Trifunctional Alcohols Research Articles

Synthesis of multifunctional 4-hydroxymethyl 2-oxazolidinones from glycidyl carbamate derivatives catalyzed by bicyclic guanidine

4-Hydroxymethyl 2-oxazolidinones have been successfully synthesized under mild conditions by the intramolecular cyclization of glycidyl carbamate derivatives with a bicyclic guanidine as the efficient catalyst. This reaction system, which is also applicable to the multifunctional compounds, can provide bi- and tri-functional alcohols having oxazolidinone moieties.

Influence of different polyol segments on the crystallisation behavior of polyurethane elastomers measured with DSC and DMA experiments

Polyurethane elastomers are polymers that exhibit both outstanding stability and flexibility and are commonly used in the sector of building and construction to absorb vibrations. Long-chained linear molecules, more precisely macrodiols, are used as the soft phase within the elastomer. The tendency of the used polyetherols to crystallise within the polymer between −40 and + 30 °C, depending on the molecule's chain length, is a major disadvantage since consistent properties over a broad temperature range are desired to have no limitations considering the elastomers' application fields. In this work, crystallisation phenomena in polyurethane elastomers due to the long-chained polyetherol components were investigated in detail with DSC and DMA experiments. Possible measures to reduce these phenomena by changing the chemical constitution, were defined. Two kinds of short-chained polyols were introduced into the system to be combined with the long-chained polyetherol component, acting as diluents and creating different networks. As a bifunctional alcohol, 1,4-butanediol was chosen, creating a larger number of hard phases (physical cross-links) within the polymer. Glycerol was used as a trifunctional alcohol, responsible for covalent threedimensional linkages (chemical cross-links). The addition of 1,4-butanediol did not eliminate, but reduced the crystallisation tendency of the polyetherol component and led to a higher storage modulus above room temperature. If a certain amount of glycerol is added to the polymeric system, it prevents the cold crystallisation. Furthermore, glycerol reduced the drop of the storage modulus at elevated temperatures due to the chemical cross-links.

Synthesis and Characterization of Anionic Polyurethane Dispersants for Waterborne Paints

Anionic polyurethane dispersants APUDs were used as dispersing agents in formulation of waterborne paints. The APUDs were synthesized by three steps. In the first step, macromonomer diisocyanate having carboxylic acid was prepared by isophorone diisocyanate IPDI, dimethylol propionic acid DMPA in presence of acetone as solvent and dibutyltin dilaurate DBTDL as catalyst. Then, carboxylic polyurethane was prepared by reaction macromonomer diisocyanate having carboxylic acid groups with alcohols. In this work, alcohols were 1,4-butanediol and 1,6-hexanediol as difunctional alcohols, trimethylol propane as trifunctional alcohol and pentaerythritol as tetrafunctional alcohol. The final step involved neutralization and dispersion in water, where acidic polyurethane was neutralized by the addition of triethylamine TEA. The polymers have been characterized with 1H-NMR and FT-IR. The dispersion of APUDs depends on their molecular weights and chemical structures. Dispersion of titanium dioxide in typical waterborne acrylic resin has been investigated.

Dynamic Mechanical Characterization of the Crosslinked and Chain-extended HTPB Based Polyurethanes

The viscoelastic response of two different polyurethane (PU) systems (crosslinked and chain-extended) based on hydroxyl terminated polybutadiene (HTPB) were analyzed and compared. The PU elastomers were fabricated by reacting HTPB with isophorone diisocyanate. A tri-functional alcohol (1,2,6 hexanetriol) and a bi-functional aliphatic diol (1,4 butanediol) were used as the crosslinking agent and the chain extender respectively. Hydrogen bonding between the hard segments is indentified by the IR spectroscopy. The segregation of these segments was manifested by dynamic mechanical analysis at characteristic frequency over a wide range of temperature. The intensity and temperature location of the relaxation peaks was identified and discussed. The phenomenon of viscous dissipation was evaluated by recording the viscoelastic parameters as a function of temperature across a series of frequencies. The results obtained indicate that the chain-extended polymer is phase segregated and more sensitive to temperature rise via viscous dissipation as compared to crosslinked polymer. Both the polymers showed similar glass transition temperature (Tg) and characteristic relaxation times. Master curves for the polymer systems investigated are produced and discussed.

Development of a triazole-cure resin system for composites: Evaluation of alkyne curatives

We are developing a resin system that cures via triazole ring formation (cycloaddition reaction of azides with terminal alkynes) instead of the traditional oxirane/amine reaction. The high exothermicity of the azido/alkyne reaction is expected to yield higher extents of reaction under ambient-cure conditions, making the resin system potentially suitable for “out-of-autoclave” curing processes. The difunctional azide-terminated resin, di(3-azido-2-hydroxypropyl) ether of bisphenol-A, was selected as the baseline diazide. A number of alkyne crosslinkers were synthesized and characterized, including propiolate esters of di- and trifunctional alcohols, propargyl esters of di- and trifunctional carboxylic acids, propargyl ethers of di- and trifunctional alcohols, and N,N,N′,N′-tetrapropargyl derivatives of primary diamines. Commercially available tripropargyl amine was also studied. Those systems employing a propiolate-based alkyne were found to be much more reactive toward the Huisgen 1,3-dipolar cycloaddition than the propargyl species. Curing energetics as a function of alkyne type, investigated through a dynamic differential scanning calorimetry approach, showed a distinct divide between the averaged activation energies of the propiolate and propargyl-type crosslinkers, 69.2–73.6 kJ/mol versus 82.3–86.4 kJ/mol, respectively. Cured network properties were readily manipulated through the incorporation of varying amounts of di- versus tri- and tetra-functional alkynes or through incorporation of soft alkylene and alkyleneoxy versus rigid aromatic polyalkynes. As expected, mechanical properties, e.g., the temperature of the tan δ peak in dynamic mechanical analysis, were found to increase with increasing crosslink density. These results have allowed us to select the most promising systems for scale-up and fabrication of samples of both pure resin and composites for traditional mechanical property testing, which will be reported in a subsequent paper.

Synthesis of New Donor-functionalized Alcohols as Organic Ligands for Metal Precursors of Metal Organic Chemical Vapor Deposition

Recently, the development and use of single precursors for metal organic chemical vapor deposition (MOCVD) has been extensively focused on application to electronic devices. However, systematic design and synthesis of organic ligands appropriate for preparation of metal complexes with relevant chemical and physical properties, such as stability, volatility, and resistance to air and moisture have not received much attention. Generalization to prepare organic ligands for MOCVD precursors is especially important because the large scale synthesis of the metal complexes exclusively depends on the potential usefulness of the ligands. It is desirable for metal complexes to be in monomeric forms because mononuclear complexes generally show high vapor pressures and low sublimation or boiling temperatures. To do so, the coordinated atom of ligands should be crowded in its own environment with some substituents by keeping the coordinated atoms from bonding to another metal through bridging configuration. Therefore, pendant groups should be introduced into organic ligands. Some research results have been reported on the synthesis and application of organic ligands containing pendant groups. Herrmann reported his pioneering works on the synthesis of donor-functionalized alcohols and their application as bidentate ligands for the preparation of metal complexes. A variety of donor-functionalized alcohols which contain two alkyls on the α–carbon of the hydroxyl group were prepared and used to give metal complexes such as M(mmp)4 (mmp = 1-methoxy-2-methyl-2-propanolate; M = Zr, Hf), M(mmp)3 (M = Cr, Bi), 9 M(dmamp)3 (dmamp = 1-dimethylamino-2-methyl-2-propanolate; M = Y, Lu), Cu(dmamp)2. 12 The ligands in the complexes have pendant groups capable of coordinating to metals as bidentate ligands. Some of trifunctional alcohols have been used for the preparation and homoleptic complexes of alkaline-earth elements as well as transition metals. For larger cations such as Ba and Sr, it is necessary to introduce a neutral ancillary ligand possessing a sufficient number of donor sites or to incorporate a donor-functionalized feature into the anionic ligand to satisfy the multiple coordination requirement. Chi reported the successful preparation of alkalineearth metal complexes using a multi-donor site monoalcohol. Herein we disclose the synthesis and characterization of novel alcohols, which have pendant groups to stabilize the metal compounds by coordinating to the metal center in the formation of metal complexes. New alkoxyalcohols were prepared by the nucleophilic addition ring opening reaction between alkoxide anions and a highly reactive alkene oxide (epoxide).

Effect of monofunctional and trifunctional modifiers on a phase mixed polyurethane system

AbstractThe dynamic mechanical behavior of a phase mixed polyurethane system modified with trifunctional and monofunctional alcohols was investigated and compared with a typical polyurethane system with a difunctional alcohol. Of interest was verifying that the average functionality of the alcohol would determine the dynamic mechanical properties and not whether that functionality was achieved by an equimolar blend of trifunctional and monofunctional alcohols or by a purely difunctional alcohol. The base system consisted of poly(tetramethylene ether)glycol (PTMG) cured with 4,4′‐diphenylmethane diisocyanate (MDI). The trifunctional alcohol was trimethylol propane (TMP). The monofunctional alcohol was decyl alcohol (DA). Samples with a typical difunctional alcohol, 2,2‐dimethyl‐1,3‐propanediol (DMPD), were prepared and their properties compared with those of the above samples. To a first approximation, the properties of TMP‐DA modified polymers are identical to those of DMPD polymers of the same hard segment concentration. These results confirm our hypothesis that the dynamic properties obtained from a combination of a trifunctional alcohol with a monofunctional alcohol are essentially equivalent to those of a difunctional alcohol.

Some linear and branched macromolecules by ring‐opening polymerization

AbstractIn the first part the ring‐opening polymerization of some macrocyclic ether‐acetals is briefly described. Of special interest are acetal polymers with functional groups, for instance C=C‐double bonds. Appropriate unsaturated monomers and their polymerizability are discussed. The second part deals with the polymerization of oxazolines, substituted in 2‐ and/or 4‐position. Branched polymers are obtained by copolymerization of 2‐ethyl‐2‐oxazoline with 2‐hexyl‐2‐oxazoline or 2‐undecyl‐2‐oxazoline. The properties of the random copolymers and corresponding block copolymers are compared. By a “mixed mechanism technique” a block copolymer composed of a poly(tert ‐butyl methacrylate) block and a poly(phenyloxazoline) block was prepared.A new initiator system for the polymerization of oxazolines using alkyl chloroformates is introduced. The chloroformate of a trifunctional alcohol led to a three‐arm star polymer. Telechelics with two chloroformate endgroups form ABA type block copolymers.Finally four chiral oxazolines are described and the influence of substitution in dioxolanes and oxazolines on the polymerizability is discussed.

New experimental analytical technique for gelling system kinetics

A new experimental analytic technqiue which may be used to monitor the progress of reaction in a gelling system up to and beyond the gel point is presented with an attempt to use the data obtained therefrom for kinetic analysis of a random non-linear polymerization involving a difunctional acid chloride, sebacoyl chloride, and a trifunctional alcohol, LHT240 [a poly(propylene oxide) hexanetriol], in the presence or absence of an ethereal solvent, diglyme. For the system studied, reactions were found to accord with simple second order kinetics, devoid of buried group effect, and are explained by means of a simple mechanism in contrast to some earlier literature reports of complex order kinetics for similar systems.