Poly Tetramethylene Glycol Research Articles

Surface structure and biocompatibility of polyurethanes

Two series of polyether polyurethanes, chain extended by ethylene glycol, have been synthesised with rigid exclusion of moisture to avoid side reactions. The polyether molecular weight was varied in each series. The polymers, which have been well characterised, are used to correlate surface properties and biocompatibility. The polyethylene glycol materials showed no significant surface segregation when examined by XPS. The polytetramethylene glycol polymers showed marked surface segregation of soft block. SIMS analysis showed that, even with surface segregation of soft block, some hard block was present at the outermost surface. Contact angle data confirmed that variations in polymer surface structure, with an increase in soft block molecular weight, were also present when the membrane was in an aqueous environment. Biocompatibility tests showed that there were no detectable differences between the polytetramethylene materials, though the surface compositions varied. The polytetramethylene polyurethanes were similar to Biomer in biocompatibility.

Compositional analysis of biomer

Biomer, a segmented polyether polyurethane, has been analyzed via hydrolysis/gas chromatography to determine its composition. In addition to the previously reported 4,4'-methylene bis(phenyl isocyanate) (MDI), polytetramethylene glycol (PTMO), and ethylenediamine, we now report the presence of diethylamine, 1,3-diaminocyclohexane and poly(diisopropylaminoethyl methacrylate-co-decyl methacrylate), Biomer's cloudy insoluble phase. In addition, a method is presented to characterize the methacrylate additive by molecular weight based on GPC. Also found by chromatography were the antioxidants Santowhite Powder and BHT. XPS shows no Si (silicone) on the Biomer surface, and a total chloride analysis reports no chloride (less than 0.03%). Time-of-flight SIMS data suggest evidence for the methacrylate additive at the surface, and mass spectroscopy can be interpreted as evidence for a diaminocyclohexane.

Sequence Distribution of Segmented Polyurethane-Urea

Segmented polyurethane-urea (SPU) elastomer was prepared from poly-tetramethyleneglycol (PTMG), 4,4′-diphenylmethane diisocyanate (MDI), and ethylenediamine (EDA). The SPU is a kind of block copolymer composed of soft and hard segments. 13C NMR spectra of the SPU were measured and the mean sequence lengths of polyurethane block and polyurea block were estimated from the signals of aromatic carbons. The mean polyurea sequence length was shorter than the hard segment as estimated by X-ray diffraction (Kimura et al.) or by other methods (Suzuki et al.). This polymer was found to be almost a random copolymer. The reactivity of the isocyanate group in MDI decreases slightly when the other side of isocyanate has reacted. The hard segment observed by X-ray diffraction or by other methods might only be the longer fraction of polyurea sequences.

Synthesis and characterization of imide containing diisocyanates and poly(imide-urethane)s therefrom

A facile synthesis of eight novel diisocyanates, viz. N,N-bis(isocyanatoalkyl)-1,2,4,5-benzenetetracarboxylic-1,2:4,5-diimides and N,N-bis(isocyanatoalkyl)-3,3′,4,4′-benzophenonetetracarboxylic-3,3′:4,4′-diimides, containing built-in imide rings, which serve as intermediates for the preparation of polyurethanes containing imide rings in the main chain, is reported. The solution polyaddition reaction of four representative diisocyanates with polytetramethylene glycol is also described. The resulting amorphous, thermally stable poly(imide-urethane)s are soluble with inherent viscosities ranging from 0.36–0.83 dL/g in m-cresol.

Structural orderliness of ion-containing polyurethanes as a function of the length of the flexible block

Abstract X-ray investigations have been made into a series of PUs differing in the length of the flexible polytetramethylene glycol block ( M = 1000, 1410 and 2000) and different concentrations of ionogenic groups. It was established that increase in the length of the flexible block in the initial PU systems substantially improves the microphase separation of the rigid and flexible blocks expressed in increase in the degrees of segregation of the components from 10 to 70%. Depending on the MM of the flexible block significantly different patterns of change in the level of microphase separation were observed on introducing ionogenic groups: it remained practically unchanged for the sample with the flexible block of MM 2000 and gradually rose (degree of segregation rose from 10 to 70%) for the sample with the flexible block of MM 1000.

Formation of Organic Polymer-Containing Gel Films and Their Application to the Fine-Patterning Process

The influences of a variety of organic polymers on the properties of the resultant gel films have been studied in the system B2O3-SiO2, with the aim of the application of these gel films to the fine-patterning process. Among the polymers examined, polyether glycols such as polyethylene glycol and polytetramethylene glycol were found to be the most suitable for the patterning process. These compounds are considered to soften effectively the resultant gel films, which enables one to leave patterns on the films. The addition of polyether glycols had no bad influences on the optical properties of the finally obtained glass films, since the additives had been eliminated completely during the heat-treatment. The newly-developed process is applicable to the formation of fine-patterns in submicrons.

Anelastic and dielectric properties of polyether-polyamide copolymer PEBAX studied by a thermally stimulated depolarisation current method

The analysis of some dielectric properties of poly-(ether block amide) PEBAX having a hard-segment polyamide 12 (Mn=4200) and soft-segment polytetramethylene glycol (Mn=2032) has been done by a thermally stimulated depolarisation current method. The relaxation peaks resulting from molecular motions are similar to those observed in pure homopolymers. The mechanical properties of PEBAX depend primarily on the hard-segment contents. The domain morphology is affected by thermal treatment. The existence of separate glass transition peaks representative of PTMG and PA12 in PEBAX has been confirmed by a compensation law.

Viscometric and Light Scattering Study in Dimethylacetamide of Linear Segment Polyurethane, Polymerized with Methylene Bis(4-phenyl isocyanate) Polytetramethylene Glycol and Ethylene Diamine

An attempt was made to determine the unperturbed chain dimension A of a segment polyurethane, prepared from polytetramethylene glycol (the number-average molecular weight 1500) methylene bis(4-phenyl isocyanate) and ethylenediamine. A whole polymer was fractionated by successive solution fractionation using dimethylacetamide (DMAc) as a solvent and methylalcohol as a precipitant into 23 fractions. Linearity of the segment polyurethane chain was confirmed by NMR and the solution viscosity change by addition of n-butylamine. The dilute solution properties of eight fractions in DMAc were investigated by the light scattering and viscometry at 25°C. The Mark–Houwink–Sakurada equation for the solution in DMAc at 25°C was [η]=0.101Mw0.59 (cm3 g−1) ([η]; limiting viscosity number, Mw; the weight-average molecular weight). A was found to be 1.02×108 cm for the solution. No significant solvation was observed by adiabatic compressibility measurement.

Phase Segregation of Polyether-Polyamide Copolymer PEBAX by Thermally Stimulated Current Method

The glass transition β of polyamide 12 (PA12, M̄n= 830) and polytetramethylene glycol (PTMG, M̄n= 2000) has been observed at 43°C and -74°C respectively by thermally stimulated current (TSC) method. The copolymer poly(ether block amide), PEBAX having hard segment PA12 (M̄n= 898) and soft segment PTMG (M̄n= 2032) has been studied by TSC. The respective peaks of PTMG and PA12 are located at -69.5°C and 13.5°C for a raw material sample and -70°C and 9°C when the sample is recrystallised after melting showing the presence of two defined phases in this system. The effect of slow cooling after polarisation on the hard segment has been observed. The influence of viscosity on the phases polytetramethylene glycol βPTMG and polyamide 12 βPA has been investigated. Activation energy and relaxation times have been calculated for βPTMG and βPA relaxations by the fractional polarisation method. Two phases are also identified.

Synthesis of polyetherurethanes containing l-serine dipeptide and their use as materials for biomedical films

Prepolymers, which were produced by the polyaddition reaction of polytetramethylene glycol (PTMG) or polyethylene glycol (PEG) and 4,4'-diphenylmethane diisocyanate (MDI) or hexamethylene diisocyanate (HMDI), were chain-extended with a linear dipeptide of L-serine (Z-Ser-Ser-OMe) or a cyclic dipeptide of L-serine [c-(Ser)2] to yield novel polyetherurethanes containing dipeptide segments. The relationship between the surface morphology and the biomedical properties of the film of the novel polyetherurethanes was investigated. The surface of PU(PTMG,Z-Ser-Ser-OMe,MDI) film was smooth, but fibrous structures were developed in the bulk of the film with increasing molecular weight of the PTMG segment. The antithrombogenicity of the film containing the low molecular weight PTMG segment was better than that of the usual polyetherurethane film without the dipeptide segments. The partial hydrolysis of the ester groups involved in the dipeptide segment improved the antithrombogenicity. In the surface and the bulk of PU[PTMG,c-(Ser)2,MDI] film, spherulite structures were developed when the molecular weight of the PTMG segment was high, while single crystals with a length of 3-4 microns were produced when the molecular weight of the PTMG segment was low. The antithrombogenicity of the film containing the high molecular weight PTMG segment was better than that of the usual polyetherurethane film without the dipeptide segments. PU(PTMG/PEG,Z-Ser-Ser-OMe,MDI) film and PU[PTMG/PEG,c-(Ser)2,MDI] film were permeated by uraemic toxins. The permeation was accelerated with increasing water content of the film and decreasing molecular weight of the solute. The oxygen permeability of the film of the polyetherurethane containing the linear or cyclic dipeptide segments was greater than that of polyetherurethane film which does not contain the dipeptide segments.

Effect of thermal treatment on the structure and the biomedical properties of polyetherurethane film containing dipeptides of l-serine

Prepolymers which were obtained by the reaction of 4,4'-diphenylmethane diisocyanate (MDI) with polytetramethylene glycol (PTMG) and polyethylene glycol (PEG) were chain-extended by the reaction with the linear or cyclic dipeptide of L-serine to yield a novel polyetherurethane containing dipeptide segments. In these polyetherurethanes, spherulites, fibrous structures, and needle-like crystals were formed according to the conditions used. Polyetherurethanes containing the cyclic dipeptide segments exhibit a thermally stable conformation when cast from solution at room temperature. On the other hand, polyetherurethanes containing the linear dipeptide segments exhibit a thermally stable conformation only after annealing. The properties of polyetherurethanes were elucidated by investigation of their morphology by electron microscopy, surface composition by electron spectroscopy for chemical analysis, hydrogen-bonding properties by i.r. spectroscopy, and degree of crystallinity by differential scanning calorimetry. The antithrombogenicity of polyetherurethane films containing linear dipeptides was increased by annealing. Their oxygen permeability was controlled by the linear or cyclic dipeptide segments or by annealing. The urea permeability of hydrophilic polyetherurethane film was easily controlled by the casting conditions and molecular weight of the polyether component. The relationship between the morphology and biomedical properties of these polyetherurethane films is discussed.

抗血せん性エラストマとしての含フッ素セグメント化ポリウレタン樹脂

A series of fluorine-containing segmented polyurethanes (FPU) was synthesized from a new fluorinated aliphatic diisocyanate, polyalkylene glycols, and diamines. Electron microscopy showed that FPU have microphase separated structures which may possibly consist of hydrophobic domains of fluorocarbon chains and hydrophilic domains of hydrocarbon chains. FPU-20 E, prepared from polytetramethylene glycol (PTMG) of 1080 in molecular weight and ethylenediamine, exhibited excellent tensile properties as an elastomer and a high degree of in vitro antithrombogenicity. An in vivo evaluation using this material as an artificial heart pump for a goat showed it to have superior blood compatibility and durability, and thus may have possible application as a new biomaterial in cardiovascular devices, such as blood pumps in particular.

IR dichroism and orientation in segmented polyurethane-urea elastomers

Abstract Reconsidered and discussed in the present work is the limited possibility of the application of the orientation parameter for characterization of the orientation behavior of segments of polymer chains during deformation when this parameter is calculated from IR dichroism with inversion of dichroism for several absorption bands. Studies on orientation effects in uniaxial deformation of a polyether-urethane-urea elastomer obtained on the basis of polytetra-methylene glycol with a molecular mass of about 1000, 2,4-tolylendiisocyanate, and 4,4′- diphenylmethanediamine have been made using the x-ray diffraction technique. The results of the investigations agree with the assumption that in the polymer investigated conformation transitions in hard segments may be responsible for the IR dichroism inversion.

Study of the short-range order of liquid polytetramethylene glycol

Abstract X-ray investigations of polytetramethylene glycol oligomers with various molecular weights were carried out. Interatomic distance correlation curves were obtained using the Fourier transformation of the intensity curves. Theoretical curves of the correlation of the intramolecular interatomic distances were also calculated. The calculation of these curves has been done using the results of conformational analysis for different conformational states of the PTMG chain. Correlation curves for the intermolecular distances were then obtained by subtraction of the theoretical curves from the experimental ones. The results obtained are considered in the framework of the various models of the structural state of liquid polymers. The model of kink isomers shows the best fit with our results.

Rheological properties of polyurethane spinning solutions in dimethylformamide

In this connection, it was important to investigate the effect of storage time, temperature, and shear speed and stress on the rheological properties of spinning solutions. We used a spinning solution of a polyurethane (PU) which was a product obtained from diphenylmethane-4,4'-diisocyanate and polytetramethylene glycol plus 1,2-diaminopropane in dimethylformamide (DMF), taken from the manufacture of spandex fibre. The viscosity properties of the PU solution were determined in the range of shear speeds from 0.167 to 5.4 sec -I using a rotation Reotest instrument under conditions of established flow in the temperature range 25120°C. To determine the stability of the solutions with respect to viscosity, we selected a temperature close to their processing temperature (6-40°C).

The Synthesis and Characterization of New Polyether Based Soluble Polyurethanes

Two soluble polyurethanes have been develped for use as castable, removable encapsulants for electronic com ponents. These polyurethanes were formulated using bitolylene diisocyanate (TODI) terminated polytetramethylene glycol, chain extended with 1,4 butanediol. TODI was chosen to furnish the isocyanate moiety in this system for its tendency to form semi crystalline polymers and provide physical crosslinking to retard creep. The required physical properties for our applications (low creep, 400% elongation, yield strength ~ 2000 psi, and T g <-55°C) were achieved after carefully removing urea from the starting isocyanate and water from the ether and glycol com ponents. The encapsulants were cured 16 hours at 80°C to achieve the desired properties. Although infrared examination showed residual isocyanate after cure, postcuri ng did not improve the physical properties.

Conformation characteristics of polymethylene glycolterephthalates

Conformation statistics in rotary-isomer approximation were used to calculate average dimensions of unperturbed chains of polymethylene glycolterephthalates containing 4,5,6,8 and 10 methylene groups in the glycol residue. Characteristics ratios (〈0〉/nl2) ∞ calculated at 303°K were 5·4; 5·5; 5·7; 5·9 and 6·0, respectively. A study was made of the effect of various structural factors on the conformation and average dimensions of chains; the role of non-equivalence of trans- and cis-isomers of the terephthaloyl residue was examined. The Monte-Carlo method was used to derive equilibrium constants of macro-cyclization for cyclic dimer and trimer of polytetramethylene glycol terephthalate, which were found to be 2·5 × 10−3 and 3·2 × 10−3m at 510°K. Results agree with the content of cyclic oligomers determined experimentally in an amorphous bulk-polymerized polymer, which is evidence of the weak disturbing effect of intermolecular and remote intramolecular interactions on the conformation of short chain segments in the unit.

Emulsion of polyurethane having thermosetting properties. II. Relation between the mechanical properties of film and the polyurethane structure

AbstractA self‐emulsifiable polyurethane emulsion having thermosetting property was prepared by the following procedure: the polyurethane–urea–amine was first prepared by the reaction of diethylene–triamine with a prepolymer containing terminal isocyanate groups in a ketone solvent, and then the primary amino group in the polyurethane–urea–amine was reacted with epichlorohydrin. The mixture was neutralized with an aqueous acid, and finally the ketone solvent was removed by distillation in vacuo. In the polyurethane, polytetramethylene glycol (PTMG) was the base polymer functioning as the soft segment. The present paper reports the effects of the following variables on the mechanical properties of the film prepared from the polyurethane emulsion, i.e., the Mn of PTMG, the molar ratio of diethylene–triamine (DTA) to prepolymer containing terminal isocyanate groups, the structure of the isocyanate end group and the molar ratio of tolylene diisocyanate (TDI) with PTMG. The best elastomer property was realized when Mn of PTMG was 2000, TDI/PTMG molar ratio was 2.0, and prepolymer/DTA molar ratio was 0.85.

Polymers containing 12‐hydroxymethyltetrahydroabietanol

Abstract12‐Hydroxymethyltetrahydroabietanol has been polymerized with hexamethylene diisocyanate and a low molecular weight polyurethane produced. Low molecular weight polyurethanes have also been prepared from 12‐hydroxymethyltetrahydroabietyl chloroformate, hexamethylenediamine, and sym.‐dimethylethylenediamine. 12‐Hydroxymethyltetrahydroabietanol has been “end‐capped” with tolylene‐2,4‐diisocyanate and hexamethylene diisocyanate. The resulting diisocyanates have been polymerized with polytetramethylene glycol, hexamethylenediamine and hydrazine.

Kinetics of crosslinked polyurethane production

THE wide use of materials based on polyurethanes (1)15) demands a s tudy of the mechanism of formation of such polymers. Of special importance is the s tudy of the formation rate of crosslinked structures. Other investigators [1, 2] had shown tha t the reaction rates of the various components of the system can determine the physico-mechanical properties of the produced 3-dimensional polymer. The presence of a steric network is completely prevented in some cases [3]. The few papers dealing with this problem [4-6] of crosslinking have assessed it on the basis of gelling time. This only permitted some general conclusions on the effect of temperature, ratio of components, and of various catalyst types on the process rate. Such an approach will lead only to an approximation of the average process rate. We believe tha t the formation of a polymer with a steric network from oligomeric molecules should be a stepwise process, in which each stage has a different reaction rate. The stages could be due to different reaction rates of the isocyanate with the separate components of the setting system. I t would be interesting to assess the rate of each stage as a function of polyester chain length, its chemical nature and structure. The report describes the results of the kinetic study of the formation of erosslinked PU, as obtained on reacting macro-diisocyanates (MDI) with trimethylol propane. The MDI were produced on the basis of polyoxypropylene glycol (PPG) with molecular weights (m.w.) 500 (PPG-500), 1000 (PPG-1000), and 2000 (PPG-2000), or polytetramethylene glycols with m.w. 1000 (PTMG-1000) and 4,4'-diphenylmethane diisocyanate (DPMD).