Pendant Hydroxyl Research Articles

Polymerization kinetics of polyurethane and vinyl ester resin interpenetrating polymer networks by using Fourier transform infrared spectroscopy

Fourier transform infrared spectroscopy (FTIR) was applied to the study of polymerization kinetics of simultaneous interpenetrating polymer networks (SINs) composed of polyurethane (PU) and vinyl ester resin (VER), in which the pendent hydroxyl groups were capped with acetyl groups to minimize the possibility of chemical binding between the two networks. It was found that during the course of synthesis the two pairs of reactants interfere with each other in the SIN systems, giving rise to depressed reaction rates, although they follow different polymerization mechanisms. Increasing the reaction temperature could be more effective than increasing the free-radical initiator level with regard to the final conversions of both components. The reaction sequence could be varied through the amount of the step-growth polymerization catalyst and free-radical initiator as well as the reaction temperature adjustment. Using VER containing pendent hydroxyl groups could strongly affect the reaction kinetics of such SINs and lead to hybrid structures. The quick formation of one network would always depress the conversion of the other network in all SINs studied. © 1996 John Wiley & Sons, Inc.

Alternating Copolymers of Functional Alkenes with Carbon Monoxide

The alternating copolymerization of functional alkenes, CH2CH(CH2)xOH (x = 2, 3, 4, 9), CH2CH(CH2)xCOOH (x = 1, 2, 4, 8), and 4-allylanisole, with carbon monoxide was achieved by using [Pd(Me-DUPHOS)(MeCN)2](BF4)2 [Me-DUPHOS = 1,2-bis(2,5-dimethylphospholano)benzene] as the catalyst. The resultant polymers were optically active with isotactic sequences in the backbone. With most alkenes, the polymers had poly(1,4-ketone) and/or “regular” poly(spiroketal) (i.e., 1,6-dioxaspiro[4.4]nonane) enchainments. However, with 4-penten-1-ol and 3-buten-1-ol, the participation of the pendant hydroxyl group in intrachain reactions led to the formation of unusual polycyclic repeating units in the backbone. A comparison of [Pd(Me-DUPHOS)(MeCN)2](BF4)2 with [Pd(DPPP)(MeCN)2](BF4)2 [DPPP = 1,3-bis(diphenylphosphino)propane] indicated that the former was a significantly better catalyst for the alternating copolymerization of alkenols and alkenoic acids with carbon monoxide.

Characterization of the Network Structure o Epoxy Resins Cured with Active Esters

Abstract Epoxy resins cured with polyfunctional active esters have no pendant hydroxyl groups but pendant ester groups. Epoxy resins without hydroxyl groups are expected to have high electric resistance, low dielectric constant, and low hygroscopicity. In this paper, the thermal, viscoelastic, dielectric, and hygroscopic properties are described on the epoxy resins cured with active esters in comparison with those of the resins with pendant hydroxyl groups that are cured with conventional curing agents. The network structure of epoxy resins with pendant ester groups is much looser than that of the resins with pendant hydroxyl groups. This is attributed to the lack of hydrogen bonds and to steric hindrance and plasticization of more bulky ester groups in the resins cured with active esters.

Star‐shaped polymers by living cationic polymerization. VIII. Size and shape of star poly(vinyl ether)s determined by dynamic light scattering and computer simulation

AbstractThe sizes and shapes of star‐shaped poly(vinyl ether)s, prepared by living cationic polymerization, were studied by dynamic light scattering and molecular mechanics‐based computer simulation. The hydrodynamic radii (Rh) of star poly(isobutyl vinyl ether)s (4a; M̄w = 2.2 × 104 − 1.7 × 105) determined by dynamic light scattering were in the range from 30 to 90 Å in tetrahydrofuran or ethyl acetate. Consistent with the expected multiarmed architecture of 4a, the radius for a given number (f) of arms per molecule increased with the degree of polymerization [DP(arm)] of the arms, and for a fixed DP(arm), the radius increased with f. The relationship between arm number f and the “shrinking” factor h [Rh(star)/Rh(linear)] was consistent with multibranched structures for the star polymers. These results are supported by those for the molecular weight itself; the apparent weight‐average molecular weights by size‐exclusion chromatography are less than the corresponding absolute values by static light scattering. The dependence of h on f suggests some degree of asymmetry in the star shape. Similar results were also obtained by the computer simulation of potential energy‐minimized conformations of the arms, which implied almost spherical but slightly asymmetric shapes. The computer simulation also demonstrated that the star polymer (4b) with pendant hydroxyl groups in the arms is smaller in size than the corresponding alkyl (isobutyl) (4a) with the identical arm number and arm degree of polymerization. © 1995 John Wiley & Sons, Inc.

Synthesis of polytitanosiloxanes and their transformation to SiO2–TiO2 ceramic fibers

AbstractA one‐pot synthesis of polytitanosiloxanes (PTS) and its transformation to SiO2–TiO2 ceramic fibers were investigated. PTS was prepared by the hydrolysis of tetraethoxysilane followed by the reaction with bis(2,4‐pentanedionato)titanium diisopropoxide in methanol in 33–95 SiO2 mol %. PTS was considered to be a ladder‐ or sheet‐type polymer consisting of SiOSi and SiOTi linkages as a main chain with pendant hydroxyl and 2,4‐pentanedionato groups. SiO–TiO ceramic fibers were prepared by the pyrolysis of SiO2–TiO2 precursor fibers, which were prepared by the dry spinning of PTS followed by steam treatment. The tensile strength was 610 MPa for the SiO2–TiO2 fibers (SiO2/TiO2 = 20) after the pyrolysis at 7000C. © 1994 John Wiley & Sons, Inc.

Preparation and thermal properties of acrylic polymers with pendant spirobislactone groups

AbstractA series of acrylic terpolymers containing varying concentrations of crosslinkable glycidyl, spirobislactone, and hydroxyl pendant groups was prepared by radical chain polymerization. The glass‐transition temperatures and weight average molecular weights of the terpolymers span broad ranges and can be independently selected by control of monomer composition. Cross‐linking at 210°C was monitored by infrared spectroscopy. The rate and extent of reaction of spirobislactone groups were found to be greater than those for glycidyl groups. The activation energies of the spirobislactone and glycidyl reactions in the range between 160 and 210°C were calculated by Arrhenius treatment of the curing kinetics and found to be 31.0 ± 1.1 kJ mol−1 and 59.1 ± 1.2 kJ mol−1, respectively. The double ring opening reaction of the spirobislactone groups has no effect on the volume of the cross‐linked polymers. © 1994 John Wiley & Sons, Inc.

Interpenetrating polymer networks of polyurethane and epoxy

Interpenetrating polymer networks of polyurethane, based on poly(oxypropylene)triol grafted with polyacrylonitrile and epoxy, were prepared by a simultaneous polymerization technique. The mechanical properties and morphology of the networks were investigated. As the epoxy content increased, the tensile strength of the interpenetrating polymer networks or the graft networks (in which some grafting reaction has taken place between polyurethane and the pendant hydroxyl group of epoxy) decreased. The shifts of the loss modulus peaks of the interpenetrating polymer networks and the graft-IPNs were different and their tan δ peaks shifted to a high temperature as the epoxy content increased.

Macromolecular synthesis from saccharic lactones. Ring‐opening polyaddition of D‐glucaro‐ and D‐mannaro‐1,4:6,3‐dilactones with alkylenediamines

AbstractRing‐opening polyaddition of a saccharic acid dilactone prepared from D‐glucose, D‐glucaro‐1,4 : 6,3‐dilactone, with several alkylenediamines proceeded at room temperature with no catalyst. The resulting new polyamides carrying many pendant hydroxyl groups, poly(alkylene D‐glucaramide)s, were more amorphous and hydrophilic than the corresponding nylons having no hydroxyl groups, and were hydrolyzed more easily than the latter in an acidic condition. The ring‐opening ability of D‐mannaro‐1,4:6,3‐dilactone, which was another saccharic acid dilactone obtained from D‐mannitol, was found to be lower than that of the D‐glucaric analogue. © 1993 John Wiley & Sons, Inc.

A CHARMm Based Force Field for Carbohydrates Using the CHEAT Approach: Carbohydrate Hydroxyl Groups Represented by Extended Atoms

Abstract Computational studies of carbohydrates that do not consider explicit solvent molecules suffer from the strong tendency of the carbohydrate pendant hydroxyl groups to form intramolecular hydrogen bonds that are unlikely to be present in protic media. In this paper a novel approach towards molecular modelling of carbohydrates is described. The average effect of intra- and intermolecular hydrogen bonding is introduced into the potential energy function by adding a new (extended) atom type representing a carbohydrate hydroxyl group to the CHARMm force field; we coin the name CHEAT (Carbohydrate Hydroxyls represented by Extended AToms) for the resulting force field. As a training set for the parametrisation of CHEAT we used ethylene glycol, 10 cyclohexanols, 5 inositols, and 12 glycopyranoses for which in total 64 conformational energy differences were estimated using a set of steric interaction energies between hydroxyl and/or methyl groups on six-membered ring compounds as derived by Angyal (Angew. Chem., 8, 172-182, (1969)). The root-mean-square deviation between the estimated energy differences and the corresponding values obtained by our CHEAT approach amounts to 0.37 kcal/mol (n = 64). The CHEAT approach, which is claimed to calculate aqueous state compatible energetical and conformational properties of carbohydrates, is computationally very efficient and facilitates the calculation of nanosecond range MD trajectories as well as systematic conformational searches of oligosaccharides.

One‐step synthesis of functional polymers by polycondensation: Polyesters with pendant hydroxyl side groups from potassium malate or tartrate and 1,4‐dibromobutane

AbstractPolyesters with pendant hydroxyl side groups such as (R,S)‐ and (S)‐poly(tetramethylene malate)s and (R,R)‐poly(tetramethylene tartrate)s of moderately high molecular weights were prepared by polycondensation, at 105°C in 1‐methyl‐2‐pyrrolidone for 16 to 80 h, from potassium malate or tartrate and 1,4‐dibromobutane. It was shown by a detailed analysis of the 1H and 13C NMR spectra of the prepared polyesters that no branching occurs in the course of the reaction. The nature of the end‐groups was also clearly established by NMR spectroscopy. The presence of large cycles in the final products cannot be completely excluded.

Synthesis of hexacarbonyldicobalt-complexed thiacycloalkynes

Reaction of [Co2(µ-HOCR1R2CCCR1R2OH)(CO)6](R1= R2= H or Me; R1= H, R2= Me) with HS(CH2)nSH (n= 2–5) or HS(CH2)2OH in the presence of HBF4·OEt2 affords predominately monomeric hexacarbonyldicobalt-complexed thiacycloalkynes. In many cases, especially with the longer chain dithiols, dimeric compounds are also formed as minor products and in some cases higher oligomers have also been characterised. Reaction of [Co2(µ-HOCH2CCCH2OH)(CO)6] with HSCH2CH(OH)CH2SH affords complexed thiacycloalkynes with pendant hydroxyl functionalities. The monomeric complexes undergo carbonyl substitution with bis(diphenylphosphino)methane (dppm) and the X-ray crystal structure of [Co2(µ-CCH2SCH2CH2SCH2C)(µ-dppm)(CO)4] has been determined. The molecule contains a co-ordinated 1,4-dithiacyclooct-6-yne which adopts two conformations in the solid state. The IR, mass, 1H and 13C NMR spectra of the new compounds are discussed.

Electrodeposition properties of self‐crosslinking epoxy–amine cationic resin modified by polycaprolactone diol

AbstractA self‐crosslinking polycaprolactone diol (PCD)‐modified epoxy–amine adduct was prepared by first synthesizing the PCD‐modified epoxy resin from diglycidyl ether of bisphenol A (DGEBA), PCD and bisphenol A (BPA), then reacting the partially pendant hydroxyl groups of this modified resin with 2‐ethylhexanol half‐blocked with toluene diisocyanate (2‐EH half‐blocked TDI), and finally reacting the terminal epoxy groups with secondary amines such as N‐methyl ethanol amine (MEA) and di(2‐methylisobutylketimino‐ethyl)amine (DKI). This epoxy–amine adduct was neutralized by acetic acid and could be dispersed in deionized water to form a stable emulsion, which could be used for the electrodeposition coating. The effects of solid content, pH value, solvent content of the emulsion, bath temperature, and applied voltage on the deposition yield and the throwing power of the resin were investigated. Meanwhile, the optimum crosslinking condition of the deposition film was also studied. It was found that the electrodeposition properties of the emulsion derived from the modified epoxy resin are superior to those of emulsion derived from the unmodified DGEBA epoxy resin.

Facile synthesis of the nickel(II) complex of a new pendant arm macrocycle

The reaction of nickel(II), ethylenediamine, formaldehyde and primary amines has been shown to give the nickel(II) complex of the macrocycle (I)(1). We have now extended this synthesis to the preparation of the new macrocycle (2), by using ethanolamine as the primary amine. This reaction gives high yields of (2), with pendant hydroxyl groups which allow attachment to solid supports or incorporation into polymer systems.

Silanes as the interphase in adhesive bonds

Substantial films of polymerized γ-glycidoxytrimethyl silane were prepared and found to be mechanically very weak. It is suggested, by analogy with natural rubber, that their structure is a spiral with pendant hydroxyl groups along the core which are thus inaccessible. Reflectance spectroscopy of much thinner films of this silane indicated a loss of freedom of the hydroxyl groups as the thickness diminished. It is suggested that this is due to destruction of the spiral structure with consequent availability of the hydroxyl groups for hydrogen bonding to the oxide surface of the substrate.

Characterization of hydroxypropylcellulose–indomethacin grafts as a function of molecular weight

AbstractThe physical characterization of hydroxypropylcellulose–indomethacin grafts (HPC–IND) is described. Using size‐exclusion chromatography (SEC) and serial differential refractive index (dRI) and ultraviolet spectrophotometric (UV) detection methods, it was possible to characterize the chemical substitution of the HPC–IND graft. Using the acid chloride of IND as the reactive intermediate, the HPC–IND graft was synthesized. The amount of IND grafted onto the polymer as a function of the HPC molecular weight (MW) was then quantitatively estimated. It was found that the substitution of IND onto the HPC was not uniform, representing chemical heterogeneity of the first kind. Increasingly higher substitution (of IND to HPC) was observed as the MW decreased (<250,000 Daltons) for the HPC backbone. Lower, more uniform substitution was observed for the higher molecular weight regions of the HPC (>250,000 Daltons). Possible contributing factors affecting the observed nonuniform substitution include (1) the chain coiling of the HPC in solution, thus limiting the availability of the pendant hydroxyl groups, (2) nonuniform substitution of the hydroxypropyl moiety onto the cellulose backbone, and (3) steric effects resulting from the incorporation of the bulky aromatic drug molecule onto the backbone HPC.

Modification of polyurethane ureas containing allyloxy groups

Linear segmented polyurethane ureas containing allyloxy groups were modified by reaction with mercaptoethanol. The reaction was followed using elemental analysis and 1H NMR. The mechanical properties of these modified polymers were improved, and their hydrophilicity was enhanced. The polyurethane ureas modified by mercaptoethanol were further reacted with 4,4′-diphenylmethane diisocyanate and polyethyleneglycol to form comb-like blocks with pendant hydroxyl groups. These reactions were followed using 1H and 13C NMR. The modified polyurethane ureas were further characterized using SEC, mechanical analysis and water-uptake tests.

The photochemistry of pyran-4-ones: intramolecular trapping of the zwitterionic intermediate with pendant hydroxyl groups

ADVERTISEMENT RETURN TO ISSUEPREVArticleNEXTThe photochemistry of pyran-4-ones: intramolecular trapping of the zwitterionic intermediate with pendant hydroxyl groupsFrederick G. West, Peter V. Fisher, and C. A. WilloughbyCite this: J. Org. Chem. 1990, 55, 24, 5936–5938Publication Date (Print):November 1, 1990Publication History Published online1 May 2002Published inissue 1 November 1990https://doi.org/10.1021/jo00311a008RIGHTS & PERMISSIONSArticle Views265Altmetric-Citations30LEARN ABOUT THESE METRICSArticle Views are the COUNTER-compliant sum of full text article downloads since November 2008 (both PDF and HTML) across all institutions and individuals. These metrics are regularly updated to reflect usage leading up to the last few days.Citations are the number of other articles citing this article, calculated by Crossref and updated daily. Find more information about Crossref citation counts.The Altmetric Attention Score is a quantitative measure of the attention that a research article has received online. Clicking on the donut icon will load a page at altmetric.com with additional details about the score and the social media presence for the given article. Find more information on the Altmetric Attention Score and how the score is calculated. Share Add toView InAdd Full Text with ReferenceAdd Description ExportRISCitationCitation and abstractCitation and referencesMore Options Share onFacebookTwitterWechatLinked InReddit PDF (341 KB) Get e-AlertsSupporting Info (1)»Supporting Information Supporting Information Get e-Alerts

Reactively Curable Rubbers—I: Diene Elastomers with Pendant Isocyanate and/or Hydroxyl Functionality

Abstract In conclusion, we have demonstrated that modified diene elastomers containing active hydrogens and/or blocked-isocyanate derivatives can be crosslinked (cured) by three distinct methods. These methods include: 1. reaction of polymer-bound active hydrogens with monomeric polyisocyanates (Type I), 2. reaction of polymer-bound isocyanates with compounds containing two or more active hydrogens (Type II), and 3. reaction between polymer segments that contain both polymer-bound isocyanates and active hydrogens (Type III). Additionally, we have shown that the new polymerizable blocked-isocyanate derivatives (Type II and III systems) can be readily incorporated into SBR and NBR elastomers by standard emulsion-polymerization techniques. The degree and distribution of these monomers within the elastomer matrix were shown to be controlled by knowledge of their reactivity ratios. Furthermore, we have shown that the processing and properties of these systems can be readily controlled by the proper combination of isocyanate blocking group, active-hydrogen component, and catalyst. In many cases, these modified elastomers can be coagulated, dried, compounded, and cured using methods common to the rubber industry. Although not optimized, we have also shown that useful vulcanizates can be produced from extremely simple recipes. Conventional acceleration systems e.g., sulfur, accelerator, zinc oxide, are eliminated. The resulting urethane or urea crosslinks are remarkably durable under both thermal and hydrolytic conditions. Obviously, the possibilities for these uniquely reactive elastomers have not been exhausted. Many other intriguing applications of this technology are currently being explored. These applications will be the subject of future publications.

Synthesis of functionalized linear poly(divinylbenzene). III. Synthesis of polymeric delocalized carbanion of poly(divinylbenzene) and its reactions

AbstractA polymeric delocalized carbanion of poly(divinylbenzene) [poly(DVB)] (2) was obtained by the proton abstraction with alkyllithium from the acidic methine moieties (HA) of linear poly(DVB) (1), which was prepared by the polymerization of DVB initiated by acetyl perchlorate. The formation of polyanion 2 was confirmed by UV–visible spectroscopy (λmax = 630 nm) and the reaction with methyl iodide to give methylated poly(DVB). Delocalized polyanion 2 reacted with various electrophilic reagents in THF at 60°C, to yield poly(DVB) derivatives having pendant trimethylsilyl, vinyl, vinyloxyl, hydroxyl, and carboxyl groups. Proton abstraction with base and subsequent reactions with electrophiles were also studied with the linear unsaturated dimer of styrene (1,3‐diphenyl‐1‐butene), as a model for poly(DVB) 1.

The synthesis of biodegradable polymers with functional side chains

AbstractTrifunctional hydroxy‐terminated oligomeric polyesters, Mn 500, 1000, and 2000, were prepared by initiating ring‐opening copolymerization of δ‐valerolactone and ε‐caprolactone with glycerol. The prepolymers were converted to crosslinked polyester‐urethanes by their reaction with hexane‐1,6‐diisocyanate in proportions corresponding to 70, 80, 90, and 100% of the hydroxyl content. The moduli of the resulting elastomers varied between 0.12 MPa and 3.83 MPa, and the elongation at break between 60 and 2000%. The residual hydroxyl groups were derivatized by heterogeneous reaction with chloroacetic anhydride or excess hexane‐1,6‐diisocyanate, and these and further transformations of the functional groups were verified by infrared spectroscopy and electron probe x‐ray microanalysis. A second series of hydroxy‐substituted elastomers was synthesized by copolymerization of δ‐valerolactone, ε‐caprolactone, and 4‐(t‐butyldimethylsilyloxy)‐ε‐caprolactone, using different amounts of 2,2‐bis(caprolacton‐4‐yl)propane as the crosslinking agent; removal of the t‐butyldimethylsilyl group to liberate pendant hydroxyl groups was achieved with acetic acid but not fluoride ion. The hydroxylated polyester (but not the polyesterurethanes) was shown to undergo enzymatic surface erosion in rabbit. The biodegradation data were compared with results previously obtained with low‐modulus elastomeric polyesters.