Polymerization Of Hexamethylene Diisocyanate Research Articles

Highly stable plastic optical fibre amplifiers containing [Eu(btfa)3(MeOH)(bpeta)]: A luminophore able to drive the synthesis of polyisocyanates

The rare-earth metal organic chelate [Eu(btfa)3(MeOH)(bpeta)] (btfa, 4,4,4-trifluoro-1-phenyl-1,3-butanedionate; bpeta, 1,2-bis(4-pyridyl)ethane) has been used to dope a plastic optical fibre (POF) prepared by the bulk homopolymerization of hexamethylene diisocyanate (HMDI) catalysed by Tin(II)-2 ethylhexanoate (SnOct), to obtain a plastic optical fibre amplifier (POFA). The Eu3+ chelate, primarily added as luminophore for the amplification of the optical signal, showed an interesting co-catalytic activity in the polymerization of HMDI, that preferentially proceeded towards the formation of the highly stable polyisocyanurate trimer form thanks to its selective driving action, as demonstrated by 13C solid-state NMR. Pumping of the POFA with xenon lamps demonstrated the occurrence of stimulated emission inside the doped fibre.

Synthesis, characterization, and application of novel amphiphilic poly(D‐gluconamidoethyl methacrylate)‐b‐polyurethane‐b‐ poly(D‐gluconamidoethyl methacrylate) triblock copolymers

AbstractNovel amphiphilic ABA‐type poly(D‐gluconamidoethyl methacrylate)‐b‐polyurethane‐b‐poly(D‐gluconamidoethyl methacrylate) (PGAMA‐b‐PU‐b‐PGAMA) tri‐block copolymers were successfully synthesized via the combination of the step‐growth and copper‐catalyzed atom transfer radical polymerization (ATRP). Dihydroxy polyurethane (HO‐PU‐OH) was synthesized by the step‐growth polymerization of hexamethylene diisocyanate with poly(tetramethylene glycol). PGAMA‐b‐PU‐b‐PGAMA block copolymers were synthesized via copper‐catalyzed ATRP of GAMA in N, N‐dimethyl formamide at 20°C in the presence of 2, 2′‐bipyridyl using Br‐PU‐Br as macroinitiator and characterized by 1H‐NMR spectroscopy and GPC. The resulting block copolymer forms spherical micelles in water as observed in TEM study, and also supported by 1H NMR spectroscopy and light scattering. Miceller size increases with increase in hydrophilic PGAMA chain length as revealed by DLS study. The critical micellar concentration values of the resulting block copolymers increased with the increase of the chain length of the PGAMA block. Thermal properties of these block copolymers were studied by thermo‐gravimetric analysis, and differential scanning calorimetric study. Spherical Ag‐nanoparticles were successfully synthesized using these block copolymers as stabilizer. The dimension of Ag nanoparticle was tailored by altering the chain length of the hydrophilic block of the copolymer. A mechanism has been proposed for the formation of stable and regulated Ag nanoparticle using various chain length of hydrophilic PGAMA block of the tri‐block copolymer. © 2012 Wiley Periodicals, Inc. J. Appl. Polym. Sci., 2013

Synthesis and Characterization of Poly(Amide-Imide)s Bearing a S-Valine Moiety in Molten Ionic Liquid

A study has been conducted to synthesize highly organosoluble and optically active poly(amide-imide)s via direct solution polycondensation of different aliphatic and aromatic diisocyanates with a chiral diacid monomer in the presence of molten tetrabutylammonium bromide (TBuAmBr) as a molten ionic liquid, and was compared with polymerization in traditional solvents like N-methyl-2-pyrrolidone (NMP). The step-growth polymerization of N-trimellitylimido-S-valine (1) as an optically active monomer with 4,4′-methylenebis(phenyl isocyanate) (MDI) (2a) was carried out by four different methods in the presence of pyridine (Py), dibutyltin dilaurate (DBTDL), triethylamine (TEA) as a catalyst and without catalyst, respectively. In these solutions polycondensations amino acid was used as chiral inducing agent. The optimized method of MDI (2a) was used for the polymerization of hexamethylene diisocyanate (HDI) (2b), isophorone diisocyanate (IPDI) (2c) and tolylene-2,4-diisocyanate (TDI) (2d). The resulting polymers have inherent viscosities in the range of 0.15–0.87 dl/g and were characterized with FT-IR, 1H-NMR, elemental and thermogravimetric analysis techniques. In comparison with conventional solvents, this approach exhibited smoothly higher inherent viscosities and comparative yields and thermal stability. This process is safe and green since toxic and volatile organic solvents such as NMP were eliminated. These polymers are optically active, thermally stable and soluble in amide-type solvents.

Studies on polyurethanes and polyurethane-ureas derived from divalent metal salts of mono(hydroxybutyl) hexolate

Divalent metal salts of mono(hydroxybutyl)hexolate [M(HBH) 2 ), M=Ca 2+ , Mn 2+ or Pb 2+ ] were synthesized by the reaction of 1,4-butanediol, 5,6,7,8,10,10-hexachloro-3a,4,4a,5,8,8a,9,9a-octahydro-5,8-methanonaphtho-[2,3-C]-furan-1,3-dione and divalent metal acetates. Hexamethylene bis [N'-(1-hydroxy-2-methyl-prop-2-yl)urea] (HBHMPU) and tolylene 2,4-bis[N'-(1-hydroxy-2-methyl-prop-2-yl)urea] (TBHMPU) were synthesized by reacting 2-amino-2-methyl-propan-1-ol with hexamethylene diisocyanate (HMDI) and tolylene 2,4-diisocyanate (TDI), respectively, in toluene solvent. Flame-retardant metal-containing polyurethanes were synthesized by the solution polymerization of HMDI with M(HBH) 2 and the polyurethane-ureas by reacting HMDI with 1:1 mixture of M(HBH) 2 and HBHMPU or TBHMPU, respectively, in DMSO as solvent. The polymers have been characterized by elemental analysis, solubility, viscosity and IR and 1 H NMR spectroscopy. The thermal stability of the polymers has been studied by thermogravimetry. The flame-retardant property of the polymers has been investigated by measuring limiting oxygen index values.

Synthesis, dynamic mechanical, and solid-state NMR spectroscopy of crown-ether-based linear aliphatic polyurethane rotaxanes

Linear aliphatic polyurethanes were synthesized from hexamethylene diisocyanate (HDI) and either ethylene glycol (EG) or diethylene glycol (DEG). Polymerization of HDI and EG in a 30-crown-10 (30c10) solvent afforded poly[(ethylene hexamethylenediurethane) n -rotaxa-(30-crown-10) x ] with x/n = 0.02 (4% by mass). Polymerization of HDI and DEG in a 36-crown-12 (36c12) solvent provided poly[(oxydiethylene hexamethylenediurethane) n -rotaxa-(36-crown-12) x ] with x/n = 0.15 (23% by mass). For both polyurethane-rotaxanes, the melting temperatures are lower than those of the unthreaded backbones, and the glass temperature decreases when the threading efficiency is sufficiently high. The dynamic mechanical (DM) spectrum of the EG-30c10-containing polyrotaxane is identical to that of its unthreaded backbone. For both EG-based polymers, vacuum drying led to the disappearance of a sub-T g mechanical loss around -85 °C (1 Hz). The DM spectrum of the DEG-36cl2-containing polyrotaxane contains additional loss peaks in its tan δ versus temperature curves, as compared to its unthreaded backbone. Solid-state 2D WISE NMR revealed the new sub-T g loss process around -53 °C to be due to the onset of 36-crown-12 mobility in the polyrotaxane.

Foam polymerization of hexamethylene diisocyanate by cobalt naphthenate

The polymerization of hexamethylenediisocyanate (HDI) by Co-naphthenate was studied to establish conditions for fast exothermic reaction required for foam polymerization. Addition of an optimal concentration of DMSO (or DMF) activated the catalyst and lowered the induction period. Better control of the reaction was obtained in the presence of tributyltin oxide which showed a synergistic effect with the catalyst, and on using prepolymers of HDI. The resulting HDI foams were friable and their flammability was lower than that of aromatic polyisocyanurates.

Properties of polyisocyanurate resins obtained by polymerization of hexamethylene diisocyanate by organotin catalysts

Results are given for the mechanical, thermal and flammability properties of polyisocyanurate resins obtained from hexamethylene diisocyanate by bis-(tributyltin)-oxide catalysis. It is shown that the mechanical properties of the isocyanurate resins and of their glass fibre-reinforced composites are comparable with those of commercial epoxy and polyester resins. The thermal stability and the flame retardance of the isocyanurate resins are far better than of epoxies or polyesters.

Relaxation in Polyurethanes in the Glass Transition Region

A study has been made of the relaxation phenomena in three series of polyurethanes in the neighborhood of their glass transition temperatures and above. The technique of dynamic mechanical relaxation was used in the investigation at various frequencies up to 110 Hz. Differential Scanning Calorimetry (DSC) was also used as a supplement to the mechanical measurements. The series are: (1) H series based on polymerization of hexamethylene diisocyanate and various diols, (2) DP series based on polymerization of 4,4′ diphenylmethane diisocyanate and various diols, and (3) 4M series based on polymerization of 4-methyl meta phenylene diisocyanate and various diols. Four relaxation regions are discernible in the temperature range investigated and these are labelled β, α, αt and αc in order of increasing temperature. The following molecular mechanisms are associated with these relaxations: (1) The β relaxation (DP and 4M series only) arises from phenyl group motion in the chain backbone, (2) the α relaxation (all series) arises from microbrownian segmental motion associated with the glass transition, (3) the αt relaxation (H series only) is associated with a solid-solid phase transition involving the change from one crystalline modification to another, (4) the αc relaxation (H and DP series only) involves rotational or translational motion of the chains in the crystalline phase.