Microwave‐assisted rapid polycondensation reaction of 4‐(4′‐acetamidophenyl)‐1,2,4‐triazolidine‐3,5‐dione with diisocyanates

4‐(4′‐Aminophenyl)‐1,2,4‐triazolidine‐3,5‐dione was reacted with 1 mol of acetyl chloride in dry N,N‐dimethylacetamide (DMAc) at ?15°C and 4‐(4′‐acetamidophenyl)‐1,2,4‐triazolidine‐3,5‐dione [4‐(4′‐acetanilido)‐1,2,4‐triazolidine‐3,5‐dione] (APTD) was obtained in high yield. The reaction of the APTD monomer with excess n‐isopropylisocyanate was performed at room temperature in DMAc solution. The resulting bis‐urea derivative was obtained in high yield and was finally used as a model for the polymerization reaction. The step‐growth polymerization reactions of monomer APTD with hexamethylene diisocyanate, isophorone diisocyanate, and tolylene‐2,4‐diisocyanate were performed under microwave irradiation and solution polymerization in the presence of pyridine, triethylamine, or dibutyltin dilaurate as a catalyst. Polycondensation proceeded rapidly, compared with conventional solution polycondensation; it was almost completed within 8 min. The resulting novel polyureas had an inherent viscosity in the range of 0.07–0.17 dL/g in dimethylformamide or sulfuric acid at 25°C. These polyureas were characterized by IR, ¹H‐NMR, elemental analysis, and thermogravimetric analysis. The physical properties and structural characterization of these novel polyureas are reported. © 2003 Wiley Periodicals, Inc. J Appl Polym Sci 91: 2103–2113, 2004     

Investigation of kinetics of 4‐methylpentene‐1 polymerization using Ziegler–Natta‐type catalysts

The kinetics of 4‐methylpentene‐1 (4MP1) polymerization by use of Ziegler–Natta‐type catalyst systems, M(acac)₃‐AlEt₃ (M = Cr, Mn, Fe, and Co), are investigated in benzene medium at 40°C. The effect of various parameters such as Al/M ratio, reaction time, aging time, temperature, catalyst, and monomer concentrations on the rate of polymerization and yield are examined. The rate of polymerization increased linearly with increasing monomer concentration with first‐order dependence, whereas the rate of polymerization with respect to catalyst concentration is found to be 0.5. For all cases, the polymer yield is maximum at an Al/M ratio of 2. The activation energies obtained from linear Arrhenius plots are in the range of 25.27–33.51 kJ mol^?1. It is found that the aging time to give maximum percentage yield of the polymer varies with the catalyst systems. Based on the experimental results, a plausible mechanism is proposed that envisages a free‐radical mechanism. Characterization of the resulting polymer product, for all the cases, through FTIR, ¹H‐NMR, and ¹³C‐NMR studies, showed isomerized polymeric structures with 1,4‐structure as dominant. © 2003 Wiley Periodicals, Inc. J Appl Polym Sci 88: 2468–2477, 2003     

Synthesis of novel azo‐containing polyureas derived from 4‐[4′‐(2‐hydroxy‐1‐naphthylazo)phenyl]‐1,2,4‐triazolidine‐3,5‐dione

4‐[4′‐(2‐Hydroxy‐1‐naphthylazo)phenyl]‐1,2,4‐triazolidine‐3,5‐dione ( HNAPTD ) ( 1 ) has been reacted with excess amount of n‐propylisocyanate in DMF (N,N‐dimethylformamide) solution at room temperature. The reaction proceeded with high yield, and involved reaction of both N? H of the urazole group. The resulting bis‐urea derivative 2 was characterized by IR, ¹H‐NMR, elemental analysis, UV‐Vis spectra, and it was finally used as a model compound for the polymerization reaction. Solution polycondensation reactions of monomer 1 with Hexamethylene diisocyanate ( HMDI ) and isophorone diisocyanate ( IPDI ) were performed in DMF in the presence of pyridine as a catalyst and lead to the formation of novel aliphatic azo‐containing polyurea dyes, which are soluble in polar solvents. The polymerization reaction with tolylene‐2,4‐diisocyanate ( TDI ) gave novel aromatic polyurea dye, which is insoluble in most organic solvents. These novel polyureas have inherent viscosities in a range of 0.15–0.22 g dL^?1 in DMF at 25°C. Some structural characterization and physical properties of these novel polymers are reported. © 2001 John Wiley & Sons, Inc. J Appl Polym Sci 82: 3177–3183, 2001     

Kinetics of microwave‐assisted polymerization of ϵ‐caprolactone

The kinetics of polymerization of ?‐caprolactone (CL) in bulk was studied by irradiating with microwave of 350 W and frequency of 2.45 GHz with different cycle‐heating periods (30–50 s). The molecular weight distributions were determined as a function of reaction time by gel permeation chromatography. Because the temperature of the system continuously varied with reaction time, a model based on continuous distribution kinetics with time/temperature‐dependent rate coefficients was proposed. To quantify the effect of microwave on polymerization, experiments were conducted under thermal heating. The polymerization was also investigated with thermal and microwave heating in the presence of zinc catalyst. The activation energies determined from temperature‐dependent rate coefficients for pure thermal heating, thermally aided catalytic polymerization, and microwave‐aided catalytic polymerization were 24.3, 13.4, and 5.7 kcal/mol, respectively. This indicates that microwaves increase the polymerization rate by lowering the activation energy. © 2003 Wiley Periodicals, Inc. J Appl Polym Sci 91: 1450–1456, 2004     

Step‐growth polymerization of 5‐[(9,10‐dihydro‐9,10‐ethanoanthracene‐11,12‐dicarboximido)‐3‐methylbutanoyl‐amino]isophthalic acid with aromatic diols

cis‐9,10‐dihydro‐9,10‐ethanoanthracene‐11,12‐dicarboxylic acid anhydride ( 1 ) was converted to imide acid ( 2 ) by reaction with S‐valine. Compound 2 was converted to the acid chloride ( 3 ) by reaction with thionyl chloride and then treated with 5‐aminoisophthalic acid in dry N,N‐dimethylacetamide to obtain 5‐[(9,10‐dihydro‐9,10‐ethanoanthracene‐11,12‐dicarboximido)‐3‐methylbutanoylamino]isophthalic acid ( 4 ). Direct step‐growth polymerization of this novel chiral diacid monomer 4 with a series of different diols in a system of tosyl chloride, pyridine, and N,N‐dimethylformamide was carried out. The optically active polyesters (PEs) were obtained with good yield and moderate inherent viscosity ranging from 0.23 to 0.48 dL/g. The resulting polymers were characterized with FTIR, ¹H‐NMR, and elemental analysis techniques. The prepared PEs showed good thermal stability up to 320°C as measured by thermogravimetric analysis. Specific rotation experiments demonstrated the induction of optical activity due to successful insertion of S‐valine in the structure of pendant groups. © 2010 Wiley Periodicals, Inc. J Appl Polym Sci, 2010     

Effects of solvent basicity on free radical polymerizations of N,N′‐bismaleimide‐4,4′‐diphenylmethane initiated by barbituric acid

The polymerizations of N,N′‐bismaleimide‐4,4′‐diphenylmethane (BMI) initiated by barbituric acid (BTA) carried out in a variety of solvents at 130°C were studied. The nitrogen‐containing cyclic solvents such as N‐methyl‐2‐pyrrolidinone acted as a catalyst to promote the formation of the three‐dimensional crosslinked network structure. By contrast, the polymerization in a cyclic solvent that did not contain nitrogen such as γ‐butyrolactone resulted in nil gel content. The higher the solvent basicity, the larger the amount of insoluble polymer species formed. The molar ratio of BTA to BMI also played an important role in the polymerizations. The resultant polymers, presumably having a hyper‐branched structure, exhibited much narrower molecular weight distributions than those prepared by conventional free radical polymerizations. The BMI polymerizations using BTA as the initiator could not be adequately described by conventional free radical polymerization mechanisms. A polymerization mechanism that took into account the generation of a ketone radical pair between BTA and BMI and the subsequent initiation, propagation and termination reactions was proposed. It was concluded that the nitrogen‐containing cyclic solvents were capable of participating in the ketone radical pair formation process, thereby increasing the extent of polymer crosslinking reactions. © 2010 Wiley Periodicals, Inc. J Appl Polym Sci, 2010     

Polymerization of acrylonitrile catalyzed by single yttrium tris(2,6‐di‐tert‐butyl‐4‐methyl phenolate)

Polymerization of acrylonitrile was carried out using yttrium tris(2,6‐di‐tert‐butyl 4‐methyl‐phenolate) (Y(OAr)₃) as single component catalyst for the first time. The effects of concentrations of the monomer and catalyst, kinds of rare earth element and solvent, as well as temperature and polymerization time were investigated. The overall activation energy of polymerization in n‐hexane and THF mixture is 18.3 kJ mol^?1. Polyacrylonitriles (PANs) obtained by using Y(OAr)₃ in n‐hexane and THF mixture at 50 °C are predominantly atactic, while yellow PANs obtained in DMF under the same conditions have a syndiotactic‐rich configuration (>50%), and their highly branched and/or cyclized structures have also been found. © 2002 Society of Chemical Industry     

Optimization of the coordination–insertion ring‐opening polymerization of poly(p‐dioxanone) by programmed decreasing reaction temperatures

The optimization of the synthesis of poly(p‐dioxanone), by ring‐opening polymerization with tin II bis(2‐ethylhexanoic acid) as the catalyst, was conducted by a new method in which programmed decreasing reaction temperatures were employed. The results were compared with those obtained for polymerization reactions performed at constant temperatures in the 80–180°C range. In the novel method, the temperature was gradually reduced, as the reaction proceeded, to maintain a maximum polymerization rate and monomer conversion as the monomer was consumed. The experiments performed at constant temperatures confirmed previous reports that the bulk polymerization of 1,4‐dioxan‐2‐one is an equilibrium polymerization reaction. With increasing polymerization temperature, the initial rate of polymerization increased, but the monomer conversion, reaching equilibrium, decreased. High conversions were obtained at low temperatures and long reaction times. Therefore, reducing the reaction temperature, to ensure working conditions that guaranteed the maximum polymerization rate and monomer conversion, could optimize the polymerization process. These conditions were calculated under the assumption of equilibrium polymerization reaction kinetics. With our proposed method, a 71% conversion was achieved in half the time needed when the polymerization was performed at a constant temperature of 120°C. Similarly, a 78% conversion was obtained with our proposed method in only a third of the time employed when the reaction was carried out at a constant temperature of 80°C. Our method guarantees high conversions in shorter times and a gradual reduction of the polymerization temperature. © 2005 Wiley Periodicals, Inc. J Appl Polym Sci 97: 659–665, 2005     

Non‐catalyst synthesis and in vitro drug release property of poly(5,5‐dimethyl‐1,3‐dioxan‐2‐one)‐block‐methoxy poly(ethylene glycol) copolymers

A series of poly(5,5‐dimethyl‐1,3‐dioxan‐2‐one)‐block‐methoxy poly(ethylene glycol) (PDTC‐b‐mPEG) copolymers were synthesized by the ring‐opening polymerization of 5,5‐dimethyl‐1,3‐dioxan‐2‐one (DTC) in bulk, using methoxy poly(ethylene glycol) (mPEG) as initiator without adding any catalysts. The resulting copolymers were characterized by Fourier transform infrared spectra, ¹H NMR and gel permeation chromatography. The influences of some factors such as the DTC/mPEG molar feed ratio, reaction time and reaction temperature on the copolymerization were investigated. The experimental results showed that mPEG could effectively initiate the ring‐opening polymerization of DTC in the absence of catalyst, and that the copolymerization conditions had a significant effect on the molecular weight of PDTC‐b‐mPEG copolymer. In vitro drug release study demonstrated that the amount of indomethacin released from PDTC‐b‐mPEG copolymer decreased with increase in the DTC content in the copolymer. © 2013 Society of Chemical Industry     

Preparation of ultra‐high‐molecular‐weight polyethylene and its morphological study with a heterogeneous Ziegler–Natta catalyst

Ultra‐high‐molecular‐weight polyethylene (PE) with viscosity‐average molecular weight (M_v) of 3.1 × 10⁶ to 5.2 × 10⁶ was prepared with a heterogeneous Ziegler–Natta MgCl₂ (ethoxide type)/TiCl₄/triethylaluminum catalyst system under controlled conditions. The optimum activity of the catalyst was obtained at a [Al]/[Ti] molar ratio of 61 : 1 and a polymerization temperature of 60°C, whereas the activity of the catalyst increased with monomer pressure and decreased with hydrogen concentration. The titanium content of the catalyst was 2.4 wt %. The rate/time profile of the catalyst was a decay type with a short acceleration period. M_v of the PE obtained decreased with increasing hydrogen concentration and polymerization temperature. The effect of stirrer speeds from 100 to 400 rpm did not so much affect the catalyst activity; however, dramatic effects were observed on the morphology of the polymer particles obtained. A stirrer speed of 200 rpm produced PE with a uniform globulelike morphological growth on the polymer particles. The particle size distributions of the polymer samples were determined and were between 14 and 67 μm. © 2010 Wiley Periodicals, Inc. J Appl Polym Sci, 2010     

Synthesis and characterization of new polyureas derived from 4‐(4′‐Methoxyphenyl)urazole

4‐(4′‐Methoxyphenyl)urazole (MPU) was prepared from 4‐methoxybenzoic acid in five steps. The reaction of monomer MPU with n‐isopropylisocyanate was performed at room temperature in N,N‐dimethylformamide solution, and the resulting bis‐urea derivative was obtained in high yield and was finally used as a model for polymerization reaction. The step‐growth polymerization reactions of monomer MPU with hexamethylene diioscyanate, isophorone diioscyanate, and toluene‐2,4‐diioscyanate were performed in N,N‐dimethylacetamide solution in the presence of pyridine as a catalyst. The resulting novel polyureas have an inherent viscosity (η_inh) in a range of 0.07–0.21 dL/g in DMF and sulfuric acid at 25°C. These polyureas were characterized by IR, ¹H‐NMR, elemental analysis, and TGA. Some physical properties and structural characterization of these novel polyureas are reported. © 2002 Wiley Periodicals, Inc. J Appl Polym Sci 85: 1141–1146, 2002     

Synthesis of poly (γ‐benzyl‐L‐glutamate) with well‐defined terminal structures and its block polypeptides with alanine,leucine and phenylalanine

The ring‐opening polymerization of γ‐benzyl‐L ‐glutamate N‐carboxyanhydride (BLG‐NCA) was initiated by n‐hexylamine in N,N‐dimethyformamide under normal pressure at 0 °C. The products were characterizated by gel permeation chromatography, matrix‐assisted laser desorption/ionization time of flight mass spectroscopy (MALDI‐TOF MS), nuclear magnetic resonance etc. MALDI‐TOF MS gave direct evidence that the side reactions during the polymerization of BLG‐NCA could be greatly reduced by decreasing the reaction temperature, e.g. from room temperature to 0 °C. As a result, over 90% of the products were amino‐terminated poly(γ‐benzyl‐L ‐glutamate) (PBLG) with low polydispersity index when the polymerization was carried out at 0 °C, which could be used to re‐initiate the polymerization of other NCAs. Then several well‐defined PBLG‐containing block copolypeptides were successfully synthesized in a convenient way. Copyright © 2012 Society of Chemical Industry     

A new post‐metallocene catalyst for alkene polymerization: copolymerization of ethylene and 1‐hexene with titanium complexes bearing N,N‐dialkylcarbamato ligands

A new type of post‐metallocene polymerization catalyst based on titanium complexes with N,N‐dialkylcarbamato ligands was used to copolymerize ethylene and 1‐hexene. These easy‐to‐synthesize and stable complexes in combination with different organoaluminium co‐catalysts produce random ethylene/1‐hexene copolymers characterized by a broad molecular weight distribution and high 1‐hexene incorporation, as confirmed by SEC, DSC and ¹³C NMR analysis. The influence of the main reaction parameters on the polymerization reactions was studied including the type of catalyst components, solvent, temperature, the ethylene partial pressure and the [Al]/[Ti] ratio in the catalyst. A higher activity and a higher 1‐hexene incorporation were achieved with AlMe₃‐depleted methylalumoxane as co‐catalyst and chlorobenzene as solvent. © 2013 Society of Chemical Industry     

Synthesis and characterization of low‐molecular‐weight poly(2,6‐dimethyl‐1,4‐phenylene oxide) in water

Low‐molecular‐weight poly(2,6‐dimethyl‐1,4‐phenylene oxide) (PPO) with unimodal polydispersity was synthesized by oxidative polymerization of 2,6‐dimethylphenol in the presence of Cu‐ethylene diamine tetraacetic acid catalyst in water. A series of low‐molecular‐weight PPO oligomers with M_n ranged from 360 to 3500 were obtained. It was found that the molecular weight and polydispersity were affected by reaction time, reaction temperature, and catalyst concentration. Based on the detector response‐elution volume curve and the molecular weight from gel permeation chromatography, a possible molecular weight growth mechanism was proposed. The structure and properties of low‐molecular‐weight PPO oligomers were characterized by atomic absorption spectroscopy, differential scanning calorimetry, Ubbelohde viscometer, and nuclear magnetic resonance spectroscopy. Compared to the commercial low‐molecular‐weight PPO, PPO oligomers synthesized in water had a much lower residual copper content. The relationships between T_g and M_n at relatively low‐molecular weight are in good agreement with the equation proposed by Fox and Loshack. © 2012 Wiley Periodicals, Inc. J. Appl. Polym. Sci., 2013     

Poly(pent‐1‐ene) Synthesized with the Syndiospecific Catalyst i‐Pr(Cp)(9‐Flu)ZrCl2/MAO

1‐Pentene was polymerized with the syndiospecific catalyst system i‐PrC(Cp)(9‐fluorenyl)ZrCl₂/MAO. The molar mass of the resulting polymers depends strongly on the reaction temperature and decreases from M̄_w = 126 000 at 0°C to M̄_w = 46 000 at 100°C, but is more or less independent of the monomer and the MAO concentration. The influence of reaction temperature and concentrations of MAO and monomer on the type of end‐groups generated during the chain termination, as well as on the type of stereoerror, was investigated. The degree of tacticity was dependent on the polymerization temperature with [rrrr] > 0.99 at 0°C and [rrrr] = 0.75 at 100°C.     

Preparation and application of sulfonated poly(1‐octene‐co‐styrene)

In this article, 1‐octene and styrene was copolymerized by the supported catalyst (TiCl₄/ID/MgCl₂). Subsequently, by sulfonation reaction, sulfonated poly(1‐octene‐co‐styrene)s which were amphiphilic copolymers were prepared. The copolymerization behavior between 1‐octene and styrene is moderate ideal behavior. Copolymers prepared by this catalyst contain appreciable amounts of both 1‐octene and styrene. Increase in the feed ratio of styrene/1‐octene leads to increase in styrene content in copolymer and decrease in molecular weight. As the polymerization temperature increases, the styrene content in the copolymers increases, however, the molecular weight decreases. Hydrogen is an efficient regulator to lower the molecular weights of poly(1‐octene‐co‐styrene)s. The sulfonation degree of the sulfonated poly(1‐octene‐co‐styrene)s increased as the styrene content in copolymer increased or the molecular weight decreased. Thirty‐six hour is long enough for sulfonation reaction. The sulfonated poly(1‐octene‐co‐styrene)s can be used as effective and durable modifying agent to improve the wettability of polyethylene film and have potential application in emulsified fuels and for the stabilization of dispersions. © 2010 Wiley Periodicals, Inc. J Appl Polym Sci, 2011     

Poly(1,4‐cyclohexylenedimethylene‐1, 4‐cyclohexanedicarboxylate): analysis of parameters affecting polymerization and cis–trans isomerization

Weatherable semicrystalline polyesters based on 1,4‐cyclohexanedimethanol, 1,4‐cyclohexanedicarboxylic acid (CHDA) or dimethyl 1,4‐cyclohexane dicarboxylate (DMCD) can be prepared under normal melt‐phase conditions, using titanium tetrabutoxide as catalyst. The effect of monomer ratio, reaction temperature and catalyst loading on the final polymer properties was studied. Under the proper polymerization conditions, poly(1,4‐cyclohexylenedimethylene‐1,4‐cyclohexanedicarboxylate) polymers with high molecular weight can be obtained. During polymerization, isomerization can occur towards the thermodynamically stable cis‐trans ratio of 34–66 mol%. Carboxylic acid end groups can catalyze the isomerization and therefore the polymerization is more critical starting from CHDA rather than DMCD. Moreover, temperature control becomes a key factor to avoid or to limit isomerization. The study of the isomerization of the different monomers permitted a better understanding of the isomerization and therefore of the polymerization process. Copyright © 2011 Society of Chemical Industry     

Solid‐state polymerization and characterization of a copolyamide based on adipic acid, 1,4‐butanediamine,and 2,5‐furandicarboxylic acid

2,5‐Furandicarboxylic acid (FDCA) is a promising biobased alternative material to terephthalic acid. In this study, three types of poly(butylene adipamide) (PA‐4,6) containing 10, 20, and 30 mol % of poly(butylene‐2,5‐furandicarboxylamide) (PA‐4,F) were synthesized through consecutive prepolymerization and solid‐state polymerization (SSP). The incorporation of a 10 mol % PA‐4,F component into PA‐4,6 resulted in slight increases in the intrinsic viscosity (IV) and glass‐transition temperature (T_g) after 12 h of SSP at 220 °C. When the SSP temperature and reaction time increased, IV increased proportionally. The highest IV value of 0.75 was obtained by 48 h of SSP at 240 °C, whereas increases in the PA‐4,F content to 20 and 30 mol % gave rise to decreases in IV, T_g, and melting temperature; this interrupted the increase in SSP temperature. The thermal decomposition temperature of the PA‐4,F‐incorporated polyamide was lower than that with PA‐4,6 because of the lower thermal stability of the FDCA component. © 2016 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2016 , 133, 43391.     

Poly(1‐octene) synthesis using high performance supported titanium catalysts

Poly(1‐octene) was synthesized by polymerization of 1‐octene using high performance MgCl₂‐supported TiCl₄ in combination with triethyl aluminum (TEAl) as cocatalyst in n‐hexane for 2 h. Two catalysts, C₁ (diester catalyst) having di‐isobutyl phthalate as internal donor and C₂ (monoester catalyst) having ethyl benzoate as internal donor were utilized for the atmospheric polymerizations to evaluate the influence of structurally different internal donors on the productivity, rate of polymerization and molecular weight profiles. The kinetic profile assessed in terms of variation of reaction parameters like temperature, cocatalyst to catalyst molar ratio and monomer concentration was found to be dependent on them. From these kinetic analyses, optimize conditions for polymerizations of 1‐octene using diester as well as monoester catalyst were elucidated. The difference in the performance of diester and monoester catalyst system can be explained in terms of stability of active titanium species and chain transfer process. NMR spectroscopy of synthesized poly(1‐octene) indicate predominantly isotactic nature. © 2009 Wiley Periodicals, Inc. J Appl Polym Sci, 2010     

Kinetic and structural studies of the polymerization of N,N′‐bismaleimide‐4,4′‐diphenylmethane with barbituric acid

Both the isothermal and non‐isothermal polymerizations of N,N′‐bismaleimide‐4,4′‐diphenylmethane (BMI) with barbituric acid (BTA) were investigated by the differential scanning calorimeter. The experimental results showed that the polymerizations of BMI with BTA were governed by the competitive Michael addition reaction and free radical polymerization mechanisms. Furthermore, the contribution of free radical polymerization becomes more important when the mole fraction of BTA decreases. ¹H NMR and ¹³C NMR measurements further support the coexistence of the Michael addition reaction and free radical polymerization mechanisms. A preliminary kinetic model that took into account the competitive Michael addition reaction and free radical polymerization mechanisms was developed. POLYM. ENG. SCI., 2011. © 2011 Society of Plastics Engineers