Novel Copolymers of Styrene and Alkoxy Ring‐Substituted 2‐Phenyl‐1,1‐dicyanoethylenes

Electrophilic trisubstituted ethylene monomers, ring‐substituted 2‐phenyl‐1,1‐dicyanoethylenes, RC₆H₄CH?C(CN)₂ (where R is 2‐methoxy, 3‐methoxy, 4‐methoxy, 4‐ethoxy, 4‐propoxy, and 4‐butoxy), were synthesized by piperidine catalyzed Knoevenagel condensation of ring‐substituted benzaldehydes and malononitrile, and characterized by CHN elemental analysis, IR, ¹H‐ and ¹³C‐NMR. Novel copolymers of the ethylenes and styrene were prepared at equimolar monomer feed composition by solution copolymerization in the presence of a radical initiator (AIBN) at 70°C. The composition of the copolymers was calculated from nitrogen analysis, and the structures were analyzed by IR, ¹H and ¹³C NMR, GPC, DSC, and TGA. High T _g of the copolymers in comparison with that of polystyrene indicates a substantial decrease in chain mobility of the copolymer due to the high dipolar character of the trisubstituted ethylene monomer unit. The gravimetric analysis indicated that the copolymers decompose in the 290–450°C range.     

Preparation of Comb‐like Styrene Grafted Silica Nanoparticles

Abstract

Comb‐like polystyrene grafted silica nanoparticles (c‐PS‐SNs) were prepared by the following steps: (a) methacryloxypropyl silica nanoparticles (MPSNs) were used as macromonomer and free radical copolymerized with 4‐vinyl benzyl chloride (VBC) by a solution polymerization method; (b) the product of (A), poly(4‐vinyl benzyl chloride) grafted silica nanoparticle (PVBC‐SN) was separated and then used as a macroinitiator for the surface‐initiated atom transfer radical polymerization (SI‐ATRP) of styrene catalyzed by the complex of Cu(I)Br and 2,2′‐bipyridyl (bipy) in toluene solutions. The structurally well‐defined polymer chains were grown from the nanoparticle surfaces to yield particles composed of a silica core and a well defined, densely grafted outer comb‐like PS layer. A percentage of grafting (PG%) (the weight ratio of the PS grafted with that of the silica charged) of more than 80% was achieved after a polymerizing time of 5?hr.     

RAFT Polymerization of Styrene in the Presence of 2‐Nonyl‐benzoimidazole‐1‐carbodithioic Acid Benzyl Ester

A novel dithiocarbamate, 2‐nonyl‐benzoimidazole‐1‐carbodithioic acid benzyl ester ( 1a ), was synthesized and successfully used in RAFT polymerization of styrene in bulk with thermal initiation. The effect of molar ratio of styrene to RAFT agent on the polymerization was investigated. The linear relationship between ln([M]₀/[M]) and polymerization time indicated that the polymerization was first‐order with respect to monomer concentration. The molecular weights increased linearly with monomer conversion and were close to corresponding theoretical values. The molecular weight distributions (M _w /M _n ) kept very narrow (M _w /M _n <1.1) at a wide range of conversions of 14.2% to 73.3%. The obtained polymer had a strong ultraviolet absorption at 329 nm, which indicated that the 1a moiety remained at the end of polymer chain.     

Synthesis of Maleated Ionomers via Ring‐Opening Reaction of Epoxidized (Styrene‐Butadiene‐Styrene) Triblock Copolymer with Potassium Hydrogen Maleate and Study of their Properties

A novel method for synthesizing maleated ionomer of (styrene‐butadiene‐styrene) triblock copolymer (SBS) from epoxidized SBS was developed. The epoxidized SBS was prepared via epoxidation of SBS with performic acid formed in situ by 30% H₂O₂ and formic acid in cyclohexane in the presence of polyethylene glycol 600 as a phase transfer catalyst. The maleated ionomer was obtained by a ring‐opening reaction of the epoxidized SBS solution with an aqueous solution of potassium hydrogen maleate. The optimum conditions for the ring‐opening reaction and some properties of the ionomers were studied. It is necessary to use phase transfer catalyst, ring‐opening catalyst and a pH regulator (dipotassium maleate) for obtaining the epoxy group conversion over 90%. The product was characterized by FTIR spectrophotometry and transmission electron microcroscopy (TEM) to be an ionomer with domains of maleate ionic groups. With increasing ionic groups, the water absorbency and the dilute solution viscosity of the ionomer increase, whereas the oil absorbency decreases. The tensile strength and ultimate elongation of ionomers increase with ionic group content and are higher than those of the original SBS without using any ionic plasticizer, which is usually used with the sulfonated ionomer. The ionomers with 1.2–1.7 mmol ionic groups/g exhibit optimum mechanical properties and behave as thermoplastic elastomers. The ionomer can be used as a compatibilizer for the blends of SBS with oil resistant chlorohydrin rubber (CHR). Addition of 3 wt% ionomer to the blend can increase the tensile strength and ultimate elongation of the blend optimally. The compatibility of the blends enhanced by adding the ionomer was shown by scanning electron microscopy (SEM). The blend of equal weight of SBS and CHR compatibilized by the ionomer behaves as a toluene resistant thermoplastic elastomer.     

Novel Copolymers of Styrene and Alkyl Ring‐Substituted Methyl 2‐Cyano‐3‐phenyl‐2‐propenoates

Electrophilic trisubstituted ethylene monomers, alkyl ring substituted methyl 2‐cyano‐3‐phenyl‐2‐propenoates, RC₆H₄CH[dbnd]C(CN)CO₂CH₃, where R is 2‐methyl, 3‐methyl, 4‐methyl, 4‐isopropyl, and 2,5‐dimethyl were synthesized by piperidine catalyzed Knoevenagel condensation of ring‐substituted benzaldehydes and methyl cyanoacetate, and characterized by CHN elemental analysis, IR, ¹H and ¹³C NMR. Novel copolymers of the ethylenes and styrene were prepared at equimolar monomer feed composition by solution copolymerization in the presence of a radical initiator (AIBN) at 70°C. The composition of the copolymers was calculated from nitrogen analysis, and the structures were analyzed by IR, ¹H and ¹³C NMR, GPC, DSC, and TGA. High T_g of the copolymers in comparison with that of polystyrene indicates a substantial decrease in chain mobility of the copolymer due to the high dipolar character of the trisubstituted ethylene monomer unit. The gravimetric analysis indicated that the copolymers decompose in the 260–400°C range.     

Atom Transfer Radical Polymerization of Styrene with 5‐Chloromethyl‐2‐hydroxy‐benzaldehyde as Initiator

Abstract

Atom transfer radical polymerization (ATRP) of styrene (St) proceeded using 5‐chloromethyl‐2‐hydroxy‐benzaldehyde as initiator, CuCl as catalyst, and N,N,N′,N′,N′‐pentamethyldiethyltriamine (PMDETA) as ligand. The results show that the polymerization is a first order reaction with respect to monomer concentration. The polymerization displayed living character as evidenced by a liner increase of monomer weight with conversation and a relatively narrow distribution (M _n/M _w ranges from 1.25 to 1.50). The end structure of PSt was analyzed by ¹H‐NMR, and PSt initiated MMA to form block copolymer (PSt‐b‐PMMA), which also proved that the polymerization could be controlled. The effects of reaction temperature and monomer to initiator mole ratio on the polymerization displayed living character were discussed.     

Novel Copolymers of Alkyl and Alkoxy Ring‐Substituted Ethyl 2‐Cyano‐3‐phenyl‐2‐propenoates and Styrene

Abstract

Electrophilic trisubstituted ethylenes, ring‐substituted ethyl 2‐cyano‐3‐phenyl‐2‐propenoates, RC₆H₄CH?C(CN)CO₂C₂H₅ (where R is 2‐CH₃, 3‐CH₃, 4‐CH₃, 2‐OCH₃, 3‐OCH₃, and 4‐OCH₃) were prepared and copolymerized with styrene (ST). The monomers were synthesized by the piperidine catalyzed Knoevenagel condensation of ring‐substituted benzaldehydes and ethyl cyanoacetate, and characterized by CHN analysis, IR, ¹H and ¹³C NMR. All the ethylenes were copolymerized with ST (M₁) in solution with radical initiation (AIBN) at 70°C. The compositions of the copolymers were calculated from nitrogen analysis and the structures were analyzed by IR, ¹H and ¹³C NMR. The order of relative reactivity (1/r ₁) for the monomers is 3‐OCH₃ (0.88)?>?4‐CH₃ (0.71)?>?2‐OCH₃ (0.68)?>?3‐CH₃ (0.55)?>?2‐CH₃ (0.47)?>?4‐OCH₃ (0.40). Higher T _g of the copolymers in comparison with that of polystyrene indicates a decrease in chain mobility of the copolymer due to the high dipolar character of the TSE structural unit. Gravimetric analysis indicated that the copolymers decompose in the 257–287°C range.     

Nitroxide‐mediated Living Radical Polymerization of Styrene with Fluorescent Initiator

A fluorescence method was used for determination of marked chain ends in polystyrene samples prepared by 4‐substituted TEMPO type nitroxide‐mediated living free radical polymerization of styrene. 2,2,6,6‐Tetramethyl‐1‐(1‐phenylethoxy)‐piperidin‐4‐yl‐4‐pyren‐1‐ylbutanoate (PYNOR) was prepared and used as an unimolecular initiator bearing pyrene as a fluorescence mark on mediating nitroxide fragment. The bulk polymerization of styrene at 120°C, in the presence of new unimolecular initiator, was a typical nitroxide mediated living radical polymerization. For comparison, two different molar ratios of initiator and monomer (1∶400 and 1∶1000 initiator ‐ monomer [I:M]) were used for polymerization. When I:M=1∶400, the obtained polydispersity was 1.12 and maximum molecular weight 27,000 g/mol was obtained at 62% conversion. For ratio 1∶1000, slightly higher polydispersity was obtained ?1.26 and the molecular weight was 53,000 g/mol at 70% conversion. The content of the polystyrene chains bearing mediating nitroxide fragment was determined by fluorescence spectroscopy. The intensity of pyrene fluorescence decreased as the molar mass, and the conversion increased as well. The extent of the incorporation of chromophore at propagating chain end or “livingness” of polymerization decreased despite the fact that the polydispersity did not change. The extent of side reaction leading to broadening of polydispersity is suppressed due to the high viscosity of the system at higher conversion. A low extent of “livingness” will have a very negative effect on possible preparation of block copolymers.     

Novel Copolymers of Styrene and Some Ring‐Substituted 2‐Cyano‐N,N‐Dimethyl‐3‐Phenyl‐2‐Propenamides

Electrophilic trisubstituted ethylene monomers, ring‐substituted 2‐cyano‐N,N‐dimethyl‐3‐phenyl‐2‐propenamides, RC₆H₄CH?C(CN)CON(CH₃)₂ (where R is 3‐benzyloxy, 4‐benzyloxy, 3‐ethoxy‐4‐methoxy, 3‐bromo‐4‐methoxy, 5‐bromo‐2‐methoxy, 2‐chloro‐6‐fluoro) were synthesized by potassium hydroxide catalyzed Knoevenagel condensation of ring‐substituted benzaldehydes and N,N‐dimethyl cyanoacetamide, and characterized by CHN elemental analysis, IR, ¹H‐ and ¹³C‐NMR. Novel copolymers of the ethylenes and styrene were prepared at equimolar monomer feed composition by solution copolymerization in the presence of a radical initiator, ABCN at 70°C. The composition of the copolymers was calculated from nitrogen analysis, and the structures were analyzed by IR, ¹H and ¹³C NMR, GPC, DSC, and TGA. High T_g of the copolymers in comparison with that of polystyrene indicates a substantial decrease in chain mobility of the copolymer due to the high dipolar character of the trisubstituted ethylene monomer unit. The gravimetric analysis indicated that the copolymers decompose in the 300–450°C range.     

Novel Copolymers of Styrene and Alkyl and Alkoxy Ring‐Trisubstituted Methyl 2‐Cyano‐3‐phenyl‐2‐propenoates

Electrophilic trisubstituted ethylene monomers, akyl and alkoxy ring‐trisubstituted methyl 2‐cyano‐3‐phenyl‐2‐propenoates, RC₆H₂CH[dbnd]C(CN)CO₂CH_3, (where R is 2,3‐dimethyl‐4‐methoxy, 2,5‐dimethyl‐4‐methoxy‐, 2,3,4‐trimethoxy‐, 2,4,5‐trimethoxy, 2,4,6‐trimethoxy, and 2,4‐dimethoxy‐3‐methyl), were synthesized by the piperidine catalyzed Knoevenagel condensation of ring‐substituted benzaldehydes and methyl cyanoacetate, and characterized by CHN elemental analysis, IR, ¹H‐ and ¹³C‐NMR. Novel copolymers of the ethylenes and styrene were prepared at equimolar monomer feed composition by solution copolymerization in the presence of a radical initiator (AIBN) at 70°C. The composition of the copolymers was calculated from nitrogen analysis, and the structures were analyzed by IR, ¹H and ¹³C NMR, GPC, DSC, and TGA. High T_g of the copolymers in comparison with that of polystyrene indicates a substantial decrease in chain mobility of the copolymer due to the high dipolar character of the trisubstituted ethylene monomer unit. The gravimetric analysis indicated that the copolymers decompose in the 283–306°C range.     

Novel Copolymers of Styrene and Halogen Ring‐Substituted 2‐Cyano‐N,N‐Dimethyl‐3‐Phenyl‐2‐Propenamides

Electrophilic trisubstituted ethylene monomers, halogen ring‐substituted 2‐cyano‐N,N‐dimethyl‐3‐phenyl‐2‐propenamides, RC₆H₄CH [dbnd]C(CN)CON(CH₃)₂ (where R is 2‐Br, 3‐Br, 4‐Br, 2‐Cl, 3‐Cl, 4‐Cl, 2‐F, 3‐F, 4‐F), were synthesized by potassium hydroxide catalyzed Knoevenagel condensation of ring‐substituted benzaldehydes and N,N‐dimethyl cyanoacetamide, and characterized by CHN elemental analysis, IR, ¹H‐ and ¹³C‐NMR. Novel copolymers of the ethylenes and styrene were prepared at equimolar monomer feed composition by solution copolymerization in the presence of a radical initiator, ABCN at 70°C. The composition of the copolymers was calculated from nitrogen analysis, and the structures were analyzed by IR, ¹H and ¹³C NMR, GPC, DSC, and TGA. High T _g of the copolymers in comparison with that of polystyrene indicates a substantial decrease in chain mobility of the copolymer due to the high dipolar character of the trisubstituted ethylene monomer unit. The gravimetric analysis indicated that the copolymers decompose in the 300–450°C range.     

Novel Copolymers of Styrene and Some Ring‐Substituted 2‐Cyano‐N,N‐Dimethyl‐3‐Phenyl‐2‐Propenamides

Electrophilic trisubstituted ethylene monomers, ring‐substituted 2‐cyano‐N,N‐dimethyl‐3‐phenyl‐2‐propenamides, RC₆H₄CH?C(CN)CON(CH₃)₂ (where R is 4‐(CH₃)₂N, 4‐CH₃CO₂, 4‐CH₃CONH, 2‐CN, 3‐CN, 4‐CN, 4‐(C₂H₅)₂N) were synthesized by potassium hydroxide catalyzed Knoevenagel condensation of ring‐substituted benzaldehydes and N,N‐dimethyl cyanoacetamide, and characterized by CHN elemental analysis, IR, ¹H‐ and ¹³C‐NMR. Novel copolymers of the ethylenes and styrene were prepared at equimolar monomer feed composition by solution copolymerization in the presence of a radical initiator, ABCN at 70°C. The composition of the copolymers was calculated from nitrogen analysis, and the structures were analyzed by IR, ¹H and ¹³C NMR, GPC, DSC, and TGA. High T_g of the copolymers in comparison with that of polystyrene indicates a substantial decrease in chain mobility of the copolymer due to the high dipolar character of the trisubstituted ethylene monomer unit. The gravimetric analysis indicated that the copolymers decompose in the 300–450°C range.     

Novel Copolymers of Styrene and Alkoxy Ring‐Substituted 2‐Cyano‐N,N‐Dimethyl‐3‐Phenyl‐2‐Propenamides

Electrophilic trisubstituted ethylene monomers, alkoxy ring‐substituted 2‐cyano‐N,N‐dimethyl‐3‐phenyl‐2‐propenamides, RC₆H₄CH?C(CN)CON(CH₃)₂ (where R is 2‐OCH₃, 3‐OCH₃, 4‐OCH₃, 2‐OCH₂CH₃, 3‐OCH₂CH₃, 4‐OCH₂CH₂CH₃, 4‐OCH₂CH₂CH₂CH₃), were synthesized by potassium hydroxide catalyzed Knoevenagel condensation of ring‐substituted benzaldehydes and N,N‐dimethyl cyanoacetamide, and characterized by CHN elemental analysis, IR, ¹H‐ and ¹³C‐NMR. Novel copolymers of the ethylenes and styrene were prepared at equimolar monomer feed composition by solution copolymerization in the presence of a radical initiator, ACBN at 70°C. The composition of the copolymers was calculated from nitrogen analysis, and the structures were analyzed by IR, ¹H and ¹³C NMR, GPC, DSC, and TGA. High T_g of the copolymers in comparison with that of polystyrene indicates a substantial decrease in chain mobility of the copolymer due to the high dipolar character of the trisubstituted ethylene monomer unit. The gravimetric analysis indicated that the copolymers decompose in the 300–450°C range.     

Novel Copolymers of Styrene and Halogen Ring‐Disubstituted 2‐Cyano‐N,N‐Dimethyl‐3‐Phenyl‐2‐Propenamides

Electrophilic trisubstituted ethylene monomers, halogen ring‐disubstituted 2‐cyano‐N,N‐dimethyl‐3‐phenyl‐2‐propenamides, RC₆H₃CH?C(CN)CON(CH₃)₂ (where R is 2,3‐dichloro, 2,4‐dichloro, 2,6‐dichloro, 3,4‐dichloro, 3,5‐dichloro, 2,3‐difluoro, 2,4‐difluoro, 2,6‐difluoro, 3,4‐difluoro, 3,5‐difluoro), were synthesized by potassium hydroxide catalyzed Knoevenagel condensation of ring‐substituted benzaldehydes and N,N‐dimethyl cyanoacetamide, and characterized by CHN elemental analysis, IR, ¹H‐ and ¹³C‐NMR. Novel copolymers of the ethylenes and styrene were prepared at equimolar monomer feed composition by solution copolymerization in the presence of a radical initiator, ABCN at 70°C. The composition of the copolymers was calculated from nitrogen analysis, and the structures were analyzed by IR, ¹H and ¹³C NMR, GPC, DSC, and TGA. High T_g of the copolymers in comparison with that of polystyrene indicates a substantial decrease in chain mobility of the copolymer due to the high dipolar character of the trisubstituted ethylene monomer unit. The gravimetric analysis indicated that the copolymers decompose in the 300–450°C range.     

Kinetic Study of Radical Polymerization VI. Copolymer Composition and Kinetic Parameters for Coplymerization of Styrene‐Itaconic Acid by On‐Line 1H‐NMR

Free radical solution copolymerization of styrene (St) and itaconic acid (IA) in dimethylsulfoxide‐d₆ (DMSO‐d₆) as the solvent and the use of 2,2′‐azobisisobutyronitrile (AIBN) as the initiator at 78°C was investigated by an on‐line ¹H‐NMR spectroscopy technique. Individual monomer conversion vs. reaction time, which was calculated from the ¹H‐NMR spectra data, was used to study the drift in monomer mixture composition vs. conversion. It was found that in general, both monomers were incorporated almost equally into the copolymer. However, when the mole fraction of IA was low, the tendency of IA toward incorporation into the copolymer chain was somewhat higher than St and by increasing the mole fraction of IA in the reaction mixture, the inverse tendency was observed. Overall monomer conversion as a function of time was calculated from individual monomer conversion data and used for the estimation of k_p /k_t ^0.5 for various monomer mixture compositions. This ratio was decreased with increasing the amount of IA in the initial feed, indicating a decrease in the rate of copolymerization. Changes in the copolymer composition vs. overall monomer conversion were investigated experimentally from the NMR spectra. This was in good agreement with the changes in monomer mixture composition vs. reaction progress. Plotting the copolymer composition vs. initial monomer feed showed tendency of the system toward alternating copolymerization.     

Copolymerization of α-Methylstyrene and Styrene

In this paper, the effects of temperature from 60 °C to 80 °C and the molar ratios in monomer feed on the copolymerization of α-methylstyrene(AMS) and styrene(St) were studied. The resulting copolymers, designated as PAS, were characterized by FTIR, GPC, NMR and TGA. When the reaction temperature was below 75 °C, the molecular weights increased almost linearly as the evolution of the copolymerization. The phenomenon revealed that AMS could mediate the conventional free radical polymerization having some features of a controlled system. As the AMS/St = 50/50(molar) in feed, the overall fraction of the AMS unit incorporated into the copolymer was as high as 42 mol%, the monomer conversion could be more than 90 wt% and the molecular weights could reach as high as 4400. However, since the styrene is more reactive than AMS, the AMS fraction in copolymer increased with the overall monomer conversion. The 13C-NMR revealed the products were random copolymers which had triads, such as-AMS-AMS-AMS-,-St-AMS-AMS-(-AMS-AMS-St-) and-St-AMS-St-. TGA curves demonstrated that the degradation temperature of the resulting copolymers went down from about 356.9 °C(0 mol% AMS) to 250.2 °C(42 mol% AMS). This behavior demonstrated that there exist weak bonds in the AMScontaining sequences which could be used as potential free radical generators.     

Influence of Cyclodextrin on the Styrene Polymerization

Cyclodextrin (CD) are oligosaccharides consisting of 6(α), 7(β), 8(γ) units of 1,4-linked glucose. Due to their polar hydrophilic outer shell and relatively hydrophobic cavity, they are able to build up host-guest complexes by inclusion of suitable hydrophobic molecules. The formation of these complexes leads to significant changes of the solubility and reactivity of the guest molecules, but without any chemical modification. Thus, water insoluble molecules may become completely water solu…     

Electrochemical Dicarboxylation of Styrene： Synthesis of 2-Phenylsuccinic Acid

Electrochemical dicarboxylation of styrene in the presence of atmospheric pressure of CO2 with a Ti cathode and a Mg rod anode readily took place efficiently in an acetonitrile solution containing 0.1 mol·L^-1 tetraethylammonium bromide to give 2-phenylsuccinic acid. Influences of the nature of the electrodes, the current density, the passed charge and the temperature on electrolysis were studied to optimize the electrolytic conditions, with the maximal isolated yield to be 86.07%. The mechanism of the elelctrocarboxylation process has been studied by cyclic voltammetry.     

An Efficient Synthesis of Derivatives of 2‐Acetamido‐4‐amino‐2,4,6‐trideoxy‐D‐galactopyranose

Abstract

Methyl 2‐acetamido‐4‐amino‐2,4,6‐trideoxy‐α‐D‐galactopyranoside (10) was synthesized from D‐glucosamine hydrochloride in eight steps in an overall yield of 31%. Key steps include the selective benzoylation at O‐3 of methyl 2‐acetamido‐2,6‐dideoxy‐α‐D‐glucopyranoside in 89% yield and the subsequent Mitsunobu reaction using diphenylphosphoryl azide as the azide source which proceeded in 92% yield. Di‐ and mono‐benzyloxycarbonyl derivatives of 10 were also prepared.     

Preparation of Some Derivatives of N‐tert‐Butyldecahydro‐3‐isoquinoline Carboxamide

N‐tert‐Butyldecahydro‐3‐isoquinoline carboxamide (1) is a key structural fragment present in a variety of medicinally important HIV protease inhibitors. Derivatives of this carboxamide were prepared by alkylation with either 2‐iodoethanol, allyl bromide, or bromoacetaldehyde dimethylacetal. The corresponding aldehyde of the dimethylacetal derivative was prepared by reaction with BBr₃ in CH₂Cl₂.