Molecular interaction of polyimide films probed by using soft-pulse dynamic compression ATR time-resolved infrared and double Fourier-transform based 2D-IR spectroscopy

An improved time-resolved step-scan Fourier transform rheo-optical system, based on the soft-pulse dynamic compression attenuated total reflection (ATR) approach, has been introduced to analyze inter-molecular interactions of poly(p-phenylene bi-phenyltetracarboximide) (BPDA–PDA) and poly(N,N-diphenyl ether bi-phenyltetracarboximide) (BPDA–ODA) films. In order to extract the full range of frequency distributions obtained from soft-pulse dynamic compression time response (relaxation) spectra, the second-Fourier transformation was applied along the relaxation time axis in addition to the interferogram axis. In the case of the BPDA–PDA, distinct periodic higher overtone bands are observed especially at C=O stretching and C=C tangential stretching vibration bands in the FFT relaxation time contour map spectra. For the BPDA–ODA, intensities of higher overtone bands are relatively weak. We have further performed 2D-IR correlation analysis at given Fourier frequencies, which includes molecular interaction information. The results suggest that the existence of molecular interaction between C=O stretching and C=C tangential stretching vibration bands.     

Anionic polymerization of N,N‐dialkyl‐2‐methylenebut‐3‐enamide: Effect of alkyl substituents on polymerization behavior

Anionic polymerizations of three 1,3‐butadiene derivatives containing different N,N‐dialkyl amide functions, N,N‐diisopropylamide (DiPA), piperidineamide (PiA), and cis‐2,6‐dimethylpiperidineamide (DMPA) were performed under various conditions, and their polymerization behavior was compared with that of N,N‐diethylamide analogue (DEA), which was previously reported. When polymerization of DiPA was performed at ?78 °C with potassium counter ion, only trace amounts of oligomers were formed, whereas polymers with a narrow molecular weight distribution were obtained in moderate yield when DiPA was polymerized at 0 °C in the presence of LiCl. Decrease in molecular weight and broadening of molecular weight distribution were observed when polymerization was performed at a higher temperature of 20 °C, presumably because of the effect of ceiling temperature. In the case of DMPA, no polymer was formed at 0 °C and polymers with relatively broad molecular weight distributions (M_w/M_n = 1.2) were obtained at 20 °C. The polymerization rate of PiA was much faster than that of the other monomers, and poly(PiA) was obtained in high yield even at ?78 °C in 24 h. The microstructure of the resulting polymers were exclusively 1,4‐ for poly(DMPA), whereas 20–30% of the 1,2‐structure was contained in poly(DiPA) and poly(PiA). © 2010 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 48: 3714–3721, 2010     

A simple FTIR spectroscopic method for the determination of the lower critical solution temperature of N‐isopropylacrylamide copolymers and related hydrogels

Linear and crosslinked polymers based on N‐isopropylacrylamide (NIPAAm) exhibit unusual thermal properties. Aqueous solutions of poly(N‐isopropylacrylamide) (PNIPAAm) phase‐separate upon heating above a lower critical solution temperature (LCST), whereas related hydrogels undergo a swelling–shrinking transition at an LCST. A linear copolymer made of NIPAAm/acryloxysuccinimide (98/2 mol/mol) and two hydrogels with different hydrophilicities were prepared. Fourier transform infrared (FTIR) spectroscopy was employed to determine the transition temperature and provide insights into the molecular details of the transition via probing of characteristic bands as a function of temperature. The FTIR spectroscopy method described here allowed the determination of the transition temperature for both the linear and crosslinked polymers. The transition temperatures for PNIPAAm and the gel resulting from the crosslinking with polylysine or N,N′‐methylenebisacrylamide (MBA) were in the same range, 30–35 °C. For the gels, the transition temperature increased with the hydrophilicity of the polymer matrix. The spectral changes observed at the LCST were similar for the free chains and the hydrogels, implying a similar molecular reorganization during the transition. The C H stretching region suggests that the N‐isopropyl groups and the backbone both underwent conformational changes and became more ordered upon heating above the LCST. An analysis of the amide I band suggests that the amide groups of the linear polymer were mainly involved in hydrogen bonding with water molecules below the LCST, the chain being flexible and disordered in a water solution. During the transition, around 20% of these intermolecular hydrogen bonds between the polymer and water were broken and replaced by intramolecular hydrogen bonds. Similar changes were also observed at the LCST of a gel crosslinked with MBA. © 2000 John Wiley & Sons, Inc. J Polym Sci B: Polym Phys 38: 907–915, 2000     

Synthesis and chemical modification of hyperbranched polyethers with terminal hydroxy groups by the anionic ring‐opening polymerization of 3‐alkyl‐3‐hydroxymethyl oxetanes

The anionic ring‐opening polymerization of oxetanes containing hydroxyl groups was carried out with potassium tert‐butoxide as an initiator in the presence of 18‐crown‐6‐ether in N‐methylpyrrolidinone at 180 °C; it yielded corresponding multifunctional hyperbranched polymers: poly(3‐ethyl‐3‐hydroxymethyloxetane)s, with number‐average molecular weights of 2200–4100 in 83–95% yields, and poly(3‐methyl‐3‐hydroxymethyloxetane)s, with number‐average molecular weights of 4600–5200 in 70–95% yields. The synthesized poly(3‐ethyl‐3‐hydroxymethyloxetane)s and poly(3‐methyl‐3‐hydroxymethyloxetane)s were hyperbranched polyethers containing an oxetane moiety and many hydroxy groups at the ends. The postpolymerization of poly(3‐ethyl‐3‐hydroxymethyloxetane)s was performed in the presence of potassium tert‐butoxide and 18‐crown‐6‐ether in N‐methylpyrrolidinone at 180 °C; it yielded corresponding polymers with higher molecular weights in good yields. The cationic polymerization of poly(3‐ethyl‐3‐hydroxymethyloxetane) derivatives was carried out with boron trifluoride etherate as an initiator and was followed by alkaline hydrolysis; this yielded a new branched polymer, a poly(hyperbranched polyether), with many pendant hydroxy groups. © 2004 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 42: 3739–3750, 2004     

Quaternization of poly(tertiary aminostyrene)s and characterization of the quaternized polymers

The Menschutkin reaction of three poly(tertiary aminostyrene)s: poly(N,N-dimethyl-4-vinylphenylamine) (PPA), poly(N,N-dimethyl-4-vinylbenzylamine) (PBA), and poly(N,N-dimethyl-4-vinylphenethylamine) (PPTA) was investigated. These three polymers having narrow molecular weight distributions were prepared via anionic living polymerization. PPA reacted homogeneously with n-butyl bromide in N,N-dimethylformamide (DMF). PBA and PPTA also reacted homogeneously with n-butyl bromide in a mixture of DMF/methanol (75/25 v/v %). GPC measurement of the quaternized polymers was carried out using a mixture of water/acetonitrile (80/20 v/v %) containing 0.5M acetic acid and 0.3M sodium sulfate (pH = 2.9) as an eluant in order to suppress adsorption of the quaternized water soluble polymers on GPC gel. Results of GPC measurement indicate that the polymer chains of the three poly(tertiary aminostyrene)s are neither severed nor crosslinked in the process of quaternization. Temperature dependence and reaction time dependence on the degree of quaternization (DQ) were studied for PPT, PBA, and PPTA. By altering reaction time and temperature, the DQ values of the three poly(tertiary aminostyrene)s could be controlled in the range from 0% to nearly 100%. Quaternization reactivity of the amino groups in the three polymers was found to decrease in the order, PPTA, PBA, and PPA. The differences in reactivity are thought to be attributable to the electron density on the nitrogen atom of the N,N-dimethylamino group, and steric hindrance in the vicinity of the nitrogen atom. © 1997 John Wiley & Sons, Inc. J Polym Sci A: Polym Chem 35: 1219–1226, 1997     

A detailed surface analytical study of degradation processes in (meth)acrylic polymers

The present study investigates the degradation behavior of various high‐molecular‐weight acrylic polymers (50,000 < M_n/g mol^?1 < 100,000), namely poly(methyl methacrylate) (PMMA), poly(n‐butyl methacrylate) (PBMA), poly(n‐butyl acrylate) (PBA), and poly(lauryl methacrylate) (PLMA), under extreme environmental conditions. These polymers were synthesized via various polymerization techniques to create different end‐groups. The polymers chosen are readily applicable in the formulation of surface coatings and were degraded under conditions which replicate the harsh Australian climate, where surface coatings may reach temperatures of up to 95 °C and are exposed to broad‐spectrum UV radiation of up to 1 kW m^?2. The degradation behavior of the polymeric materials on their surface was followed via ATR‐IR spectroscopy, high resolution FTIR microscopy, and X‐ray photoelectron spectroscopy. The extent of the observed thermal and photo‐oxidation is directly related to the length of the ester side group, with the degradation susceptibility decreasing in the order of PLMA > PBMA/PBA > PMMA, with PMMA still stable even after 5 months exposure to the harshest condition used (UV light at 95 °C). The general degradation mechanism involves the loss of the ester side groups to form methacrylic acid followed by cross‐linking. The effect of the variable end groups was found to be minimal. The results from this study are in good agreement with previous studies of low‐molecular‐weight model polymers under identical conditions. © 2012 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem, 2012     

Poly(arylene ether)s and poly(arylene thioether)s containing the 1,2-dihydro-4-phenyl(2H)- phthalazinone moiety

A series of new high molecular weight poly(arylene ether)s containing the 1,2-dihydro-4-phenyl(2H)phthalazinone moiety have been synthesized. The inherent viscosities of these polymers are in the range of 0.33–0.64 dL/g. They are amorphous and readily soluble in chloroform, DMF, and DMAc. The glass transition temperatures of the polymers range from 241 to 320°C and the 5% weight loss temperatures in nitrogen atmosphere range from 473 to 517°C. The hydroxy group in the monomer 1,2-dihydro-4-(4-hydroxyphenyl)(2H)phthalazin-1-one has been selectively transformed into the N,N′-dimethylthiocarbamate group, which was then rearranged to give the S-(N,N′-dimethylcarbamate) group via the Newman–Kwart rearrangement reaction. A series of poly(arylene thioether)s containing the 1,2-dihydro-4-phenyl(2H)phthalazinone moiety have also been synthesized via two types of reactions, a N C coupling reaction and a one-pot reaction between the S-(N,N′-dimethylcarbamate) and activated dihalo compounds, in diphenyl sulfone in the presence of a cesium carbonate and calcium carbonate mixture. These poly(arylene thioether)s also have high glass transition temperatures (ranging from 217–303°C) and high thermal stabilities. Compared with their poly(ether) analogs, the poly(arylene thioether)s have glass transition temperatures several degrees lower, which is attributed to the more flexible C S C bonds. © 1998 John Wiley & Sons, Inc. J Polym Sci A: Polym Chem 36 : 455–460, 1998     

A novel synthesis of semitelechelic functional poly(methacrylate)s through an alcoholate initiated polymerization. Synthesis of poly[2-(N,N-diethylaminoethyl) methacrylate] macromonomer

Potassium alcoholate was found to initiate the anionic polymerization of 2-(N,N-diethylaminoethyl) methacrylate (AMA) to form poly[2-(N,N-diethylaminoethyl) methacrylate] (PAMA). The molecular weight of the polymers was controlled by the monomer-initiator ratio with a narrow molecular weight distribution. Increased reactivity of the initiator by chelation of the monomer to the cation may be important for the polymerization. Using potassium (4-vinylbenzyl) alcoholate as an initiator, PAMA having a vinylbenzyl group was prepared which is a macromonomer having pH sensitive amino groups in each monomeric unit. By radical copolymerization with styrene, the PAMA macromonomer was incorporated as a graft chain.     

Multifunctional hydrolytic catalyses. IX. Hydrolysis of p-nitrophenyl acetate by bifunctional polymer catalysts containing zwitterionic (hydroxamate) nucleophiles

The hydrolysis of p-nitrophenyl acetate by bifunctional polymer catalysts was studied in 28.9% EtOH–H₂0 at 30°C. Partial (ca. 10 mole%) quaternization of poly(4-vinylpyridine) and poly(1-vinyl-2-ethylimidazole) with benzyl N-benzyl chloroacetohydroxamate and the subsequent removal of the benzyl group produced water-soluble polymers containing zwitterionic hydroxamate groups and free pyridine (or imidazole) groups. The zwitterionic hydroxamate was a nucleophile more than 10 times as effective as simple hydroxamate anions, and the acetyl hydroxamate intermediate was efficiently hydrolyzed by the intrapolymeric pyridine (or imidazole) group. Thus, the catalytic efficiency of these bifunctional polymers was much better than monofunctional polymers which contain either hydroxamate or imidazole, and amounted to 10–20% of that of α-chymotrypsin under a comparable condition.     

Role of hydration in the phase transition of polypeptides investigated by NMR and Raman spectroscopy

NMR, Raman spectroscopy and ab initio quantum-chemical calculations have been employed to investigate the role of the hydration water in the inverse temperature transition of elastin-derived biopolymers represented by poly(Gly-Val-Gly-Val-Pro) and poly(Ala-Val-Gly-Val-Pro). Temperature and concentration dependences of the Raman spectra measured for water solutions of polymers and of a low-molecular-weight model have been correlated with the vibrational frequencies calculated at the DFT (B3LYP) and MP2 levels for the peptide segment surrounded by a growing number of water molecules. The results indicate strong hydration before the transition that, in addition to water hydrogen-bonded to amide groups, includes hydrophobic hydration of non-polar groups by a dynamic cluster of several water molecules. According to ¹H longitudinal and transverse relaxation of HOD signals in D₂O solutions, the number of water molecules motionally correlated with the polymer is about 4 per one amino acid residue.     

Synthesis and properties of poly(phenylacetylenes) having two polar groups or one cyclic polar group on the phenyl ring

Phenylacetylene (PA) derivatives having two polar groups (ester, 2a – d ; amide, 4) or one cyclic polar group (imide, 5a – c ) were polymerized using (nbd)Rh⁺[(η⁶‐C₆H₅)B^?(C₆H₅)₃] catalyst to afford high molecular weight polymers (～1 × 10⁶ – 4 × 10⁶). The hydrolysis of ester‐containing poly(PA), poly( 2a) , provided poly(3,4‐dicarboxyPA) [poly ( 3 )], which could not be obtained directly by the polymerization of the corresponding monomer. The solubility properties of the present polymers were different from those of poly(PA) having no polar group; that is, poly( 2a )–poly( 2d ) dissolved in ethyl acetate and poly( 4 ) dissolved in N,N‐dimethylformamide, while poly(PA) was insoluble in such solvents. Ester‐group‐containing polymers [poly( 2a )–poly( 2d )] afforded free‐standing membranes by casting from THF solutions. The membrane of poly( 2a ) showed high carbon dioxide permselectivity against nitrogen (PCO₂/PN₂ = 62). © 2006 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 44: 5943–5953, 2006     

Synthesis and polymerization of N‐(4‐tetrahydropyranyl‐oxyphenyl)maleimide

N‐(4‐Tetrahydropyranyl‐oxy‐phenyl)maleimide (THPMI) was prepared and polymerized by radical or anionic initiators. THPMI could be polymerized by 2,2′‐azobis(isobutyronitrile) (AIBN) and potassium tert‐butoxide. Radical polymers (poly(THPMI)r) were obtained in 15–50% yields for AIBN in THF at 65°C after 2–5 h. The yield of anionic polymers (poly(THPMI)a) obtained from potassium tert‐butoxide in THF at 0°C after 20 h was 91%. The molecular weights of poly(THPMI)r and poly(THPMI)a were M_n = 2750–3300 (M_w/M_n = 1.2–3.3) and M_n = 11300 (M_w/M_n = 6.0), respectively. The difference in molecular weights of the polymers was due to the differences in the termination mechanism of polymerization and the solubility of these polymers in THF. The thermal decomposition temperatures were 205 and 365°C. The first decomposition step was based on elimination of the tetrahydropyranyl group from the poly(THPMI). Positive image patterns were obtained by chemical amplification of positive photoresist composed of poly(THPMI) and 4‐morpholinophenyl diazonium trifluoromethanesulfonate used as an acid generator. © 1999 John Wiley & Sons, Inc. J Polym Sci A: Polym Chem 37: 341–347, 1999     

Catalytic effect of poly(4-vinyl-N-alkylpyridinium) salts on the hydrolysis of ester- and amide-containing indolyl groups

Alkaline hydrolyses of p-nitrophenyl-3-indoleacetate (p-NPIA) and N-(indole-3-acryloyl)imidazole (IAI) were studied in the presence of poly(4-vinyl-N-propylpyridinium bromide) (C3PVP), poly(4-vinyl-N-benzylpyridinium chloride) (BzPVP), and copolymers of 4-vinyl-N-benzylpyridinium chloride and 4-vinyl-N-cetylpyridinium bromide (C16BzPVP). The hydrolyses were enhanced by the addition of these cationic polyelectrolytes. The magnitudes of the enhancement were in the order C16BzPVP > BzPVP > C3PVP, which is explainable in terms of the hydrophobicity of the polymers. The result and activation parameters obtained indicated that the substrates bound to polymers were more reactive than free substrates. The association constants obtained from the kinetic measurements (K) increased in the order BzPVP < C3PVP < C16BzPVP, which may suggest an important contribution of charge transfer interaction, in addition to electrostatic and hydrophobic interactions, between the polymers and the substrates. The association constants between the polymers and IAI were also obtained independently from the spectrophotometric measurements (K^*) with the charge transfer absorption bands. The lack of a satisfactory agreement between K and K^* is discussed.     

Preparation of novel acrylamide‐based thermoresponsive polymer analogues and their application as thermoresponsive chromatographic matrices

New thermoresponsive polymers based on poly(N‐(N′‐alkylcarbamido)propyl methacrylamide) analogues were designed with increased hydrophobic content to facilitate temperature‐dependent chromatographic separations of peptides and proteins from aqueous mobile phases. These polymer solution exhibited a lower critical solution temperature (LCST) when the alkyl group is methyl, ethyl, isopropyl, propyl, butyl, and isobutyl. However, larger alkyl groups such as hexyl and phenyl were not soluble in aqueous solutions at any temperature. Phase transition temperatures were lower for larger alkyl groups and increased with decreasing polymer molecular weight and concentration in solution. LCST dependence on polymer molecular weight and concentration is more significant compared with well‐studied poly(N‐isopropylacrylamide) (PIPAAm). Partition coefficient (log P) values for N‐(N′‐butylcarbamide)propylmethacrylamide and N‐(N′‐isobutylcarbamide)propyl methacrylamide (iBuCPMA) monomers are larger than that for IPAAm monomer, suggesting higher hydrophobicity than IPAAm. Chromatographic evaluation of poly(N‐(N′‐isobutylcarbamide)propyl methacrylamide) (PiBuCPMA) grafted silica particles in aqueous separations revealed larger k′ values for peptides, insulin, insulin chain B, and angiotensin I than PIPAAm‐grafted silica beads. In particular, k′ values for insulin obtained from PiBuCPMA‐grafted silica separations were much larger than those from PIPAAm‐grafted surface separations, indicating that PiBuCPMA should be more hydrophobic than PIPAAm. These results support the introduction of alkylcarbamido groups to efficiently increase thermoresponsive polymer hydrophobicity of poly(N‐alkylacrylamides) and poly(N‐alkylmethacrylamides). Consequently, poly(N‐(N′‐alkylcarbamido)propyl methacrylamide) analogues such as PiBuCPMA and poly(N‐(N′‐alkylcarbamido)alkylmehacrylamide) are new thermoresponsive polymers with appropriate hydrophobic partitioning properties for protein and peptide separations in aqueous media, depending on selection of their alkyl groups. © 2008 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 46: 5471–5482, 2008     

Optoeletronic properties of poly(N‐alkenyl‐carbazole)s driven by polymer stereoregularity

Stereoregular polymers like isotactic poly(N‐butenyl‐carbazole) (i‐PBK), isotactic and syndiotactic poly(N‐pentenyl‐carbazole) (i‐PPK and s‐PPK), and poly(N‐hexenyl‐carbazole) (i‐PHK and s‐PHK) are synthesized using the stereospecific homogeneous “single site” Ziegler‐Natta (Z‐N) catalysts: rac‐dimethylsilylbis(1‐indenyl)zirconium dichloride ( 1 )/methylaluminoxane (MAO) and diphenylmethylidene(cyclopentadienyl)‐(9‐fluorenyl)zirconium dichloride ( 2 )/MAO. Catalytic activity is rationalized by density functional theory (DFT) calculations. All synthesized polymers are fully characterized by NMR, thermal, wide‐angle X‐ray diffraction, and fourier transform infrared spectroscopy analysis. Fluorescence measurements on isotactic and syndiotactic polymer films indicate that all polymers give rise to excimers, both “sandwich‐like” and “partially overlapping.” Excimer formation is essentially driven by the polymer tacticity. Isotactic polymers generate both sandwich‐like and partially overlapping excimers, while syndiotactic polymers give rise especially to partially overlapping ones. A theoretical combined molecular dynamics–time dependent DFT approach is also used to support the experimental results. © 2017 Wiley Periodicals, Inc. J. Polym. Sci., Part A: Polym. Chem. 2018 , 56, 242–251     

Anionic polymerization of N,N‐dialkylacrylamides containing alkoxysilyl groups in the presence of Lewis acids

With Ph₂CHK as an initiator, the anionic polymerization of N‐propyl‐N‐(3‐triisopropoxysilylpropyl)acrylamide ( 4 ) and N‐propyl‐N‐(3‐triethoxysilylpropyl)acryl‐amide generated polymers with predicted molecular weights and narrow molecular weight distributions (MWDs) in the presence of Et₂Zn or Et₃B; however, the resulting polymers obtained in the absence of such Lewis acids had very broad MWDs. The results were ascribed to the coordination of the propagating anionic end to a relatively weak Lewis acid, in which the activity of the end anion was appropriately controlled for moderate polymerization without side reactions. A well‐defined diblock copolymer of 4 and N,N‐diethylacrylamide was also prepared with the binary initiating system of Ph₂CHK and Et₂Zn, whereas no such block copolymer was prepared by polymerization initiated with 1,1‐diphenyl‐3‐methylpentyllithium, as the propagating anion together with the lithium ion reacted with alkoxysilyl side groups on the poly( 4 ) backbone to produce grafted polymers with high molecular weights. The hydrolysis of the alkoxysilyl side groups of poly( 4 ) in acidic water yielded an insoluble gel. © 2005 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 43: 2754‐2764, 2005     

Interaction of water in polymers: Poly(ethylene‐co‐vinyl acetate) and poly(vinyl acetate)

We studied the interaction of water in poly(ethylene‐co‐vinyl acetate) of various vinyl acetate compositions and poly(vinyl acetate), on the basis of the infrared spectrum of the water dissolved therein. The spectrum shows a very sharp and distinct band at about 3690 cm^?1 (named as A), and less‐sharp two bands around 3640 (B) and 3550 cm^?1 (C), the A band being outstanding especially at a low vinyl acetate composition. As the vinyl acetate composition increases, the A band decreases in intensity relative to the C band, whereas the B band increases contrarily. Analysis of the spectral change has elucidated that one‐bonded water (of which one OH is hydrogen‐bonded to the C?O of an ester group and the other OH is free) and two‐bonded water (each OH of which is hydrogen‐bonded to one C?O) coexist in the copolymer and that two‐bonded water increases in relative population with increasing vinyl acetate composition. Dissolved water is entirely two‐bonded in poly(vinyl acetate), in which C?O groups are densely distributed in the matrix. We proved that dissolved water in polymers is hydrogen‐bonded through one or two OH groups to the possessed functional groups but does not cluster. © 2005 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 43: 777–785, 2005     

Micro ATR‐FTIR study of the hydration state of poly(N‐tert‐butylacrylamide‐co‐acrylamide) copolymers during phase transition in aqueous media and in the mixture of water–methanol

Coil‐globule transition of poly(N‐tert‐butylacrylamide‐co‐acrylamide) P(NTBAM‐co‐AM) copolymers is investigated in the aqueous solution and in the mixture of water–methanol by micro ATR‐FTIR spectroscopy technique. In this study the microstructure and its changes in the hydration states of the distinct groups of these copolymers are investigated by micro ATR/FTIR technique. The results showed that by heating the solution above the LCST hydrogen bonding between C?O and water was decreased but the hydrogen bonding between polymeric chains increased, which prove the aggregation of polymer chain during phase separation. The chemical shifts of IR bands are also studied in the mixture of water–methanol. © 2009 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 48: 356–363, 2010     

Sodium hydride-initiated polymerizations of vinyl monomers in aprotic solvents

Polymerizations of several vinyl monomers at 25°C in aprotic solvents (dimethyl sulfoxide, N,N-dimethylacetamide, and hexamethylphosphoric triamide) using sodium hydride dispersion as initiator yield low to intermediate molecular weight polymers. The molecular weight of the resulting polymer as well as the mode of initiation depends on the monomer and aprotic solvent used. Initiation of polymerization of monomers with available α hydrogens (methyl acrylate, acrylonitrile) involves monomer anion, while initiation of a monomer with no α hydrogen (methyl methacrylate) proceeds by a more complex mechanism. In contrast, initiation of styrene and α-methylstyrene proceeds by dimsyl anion addition to monomer in dimethylsulfoxide. Although the triad tacticities and number-average molecular weights of poly(methyl methacrylate) samples obtained from all three aprotic solvents are nearly the same, poly(methyl methacrylates) prepared in dimethyl sulfoxide and N,N-dimethylacetamide give polymers having polydispersities of ～3, while a very polydisperse polymer is obtained in hexamethylphosphoric triamide.     

Synthesis of Poly(arylene ether amide)s Containing CF3 Groups by Nitro Displacement Reaction of AB‐Type Monomers

New poly(arylene ether amide)s with trifluoromethyl pendent groups were prepared via nucleophilic nitro displacement reaction of AB‐type monomers. 4‐Nitro‐3‐trifluoromethyl‐[N‐(4‐hydroxyphenyl)]benzamide ( 3 ) and 4‐nitro‐3‐trifluoro‐methyl‐[N‐(3‐hydroxyphenyl)]benzamide ( 4 ) gave polymers with weight‐average molecular weights over 42 000 g/mol and glass transition temperatures of 269°C and 213°C, respectively. Both polymers were soluble in common organic solvents including THF, and formed transparent films upon casting.