General matrix formula for the weight-average molecular weights of crosslinked polymer systems

On the basis of the first-order Markovian statistics, we propose a general matrix formula for the weight-average molecular weight of crosslinked polymer systems, explicitly given by M̄_w = M̄_w,0 + WX₀ (I − X)⁻¹ S_f . This equation is valid for both step and chain-growth polymerizations, including those in a nonequilibrium state irrespective of the reactor types used. In the context of the present theory, the onset of gelation is simply stated as a point at which the largest eigenvalue of the matrix X reaches unity (i.e., det( I − X ) = 0). The present theory provides a unified point of view for various types of gelling systems. © 1998 John Wiley & Sons, Inc. J. Polym. Sci. B Polym. Phys. 36: 2423–2433, 1998     

Effect of ion content in ionomer on the ion conductivity of polymer electrolytes based on the P(MMA-co-LiMA)/PEG/LiCF3SO3 blend

We have prepared polymer electrolytes composed of poly(methyl methacrylate-co-lithium methacrylate) ionomer (P(MMA-co-LiMA)), low molecular weight PEG, and LiCF₃SO₃ salt. The ion groups in P(MMA-co-LiMA) could enhance the miscibility between the MMA units and PEG in the polymer electrolytes. This miscibility enhancement made the pathway of ion transport less tortuous, and consequently led to the increase in ion conductivity. The maximum ambient ion conductivities in these systems were measured to be in the range of 10⁻⁴–10⁻⁵ S/cm. The polymer electrolytes became transparent at the higher ion content owing to the enhanced miscibility. The mechanical stability of the polymer electrolytes was also improved through the introduction of ion groups into the PMMA. © 1998 John Wiley & Sons, Inc. J Polym Sci B: Polym Phys 36: 991–997, 1998     

Atactic polymerization of propylene catalyzed by mono(η5-cyclopentadienyl)titanium tribenzyloxide combined with methylaluminoxane

Propylene has been polymerized with mono(η⁵-cyclopentadienyl)titanium tribenzyloxide activated with methylaluminoxane (MAO). It was found that the content of residual trimethylaluminium (TMA) in MAO has a determinative effect on the polymerization. An excess of TMA in the catalyst system reduces the Ti species to inactive lower valent states. The catalyst system gives medium molecular-weight atactic polypropylene (M_v = 2–7 × 10⁴) with narrow molecular weight distribution (M_w/M_n = 1.4–1.8). The polymer has a stereoirregular structure described by Bernoullian statistics. Statistical analysis of the regiotriad distribution of the polypropylene chains indicates a regioblock microstructure. © 1998 John Wiley & Sons, Inc. J Polym Sci A: Polym Chem 36: 2051–2057, 1998     

Epoxidation of bacterial polyesters with unsaturated side chains. II. Rate of epoxidation and polymer properties

Poly(3-hydroxyoctanoate-co-3-hydroxy-10-undecenoate)s (PHOUs) with controlled amounts of unsaturated repeating units were epoxidized to various extents with m-chloroperbenzoic acid (MCPBA) in homogeneous solution. The epoxidation reaction was second order, with an initial rate constant of 1.1 × 10⁻³Lmol^−1.s⁻¹ at 20°C, regardless of the unsaturated unit content in PHOU. No substantial change in either molecular weight or molecular weight distribution occurred as a result of epoxidation, but the melt transition temperature and enthalpy of melting both decreased as the unsaturated groups were increasingly converted into epoxide groups. In contrast, the glass transition temperature (T_g) increased by approximately 0.25°C for each 1 mol % of epoxidation, irrespective of the composition of the PHOU. © 1998 John Wiley & Sons, Inc. J. Polym. Sci. A Polym. Chem. 36: 2381–2387, 1998     

Study of the composition and morphology of new modifications of titanium‐magnesium catalysts with improved properties in ethylene polymerization

Data on new modifications of supported titanium‐magnesium catalysts (TMCs) with improved performance in ethylene polymerization are reported. These catalysts possess a high and stable activity, an enhanced ability to regulate molecular weight of the polymer by hydrogen, a controllable particle size at a narrow particle size distribution, and the ability to produce the polymer with an increased bulk density. Various physicochemical methods were used to obtain data on the chemical composition of novel supports and catalysts, their phase composition and crystal structure as well as the pore structure. The results obtained were used to discuss possible correlations between composition and structure of TMCs and their catalytic properties. © 2016 Wiley Periodicals, Inc. J. Polym. Sci., Part A: Polym. Chem. 2016 , 54, 2545–2558     

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     

Photoinduced controlled/living free‐radical polymerization of 4‐methacryloyl‐1,2,2,6,6‐pentamethyl‐piperidenyl

The photoinduced solution polymerization of 4‐methacryloyl‐1,2,2,6,6‐pentamethyl‐piperidinyl (MPMP), used as a reactive hindered amine piperidinol derivative, was performed. The obtained MPMP homopolymer had a very narrow molecular weight distribution (1.06–1.39) according to gel permeation chromatography. The number‐average and weight‐average molecular weights increased linearly with the monomer conversion, this being characteristic of controlled/living free‐radical polymerizations. Electron spin resonance signals were detected in the MPMP homopolymer and in a polymer mixture solution, and they were assigned to nitroxide radicals, which were bound to the polymer chains and persisted at a level of 10^?9 mol/L during the polymerization. Instead of the addition of mediated nitroxide radicals such as 2,2,6,6‐tetramethyl‐piperidinyl‐1‐oxy (TEMPO), those radicals (>N? O ·) were formed in situ during the photopolymerization of MPMP, and so the reaction mechanism was understood as being similar to that of TEMPO‐mediated controlled/living free‐radical polymerization. © 2004 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 42: 2659–2665, 2004     

Preparation and thermal behavior of poly-p-phenylene diacrylic acid dimethyl ester

The photopolymerization behavior of p-phenylene diacrylic acid dimethyl ester (p-PDA Me) crystal and the thermal behavior of the resultant poly-p-PDA Me were investigated. From the kinetic study of polymerization at various temperatures a topochemical process via a stepwise mechanism was observed. Continuous change from monomer to polymer crystals was demonstrated by x-ray diffraction pattern and DSC analysis. Crystallinity of the reacting phase was maintained at an extremely high degree during the polymerization process in support of monomer crystal lattice control. Thermal study on as-polymerized poly-p-PDA Me crystal confirmed that the thermal reaction was a polymer crystal lattice-controlled depolymerization, which was followed by miscellaneous processes that involved vaporization, sublimation, and deterioration of the oligomeric or monomeric units of p-PDA Me. Thermal stability was dependent on the molecular weight. All the results are compared with those of four-center-type photopolymerization in the crystalline state.     

Polymer grafting onto carbon black by use of TEMPO-terminated polystyrene with controlled molecular weight

The grafting of polystyrene with controlled molecular weight and narrow molecular weight distribution onto the carbon black surface through the trapping of polymer radicals formed by the thermal dissociation of 2,2,6,6-tetramethyl-1-piperidinyloxy (TEMPO)-terminated polystyrene (PSt-TEMPO) by the carbon black surface was investigated. PSt-TEMPO was prepared by living radical polymerization of St with the benzoyl peroxide/TEMPO system. When PSt having no terminal TEMPO moiety was heated with carbon black, no grafting of PSt onto the surface was observed. On the contrary, by the heating of PSt-TEMPO with carbon black in m-xylene at 125°C, PSt with controlled molecular weight and narrow molecular weight distribution was grafted onto the surface: the percentage grafting of PSt (M_n = 3.2 × 10³;M_w/M_n = 1.07) onto furnace black was determined to be 16.0%. On the basis of the above results, it is concluded that PSt radicals formed by the thermal dissociation of the C ON bond between PSt and TEMPO are trapped by polycondensed aromatic rings of carbon black. The mole number of grafted PSt chains on the carbon black surface decreased with increasing molecular weight of PSt-TEMPO. PSt-grafted carbon black gave a stable colloidal dispersion in THF. © 1998 John Wiley & Sons, Inc. J Polym Sci A: Polym Chem 36: 3165–3172, 1998     

Effect of molecular weight of macro‐iniferter on electro‐optical properties of polymer dispersed liquid crystal films prepared by iniferter polymerization

Polymer dispersed liquid crystal (PDLC) films were prepared by a devised method, in which photo‐polymerization induced phase separation in a mixtures of a macro‐iniferter, methyl acrylater, and liquid crystal. The morphology of the obtained PDLC films was examined on a polarized optical microscopy, and the effect of molecular weight of MIs on the electro‐optical properties was deliberately investigated. Decreasing the molecular weight of MIs in the films led to formation of larger liquid crystal droplets and a lower V_th values. V_sat increased and the memory effect decreased because of the increased interface anchoring strength induced by the higher molecular weight of polymer matrices. © 2009 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 47: 1530–1534, 2009     

Induction of Helical Structure by Sesamin,and Production of Oriented Helical Polymer with Liquid Crystal Magneto‐Electrochemical Polymerization

Sesamin was employed as a chiral dopant for preparing cholesteric liquid crystals with right‐handed helical architecture. Helical twisting power of sesamin is to be 13.4 μm^?1. Electrochemical polymerizations were carried out with sesamin‐induced cholesteric liquid crystal electrolyte solution for obtaining conjugated polymer films with helical structure. The film was transcribed the helical order from the liquid crystal electrolyte solution with helical structure produced by sesamin during the polymerization process. The helical axes of the macromolecular superstructure of the polymer films were oriented in a magnetic field of 4.5 T. This results demonstrated liquid crystal magneto‐electrochemical polymerization with helical structure induced by sesamin as a natural chiral compound. © 2017 Wiley Periodicals, Inc. J. Polym. Sci., Part A: Polym. Chem. 2017 , 55 , 1894–1899     

Emulsion polymerization of vinyl acetate using iodine‐transfer and RAFT radical polymerizations

This study deals with control of the molecular weight and molecular weight distribution of poly(vinyl acetate) by iodine‐transfer radical polymerization and reversible addition‐fragmentation transfer (RAFT) emulsion polymerizations as the first example. Emulsion polymerization using ethyl iodoacetate as the chain transfer agent more closely approximated the theoretical molecular weights than did the free radical polymerization. Although ¹H NMR spectra indicated that the peaks of α‐ and ω‐terminal groups were observed, the molecular weight distributions show a relatively broad range (M_w/M_n = 2.2–4.0). On the other hand, RAFT polymerizations revealed that the dithiocarbamate 7 is an excellent candidate to control the polymer molecular weight (M_n = 9.1 × 10³, M_w/M_n = 1.48), more so than xanthate 1 (M_n = 10.0 × 10³, M_w/M_n = 1.89) under same condition, with accompanied stable emulsions produced. In the M_n versus conversion plot, M_n increased linearly as a function of conversion. We also performed seed‐emulsion polymerization using poly(nonamethylene L ‐tartrate) as the chiral polyester seed to fabricate emulsions with core‐shell structures. The control of polymer molecular weight and emulsion stability, as well as stereoregularity, is also discussed. © 2012 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem, 2013     

Synthesis and characterization of random hydrophilic/hydrophobic copolymers of styrene and D-lactose-O-vinylbenzylhydroxime

D -Lactose-O-(vinylbenzyl)oxime (LVO), prepared from α-D -lactose and [O-(vinylbenzyl)oxy]amine ( 1 ) was copolymerized with styrene (ST) in dimethylsulfoxide (DMSO)-toluene (1 : 1, v/v) at 65°C using 2,2′-azobisisobutyronitrile (AIBN) as a free radical initiator. The polymerization was rapid when using AIBN as the initiator. The resultant copolymers were characterized by elemental analyses, infrared, viscometry, TGA, DSC, and ¹H-NMR spectroscopy. The poly(ST-co-LVO) had an intrinsic viscosity in the range of 0.11–0.51 dL/g in DMSO at 30°C. The molecular weight was determined by gel permeation chromatography (GPC), and the molecular weight of the resulting polymers ranged from 2.11 × 10⁴ to 6.53 × 10⁷ with low polydispersities. The solubility of the copolymers with different monomer compositions in solvents of varied polarities was also studied. Incorporation of up to 65% (mol %) of lactose-based monomer onto polystyrene backbone led to a water-soluble polymer. Thermal behavior of the synthesized copolymers was evaluated by thermogravimetric analysis (TGA) and correlated very well with the polymer composition. Introduction of a pendant disaccharide compromised the thermal stability of the copolymer. The synthetic approach described in this report provides a route to prepare a novel disaccharide surfactant polymer with well-defined structures and hydrophilic/hydrophobic balances, by adjusting feed ratio of the lactose-based monomer ( 1 ) to styrene. © 1998 John Wiley & Sons, Inc. J Polym Sci A: Polym Chem 36: 2971–2978, 1998     

Stereoselective synthesis and polymerization of Exo‐5‐trimethylsilylnorbornene

Herein the stereoselective two‐step synthesis of pure exo‐5‐trimethylsilylnorbornene is reported. The monomer proved to be highly reactive in both metathesis and addition polymerization. ROMP polymerization was catalyzed by the first‐generation Grubbs catalyst. High‐molecular‐weight saturated addition polymers were prepared using nickel or palladium complexes as precatalysts and Na⁺[B(3,5‐(CF₃)₂C₆H₃)₄]⁻ and/or MAO as cocatalysts. The obtained addition polynorbornenes are highly gas permeable and microporous materials possessing large free volume and BET surface area (up to 540 m²/g). The influence of the substituent orientation (exo‐ vs. exo‐/endo‐mixture) on polymer properties was established. The metathesis polymer based on exo‐isomer exhibits 1.5‐ to 2‐fold increase of permeability coefficients for all gases in comparison to the similar polymer based on the mixture of exo‐ and endo‐isomers. © 2018 Wiley Periodicals, Inc. J. Polym. Sci., Part A: Polym. Chem. 2018 , 56, 1234–1248     

Stereoselective polymerization of rac‐lactide with a bulky aluminum/Schiff base complex

An aluminum/Schiff base complex {[2,2-dimethyl-1,3-propylenebis(3,5-di-tert-butylsalicylideneiminato)](isopropanolato)aluminum(III) ( 2 )} based on a bulky ligand and aluminum isopropoxide was prepared and employed for the stereoselective ring-opening polymerization (ROP) of rac-lactide (rac-LA). The initiator was characterized with nuclear magnetic resonance (NMR), crystal structure measurements, and elemental analysis. It contained a five-coordinate aluminum atom that was trigonal bipyramidal in the solid state according to the crystal structure measurements. The two conformational stereoisomers of 2 exchanged quickly on the NMR scale. Compound 2 polymerized rac-LA into a crystalline polymer that was characterized with ¹H NMR, wide-angle X-ray diffraction, electrospray ionization mass spectrometry, and gel permeation chromatography. The kinetics of the polymerization were first-order in both the monomer and initiator, and there was a linear relationship between the rac-LA conversion and the number-average molecular weight of poly(rac-LA) with a narrow molecular distribution (1.04–1.08). These features showed that the polymerization was well controlled. The high melting temperature (196–201 °C) and isotacticity of poly(rac-LA) indicated that complex 2 was a highly stereoselective initiator for the ROP of rac-LA. The stereoselectivity was as high as 90%, and the stereoblocks of poly(rac-LA) by complex 2 contained an average of 20 units (average block length = 20) of enantiomerically pure lactic acid. The activation energy (23.6 kJ mol⁻¹) was obtained according to an Arrhenius equation. © 2004 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 42: 5974–5982, 2004     

Kinetics of the photoinitiated inverse microemulsion polymerization of 2-methacryloyl oxyethyl trimethyl ammonium chloride

The polymerization of inverse microemulsions of 2-methacryloyl oxyethyl trimethyl ammonium chloride stabilized by a blend of nonionic emulsifiers (a sorbitan sesquioleate and a sorbitan monooleate) and initiated by UV light in the presence of Azobis(isobutyronitrile) (AIBN) was investigated. The effect of initiator concentration, light intensity, emulsifier concentration, and dispersed phase weight fraction on the polymerization rate (R_p), number of polymer particles (N_p), and polymer molecular weight (M_w) was studied. The application of this process to tubular reactors is discussed. © 1998 John Wiley & Sons, Inc. J Polym Sci A: Polym Chem 36: 737–748, 1998     

Synthesis of polymers by template polymerization. I. Template polymerization of poly(methacrylic acid) with β‐cyclodextrin

A novel template monomer with multiple methacryloyl groups was synthesized with β‐cyclodextrin by the acetylation of primary hydroxyl groups and the esterification of secondary hydroxyl groups with methacrylic acid anhydride. The average number of methacryloyl groups in the monomer was 11. The radical polymerization of the monomer was carried out with the following initiators: α,α′‐azobisisobutylonitrile, H₂O₂? Fe²⁺ redox initiator, p‐xylyl‐N,N‐dimethyldithiocarbamate (XDC), and α‐bromo‐p‐xylyl‐N,N‐dimethyldithiocarbamate (BXDC). When the concentration of the monomer was less than 4.12 × 10^?3 M, polymerization was limited inside the molecule, and gelation of the system was hindered. For controlled radical photopolymerization with XDC and BXDC, the methacryloyl groups of the monomer were homogeneously polymerized, and poly(methacrylic acid) with a narrow molecular weight distribution was obtained by the hydrolysis of the polymerized products. © 2001 John Wiley & Sons, Inc. J Polym Sci Part A: Polym Chem 39: 3539–3546, 2001     

Solution characterization of the novel organometallic polymer poly(ferrocenyldimethylsilane)

A series of four well‐defined poly(ferrocenyldimethylsilane) (PFS) samples spanning a molecular weight range of approximately 10,000–100,000 g mol⁻¹ was synthesized by the living anionic polymerization of dimethyl[1]silaferrocenophane initiated with n‐BuLi. The polymers possessed narrow polydispersities and were used to characterize the solution behavior of PFS in tetrahydrofuran (THF). The weight‐average molecular weights (M_w ) of the polymers were determined by low‐angle laser light scattering (LALLS), conventional gel permeation chromatography (GPC), and GPC equipped with a triple detector (refractive index, light scattering, and viscosity). The molecular weight calculated by conventional GPC, with polystyrene standards, underestimated the true value in comparison with LALLS and GPC with the triple detection system. The Mark–Houwink parameter a for PFS in THF was 0.62 (k = 2.5 × 10⁻⁴), which is indicative of fairly marginal polymer–solvent interactions. The scaling exponent between the radius of gyration and M_w was 0.54, also consistent with marginal polymer–solvent interactions for PFS in THF. © 2000 John Wiley & Sons, Inc. J Polym Sci B: Polym Phys 38: 3032–3041, 2000     

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     

Facile one‐pot/one‐step technique for preparation of side‐chain functionalized polymers: Combination of SET‐RAFT polymerization of azide vinyl monomer and click chemistry

An azido‐containing functional monomer, 11‐azido‐undecanoyl methacrylate, was successfully polymerized via ambient temperature single electron transfer initiation and propagation through the reversible addition–fragmentation chain transfer (SET‐RAFT) method. The polymerization behavior possessed the characteristics of “living”/controlled radical polymerization. The kinetic plot was first order, and the molecular weight of the polymer increased linearly with the monomer conversion while keeping the relatively narrow molecular weight distribution (M_w/M_n ≤ 1.22). The complete retention of azido group of the resulting polymer was confirmed by ¹H NMR and FTIR analysis. Retention of chain functionality was confirmed by chain extension with methyl methacrylate to yield a diblock copolymer. Furthermore, the side‐chain functionalized polymer could be prepared by one‐pot/one‐step technique, which is combination of SET‐RAFT and “click chemistry” methods. © 2011 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem, 2012