization of styrene with short‐chain alcohols as the cosurfactant

The kinetics of styrene microemulsion polymerization stabilized by sodium dodecyl sulfate (SDS) and a series of short‐chain alcohols (n‐C_iH_2i+1OH, abbreviated as C_iOH, where i = 4, 5, or 6) at 60 °C was investigated. Sodium persulfate was used as the initiator. The microemulsion polymerization process can be divided into two intervals: the polymerization rate (R_p) first increases to a maximum at about a 20% conversion (interval I) and thereafter continues to decrease toward the end of the polymerization (interval II). For all the SDS/C_iOH‐stabilized polymerization systems, R_p increases when the initiator or monomer concentration increases. The average number of free radicals per particle is smaller than 0.5. The molecular weight of the polymer produced is primarily controlled by the chain‐transfer reaction. In general, the reaction kinetics for the polymerization system with C₄OH as the cosurfactant behaves quite differently from the kinetics of the C₅OH and C₆OH counterparts. This is closely related to the different water solubilities of these short‐chain alcohols and the different concentrations of the cosurfactants used in the preparation of the microemulsion. © 2001 John Wiley & Sons, Inc. J Polym Sci A: Polym Chem 39: 898–912, 2001     

Oxidative coupling polymerization of 2,3‐dihydroxynaphthalene with dinuclear‐type copper(II) catalyst

The oxidative coupling polymerization of 2,3‐dihydroxynaphthalene with the novel dinuclear‐type copper(II) catalysts successfully produced poly(2,3‐dihydroxy‐1,4‐naphthylene). For example, the MeOH‐insoluble polymer with a number average molecular weight of 4.4 × 10³ from the polymerization using the complex of CuCl₂ and N,N′‐bis(2‐morpholinoethyl)‐p‐xylylenediamine ( p ‐ 1 ) at room temperature under an O₂ atmosphere followed by acetylation of the hydroxyl groups was obtained in 63% yield. The structures of the tetraamine ligands and the counter anion of the copper(II) salts significantly influenced the catalyst activity. The polymerization of 2,2′‐dimethoxy‐1,1′‐binaphthalene‐3,3′‐diol with the 2CuCl₂‐ p ‐ 1 catalyst, however, resulted in a lower yield. © 2005 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 43: 1635–1640, 2005     

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 elucidation of comonomer‐induced chemical and physical activation in heterogeneous ziegler‐natta propylene polymerization

We have kinetically elucidated the origins of activity enhancement because of the addition of comonomer in Ziegler‐Natta propylene polymerization, using stopped‐flow and continuously purged polymerization. Stopped‐flow polymerization (with the polymerization time of 0.1–0.2 s) enabled us to neglect contributions of physical phenomena to the activity, such as catalyst fragmentation and reagent diffusion through produced polymer. The propagation rate constant k_p and active‐site concentration [C*] were compared between homopolymerization and copolymerization in the absence of physical effects. k_p for propylene was increased by 30% because of the addition of a small amount of ethylene, whereas [C*] was constant. On the contrary, both k_p (for propylene) and [C*] remained unchanged by the addition of 1‐hexene. Thus, only ethylene could chemically activate propylene polymerization. However, continuously purged polymerization for 30 s resulted in much more significant activation by the addition of comonomer, clearly indicating that the activation phenomenon mainly arises from the physical effects. © 2011 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem, 2011     

Study on the enzymatic polymerization mechanism of lactone and the strategy for improving the degree of polymerization

Polymerization of several lactones were carried out by employing Pseudomonas sp. lipase as the catalyst. The data indicate that water is consumed at the onset of polymerization and released in part during subsequent stages, leading us to propose a complex mechanism for the enzymatic polymerization of lactone. This mechanism involves both ring‐opening and linear condensation polymerization. The former was dominant at the early stage while the latter was dominant in the later stage. In addition, the reaction media showed complex influences on enzymatic polymerization. Some organic solvents increased the degree of polymerization (DP) and decreased the molecular weight distribution. A strategy to increase the molecular weight of the polymer is introduced, which led to the synthesis of a polymer with a number‐average molecular weight (M_n) of 14,500—the highest M_n of poly(ε‐caprolactone) prepared by enzyme‐catalyzed polymerization thus far—and molecular weight distribution of 1.23. © 1999 John Wiley & Sons, Inc. J Polym Sci A: Polym Chem 37: 1265–1275, 1999     

Dual bimodal polyethylene prepared by intercalated silicate with nickel diimine complex

The ethylene polymerization was catalyzed by the intercalated montmorillonite with the nickel complex, [ArN?C(Me)? C(Me)?NAr]NiBr₂ (Ar = 2,6‐C₆H₃ (i‐Pr)₂). Polymer with low melting point and high molecular weight was produced at the early stage of polymerization followed by formation of polymer with high melting point and low molecular weight. It is proposed that the gallery of silicate lowers the propagation rate of polymerization and frequency of “chain walking” process of nickel complex anchored inside the gallery, which produces polymer with low molecular weight and low branching, whereas the nickel complex immobilized on the surface of silicate generates polymer with high molecular weight and high branching. © 2005 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 43: 5506–5511, 2005     

Living cationic polymerization of vinyl ethers in the presence of a strong base: Poisonous or helpful?

A quite small dose of a poisonous species was found to induce living cationic polymerization of isobutyl vinyl ether (IBVE) in toluene at 0 °C. In the presence of a small amount of N,N‐dimethylacetamide, living cationic polymerization of IBVE was achieved using SnCl₄, producing a low polydispersity polymer (weight–average molecular weight/number–average molecular weight (M_w/M_n) ≤ 1.1), whereas the polymerization was terminated at its higher concentration. In addition, amine derivatives (common terminators) as stronger bases allow living polymerization when a catalytic quantity was used. On the other hand, EtAlCl₂ produced polymers with comparatively broad MWDs (M_w/M_n ～ 2), although the polymerization was slightly retarded. The systems with a strong base required much less quantity of bases than weak base systems such as ethers or esters for living polymerization. The strong base system exhibited Lewis acid preference: living polymerization proceeded only with SnCl₄, TiCl₄, or ZnCl₂, whereas a range of Lewis acids are effective for achieving living polymerization in the conventional weak base system such as an ester and an ether. © 2008 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 46: 6746–6753, 2008     

Light‐induced controlled free radical polymerization of methacrylates using iron‐based photocatalyst in visible light

A novel visible light mediated catalytic system based on low cost iron complex, that is, Fe(bpy)₃(PF)₆ photocatalyst that initiates and control the free radical polymerization of methacrylates using ethyl α‐bromoisobutyrate (EBriB) as an initiator and 20 watt LED as light source is developed. The polymerization is initiated with turning the light on and immediately terminated by turning the light off. In addition, the molecular weight of polymer can be varied by changing the ratio of monomer and initiator. The merits of the present methodology lie in the use of low cost less precious, highly abundant iron‐based photocatalyst, avoidance of sacrificial donor and need of lower catalyst amount under visible light. The optimum amount of catalyst and initiator were established and successful polymerization of various methacrylates was achieved under the optimized polymerization conditions. © 2015 Wiley Periodicals, Inc. J. Polym. Sci., Part A: Polym. Chem. 2015 , 53, 2739–2746     

Chain‐growth condensation polymerization of 4‐aminobenzoic acid esters bearing tri(ethylene glycol) side chain with lithium amide base

Chain‐growth condensation polymerization of p‐aminobenzoic acid esters 1 bearing a tri(ethylene glycol) monomethyl ether side chain on the nitrogen atom was investigated by using lithium 1,1,1,3,3,3‐hexamethyldisilazide (LiHMDS) as a base. The methyl ester monomer 1a afforded polymer with low molecular weight and a broad molecular weight distribution, whereas the polymerization of the phenyl ester monomer 1b at ?20 °C yielded polymer with controlled molecular weight (M_n = 2800–13,400) and low polydispersity (M_w/M_n = 1.10–1.15). Block copolymerization of 1b and 4‐(octylamino)benzoic acid methyl ester ( 2 ) was further investigated. We found that block copolymer of poly 1b and poly 2 with defined molecular weight and low polydispersity was obtained when the polymerization of 1b was initiated with equimolar LiHMDS at ?20 °C and continued at ?50 °C, followed by addition of 2 and equimolar LiHMDS at ?10 °C. Spherical aggregates were formed when a solution of poly 1b in THF was dropped on a glass plate and dried at room temperature, although the block copolymer of poly 1b and poly 2 did not afford similar aggregates under the same conditions. © 2010 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 48: 1357–1363, 2010     

Synthesis of ordered polymer by direct polycondensation. VIII. Ordered polymer from two nonsymmetric monomers

The ordered (-aacdbbdc-) polymer was prepared by the direct polycondensation of a pair of symmetric monomers (XabX), 4,4′-(oxydi-p-phenylene)dibutanoic acid (XaaX) and 2-methoxyisophthalic acid (XbbX), with a nonsymmetric monomer (YcdY), 4-aminobenzhydrazide, using the condensing agent diphenyl (2,3-dihydro-2-thioxo-3-benzoxazolyl)phosphonate ( 1 ). The polymerization was carried out by a one-pot procedure, that is, mixing the dicarboxylic acids, condensing agent 1 and triethylamine in NMP for 2 h at room temperature, followed by the addition of 4-aminobenzhydrazide. This polymerization proceeded smoothly, yielding the ordered polymer with an inherent viscosity of 0.34 dL g⁻¹. The microstructure of the ordered polymer was confirmed by comparing the authentic ordered polymer in their ¹³C-NMR spectrum. © 1998 John Wiley & Sons, Inc. J. Polym. Sci. A Polym. Chem. 36: 2309–2314, 1998     

Polymerization initiated by an electron donor–acceptor complex. Part IV. Kinetic study of polymerization of methyl methacrylate initiated by the charge-transfer complex consisting of poly-2-vinylpyridine and liquid sulfur dioxide

A kinetic study has been made of the polymerization of methyl methacrylate (MMA) initiated by a charge-transfer complex of poly-2-vinylpyridine (electron donor) and liquid sulfur dioxide (acceptor) in the presence of carbon tetrachloride. It is concluded that the polymerization proceeds through free-radical intermediates, as with the pyridine-liquid sulfur dioxide complex system. The association constants K of acceptor and polymer electron donors which range widely in their molecular weight were determined spectrophotometrically, and it has been found that both K and overall rate of polymerization R_p of MMA decrease with increasing molecular weight of polymer donor; contrary to this, molecular weight of PMMA formed increases with increasing molecular weight of the polymer donor. Other kinetic behaviors was essentially the same as in the pyridine–liquid sulfur dioxide system, i.e., R_p is proportional to the square root of the concentration of the complex and to the 3/2-order of the monomer concentration; R_p is clearly sensitive to the carbon tetrachloride concentration at low concentration of carbon tetrachloride, but for a higher concentration it is practically independent of the carbon tetrachloride concentration. It has been deduced from a kinetic mechanism for the initiation that a primary radical may be produced from the reduction of carbon tetrachloride by an associated complex consisting of liquid sulfur dioxide–polymer donor and the monomer.     

Radical polymerization of benzyl N-(2,6-dimethylphenyl)itaconamate

The polymerization of benzyl N-(2,6-dimethylphenyl)itaconamate (BDMPI) with benzoyl peroxide (BPO) in N,N-dimethylformamide (DMF) was studied kinetically by ESR. The polymerization rate (R_p) at 70°C was given by R_p = k[BPO]^0.78[BDMPI]^1.1. The overall activation energy of polymerization was determined to be 83.7 kJ/mol. The number-average molecular weight of poly(BDMPI) was in the range of 1500–2000 by gel permeation chromatography. From the ESR study, the polymerization system was found to involve ESR-observable propagating radicals of BDMPI under practical polymerization conditions. Using the polymer radical concentration by ESR, the rate constants of propagation (k_p) and termination (k_t) were determined in the temperature range of 50–70°C. The k_p value seemed dependent on the chain-length of propagating radical. The analysis of polymers by the MALDI-TOF mass spectrometry suggested that most of the resulting polymers contain the dimethylamino terminal group. The copolymerization of BDMPI (M₁) and styrene (M₂) at 50°C in DMF gave the following copolymerization parameters; r₁ = 0.49, r₂ = 0.26, Q₁ = 1.2, and e₁ = +0.63. The thermal behavior of poly(BDMPI) was examined by dynamic thermogravimetry and differential scanning calorimetry. © 1997 John Wiley & Sons, Inc. J Polym Sci A: Polym Chem 35 : 1891–1900, 1997