Preparation and characterization of transparent and foldable polysiloxane‐poly(methyl methacrylate) membrane with a high refractive index

In this article, carbazole‐grafted methacrylic polysiloxane (MA‐CZ‐PDMS) macromonomer was synthesized and its structure was confirmed by proton nuclear magnetic resonance (¹H NMR). The polysiloxane macromonomer can homogeneously copolymerize with methyl methacrylate (MMA) to prepare transparent and foldable carbazole‐grafted polysiloxane‐poly(methyl methacrylate) (PDMS‐PMMA) membranes with a high refractive index (RI). The membranes were characterized by light transmittance, RI value, and dynamic mechanical thermal analysis (DMTA). The results indicated that the carbazole‐grafted PDMS‐PMMA membranes had excellent light transmittance that decreased slightly with increasing carbazole‐grafted polysiloxane content. Incorporation of carbazole‐grafted polysiloxane in the materials improved its RI value; however decreased the glass transmission temperature (T_g) that can be adjusted to less than 30°C, enable the membrane foldable at room temperature. The data demonstrate that the carbazole‐grafted PDMS‐PMMA membranes have a potential application as high RI intraocular lens (IOL) suitable for implantation by minimally invasive surgery. © 2015 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2015 , 132, 42491.     

In situ cross‐linked‐PDMS/BPPO membrane for the recovery of butanol by pervaporation

In this study, an in situ crosslinked polydimethylsiloxane/brominated polyphenylene oxide (c‐PDMS/BPPO) membrane on ceramic tube has been prepared for the recovery of butanol by pervaporation. A series of BPPO with different bromide‐substituted ratio were firstly synthesized through Wohl–Ziegler reaction. BPPO and PDMS were sequentially assembled and in situ crosslinked to form the final c‐PDMS/BPPO membrane. The results of solid‐state NMR and Differential Scanning Calorimeter demonstrated that the c‐PDMS/BPPO copolymer has a crosslinking structure and the SEM result proved the coverage of ceramic tube by copolymer layer. The effects of preparation conditions including dipping time and bromide‐substituted ratio of BPPO on the membrane performance were studied. The pervaporation experiments of butanol–water mixture indicated that the c‐PDMS/BPPO membrane exhibited an acceptable flux of 220 g·m^?2·h^?1 and high separation factor of 35 towards butanol, when the bromide‐substituted ratio was 34 wt % and the dipping time was 1.33 h. Moreover, the c‐PDMS/BPPO membrane performed excellent stability in an about 200 h continuous butanol recovery, as compared to the PDMS membrane. © 2013 Wiley Periodicals, Inc. J. Appl. Polym. Sci., 2014 , 131, 40004.     

Synthesis and characterization of polyurethane hybrids: Influence of the polydimethylsiloxane linear chain and silsesquioxane cubic structure on the thermal and mechanical properties of polyurethane hybrids

The structural effects of polydimethylsiloxane (PDMS) or polyhedral oligosilsesquioxanes (POSSs) on the thermomechanical properties of polyurethane (PU) networks were studied. An ester–amine‐functionalized silsesquioxane and a PDMS macromer were synthesized, and the macromer (10 wt %) was crosslinked with the PU prepolymer to obtain PU networks. The synthesized macromers and hybrids were characterized with Fourier transform infrared, ¹H‐NMR, ¹³C‐NMR, and ²⁹Si‐NMR spectroscopy techniques. The influence of POSS cubes on the thermal and mechanical properties of the polymer network films was studied comparatively with the similarly functionalized PDMS linear chain via thermogravimetric analysis (TGA), differential scanning calorimetry (DSC), and dynamic mechanical analysis (DMA) measurements. The degradation pattern of the POSS‐incorporated PU nanocomposites was almost the same as that of the PU network synthesized from the linear PDMS macromer. The differences in the char yields and activation energies of the hybrids reflected the enhancement of the thermal properties of the nanohybrids. The TGA and DSC curves of the macromers suggested that the thermal properties of the macromers not only depended on either the PDMS or POSS inorganic core but also depended on the organic peripheral attached to the inorganic core. The glass‐transition temperatures of the nanohybrids were higher than those of the linear‐PDMS‐incorporated hybrids. The storage modulus values increased 3‐fold upon the incorporation of POSS rigid groups into the PU hybrids in comparison with the flexible PDMS‐chain‐incorporated PU hybrids. The DMA measurements showed a long‐range rubbery plateau region for all the PU hybrids, with high storage modulus and tan δ values showing the structural homogeneity of the crosslinked networks. © 2009 Wiley Periodicals, Inc. J Appl Polym Sci, 2009     

Synthesis and characterization of hydroxy‐terminated polyether‐polydimethylsiloxane‐polyether (PE‐PDMS‐PE) triblock oligomers and their use in the preparation of thermoplastic polyurethanes

A series of hydroxy‐terminated polyether‐polydimethylsiloxane‐polyether (α,ω‐dihydroxy‐(PE‐PDMS‐PE)) ABA triblock oligomers were synthesized from silanic fluids and methyl polyallyloxide polyethers. The reaction was a one‐step solventless hydrosilylation reaction with chloroplatinic acid (CPA) catalyst in the presence of heat. These ABA oligomers were characterized via ¹H‐NMR, ¹³C‐NMR, ²⁹Si‐NMR, FT‐IR, and GPC to demonstrate that they exhibit a 100% linear ABA structure with a siloxane Si? O chain in the center and polyether ethylene oxide (EO)/propylene oxide (PO) chains on the two sides terminated by hydroxy groups. The triblock oligomers were used to form thermoplastic polyurethanes (TPUs) using two‐step solventless bulk polymerization. The investigation of triblock oligomers impact on TPUs mechanical properties, thermal performance, surface water repellency, and morphology performance were analyzed by Instron material tester, differential scanning calorimetry (DSC), thermogravimetric analysis (TGA), water contact angles (WCA), scanning electron microscope (SEM), and transmission electron microscope (TEM). DSC and TGA indicated that PE‐PDMS‐PE modified TPUs had a clear lower T_g under ?120°C and the temperature of 50% weight loss was improved from 280 to 340°C. PE‐PDMS‐PE–modified TPU did not have the marked reduction on mechanical properties than pure polyether produced TPU. Tensile strength was maintained at 13 MPa and elongation was maintained at 300%. SEM and TEM were used to investigate the copolymers’ morphology performance and found that all PO PE‐PDMS‐PE had a pseudo‐three phase separation. WCA analysis confirmed that PE‐PDMS‐PE–modified TPU had significantly improved hydrophobic performance because the silicone structure linked into TPU copolymers. © 2015 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2015 , 132, 42521.     

Hydrophobic properties of poly(arylene ether)s derived from linear polydimethysiloxanes and decafluorobiphenyl

A series of novel poly(arylene ether)s were synthesized with diphenol liner polydimethysiloxanes with different silicon numbers (2OH‐PDMS‐P; P = 2, 6, 10, 12, 16) and decafluorobiphenyl via a two‐step nucleophilic substitution polymerization. The chemical structures of the polymers were confirmed by Fourier transform infrared spectrometer, ¹⁹F‐NMR and ¹H‐NMR spectra. All the polymers provided outstanding hydrophobic properties, high thermal stability and good solubility. The water contact angle (WCA) first increased and then suddenly decreased with the increasing of silicon numbers in PDMS. The highest WCA about 112° was obtained when silicon numbers was ten. © 2017 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2018 , 135, 46187.     

Preparation,surface properties,and antibacterial activity of a poly(dimethyl siloxane) network containing a quaternary ammonium salt side chain

To obtain a copolymer network with low surface energy and antibacterial properties, a series of hydroxyl‐terminated poly(dimethyl siloxane)s (PDMSs) modified by a quaternary ammonium salt (QAS) side chain was synthesized via hydrolytic polycondensation and quaternization. The structures of the intermediate and final products were confirmed by Fourier transform infrared spectroscopy, ¹H‐NMR, and gel permeation chromatography. The results show that each step was successfully carried out, and objective products were obtained. The modified PDMSs were crosslinked with a commercial polyisocyanate to obtain cured QAS‐modified PDMS coatings. The target functional coatings exhibited excellent antibacterial performance with a low surface energy. When the molar content of QAS in PDMS was varied from 10 to 30%, the critical surface energy of the coatings remained in the range 24.05–26.88 mN/m; this indicated that the coatings had minimal adhesion with fouling according to the Baier curve. The bactericidal tests showed that the antibacterial activity was independent of the PDMS molecular weight but was closely correlated with the QAS content in PDMS. The bactericidal rate of the coatings to Escherichia coli and Staphylococcus aureus was higher than 97% when the molar content of QAS in PDMS was above 20%. © 2014 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2015 , 132, 41725.     

Synthesis and characterization of thermoplastic poly(ester–siloxane)s

Two series of thermoplastic poly(ester–siloxane)s, based on poly(dimethylsiloxane) (PDMS) as the soft segment and poly(butylene terephthalate) as the hard segment, were synthesized by two‐step catalyzed transesterification reactions in the melt. Incorporation of soft poly(dimethylsiloxane) segments into the copolyester backbone was accomplished in two different ways. The first series was prepared based on dimethyl terephthalate, 1,4‐butanediol and silanol‐terminated poly(dimethylsiloxane) (PDMS‐OH). For the second series, the PDMS‐OH was replaced by methyl diesters of carboxypropyl‐terminated poly(dimethylsiloxane)s. The syntheses were optimized in terms of both the concentration of catalyst, tetra‐n‐butyl‐titanate (Ti(OBu)₄), and stabilizer, N,N′‐diphenyl‐p‐phenylene‐diamine, as well as the reaction time. The reactions were followed by measuring the inherent viscosities of the reaction mixture. The molecular structures of the synthesized poly(ester–siloxane)s were verified by ¹H NMR spectroscopy, while their thermal properties were investigated using differential scanning calorimetry. © 2001 Society of Chemical Industry     

Synthesis and characterization of poly(ester ether siloxane)s

A series of novel thermoplastic elastomers based on ABA‐type triblock prepolymers, poly[(propylene oxide)–(dimethylsiloxane)–(propylene oxide)] (PPO‐PDMS‐PPO), as the soft segments, and poly(butylene terephthalate) (PBT), as the hard segments, was synthesized by catalyzed two‐step melt transesterification of dimethyl terephthalate (DMT) with 1,4‐butanediol (BD) and α,ω‐dihydroxy‐(PPO‐PDMS‐PPO) (M?_n = 2930 g mol^?1). Several copolymers with a content of hard PBT segments between 40 and 60 mass% and a constant length of the soft PPO‐PDMS‐PPO segments were prepared. The siloxane‐containing triblock prepolymer with hydrophilic terminal PPO blocks was used to improve the compatibility between the polar comonomers, i.e. DMT and BD, and the non‐polar PDMS segments. The structure and composition of the copolymers were examined using ¹H NMR spectroscopy, while the effectiveness of the incorporation of α,ω‐dihydroxy‐(PPO‐PDMS‐PPO) prepolymer into the copolyester chains was controlled by chloroform extraction. The effect of the structure and composition of the copolymers on the transition temperatures (T_m and T_g) and the thermal and thermo‐oxidative degradation stability, as well as on the degree of crystallinity, and some rheological properties, were studied. Copyright © 2006 Society of Chemical Industry     

Atom transfer radical polymerization of styrene and methyl (meth)acrylates initiated with poly(dimethylsiloxane) macroinitiator: Synthesis and characterization of triblock copolymers

Poly(dimethylsiloxane)(PDMS)‐based triblock copolymers were successfully synthesized via atom transfer radical polymerization (ATRP) initiated with bis(bromoalkyl)‐terminated PDMS macroinitiator (Br‐PDMS‐Br). First, Br‐PDMS‐Br was prepared by reaction between the bis(hydroxyalkyl)‐terminated PDMS and 2‐bromo‐2‐methylpropionyl bromide. PSt‐b‐PDMS‐b‐PSt, PMMA‐b‐PDMS‐b‐PMMA and PMA‐b‐PDMS‐b‐PMA triblock copolymers were then synthesized via ATRP of styrene (St), methyl methacrylate (MMA) and methyl acrylate (MA), respectively, in the presence of Br‐PDMS‐Br as a macroinitiator and CuCl/PMDETA as a catalyst system at 80 ^oC. Triblock copolymers were characterized by FTIR, ¹H‐NMR and GPC techniques. GPC results showed linear dependence of the number‐average molecular weight on the conversion as well as the narrow polydispersity indicies (PDI < 1.57) for the synthesized triblock copolymers which was lower than that of Br‐PDMS‐Br macroinitiator (PDI = 1.90), indicating the living/controlled characteristic of the reaction. Also, there was a very good agreement between the number‐average molecular weight calculated from ¹HNMR spectra and that calculated theoretically. Results showed that resulting copolymers have two glass transition temperatures, indicating that triblock copolymers have microphase separated morphology. © 2011 Wiley Periodicals, Inc. J Appl Polym Sci, 2012     

Effects of polymeric curing agent modified with silazanes on the mechanical properties of silicone rubber

Polymeric curing agent modified with hexamethyldisilazane (PCA‐D), or with hexamethylcyclotrisilazane (PCA‐T), was used to improve the mechanical properties of hydroxyl‐teminated polydimethylsiloxane (PDMS) rubber. The structure and the gel time of PCA were characterized by ²⁹Si NMR and shear viscosity measurement, respectively. The PCA modified with silazanes was more stable in storage than that without treatment (PCA‐0). Chemical bonds were formed during the reaction of silazanes and PCA according to ²⁹Si NMR results. The crosslink density (γ_e) and the mechanical properties of PCA/PDMS rubber were determined by swelling equilibrium and stress–strain tests. It was found that PCA treated with both silazanes could better enhance the mechanical properties of PCA/PDMS rubber compared with PCA‐0. PCA‐T/PDMS rubber, with additional crosslinks, was the best among the three types of PCA/PDMS rubber on the mechanical properties. © 2008 Wiley Periodicals, Inc. J Appl Polym Sci, 2009     

NMR properties of poly(dimethyl siloxane) colloids as new contrast agents for NMR imaging

By connecting the field‐gradient spin‐echo theory to spin–spin relaxation, we have found that the relationship between the tube‐reptation model and spin–spin relaxation can be represented by G(t) = exp[−(t/T₂) ⁿ] in which n = 1 and 0.5 for regimes IV and III, respectively. In our experiments, the spin–spin relaxation of linear poly(dimethyl siloxane) (PDMS) agrees with G(t) = exp[−(t/T₂)] while that of crosslinked PDMS coincides with G(t) = exp[−(t/T₂)^0.5]. These results reflect that in the time interval 8–800 ms the dynamics of linear PDMS are in regime IV (governed by reptation motions) and those of the crosslinked PDMS are in regime III (dominated by wriggling motions). The line‐shapes of NMR spectra of crosslinked PDMS are consistent with the Lorentzian rather than the Gaussian model. This can be accounted for by supposing that the PDMS chains between crosslinks have liquid‐like motions even though crosslinked PDMS is a solid. The liquid‐like motions of crosslinked PDMS could be regarded as wriggling motions described by the tube‐reptation model. In addition, the experimental results of diameter distribution, viscosity, NMR image and spin–lattice relaxation are presented in this work. © 2000 Society of Chemical Industry     

Improvement of thermal ageing and transparency of methacrylate based poly(siloxane–silsesquioxane) for optoelectronic application

Trisilanolphenyl–polyhedral oligosilsesquioxane (trisilanolphenyl–POSS) structure is introduced into a polysiloxane network in an attempt to produce thermally stable material with improved transparency. A series of organic–inorganic resins comprised of diphenylsilanediol, 3‐methacryloxypropyl trimethoxysilane, and varying content of trisilanolphenyl–POSS were copolymerized through condensation followed by curing using phenyltris(hydrogendimethylsiloxy)silane as curing agent. Fourier transform infrared spectroscopy (FTIR), proton‐nuclear magnetic resonance spectroscopy (¹H‐NMR), and silicon‐nuclear magnetic resonance spectroscopy (²⁹Si‐NMR) were used to confirm the synthesized product. Excellent thermal stability, improved glass transition temperature (T_g), and lower coefficient of thermal expansion with the increasing POSS content were observed from thermomechanical analysis. Its extreme thermal degradation stability was attributable to the crosslinked network as well as the heavily substituted aromatic ring present in the system. Steric hindrance effect is noticeable beyond 5.66 mol % trisilanolphenyl–POSS content. Incorporation of POSS substituent in methacrylate‐based polysiloxane give excellent transparency and improved thermal discoloration resistance as deduced from UV/vis Spectrophotometer, making it a potential material to be used in optoelectronics. © 2017 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2017 , 134, 45285.     

Synthesis of isoelectronic polyazomethine and poly(arylene vinylene) by a palladium‐catalyzed Suzuki coupling method

Two fully conjugated copolymers containing 2,7‐(9,9‐dioctyl) fluorene and 3,6‐(N‐hexyl‐9H‐carbazole) disubstituted rings and arylene vinylene or azomethine units in the main chain were synthesized through a palladium‐catalyzed Suzuki coupling method of 2,7‐bis(4,4,5,5‐tetramethyl‐1,3,2‐dioxaborolan‐2‐yl)‐9,9‐dioctyl fluorene with 1,4‐bis(6‐bromo‐N‐hexyl‐9H‐carbazole‐3‐yl vinyl) benzene or N,N‐bis(6‐bromo‐N‐hexyl‐9H‐carbazole‐3‐yl methylidene) 1,4‐phenylenediamine. Bisbromine arylene vinylene and arylenazomethine monomers were synthesized by condensation of 3‐formyl‐N‐hexyl‐6‐bromo carbazole with tetraethyl‐p‐xylylene diphosphonate or 1,4‐phenylenediamine. Copolymers were characterized by FTIR, ¹H‐NMR, DSC, UV‐visible and photoluminescence methods. Copyright © 2005 Society of Chemical Industry     

Viscosity/molecular‐weight relationship for γ‐(2,3‐dihydroxypropoxy)propyl‐terminated poly(dimethylsiloxane)s

A series of γ‐(2,3‐dihydroxypropoxy)propyl‐terminated poly(dimethylsiloxane) (DHT‐PDMS) samples with different molecular weights were prepared through the acid‐catalyzed equilibrium copolymerization of octamethylcyclotetrasiloxane and 1,3‐bis[γ‐(2,3‐dihydroxypropoxy)propyl]tetramethyldisiloxane. The intrinsic viscosity in toluene ([η]_toluene) and the number‐average molecular weight (M_n) were determined with an Ubbelohde viscometer and ¹H‐NMR spectra, respectively. In this way, the relationship between [η]_toluene and M_n was established. For 2.0 × 10⁴ < M_n < 4.0 × 10⁴, [η]_{toluene,25°C} was 1.874M_n ^0.323. The solution behavior of DHT‐PDMS was also investigated. © 2004 Wiley Periodicals, Inc. J Appl Polym Sci 94: 1759–1762, 2004     

Microscopic surface and bulk morphology of semicrystalline poly(dimethylsiloxane)–polyester copolymers

In this study, two series of semicrystalline poly(dimethylsiloxane) (PDMS)–polyester segmented copolymers with various PDMS contents were synthesized. One series was based on polybutylene adipate (PBA) as the polyester segment and the other was based on a polybutylene cyclohexanedicarboxylate ester (PBCH) segment. The copolymers were characterized using ¹H‐nuclear magnetic resonance, size exclusion chromatography, dynamic mechanical analyses, differential scanning calorimetry (DSC), and wide‐angle X‐ray diffraction (WAXD). The microscopic surface morphology and the microscopic bulk morphology were investigated using atomic force microscopy (AFM) and transmission electron microscopy, respectively. The effects of the polyester type and the PDMS content on the crystallinity degree as well as the copolymer surface and bulk morphology at room temperature were investigated for each series. DSC and WAXD results showed the ability of the copolymers to crystallize, to various degrees, depending on the polyester type and the PDMS content. The results showed that the PDMS content had a greater influence on the crystallinity degree in the PDMS‐s‐PBCH (cycloaliphatic) copolymer series than in the PDMS‐s‐PBA (aliphatic) copolymer series. In the copolymers with a low PDMS content, the AFM images showed spherulitic crystal morphology and evidence of PDMS nanodomains in between the crystal lamellae of the ester phase on the copolymer surface. A heterogeneous distribution of the PDMS domains was also observed for these copolymers in the bulk morphology as a result of this segregation between the polyester lamellae. All the copolymers, in both series, showed microphase separation as a result of the incompatibility between the PDMS segment and the polyester segment. Three types of surfaces and bulk morphologies were observed: spherical microdomains of PDMS in a matrix of polyester, bicontinuous double‐diamond type morphology, and spherical microdomains of polyester in a matrix of PDMS as the PDMS content increases. © 2009 Wiley Periodicals, Inc. J Appl Polym Sci, 2010     

Synthesis and characterization of N‐acryloylcarbazole/methyl methacrylate copolymers

Copolymers of N‐acryloylcarbazole (A) and methyl methacrylate (M) were synthesized in different in‐feed ratios. The composition of the copolymer was determined by the help of ¹H NMR spectrum. The comonomer reactivity ratios determined by Kelen‐Tudos (KT) and nonlinear error‐in‐variables methods were r_A = 1.12 ± 0.16, r_M = 0.94 ± 0.14, and r_A = 1.05, r_M = 0.90, respectively. Complete spectral assignments of the ¹H and ¹³C ¹H NMR spectra of the copolymers were done by the help of distortionless enhancement by polarization transfer (DEPT) and two‐dimensional NMR techniques, such as heteronuclear single quantum coherence (HSQC), total correlation spectroscopy (TOCSY), and heteronuclear multiple bond correlation (HMBC). The methine, α‐methyl, and carbonyl carbon resonances were found to be sequence sensitive. The signals obtained were broad because of the restricted rotation of bulky carbazole group and the quadrupolar effect of nitrogen present in carbazole moiety. Glass transition temperatures (T_g) were determined by differential scanning calorimetry and were found to be characteristic of copolymer composition. As the N‐acryloylcarbazole content increases, the T_g increases from 378.3 K for poly(methyl methacrylate) to 430.4 K for poly(N‐acryloylcarbazole). Variation in T_g with the copolymer composition were found to be in good agreement with theoretical values obtained from Johnston and Barton equations. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 100: 2667–2676, 2006     

Synthesis and characterization of Pst‐b‐PDMS‐b‐PSt copolymers by atom transfer radical polymerization

Polystyrene‐b‐poly(dimethylsiloxane)‐b‐polystyrene (Pst‐b‐PDMS‐b‐PSt) triblock copolymers were synthesized by atom transfer radical polymerization (ATRP). Commercially available difunctional PDMS containing vinylsilyl terminal species was reacted with hydrogen bromide, resulting in the PDMS macroinitiators for the ATRP of styrene (St). The latter procedure was carried out at 130°C in a phenyl ether solution with CuCl and 4, 4′‐di (5‐nonyl)‐2,2′‐bipyridine (dNbpy) as the catalyzing system. By using this technique, triblock copolymers consisting of a PDMS center block and polystyrene terminal blocks were synthesized. The polymerization was controllable; ATRP of St from those macroinitiators showed linear increases in M_n with conversion. The block copolymers were characterized with IR and ¹H‐NMR. The effects of molecular weight of macroinitiators, macroinitiator concentration, catalyst concentration, and temperature on the polymerization were also investigated. Thermodynamic data and activation parameters for the ATRP are reported. © 2004 Wiley Periodicals, Inc. J Appl Polym Sci 92: 3764–3770, 2004     

The calculation of sensitometric properties of 1,2,4-triazolo[1,5-a]pyrimidines

Quantitative structure–property relationships were proposed by using artificial neural networks and information received from ¹³C NMR spectra. The suitability of 1,2,4-triazolo[1,5-a]pyrimidines as stabilizers in photographic silver halide materials was determined from their chemical structures. For the numeric coding of the chemical structures of differently substituted 1,2,4-triazolo[1,5-a]pyrimidines 1 – 44 only information available from their ¹³C NMR spectra was used. Even an assignment of the ¹³C NMR chemical shift values to the carbons was not necessary. The best results were achieved by combination of the ¹³C NMR chemical shifts of carbons of the basic heterocycle and the relative fog D_rel using a feed-forward two-layer neural network. For some compounds with a good stabilizing effect the calculated results strongly differ from experimental values giving indication of a mechanism which is not covered by the ¹³C NMR chemical shifts.     

Microstructure determination and thermal studies of n‐acryloylcarbazole/vinyl acetate copolymers

Copolymers of N‐acryloylcarbazole (A) and vinyl acetate (V) were synthesized by bulk polymerization using benzoyl peroxide (BPO) as free‐radical initiator at 65°C in different in‐feed ratios. The composition of the copolymer was determined by ¹H‐NMR spectrum. The comonomer reactivity ratios, determined by Kelen–Tudos (KT) and nonlinear error‐in‐variables (EVM) methods, were r_A= 16.75 ± 1.38, r_V = 0.015 ± 0.002, and r_A = 16.36, r_V = 0.015, respectively. Complete spectral assignments of the ¹H and ¹³C{¹H} NMR spectra of the copolymers were done by the help of distortionless enhancement by polarization transfer (DEPT) and two‐dimensional NMR techniques such as heteronuclear single quantum coherence (HSQC) and total correlation spectroscopy (TOCSY). The methine and methylene carbon resonances were found to be compositional as well as configurational sensitive. The signals obtained were broad pertaining to the restricted rotation of bulky carbazole group. The thermal stability and glass‐transition temperatures (T_g) of the copolymers were found to be dependant on polymer composition and characteristic of rotational rigidity of the polymer chain. Variation in the values of T_g with the copolymer composition was found to be in good agreement with theoretical values obtained from Johnston and Barton equations. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 103: 2720–2733, 2007     

Synthesis,photochemical characterization,and thermal stability of a series of substituted formamidines as ultraviolet light absorbers

The three‐step reactions of ethyl 4‐aminobenzoate, formic acid, and halohydrocarbons afforded 10 N‐substituted‐N,N′‐diaryl‐formamidine derivatives ( F1 – 10 ) as ultraviolet absorbers. These N‐substituted formamidines were characterized by ¹H NMR, ¹³C NMR, FT‐IR, and ESI‐MS spectroscopies. The UV–vis absorbance and fluorescence properties of the compounds F1 – 10 were investigated in different solvents and in the presences of different metal ions. The effects of the amount of Al³⁺, Pb²⁺, Zr⁴⁺ ions on the UV–vis absorbance and fluorescence properties of compound F1 were also investigated. Moreover, the thermal stability of the compounds F1 – 10 was evaluated as well as the intermediate N,N′‐bis(4‐ethoxycarbonylphenyl)‐formamidine. J. VINYL ADDIT. TECHNOL., 25:E108–E113, 2019. © 2019 Society of Plastics Engineers