Esterification reactions on syndiotactic poly(2-methallyl alcohol). II. Esterification with protected (L)-aspartic and (L)-glutamic acids

The esterification of syndiotactic poly(2-methallyl alcohol) by N^α- and O^ω- protected aspartic and glutamic acids by the DCC/HOBT method is described. Depending on the extent of conversion, either homopolymers or copolymers are obtained. Both homo- and copolymers are characterized by ¹H- and ¹³C-NMR. A second route to the homopolymers has been followed, whereby the poly(2-methallyl alcohol) is first esterified by N^α-protected aspartic or glutamic acid anhydrides and, in a second step, the resulting free carboxyl group on the side chain is esterified by alcohols which are the same as the alcohol moiety of the O^ω-protecting groups. Because the homopolymers were identical to those of the first route, the formation of α-esters with the acid anhydrides is indicated.     

Esterification reactions on syndiotactic poly(methallylalcohol). IV. Homo- and copolymers of N-protected methallyl-(L)-histidinate

Syndiotactic poly(methylallylalcohol) is fully esterified with N^α-protected (L )-histidine by carbodiimide in pyridine to yield the corresponding homopolymers, i.e., N^α-protected 2-methylallyl-(L )-histidinate monomer units and unreacted 2-methylallyl alcohol units are obtained, which in a second exhaustive esterification step are reacted with N^α-(benzyloxycarbonyl)-(L )-aspartic acid anhydride. The resulting copolymers consist of N^α-protected 2-methylallyl-(L )-histidinate and 2-methylally-N^α-(benzyloxycarbonyl)-(L )-hydrogen-α-aspartate monomer units. They are polyampholytes containing both imidazole and carboxyl groups. The structure, including composition of the copolymers, is determined by ¹H- and ¹³C-NMR, while water solubility and apparent pK_aa values are investigated by potentiometry.     

Synthesis and reactions of a poly(methacrylate) from an optically active amino alcohol

Synthesis and radical polymerization of a novel optically active methacrylate, (S)–2–tert–butoxycarbonylamino–3–phenylpropyl methacrylate (MA–F–BOC), were examined. MA–F–BOC was synthesized from methacrylic acid and N–protected (L)–phenylalaninol. Radical polymerization of MA–F–BOC quantitatively afforded the corresponding polymethacrylate with a relatively high molecular weight. Radical copolymerizations of MA–F–BOC were carried out with styrene and acrylamide to afford the copolymers. Radical polymerization of MA–F–BOC in the presence of n–butanethiol afforded the oligomers, whose degrees of polymerizations were 3.3–8.0. The BOC group was completely cloven with HBr to afford the corresponding optically active polymeric amine quantitatively. © 1998 John Wiley & Sons, Inc. J. Polym. Sci. A Polym. Chem. 36: 1981–1986, 1998     

Reagent control of stereochemistry in allylic additions to chiral aldehydes with CpMo(NO)(X)(2-methallyl) complexes of high enantiomeric purity

Reactions of (R)- and (S)-CpMo(NO)(η³-methallyl)X(X=camphorsulfonate, Cl, Br, I) with chiral α-substituted aldehydes yield homoallylic alcohols with high diastereoselectivity. Reactions of (R)- and (S)-CpMo(NO)(η³- methallyl)L ^S[L^S = (IS)-(+)-10-camphorsulfonate] with D -glyceraldehyde acetonide yield the corresponding homoallylic alcohols in >98% diastereomeric excess. Reactions with racemic 2-phenyl-propionaldehyde and nonracemic 3-benzyloxy-2-methylpropanol are also considered and show that there is very high reagent control of stereo-chemistry in additions to the carbonyl group.     

Synthesis and functionalities of poly(N-vinylalkylamide). V. Control of a lower critical solution temperature of poly(N-vinylalkylamide)

N-vinyl-n-butyramide (NVBA), N-vinylisovaleramide (NVIVA), and N-vinyl-n-valeramide (NVVA), which are N-vinylalkylamides with different alkyl groups were synthesized and their solution behavior in a polymeric form was examined. Copolymers of N-vinylisobutyramide (NVIBA) with N-vinylacetamide (NVA), NVIBA with NVVA, and NVVA with NVA were prepared by the solution polymerization to control the LCSTs. The resultant polyNVBA showed a lower critical solution temperature (LCST) sharply at 32°C, but polyN-vinylisovaleramide (polyNVIVA) and polyN-vinyl-n-valeramide(polyNVVA) that have n-butyl and isobutyl groups, respectively, on their side chains were insoluble even in cold water. The water solubility of the resulting polymers was found to vary, depending on the molecular shapes as well as the side chain length of the alkyl groups in question. The copolymers consisting of NVVA, NVIBA, and NVA in water showed LCSTs sharply between 10 and 90°C, depending on changes in their comonomer content. It was found that the changes in LCST that are caused by the incorporation of comonomers are due to changes in the overall hydrophilicity of the polymer. © 1997 John Wiley & Sons, Inc. J Polym Sci A: Polym Chem 35: 3087–3094, 1997     

Disruptions in the crystallinity of poly(lauryl methacrylate) due to adsorption on silica

The effects of adsorption of poly(lauryl methacrylate) (PLMA), a side‐chain crystalline polymer, on silica were investigated. Fourier transform infrared spectroscopy and differential scanning calorimetry (DSC) measurements were made on both bulk and adsorbed PLMA. The reversible heat flow rates were observed as a function of temperature and the degree of crystallinity of the samples determined based on the broad melting transitions of the side chains in the surface samples. It was found that adsorption caused a disruption of the side‐chain crystallinity primarily in the tightly bound layer of the polymer, but did not significantly affect its glass transition temperature. A change in the packing of the hydrophobic side chains, as a result of adsorption, was also observed for the tightly adsorbed polymer. These results indicated that PLMA side chains in proximity to the silica surface have different properties from those in bulk PLMA. © 2017 Wiley Periodicals, Inc. J. Polym. Sci., Part B: Polym. Phys. 2018 , 56, 89–96     

Synthesis of polymers possessing tetraphenylethylene units by three‐component coupling reactions of poly(p‐phenylene ethynylene) derivative with aryl halides and phenylboronic acid

A derivative of poly(p‐phenylene ethynylene) was subjected to the palladium‐catalyzed three‐component coupling reactions with aryl halides and phenylboronic acid to obtain polymers having tetrasubstituted cis‐vinylene units. For example, 69% of the acetylene units in the prepolymer were converted to cis‐vinylene (i.e., tetrasubstituted cis‐vinylene) units using iodobenzene and phenylboronic acid (5 equiv each with respect to acetylene units). In the UV–vis absorption spectra of the resulting polymers, clear hypsochromic shifts of the absorption maxima were observed, while bathochromic shifts and suppression of the efficiency were observed in their photoluminescence spectra. © 2015 Wiley Periodicals, Inc. J. Polym. Sci., Part A: Polym. Chem. 2015 , 53, 787–791     

Specific features characterizing electrochemical synthesis of polyaniline conducted in the presence of poly(2-acrylamido-2-methyl-1-propanesulfonic acid) and the spectroelectrochemical characteristics of the obtained films

The electrochemical matrix polymerization of aniline in the presence of poly(2-acrylamido-2-methyl-1-propanesulfonic acid) (PAMPSA) is performed in conditions that lead to the formation of an interpolymer complex comprising polyaniline and PAMPSA of the 1: 2 composition. The acceleration of the process of polymerization of aniline in the presence of PAMPSA as compared with traditional electropolymerization of aniline in hydrochloric acid is caused by the association of aniline molecules with the sulfo groups of PAMPSA and by a high concentration of hydrogen ions in the vicinity of a molecule of PAMPSA. It is established for the first time ever that, in the initial stages of synthesis for both polymeric and low-molecular-weight acids, the rate of polymerization is substantially greater at a smaller concentration of the acid. The distinguishing feature of the initial stage of electropolymerization of aniline at a low acidity of the environment is a non-autocatalytic character of the process, which may exert a discernible influence on a complex of physicochemical properties of polyaniline, including electric conduction. Studying spectroelectrochemical properties of the obtained films shows practical identity of their spectra with the spectra of standard polyaniline.     

Effect of copolymerized butylene terephthalate chains on polymorphism and enzymatic degradation of poly(butylene adipate)

The introduction of aromatic butylene terephthalate (BT) units into the backbone chains of aliphatic poly(butylene adipate) (PBA) not only changes the mechanical performance of the resultant P(BA-co-BT) copolymers but also affects their biodegradability. Because of the polymorphism of PBA homopolymer, the copolymerized BT units may also influence the polymorphic crystal structure as well as the biodegradation behavior. In this work, three P(BA-co-BT) copolymers with BT contents as 10, 20, and 25 mol% were chosen to study their polymorphic crystal structure, thermal properties and enzymatic degradation by means of wide-angle X-ray diffraction (WAXD), differential scanning calorimetry (DSC) and gravimetric methods. The results reveal that the P(BA-co-BT) copolymers with BT contents below 25 mol% can form polymorphic crystal structures after melt-crystallization at different temperatures. However, the recrystallization and transformation of polymorphic crystals are strongly affected by the rigid BT units. The enzymatic degradation rates of P(BA-co-BT) copolymers decrease with increasing the BT contents. The influences of the BT units on the polymorphism and enzymatic degradation are discussed in terms of the motion of PBA chains that copolymerized with BT units. It has been concluded from the examination of solid-state microstructure that the influence of the aromatic BT units on the motion of biodegradable PBA chains heavily influences the biodegradability.     

High‐pressure‐synthesis of poly(isopropenyl alcohol) and its biocompatibilities

Free radical polymerization under ambient conditions gives very low‐molecular weight homopolymer of isopropenyl acetate (IPAc). On the other hand, poly (isopropenyl acetate) (PIPAc) with a weight average molecular weight over 10⁴ was found to be synthesized by high‐pressure (1 GPa) radical polymerization. Poly(isopropenyl alcohol) (PIPOH) was then derived from PIPAc by saponification. The structure and properties of PIPAc and PIPOH were investigated using X‐ray diffraction, thermal analyses, X‐ray photoelectron spectroscopy, and dynamic contact angles. Though PIPOH is insoluble in water, the surface free energy (55 mJ/m²) was comparable with that of poly(vinyl alcohol). To utilize the peculiar combination of “aqueous insolubileity and high hydrophilicity” of PIPOH, biocompatibilities of PIPOH surface was investigated. The PIPOH surface was found to show high repellencies to albumin adsorption, whole thrombogenesis, and cell adhesion. © 2008 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 47: 754–761, 2009     

Study on ketalization reaction of poly(vinyl alcohol) by ketones. VIII. kinetic study on acetalization and ketalization reactions of poly(vinyl alcohol)

The kninetics of acid-catalyzed acetalization and ketalization of poly(vinyl alcohol) (PVA) were systematically studied in completely homogeneous media with carefully selected solvents. Thus the acetalization reaction was run in water with six aldehydes [R₁CHO (R₁ = H, CH₃, C₂H₅, n-C₃H₇, i-C₃H₇, ClCH₂)], whereas the ketalization in dimethylslfoxide with 11 ketones [R₂CH₃CO (R₂ = CH₃, C₂H₅, n-C₃H₇, i-C₃H₇, n-C₄H₉, i-C₄H₉, tert-C₄H₉, C₆H₅CH₂, C₆H₅CH₂CH₂), cyclopentanone, and cyclohexanone]. The latter was difficult to proceed in aqueous media. Both reactions were reversible and bimolecular and, despite the use of different solvents, gave similar heats of reaction (7.5 kcal/mol) and activation energies (ca. 15 kcal/mol) except for the case of formaldehyde and chloroacetaldehyde; however the equilibrium constants at 25°C showed that the acetalization is thermodynamically much more favored than the ketalization (ca. 5000 vs. 0.01–0.9), probably because of steric hindrance of the ketone substrate. The rate constants of hydrolysis (reverse reactions) for the poly(vinyl acetal) and poly(vinyl ketal) followed the Hammett-Taft equation to give a single p* (=3.60) that is very close to that for the hydrolysis of diethyl acetal and ketal. From these and other data, it was concluded that the polymer hydrolysis, as well as PVA acetalization and ketalization, are all electrophilic reaction where the formation of hemiacetal or hemiketal is the rate-determining step. © 1996 John Wiley & Sons, Inc.     

Comparative study on post‐polymerization modification of C1 poly(benzyl 2‐ylidene‐acetate) and its C2 analog poly(benzyl acrylate)

The present study investigates the challenging approach of post‐polymerization modification on polymers with a sterically demanding reaction center. Therefore, the general possibility to functionalize polymethylene moieties was investigated. Poly(benzyl 2‐ylidene‐acetate) was synthesized by polymerization of benzyl 2‐diazoacetate utilizing [(L‐prolinate)Rh^I(1,5‐dimethyl‐1,5‐cyclooctadiene)] as a catalyst. Subsequently, the modification of C1 polymerized poly(benzyl 2‐ylidene‐acetate) with amines was analyzed and the obtained data set was compared with experimental data derived for the C2 analog poly(benzyl acrylate). This is the first study on post‐polymerization modification utilizing densely functionalized polymethylenes as starting materials. © 2015 Wiley Periodicals, Inc. J. Polym. Sci., Part A: Polym. Chem. 2016 , 54, 686–691     

Structure–property relationships of poly(vinyl alcohol). I. Influence of polymerization solvents and temperature on the structure and properties of poly(vinyl alcohol) derived from poly(vinyl acetate)

The solubility properties of poly(vinyl alcohol) (PVA) vary with the method of preparation of the poly(vinyl acetate) (PVAc) from which it is derived. PVAc was prepared with free-radical catalysts over a range of temperatures from ?78 to 90°C. with solvents of varying chain-transfer ability. The corresponding PVA samples varied in their resistance to dissolution in water. Their high-resolution proton nuclear magnetic resonance spectra showed on differences in tacticity. Data on 1,2-diol content showed only minor differences. Hence, the increase in resistance of PVA to dissolution in water arising from changes in chain-transfer activity of the solvent used in vinyl acetate polymerization is largely attributable to a decrease in molecular weight, and the increase in resistance of PVA to dissolution in water arising from a decrease in the temperature of the vinyl acetate polymerization is largely attributable to a decrease in both long and short branches. Evidently, with polar polymers having small side groups, tacticity is not the only factor influencing property variation; that is, variations in stereoregularity influence more the crystallinity of the sample as measured by density or x-ray methods than the ultimate crystallizability under conditions of mechanical and thermal treatment. In this regard polar polymers having small side groups differ from nonpolar polymers.     

Synthesis of poly(ester‐amide) dendrimers based on 2,2‐Bis(hydroxymethyl) propanoic acid and glycine

Water‐soluble, biodegradable, and biocompatible poly(ester‐amide) dendrimers with hydroxyl functional groups are synthesized from previously prepared AB₂ adduct of 2,2‐bis(hydroxymethyl) propanoic acid (bis‐MPA) and glycine as a repeating unit. Two esterification procedures using different coupling reagent/catalyst systems (DCC/DPTS or EDC/DMAP) are studied with respect to efficiency, ease of products purification, and quality of the final products. Both procedures have their own benefits and drawbacks, depending on dendrimer generation. The synthesized poly(ester‐amide) dendrimers as well as commercially available bis‐MPA dendrimers, poly(ester‐amide) hyperbranched polymer, and poly(vinyl alcohol) are used for preparation of solid dispersions of sulfonylurea antidiabetic drug glimepiride to improve its poor water‐solubility. In vitro dissolution studies show in comparison with pure glimepiride in crystalline or amorphous form, to the same extent improved glimepiride solubility for solid dispersions based on dendritic polymers, but not for poly(vinyl alcohol). The amount of glimepiride complexed with both dendrimer types increases with dendrimer generation. © 2014 Wiley Periodicals, Inc. J. Polym. Sci., Part A: Polym. Chem. 2014 , 52, 3292–3301     

New synthetic routes to poly(isothianaphthene). II. Mechanistic aspects of the reactions of phthalic anhydride and phthalide with phosphorus pentasulfide

The results of some mechanistic studies on the formation of poly(isothianaphthene) from phthalic anhydride and phthalide by reaction with phosphorus pentasulfide (P₄S₁₀) are described. Based on the observed intermediates during the polymerization and their reactivity, it is proposed that both reactions occur by a sequence of substitution (thionation), isomerization, and polymerization reactions. P₄S₁₀ is the most efficient reagent for the conversion of phthalic anhydride and phthalide, and Lawesson's Reagent (a commonly used thionating reagent) gives less satisfactory results. It is suggested that P₄S₁₀ assists the rate-determining step. Oxygen-containing monomers do not polymerize in the absence of a thionating reagent under the conditions for the synthesis of PITN, thereby keeping the incorporation of oxygen into the polymeric backbone to a minimum. © 1996 John Wiley & Sons, Inc.     

Synthesis and characterization of poly(1,4‐bis((E)‐2‐(3‐dodecylthiophen‐2‐yl)vinyl)benzene) derivatives

New amorphous semiconducting copolymers, poly(9,9‐dialkylfluorene)‐alt‐(3‐dodecylthienyl‐divinylbenzene‐3‐dodecylthienyl) derivatives (PEFTVB and POFTVB), were designed, synthesized, and characterized. The structure of copolymers was confirmed by H NMR, IR, and elemental analysis. The copolymers showed very good solubility in organic solvents and high thermal stability with high T_g of 178–185 °C. The weight average molecular weight was found to be 107,900 with polydispersity of 3.14 for PEFTVB and 76,700 with that of 3.31 for POFTVB. UV–vis absorption studies showed the maximum absorption at 428 nm (in solution) and 435 nm (in film) for PEFTVB and at 430 nm (in solution) and 436 nm (in film) for POFTVB. Photoluminescence studies showed the emission at 498 nm (in solution) and 557 nm (in film) for PEFTVB and at 498 nm (in solution) and 536 nm (in film) for POFTVB. The solution‐processed thin‐film transistors showed the carrier mobility of 2 × 10^?4 cm² V^?1 s^?1 for PEFTVB‐based devices and 2 × 10^?5 cm² V^?1 s^?1 for POFTVB‐based devices. © 2010 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 48: 3942–3949, 2010     

Thermodynamics of semi-interpenetrating polymeric networks based on crosslinked poly(cyanurate) and linear poly(urethane) in the temperature region from T → 0 to 350 K

The temperature dependences of the heat capacity of linear poly(urethane) (PU) (M _n = 4·10⁴), which was synthesized from 4,4′-diphenylmethane diisocyanate, oligo(butylene glycol adipinate) (M _n = 1000), and chain-elongating agent butane-1,4-diol, and three samples of related semi-interpenetrating polymeric networks containing 25, 50, and 75 wt.% of crosslinked poly(bisphenol A) cyanurate were studied in a region of 6–350 K by adiabatic vacuum calorimetry. Their combustion energies were determined in a calorimeter with a static bomb and an isothermic shell. The thermodynamic functions of the compounds under study for the temperature region from T → 0 to 350 K, enthalpies of combustion, and thermodynamic characteristics of formation from simple substances at T = 298.15 K and p = 0.1 mPa were calculated. The thermodynamic parameters of formation of the semi-interpenetrating networks were calculated. The dependences of the isotherms of the thermodynamic properties and thermodynamic compatibility of the semi-interpenetrating networks on their composition were determined. Published in Russian in Izvestiya Akademii Nauk. Seriya Khimicheskaya, No. 4, pp. 648–654, April, 2006.     

Synthesis and X-ray structural investigation of 1,3,5-tris[4-(2-propynyloxy)phenyl]benzene

Synthesis and X-ray structural investigation of 1,3,5-tris[4-(2-propynyloxy)phenyl]benzene (1) were carried out. Compound1 is a trifunctional monomer for the synthesis of cross-linked polymers and a model of a section of polymeric network of this kind. In a crystal, the molecule of1 is located on the threefold symmetry axis and has a propeller-like conformation (the dihedral angle between the central and peripheral benzene rings is 35°). An essential feature of the crystal structure of1 is the proximity of the ethynyl groups of the neighboring molecules, which may be favorable to cyclotrimerization in the crystal. The spatial prerequisite to this process is the simultaneous rotation of the neighboring molecules1 about their symmetry axes by 10°. The displacements of the atoms in the reacting groups should amount to 1.6–1.8 Å.Deceased March, 1993.Translated fromIzvestiya Akademii Nauk. Seriya Khimicheskaya, No. 9, pp. 1601–1605, September, 1993.     

Revisiting the crystallization of poly(2‐alkyl‐2‐oxazoline)s

Poly(2‐alkyl‐2‐oxazoline)s (PAOx) exhibit different crystallization behavior depending on the length of the alkyl side chain. PAOx having methyl, ethyl, or propyl side chains do not show any bulk crystallization. Crystallization in the heating cycle, that is, cold crystallization, is observed for PAOx with butyl and pentyl side chains. For PAOx with longer alkyl side chains crystallization occurs in the cooling cycle. The different crystallization behavior is attributed to the different polymer chain mobility in line with the glass transition temperature (T_g) dependency on alkyl side chain length. The decrease in chain mobility with decreasing alkyl side chain length hinders the relaxation of the polymer backbone to the thermodynamic equilibrium crystalline structure. Double melting behavior is observed for PButOx and PiPropOx which is explained by the melt‐recrystallization mechanism. Isothermal crystallization experiments of PButOx between 60 and 90 °C and PiPropOx between 90 and 150 °C show that PAOx can crystallize in bulk when enough time is given. The decrease of T_g and the corresponding increase in chain mobility at T > T_g with increasing alkyl side chain length can be attributed to an increasing distance between the polymer backbones and thus decreasing average strength of amide dipole interactions. © 2015 Wiley Periodicals, Inc. J. Polym. Sci., Part B: Polym. Phys. 2016 , 54, 721–729