Synthesis of linear and hyperbranched sugar‐grafted polysiloxanes using N‐hydroxysuccinimide‐activated esters

A straightforward method for the preparation of polysiloxanes grafted with carbohydrate side groups is described. Two kinds of backbones have been functionalized, namely one‐dimensional, linear polysiloxanes, and hyperbranched poly(siloxysilane)s based on cyclotetrasiloxanes. The method enables us to keep a good integrity of the polysiloxane backbone. The introduction of intermediate activated esters as side groups on the polysiloxane backbone ensures a complete homogeneity of the reaction medium during sugar grafting in dimethyl sulfoxide, and consequently an easy grafting with the unprotected amino sugar. Solubility of the resulting polysiloxanes has been tested in various solvents. The sugar‐grafted polysiloxanes are good candidates for applications such as silicone formulations, hydrophilic silicone elastomers, interactions with metallic nanoparticles, and suspension stabilization, or as starting point for the design of more complex polysiloxanes for molecular recognition. © 2013 Wiley Periodicals, Inc. J. Polym. Sci., Part A: Polym. Chem. 2013, 51, 3607–3618     

Diels–Alder reaction of anthracene on grafted polysiloxane and cylindrical carbosilane dendrimer

Anthracene‐grafted polysiloxane was prepared by the dehydrocoupling between linear siloxane polymers and anthracenecarbinol. The cylindrical type of dendritic polysiloxane was prepared up to the second generation by the hydrosilation between polysiloxane and vinyltrichlorosilane, and the continual addition of allyl alcohol. The anthracene groups on cylindrical dendrimers were prepared by the reaction of Si? Cl bonds on the polymer and anthracenecarbinol. The Diels–Alder reaction of anthracene moieties on polysiloxane and maleimide derivatives, maleic acid anhydride, and 1,4‐quinone derivatives was carried out under mild conditions. The polymers prepared were characterized by NMR and gel‐permeation chromatography. Copyright © 2005 John Wiley & Sons, Ltd.     

Polysiloxanes with chlorobenzyl groups as precursors of new organic‐silicone materials

Various polysiloxanes bearing chlorobenzyl side groups were synthesized by the hydrolytic polycondensation of the 73:27 mol/mol mixture of [2‐(4‐chloromethylphenyl)ethyl] methyldichlorosilane and [1‐(4‐chloromethylphenyl)ethyl] methyldichlorosilane followed by the cationic equilibration or coequilibration with octamethylcyclotetrasiloxane, D₄. 1,3‐Divinyltetramethyl‐disiloxane was used as the chain end blocker to obtain a vinyl–Si ended chlorobenzyl‐substituted polysiloxane. In some cases, the polymer was additionally treated with dimethylvinylchlorosilane to achieve full substitution of chain ends by the vinyl group. Cohydrolysis of the chlorobenzylic monomer mixture with dimethyldichlorosilane was also practiced. Multiblock copolymers were obtained by polyhydrosilylation of the α,ω‐divinylsilyl chlorobenzyl‐substituted polysiloxanes with α,ω‐dihydrosilyl polydimethylsiloxanes. All these polymers and copolymers containing reactive chlorobenzylic groups were demonstrated to be convenient precursors of functional polysiloxanes of potential practical use. Some specific functional groups, such as quaternary ammonium salt groups of biocidal activity or azobenzene groups making the polymer sensitive to external stimuli by light, may be readily generated on polysiloxane under mild conditions. The chlorobenzylic substituted polysiloxanes may be also used as macroinitiators of the atom transfer radical polymerization, to obtain polysiloxanes with grafted organic polymers, such as styrene, 4‐chloromethylstyrene, and n‐butylacrylate. © 2004 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 42: 1682–1692, 2004     

Photografting of polymers onto nanosized silica surface initiated by eosin moieties immobilized onto the surface

The photograft polymerization of various vinyl monomers onto nanosized silica surfaces was investigated. It was initiated by eosin moieties introduced onto the silica surface. The preparation of the silica with eosin moieties was achieved by the reaction of eosin with benzyl chloride groups on the silica surface.These were introduced by the reaction of surface silanol groups with 4‐(chloromethyl)phenyltrimethoxysilane in the presence of t‐butyl ammonium bromide as a phase‐transfer catalyst. The photopolymerization of various vinyl monomers, such as styrene, acrylamide, acrylic acid, and acrylonitrile was successfully initiated by eosin moieties on the silica surface in the presence of ascorbic acid as a reducing agent and by oxygen. The corresponding polymers were grafted from the silica surface. The grafting efficiency (percentage of grafted polymer to total polymer formed) in the photoinitiation system was much larger than that in the radical polymerization initiated by surface radicals; these radicals were formed by the thermal decomposition of azo groups introduced onto the silica surface. It was found that the polymer‐grafted silica gave stable dispersions in good solvents of grafted polymer and the wettability of the surfaces can be easily controlled by grafting of polymers. © 2004 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 43: 600–606, 2005     

Use of hydrolyzed chlorosilanes for the preparation of high resolution glass capillary columns

Summary A new procedure for the preparation of high resolution open tubular glass capillary columns is described. This procedure involves the preparation of polysiloxane polymers obtained by alkaline hydrolysis of alkyl chlorosilane. The mixture of polysiloxane polymers is then coated on the wall of previously HCl treated glass capillary columns using a dynamic method. A base-catalysed reaction using gaseous ammonia, applied to the coated polymers leads to a stable chemically bonded stationary phase, with non-polar characteristics. This type of column is easier to prepare than conventional ones and exhibits excellent chromatographic properties, both with regard to their resolution, stability and reproducibility. The flexibility of this method permits the use of other types of commercially available chlorosilanes (i.e. methylphenyl chlorosilane) to prepare polar polysiloxane polymers suitable for analysis of complex biochemical mixtures, such as steroid metabolites.     

Ring‐opening grafting polymerization of cyclic monomers onto human hair

Natural human hair was successfully modified by the graft polymerization of trimethylene carbonate, β‐propiolactone, ε‐caprolactone, glycidol, ε‐caprolactam, and 5,5‐dimethyl‐1,3‐dioxane‐2‐thione. In contrast, we could not modify natural human hair by the graft polymerization of oxetane under similar conditions. The model reaction suggested that the main initiating species in these polymerizations were the amino, thiol, and hydroxyl groups in hair, which could induce ring‐opening polymerization. Among the tested monomers, β‐propiolactone was most effective for hair modification with its graft polymer, whose concentration was as high as 0.5 g/g of hair though polymerization under mild conditions. The effects of the hair pretreatment and polymerization temperature on the weight ratio of the grafted polymers were also investigated. Hair modified by grafted polymers was characterized with scanning electron microscopy and Fourier transform infrared measurements. © 2007 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 45: 736–744, 2007     

New poly(arylene ether)s with pendant phosphonic acid groups

Soluble brominated poly(arylene ether)s containing mono‐ or dibromotetraphenylphenylene ether and octafluorobiphenylene units were synthesized. The polymers were high molecular weight (weight‐average molecular weight = 115,100–191,300; number‐average molecular weight = 32,300–34,000) and had high glass‐transition temperatures (>279 °C) and decomposition temperatures (>472 °C). The brominated polymers were phosphonated with diethylphosphite by a palladium‐catalyzed reaction. Quantitative phosphonation was possible when 50 mol % of a catalyst based on bromine was used. The diethylphosphonated polymers were dealkylated by a reaction with bromotrimethylsilane in carbon tetrachloride followed by hydrolysis with hydrochloric acid. The polymers with pendant phosphonic acid groups were soluble in polar solvents such as dimethyl sulfoxide and gave flexible and tough films via casting from solution. The polymers were hygroscopic and swelled in water. They did not decompose at temperatures of up to 260 °C under a nitrogen atmosphere. © 2001 John Wiley & Sons, Inc. J Polym Sci Part A: Polym Chem 39: 3770–3779, 2001     

Aromatic poly(1,3,4‐oxadiazole)s and poly(amide‐1,3,4‐oxadiazole)s containing ether sulfone linkages

Polyhydrazides and poly(amide‐hydrazide)s were prepared from two ether‐sulfone‐dicarboxylic acids, 4,4′‐[sulfonylbis(1,4‐phenylene)dioxy]dibenzoic acid and 4,4′‐[sulfonylbis(2,6‐dimethyl‐1,4‐phenylene)dioxy]dibenzoic acid, or their diacyl chlorides with terephthalic dihydrazide, isophthalic dihydrazide, and p‐aminobenzhydrazide via a phosphorylation reaction or a low‐temperature solution polycondensation. All the hydrazide polymers were found to be amorphous according to X‐ray diffraction analysis. They were readily soluble in polar organic solvents such as N‐methyl‐2‐pyrrolidone and N,N‐dimethylacetamide and could afford colorless, flexible, and tough films with good mechanical strengths via solvent casting. These hydrazide polymers exhibited glass‐transition temperatures of 149–207 °C and could be thermally cyclodehydrated into the corresponding oxadiazole polymers in the solid state at elevated temperatures. Although the oxadiazole polymers showed a significantly decreased solubility with respect to their hydrazide prepolymers, some oxadiazole polymers were still organosoluble. The thermally converted oxadiazole polymers had glass‐transition temperatures of 217–255 °C and softening temperatures of 215–268 °C and did not show significant weight loss before 400 °C in nitrogen or air. For a comparative study, related sulfonyl polymers without the ether groups were also synthesized from 4,4′‐sulfonyldibenzoic acid and the hydrazide monomers by the same synthetic routes. © 2001 John Wiley & Sons, Inc. J Polym Sci Part A: Polym Chem 39: 2271–2286, 2001     

Modification and Dispersion of the Polysiloxane Materials with Perfluorocarbon Groups and Cationic Side Chains

Novel polysiloxane material modified with perfluorocarbon groups and quaternary cationic side chains was synthesized by ring-opening polymerization of cyclosiloxane and graft reaction. The polysiloxane polymers containing pendant groups were the polysiloxanes modified with amino group, perfluorocarbon side chain, tertiary and perfluorocarbon side chains, or quaternary cationic and perfluorocarbon groups. The yields of the modified polymers were 94.2%, 86.7%, 88.4%, 82.5%, respectively. FTIR, ¹H NMR, ¹³C NMR, and ¹⁹F NMR were used to characterize the structures of the polysiloxane materials. The dispersion technology of the polysiloxane materials was investigated. The polysiloxane material modified with perfluorocarbon and cationic groups imparted high surface activity. The polyesters treated with the polymers had good repellency to water.     

Synthesis of ferrocene-grafted poly(p-phenylene-ethynylenes) and control of electrochemical behaviors of their thin films

New ferrocene-coated poly(p-phenylene-ethynylenes) (PPEs) with end capping groups of protected thiol were prepared by a palladium-catalyzed Sonogashira coupling reaction. Ferrocene groups were covalently attached to polymers A and B through ethylene oxide tethers and to polymer C through methylene tethers. Polymers A and B are soluble in common solvents such as tetrahydrofuran (THF), chloroform, methylene chloride, acetone, dimethylformamide (DMF), and dimethyl sulfoxide (DMSO), and polymer C is soluble in toluene, THF, chloroform, and methylene chloride. Polymers A-C display low quantum yield, caused by electron-transfer quenching of ferrocene groups as electron donors. The polymer thin films were prepared through incubation of gold electrodes in THF solutions containing the polymers for 2 days. Ferrocene in thin films of polymers A and B display significantly faster electron-transfer rate than that of polymer C. Hydrophilic ethylene oxide side chains of polymers A and B decrease formal potential of tethered ferrocene groups because of electron-donating effect from ethylene oxide side chains, which stabilizes the ferrocenium ion and leads to a cathodic shift of the redox wave.     

Surface grafting of cobalt complexes on polymeric supports: Evidence for site isolation and applications to reversible dioxygen binding

Imprinted polymers were synthesized using the surface‐grafting technique with [Co(III) 1 (vpy)(dmap)]PF₆ { 1 , bis[2‐hydroxy‐4‐(4‐vinylbenzyloxy)benzaldehyde]ethylene‐diimine; vpy: 4‐vinylpyridine; dmap: N,N′‐dimethyl‐4‐aminopyridine} as the template. The metallated sites were probed using spectroscopic techniques including UV–vis, Fourier transform infrared, and electron paramagnetic resonance (EPR) spectroscopies to investigate the site architecture and isolation of the immobilized sites in the surface‐grafted polymers. EPR studies showed a distribution of four and five coordinated sites similar to the bulk copolymers, and the surface‐grafted polymer showed reversible binding to dioxygen in multiple cycles. Both results indicated site isolation in the surface‐grafted polymers analogous to the bulk polymers. Although the dioxygen binding in surface‐grafted polymers is reversible, the spin density decreases to 50% in the third cycle as opposed to bulk copolymers. This indicates that the sites are more heterogeneous and more exposed to the environment than the analogous sites in bulk copolymers. © 2001 John Wiley & Sons, Inc. J Polym Sci A: Polym Chem 39: 888–897, 2001     

Surface free energy of ladderlike polyepoxysiloxane–diamine reaction systems

We studied three kinds of ladderlike polyepoxysiloxanes, which have different side groups grafted on the ladderlike backbones. 1,3‐Bis(aminopropyl)tetramethyl disiloxane (diamine) was used as the curing agent. The reaction between ladderlike polyepoxysiloxanes and diamine was investigated by contact angle measurements and surface free energy study. Several factors such as diamine amount, reaction time, and temperature can affect the systems' surface tension (or surface free energy), which were determined by two‐liquid geometric and three‐liquid acid‐base methods. The experimental results showed that an increase in the diamine amount in the reaction systems results in an increase in the polar part of surface free energy because of electron donate characteristics of the diamine. However, because epoxy (electron acceptor) and diamine (electron donor) react fast at elevated temperatures, increasing reaction temperature decreases the polar part of the surface free energy, while increases the nonpolar part of the surface free energy. The evolution of surface free energy with time for various epoxy–diamine reaction systems at various temperatures has also been studied. It was found that it took a relatively long time (50–60 h) to reach the equilibrium state. The experimental results can be well interpreted by the epoxy–diamine reaction mechanism and van Oss–Good's Lewis acid‐base theory. © 2000 John Wiley & Sons, Inc. J Polym Sci B: Polym Phys 38: 1449–1460, 2000     

Toward efficient nanoporous catalysts: controlling site-isolation and concentration of grafted catalytic sites on nanoporous materials with solvents and colorimetric elucidation of their site-isolation

We report that the polarity and dielectric constants of solvents used for grafting organosilanes on mesoporous materials strongly affect the concentration of grafted organic groups, the degree of their site-isolation, and the catalytic properties of the resulting materials. Polar and nonpolar organosilanes as well as polar-protic, dipolar-aprotic, and nonpolar solvents were investigated. Polar-protic solvents, which have high dielectric constants, resulted in smaller concentrations ( approximately 1-2 mmol/g) of polar organic groups such as 3-aminopropyl groups, higher surface area materials, site-isolated organic groups, and more efficient catalytic properties toward the Henry reaction of p-hydroxybenzaldehyde with nitromethane. On the other hand, dipolar-aprotic and nonpolar solvents resulted in larger concentrations ( approximately 2-3 mmol/g) of grafted polar functional groups, lower-to-higher surface area materials, more densely populated catalytic groups, and poor-to-efficient catalytic properties toward the Henry reaction. Both the polar-protic and dipolar-aprotic solvents resulted in significantly lower concentration of grafted groups for nonpolar organosilanes such as (3-mercaptopropyl)trimethoxysilane compared to corresponding grafting of the polar amino-organosilanes. The relationship between the solvent properties and the percentage and degree of site-isolation of the grafted functional groups was attributed to differences in solvation of the organosilanes and silanols in various solvents and possible hydrogen-bonding between the organsilanes and the solvents. The degree of site-isolation of the amine groups, which affect the material's catalytic properties, was elucidated by a new colorimetric method involving probing of the absorption maxima (lambdamax) on the d-d electronic spectrum of Cu2+ complexes with the amine-functionalized materials and the colors of the samples. The absorption lambdamax and the colors of the materials were found to be uniquely dependent on the type of solvents used for grafting the organoamines. For instance, the monoamine- and diamine-functionalized samples grafted in methanol resulted in pale blue and light purple colors with lambdamax at approximately 720 and 650 nm, respectively. These correspond to CuNO5 and CuN2O4 structures, respectively, which are indicative of the presence of site-isolated organoamines in samples grafted in methanol. The monoamine and diamine samples grafted in toluene resulted in purple and deep purple colors with lambdamax at approximately 590 and 630 nm, respectively. These correspond to CuN2O4 and CuN4O2, which are indicative of the presence of closely spaced organoamines in samples grafted in toluene. The samples grafted in isopropanol gave colors and lambdamax intermediate between those of samples grafted in toluene and methanol.     

Grafting of hyperbranched poly(amidoamine) onto waste tire rubber powder and its potential application as the curing agent for epoxy resin

To realize the high‐valued application of waste tire rubber (WTR), hyperbranched poly(amidoamine) (PAMAM) were synthesized from the surface of WTR powders to endow its chemical reactivity. The hyperbranched PAMAM‐grafted WTR powders containing a large amount of amine groups on their surface were obtained through “divergent procedure.” First, methyl methacrylate‐grafted WTR powders (MMA‐g‐WTR) were prepared by ozone‐induced grafting polymerization. Afterwards, Michael reaction and subsequent amidation reactions were carried out repetitively to obtain hyperbranched PAMAM chains grafted from the surface of the MMA‐g‐WTR powders. The resulting hyperbranched PAMAM‐grafted WTR powders exhibit good dispersibility in water. Fourier transform infrared spectroscopy, X‐ray photoelectron spectroscopy, and thermogravimetric analysis demonstrate the successful grafting of hyperbranched PAMAM on WTR surface. The hyperbranched PAMAM‐grafted WTR powder could be utilize as curing agent and potential toughener for epoxy resin due to abundant amine groups and elastomeric feature of WTR. Differential scanning calorimetry shows that the hyperbranched PAMAM‐grafted WTR powders can be used as effective curing agent for epoxy resin. Copyright © 2011 John Wiley & Sons, Ltd.     

Generation of radical species on polypropylene by alkylborane‐oxygen system and its application to graft polymerization

Graft polymerization of ethyl acrylate and n‐butyl acrylate onto surface of polypropylene (PP) beads (diameter: 3.2 mm) were carried out by using a redox system composed of triethylborane (Et₃B) and molecular oxygen in air. The amounts of the grafted polymers increased by prolonging a period of soaking PP beads in a solution of Et₃B in hexane, a less polar solvent of which affinity with PP would be higher than that of tetrahydrofuran, a highly polar solvent. These results implied that the present graft polymerization involved: (1) interpenetration of Et₃B into the surface area with the aid of hexane as a solvent, (2) its aerobic oxidation to generate a radical species, (3) abstraction of proton from PP by the radical species, and (4) initiation of polymerization from the resulting radical on the PP surface. Besides the acrylates, acrylic acid, and glycidyl methacrylate were also grafted onto the surface of PP to endow it with carboxyl and epoxy moieties, respectively. © 2009 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 47: 6163–6167, 2009     

Mechanism of the grafting of organosilanes on mineral surfaces

The grafting of organosilyl groups in the interlamellar space of certain crystalline silicic acids, such as H-magadiite, occurs when the interlayer spaces have been expanded previously by intercalation of some polar organic substances. The interlamellar Si-OH groups are then accessible to silylating reagents and Si-O-Si bridges form between the silicic acid surface and the organic groups.The grafting reaction is controlled by a diffusion mechanism: desorption of the polar organic guest molecules has to occur simultaneously with the diffusion of the reacting molecules into the interlayer space.The resulting materials are organosilicic compounds which retain the lamellar structure of the starting crystalline silicic acids. Their surface properties are determined by the grafted groups.Part I: This Journal 256:135 (1978); Part II: This Journal 257:178 (1979).     

Synthesis of gold nanocomposite via chemisorption of gold nanoparticles with poly(p‐methylstyrene) containing multiple bonding groups on the chain side

Styrenic nanocomposite containing gold nanoparticles (AuNPs) has been synthesized by anchoring polymer molecules containing multiple functional groups onto the gold surface. p‐Methylstyrene was first anionically polymerized and the resulting polymer was chlorinated with sodium hypochlorite in the presence of a phase transfer catalyst. The chlorinated poly(p‐methylstyrene) was next reacted with methylthiomethyllithium, which had been prepared via a metalation reaction of dimethyl sulfide with n‐butyllithium, to form a styrenic polymer containing thioether groups on the sides of the molecule. These thioether groups on the chain sides afforded more chemisorption sites per molecule to AuNPs. The nanocomposite was analyzed using NMR, TEM, UV‐VIS, TGA, and XPS. © 2005 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 43: 4710–4720, 2005     

New piperazine‐based polymerizable monoquaternary cationic surfactants: Synthesis,polymerization, and swelling characteristics of gels

Monoquaternary cationic polymerizable surfactants of type N‐acryloyl‐N′‐methyl‐N′‐alkyl piperazinium bromide based on piperazine heterocycle was synthesized by reacting N‐acryloyl‐N′methyl piperazine with the corresponding n‐alkyl bromide (decyl, dodecyl, tetradecyl, and hexadecyl) in anhydrous acetone at room temperature. The resulting surfactants were deliquescent to display any sharp melting points. The surface activity was studied by surface tension measurements. Due to the complex head group geometry of these surfactants, the critical micelle concentration value was high in comparison to the analogous alkyltrimethyl ammonium bromides of similar alkyl chain length. The surfactants were polymerized by micellar (in water) and isotropic (in benzene) conditions and the resulting polymers were characterized by solubility and viscosity studies. The polymers prepared in water showed higher viscosity than the ones prepared in benzene as a result of micellar aggregation in water. The reduced viscosity of the polymers in polar solvents such as methanol and dimethyl formamide (DMF) showed polyelectrolyte‐like behavior, whereas nonelectrolyte behavior was observed in chloroform. pH‐responsive hydrogels were prepared by polymerizing the surfactants in the bicontinuous phase of a microemulsion. The resulting polymers did not exhibit any definite micro/nanostructure due to cross‐polymerization of the hydrophilic oil in the bicontinuous network structure. The gels were highly responsive to changes in pH of the medium and showed high‐swelling degree in acidic media owing to the protonation of the tertiary nitrogen of the piperazine ring. © 2009 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 47: 2059–2072, 2009     

Multiwalled Carbon Nanotubes Functionalized by Hyperbranched Poly(urea‐urethane)s by a One‐Pot Polycondensation

Summary: Hyperbranched poly(urea‐urethane)‐functionalized multiwalled carbon nanotubes (MWNT‐HPUs) have been synthesized by a one‐pot polycondensation of tolylene 2,4‐diisocyanate and diethanolamine in the presence of MWNTs terminated with multiple hydroxy groups. FT‐IR, Raman, ¹H NMR, and ¹³C NMR spectra reveal that the HPU trees are covalently grafted onto the MWNT surfaces. After a high density of HPU trees (83.5 wt.‐%) is attached to the MWNTs, core‐shell nanostructures with MWNTs as the core and the HPU trees as the shell are formed. A loose and uniform nanotube network can be observed by TEM, SEM, and AFM. The resulting MWNT‐HPUs are soluble in polar solvents such as dimethylformamide, dimethylacetamine, 1‐methyl‐2‐pyrrolidinone, and dimethyl sulfoxide.

Hyperbranched poly(urea‐urethane)s functionalized multiwalled carbon nanotubes.     

Properties of ABA and BA polysiloxane amphiphiles modified by polyether

To investigate the effect of content of polyether (F400) grafted on the properties of polysiloxane amphiphiles, polyether was grafted on the polysiloxane by hydrosilylation reaction with H₂PtCl₆ catalyst. The modified polysiloxanes were divided into two types; moreover, the ratio of polyether and polysiloxane was 1:1 or 1:2. The first one was similar to the conventional surfactant structure that is BA polysiloxane amphiphile, which own one hydrophobic chain and one hydrophilic group. Another one was ABA polysiloxane amphiphile, which possess one hydrophobic chain and two hydrophilic groups at the terminal. In our work, we compared the property of modified polysiloxanes with various contents of polyether in aqueous solution at room temperature to analyze the impact of polyether content on siloxane surfactants. The conclusion was that siloxane amphiphiles possess good solubility, high surface activity, and excellent spreading property.