Poly Tetramethylene Oxide Glycol Research Articles

Improvement for yellowing resistance of aromatic PU film by fluoro alcohol termination and branching modification

The fluoro alcohol-terminated branched polyurethanes with different fluorine content (FABPU-0, FABPU-1 and FABPU-2) was successfully synthesized via step-by-step polymerization in which polytetramethylene oxide glycol (PTMG-2000) and 4,4′-diphenylmethane diisocyanate (MDI) were used as raw materials, 1,4- butanediol (BDO) as the chain extender, pentaerythritol as crosslinking agent, anhydrous ethanol (EtOH) or perfluorinated hexyl alcohol (S104) as end capping agent. The molecular structure and relative molecular weight of aromatic polyurethane (PU) and FABPU were characterized by means of Fourier-transform infrared (FTIR) and Gel permeation chromatography (GPC). The results showed that the average molecular weight of FABPUs increased compared with that of PU. The characterization results by thermogravimetric (TG) and X-ray diffraction (XRD) showed that the crystallinity of FABPU-2 was enhanced 148.3 %, as well as the thermal decomposition temperature was raised by 38 ℃. The yellowing resistance of FABPU and aromatic fluorine-free PU was investigated by the change of yellowness index (YI), chromatic aberration (ΔE). The results showed that compare with that of aromatic fluorine-free PU, YI of FABPU-2 decreased to 14.3 from 32.48, as well as ΔE reduced to 5.07 from 16.34. Moreover, the water contact angle of FABPU-2 increased to 141° from 89.3°. These indicated that the crosslinking of pentaerythitol and the introduction of fluorine obviously improved the hydrophobicity and yellowing resistance of aromatic PU.

Multi Self-Healable UV Shielding Polyurethane/CeO2 Protective Coating: The Effect of Low-Molecular-Weight Polyols.

We prepared a series of polyurethane (PU) coatings with defined contents using poly(tetramethylene oxide)glycol (PTMG) with two different molecular weights (i.e., Mn = 2000 and 650), as well as polydimethyl siloxane (PDMS) with a molecular weight of Mn 550. For every coating, maximum adhesive strength and excellent self-healing character (three times) were found using 6.775 mol% mixed with low-molecular-weight-based polyols (PU-11-3-3). Defined 1.0 wt% CeO2 was also used for the PU-11-3-3 coating (i.e., PU-11-3-3-CeO2) to obtain UV shielding properties. Both the in situ polymerization and blending processes were separately applied during the preparation of the PU-11-3-3-CeO2 coating dispersion. The in situ polymerization-based coating (i.e., PU-11-3-3-CeO2-P) showed similar self-healing properties. The PU-11-3-3-CeO2-P coating also showed excellent UV shielding in real outdoor exposure conditions.

Poly(glycerol sebacate)-Based Polyester-Polyether Copolymers and Their Semi-Interpenetrated Networks with Thermoplastic Poly(ester-ether) Elastomers: Preparation and Properties.

Poly(glycerol sebacate) (PGS), produced from renewable monomers such as sebacic acid and glycerol, has been explored extensively for various biomedical applications. However, relatively less attention has been paid to explore PGS as sustainable materials in applications such as elastomers and rigid plastics, primarily because of serious deficiencies in physical properties of PGS. Here, we present two new approaches for enhancing the properties of PGS; (i) synthesizing block copolymers of PGS with poly(tetramethylene oxide)glycol (PTMO) and (ii) preparing a blend of PGS-b-PTMO with a poly(ester–ether) thermoplastic elastomer. The consequence of molar ratio (hard and soft segments) and Mn of soft segment on tensile properties of the material was investigated. The PGS-b-PTMO with 25:75 mole ratios of hard and soft segments and having a medium Mn soft segment (5350 g mol–1) exhibits an appreciable increase in percentage of elongation that is from 32% for PGS to 737%. Blends of PGS-b-PTMO and a thermoplastic polyester elastomer, Hytrel 3078, form a semi-interpenetrated polymer network, which exhibits increased tensile strength to 2.11 MPa and percentage of elongation to 2574. An elongation of such magnitude is unprecedented in the literature for predominantly aliphatic polyesters and demonstrates that the simple polyester can be tailored for superior performance.

Corrosion Inhibition Properties of Waterborne Polyurethane/Cerium Nitrate Coatings on Mild Steel

Waterborne polyurethane (WBPU)/cerium nitrate (Ce(NO3)3) dispersions were synthesized with different defined Ce(NO3)3 content. All pristine dispersions were stable with different poly(tetramethylene oxide) glycol (PTMG) number average molecular weights (Mn) of 650, 1000, and 2000. The interaction between the carboxyl acid salt group and Ce(NO3)3 was analyzed by Fourier-transform infrared spectroscopy (FT-IR) and X-ray photoelectron spectroscopy (XPS) techniques. Coating hydrophilicity, water swelling (%), water contact angle, leaching, and corrosion protection efficiency were all affected when using different Ce(NO3)3 content and PTMG molecular weights. The maximal corrosion protection of the WBPU coating was recorded using a higher molecular weight of PTMG with 0.016 mole Ce(NO3)3 content.

Creating Poly(tetramethylene oxide) Glycol-Based Networks with Tunable Two-Way Shape Memory Effects via Temperature-Switched Netpoints

Polymers with two-way shape memory effect (2W-SME) are of great potential in real applications due to the reversible nature. Though 2W-SME has been already realized in some semicrystalline networks by the crystallization-induced elongation (CIE) and melting-induced contraction (MIC), more adaptable 2W-SME systems are highly expected. In this work, to achieve tunable 2W-SME with different reversible deformation ranges, we designed a semicrystalline poly(tetramethylene oxide) glycol (PTMEG) network with temperature-switched netpoints. This adaptable network was constructed by photo-cross-linking of the PTMEG-based copolymer containing amorphous poly(d,l-lactide) (PDLLA) segments in main chain and photosensitive anthracene groups in side chain. The photo-cross-linking degrees of networks were adjusted by controlling irradiation time. Remarkably, 2W-SME in the current system was realized by the CIE and MIC of PTMEG segments for the first time. Here, along with the photo-cross-links, the low content of PDLLA s...

Synthesis and properties of segmented polyurethanes with hydroquinone ether derivatives as chain extender

Two series of 4, 4′-diphenylmethane diisocyanate (MDI) type polyurethanes based on poly(tetramethyleneoxide) glycol (PTMO) and polybutylene adipate glycol (PBA) as soft segments were synthesized by one-step bulk polymerization process. Various hard segments were obtained from hydroquinone ether derivatives with or without ether oxygen structure bonded with the aromatic units in main chain, including hydroquinone (HQE), hydroquinone bis(b-hydroxyethy) ether (HQEE), and 4-hydroxyethyl ethyl oxygen-1-hydroxy ethyl benzene ether (HQEE-L) as chain extenders. The effect of chain extender structure on aggregation structure, thermal and mechanical properties was studied. ATR-FTIR suggested that hydrogen bonding interactions were significantly changed in the presence of flexible ether oxygen structure in hard segment. HQEE-based polyurethanes and HQEE-L-based polyurethanes displayed microphase separation and microphase mixing behavior respectively based on DMA and DSC results. XRD curves confirmed that flexible ether oxygen chain bonded with the rigid aromatic units played a balancing role in the steric effect caused by aromatic chain extender. Thermal properties of polyurethanes were affected mainly by the hard segment packing while mechanical properties were influenced by both phase separation and phase mixing which possess strong hydrogen bonding interactions. The excellent elongation in PTMO/HQEE-L and the high ultimate tensile strength in PBA/HQEE-L can be attributed to the phase mixing with strong hydrogen bonding interactions presented in HQEE-L-based polyurethanes.

Preparation and properties of waterborne siloxane-containing polyurethane for moisture permeable textile coating

AbstractWaterborne siloxane-containing polyurethanes (WSPU) were prepared by polyaddition reaction using poly(tetramethylene oxide)glycol (PTMG), polyethylene glycol (PEG), and α,ω-aminopropyl polydimethylsiloxane (APDMS) as mixing soft segments; 2,2-di(hydroxymethyl)propionic acid, as a hydrophilic chain extender; 1,4-butanediol and isophorone diisocyanate as hard segment; triethylamine as a neutralization agent. The thermal properties of WSPU films were analyzed by differential scanning calorimetry (DSC), dynamic mechanical analysis (DMA) and thermal gravimetric analysis (TGA). The mechanical properties of WSPU film were also investigated. Water vapor permeability (WVP) was examined according to GB_T 12704-1991. The DSC and DMA results indicated that there is a micro-phase separation in the WSPU film. The incorporation of APDMS into PU made the thermal stability of hard segment worse while that of soft segment better. The elasticity of WSPU was improved when the APDMS content was not more than 10%, the vapor permeability of coated fabric increased firstly and then decreased as the APDMS content increased, which was resulted from the hydrophilicity change and microstructure change of membrane. When 10% APDMS was incorporated into the WSPU, the WVP of coated fabric was 2130.15 g/(m2·24h), equal to one coated with a widely used solvent-based PU sample (UECCOAT), and the water resistance (WR) reached 30.0 KPa.

In Situ synthesis of multiblock copolymers of poly(ϵ‐caprolactone) with different poly(ether diols) based polyurethane by reactive extrusion

AbstractPolyurethanes with multiblock copolymers of poly(ϵ‐caprolactone) (PCL) and poly(tetramethylene oxide) glycol (PTMG) or poly(ethylene glycol) (PEG) as a soft segment were synthesized in situ via reactive extrusion from ϵ‐caprolactone (CL) and 4,4′‐diphenylmethane diisocyanate (MDI). The titanium alkoxide mixture generated from an ester‐exchange reaction between titanium propoxide [Ti(OPr)4], and excessive PTMG or PEG was used as an initiator and catalyst. Compared to the reported fabrication of polycaprolactone‐based polyurethane (PCLU), the in situ reactive extrusion preparation not only explored a new rapid route for the fabrication of PCLU but also offered a simplified, controllable approach for the production of PCLU in a successive mass scale. A series of PTMG–PCLUs and PEG–PCLUs with different PCL block‐average degrees of polymerization (DPn's) were prepared by only an adjustment of the relative concentration of CL in the reaction system, with a certain constant molar ratio of MDI to titanium alkoxide. 1H‐NMR, gel permeation chromatography, and differential scanning calorimetry results indicate that all of the CL monomers were converted in the polymerization, and the molecular weight of the copolymers was about 8 × 104 g/mol with a polydispersity index of approximate 2.4. With an increase in the PCL block‐average DPn in PTMG–PCLU from 25 to 40, the tensile strength increased from 16.5 to 22.7 MPa, and the melting point increased from 46.1 to 49.5°C. It was also verified by PEG–PCLU prepared with organic Ti of lowered content in the initiator mixture that the mechanical properties could be greatly affected and dropped with decreasing content of organic Ti in the initiator mixture. © 2011 Wiley Periodicals, Inc. J Appl Polym Sci, 2012

Synthesis and properties of waterborne poly(urethane urea)s containing polydimethylsiloxane

AbstractTo obtain flexible waterborne poly(urethane urea) (WBPU) coatings with functionalities such as shape recovery and water resistance, we synthesized a series of WBPUs by a prepolymer mixing process from hexamethylene diisocyanate, polyol, 2,2‐bis(hydroxymethyl) propionic acid, ethylenediamine, and triethylamine with polyol blends [hydroxyl‐terminated polydimethylsiloxane (PDMS) with a number‐average molecular weight of ≈ 550 and poly(tetramethylene oxide) glycol (PTMG) with a number‐average molecular weight of 650] of different molar ratios. The effects of the PDMS content in PDMS/PTMG on the dynamic thermal and mechanical properties, hardness, tensile properties, water resistance (water absorption, contact angle, and surface energy), and shape‐memory properties of WBPU films were investigated. As the molar percentage of PDMS in WBPUs increased, the storage modulus, tensile strength and modulus, elongation at break, hardness, and shape‐retention rate (30–15%) decreased; however, the water resistance and shape‐recovery rate (80–90%) increased. © 2010 Wiley Periodicals, Inc. J Appl Polym Sci, 2010

Real time mechano-optical study on deformation behavior of PTMO/CHDI-based polyetherurethanes under uniaxial extension

Real time mechano-optical properties of two homologous segmented, thermoplastic polyurethanes (TPUs) obtained from the stoichiometric reactions of trans-1,4-cyclohexyl diisocyanate (CHDI) and poly(tetramethylene oxide)glycol (PTMO) were investigated. PTMO oligomers used had number average molecular weights 〈Mn〉 of 1020 and 2040 g/mol, resulting in TPUs with urethane hard segment contents of 14 and 7.5% by weight. AFM studies showed intertwined microphase morphology. Stress–strain measurements demonstrated the formation of very strong, elastomeric materials, with ultimate tensile strengths of 23–25 MPa and elongation at break values of about 1000%. Mechano-optical behavior of these polymers exhibited multiple regime behavior. The first strain optical regime is linear where primarily the soft segments orient. The transition between the first and second strain optical regimes was found to correspond to the saturation of straining of the soft segments that lead to start of rotation of hard segments in the stretching direction. The start of Regime II coincides with the onset of strain hardening and the distance between the hard segments increases appreciably with stretching in this regime. Increasing the soft segment length was found to promote its strain-induced crystallization.

Novel blood‐compatible waterborne polyurethane using chitosan as an extender

AbstractA series of novel block polymers of polyurethane (PU) and chitosan have been prepared in two steps. The first step is the preparation of PU prepolymer, obtained from polytetramethylene oxide glycol (PTMO, Mn = 1000), isophrone diisocyanate (IPDI), and 2,2′‐dimethylol propionic acid (DMPA), followed by ionizing PU prepolymer with triethylamine (TEA). The second step involves PU chain‐extended by water‐soluble chitosan of low molecular weight (Mn = 5000) by self‐emulsion polymerization method. The sizes of the latex particles, morphology, and copolymer architecture have been characterized by dynamic light scattering (DLS), general tensile test, infrared spectroscopy (IR), surface contact angle measurement, and transmission electron microscopy (TEM). Furthermore, it shows that the addition of chitosan remarkably increases anticoagulative property of PU elastomers confirmed by the recalcification time. © 2008 Wiley Periodicals, Inc. J Appl Polym Sci, 2008

Unsaturated poly(ester–imide)s from hydroxy-terminated polybutadiene, dianhydride and diisocyanate

Hydroxy terminated polybutadiene has been used for the first time in the synthesis of poly(ester–imide)s [P(E–I)s]. Anhydride terminated polyester prepolymers were prepared by the reaction of two different polyols––polytetramethyleneoxide glycol (PTMG) of molecular weight 1000 and hydroxy terminated polybutadiene (HTPB) of molecular weight 2500––and different dianhydrides––pyromellitic dianhydride (PMDA), benzophenonetetracarboxylic dianhydride (BTDA) and 4,4 ′-(hexafluoroiso-propylidene)diphthalic anhydride (HFDA). The prepolymers were then reacted with different diisocyanates––80:20 mixture of 2,4- and 2,6-tolylene diisocyanate (TDI), 1,6-hexamethylene diisocyanate (HDI), isophorone diisocyanate (IPDI) and 4,4 ′-methylene bis(phenylisocyanate) (MDI) resulting in P(E–I)s. The P(E–I)s were characterised by FT-IR, FT-NMR, GPC, TGA, DSC and for static and dynamic mechanical properties. The polymers based on PTMG showed two distinct melting points and behave as thermoplastic elastomers. The thermal stability and mechanical properties of P(E–I)s based on HTPB were substantially higher than those based on PTMG.

Liquid crystalline properties of unsegmented and segmented polyurethanes synthesised from high aspect ratio mesogenic diols

AbstractA series of novel tetrad high aspect ratio mesogenic diol monomers 4‐{[4‐(n‐hydroxyalkoxy)‐phenylimino]‐methyl}‐benzoic acid 4‐{[4‐(n‐hydroxyalkoxy)‐phenylimino]‐methyl}‐phenyl ester were prepared with varying alkoxy spacer length (n=2,4,6,8,10) by reacting 4‐formylbenzoic acid 4‐formylphenyl ester and 4‐(n‐hydroxyalkoxy) anilines. Two series of thermotropic main chain liquid crystalline unsegmented polyurethanes (PUs) were obtained by the polyaddition of the mesogenic diols with hexamethylene diisocyanate (HMDI) and methylene bis(cyclohexylisocyanate) (H12MDI) in dimethylformamide respectively. The effect of the incorporation of a third component namely polyol on the liquid crystalline properties of the polyurethanes was also studied. Linear segmented PUs were synthesised by a two‐step block copolymerisation method. The PUs synthesised were based on six spacer mesogenic diol chain extender, soft segments poly(tetramethylene oxide)glycol (PTMG) (Mn= 650,1000,2000) and polycaprolactone diol (PCL) (Mn=530,1250,2000) of varying molecular weights and different diisocyanates including HMDI, H12MDI and methylene bis(phenylene isocyanate) (MDI). Structural elucidation was carried out by elemental analysis, fourier transform infra red (FT‐IR), nuclear magnetic resonance (1H NMR and 13C NMR) spectroscopy. Inherent viscosity of the unsegmented polymers measured in methanesulphonic acid at 26°C was in the range of 0.13 ‐ 0.65 dL/g while the molecular weights and molecular weight distribution of the segmented polyruethanes was determined using gel permeation chromatography (GPC). Mesomorphic properties were studied by differential scanning calorimetry (DSC) and hot stage polarising optical microscopy and the thermal stability was determined by thermogravimetric(TG)analysis. The monomeric diols and the polyurethanes exhibited nematic texture and good mesophase stability. It was observed that the partial replacement of the mesogenic diol by the polyol of varying molecular weights influenced the phase transitions and the occurrence of mesophase textures. The phase transition temperatures of the investigated polyurethanes showed dependence on the chain length of the soft segment and on the content of the mesogen moiety. A higher content of mesogenic moiety was needed to obtain liquid crystalline property when the soft segment length was increased as observed in the case of PTMG. Grained and threaded textures were observed depending on the molecular weight of the soft segment, the mesogen content and the diisocyanate. The stress‐strain analyses showed that the polymers bused on high molecular weight PTMG soft segment have elastomeric property while the PCL based PUs displayed no elastomeric property.

Preparation and properties of waterborne polyurethanes for water‐vapor‐permeable coating materials

AbstractWaterborne polyurethanes were prepared by polyaddition reaction using isophorone diisocyanate, dimethylol propionic acid, various polyols with a fixed molecular weight (Mn = about 2000), ethylene diamine as a chain extender, and triethylamine as a neutralization agent. Three types of polyols such as (1) solo glycols [polypropylene glycol (PPG) (Mn = 2000), poly(tetramethylene oxide) glycol (PTMG) (Mn = 2000), poly(tetramethylene adipate glycol) (PTAd) (Mn = 2000), or polycaprolactone glycol (PCL) (Mn = 2000)], (2) the polyol blends (PPG/PCL, PTMG/PCL, PPG/PTAd, PTMG/PTAd), and (3) a triblock glycol (TBG) (Mn = 1990) were used in this study. The triblock glycol (TBG) [(CL)4.5–PTMG (Mn = 1000)–(CL)4.5 (Mn =1990] was synthesized from PTMG and ϵ‐caprolactone (CL) in this study. The triblock glycol was found to have two main melting peaks at about 13 and 40°C. This study was examined on the effect of the types of polyols on the particle size, viscosity, dynamic thermal properties, and water vapor permeability. The particle size of the aqueous polyurethane–urea dispersion increased in the order of polyol‐blends‐based samples (183–350 nm) > TBG‐based sample (167 nm) > solo‐polyol‐based sample (58–96 nm). By dynamic thermal mechanical analysis, the ester‐type polyol‐ (PTAd and PCL) based samples were found to have higher storage modulus and Tg than those of ether‐type polyol‐ (PPG and PTMG) based samples. The water vapor permeability (WVP) increased in the order of TGB‐based sample > PCL/PTMG‐based sample > PTAd/PTMG‐based sample > PCL/PPG‐based sample > PTAd/PPG‐based sample > PTMG‐based sample > PPG‐based sample > PCL‐based sample > PTAd‐based sample. WVP was found to increase in the order of TBG‐based sample > polyol‐blend based samples > solo‐polyol‐based samples. It was also found that the samples containing ether‐type glycols (PTMG, PPG) had higher permeability than samples having ester‐type glycols (PCL, PTAd). PTMG‐based samples were found to have higher permeability than PPG‐based samples if other compositions were constant. © 2003 Wiley Periodicals, Inc. J Appl Polym Sci 89: 123–129, 2003

Studies on Thermotropic Main Chain Liquid Crystalline Segmented Polyurethanes. II. Synthesis and Properties of H 12 MDI- and MDI-Based Polyurethanes from High Aspect Ratio Mesogenic Diol as Chain Extender

Previous studies on thermotropic main chain liquid crystalline polyurethanes (TLCPUs) prepared from 4-{[4-(6-hydroxyhexyloxy)-phenylimino]-methyl}-benzoic acid 4-{[4-(6-hydroxyhexyloxy)-phenylimino-methyl}-phenyl ester (mesogenic diol) as chain extender were continued. In this article, the main chain liquid crystalline polyurethanes are based on the mesogenic diol as chain extender, poly(tetramethylene oxide)glycol (PTMG) soft segment of different molecular weight PTMGs (M n =650, 1000, 2000), different diisocyanates including 4,4′-methylene bis(cyclohexyl isocyanate) (H 12 MDI) and 4,4′-methylene bis(phenyl isocyanate) (MDI). The polyurethanes were investigated by FTIR spectroscopy for structural confirmation and DSC and hot stage optical polarizing microscope to study the mesomorphic properties. The molecular weight distribution was determined by GPC. The effect of partial replacement of the mesogenic diol by 20-50 mol% PTMG and the effect of the diisocyanates on the liquid crystalline properties were studied. It was observed that the partial replacement of the mesogenic diol by PTMG of varying molecular weights and also the diisocyanates influenced the phase transitions and the occurrence of mesophase textures. Characteristic liquid-crystalline textures were observed when sufficient content of the mesogenic diol was present. If the flexible spacer was longer, a higher content of mesogenic agent was needed to obtain LC properties. Depending on the flexible spacer length and the mesogenic content, grained and threadlike textures were obtained for the H 12 MDI series polymers while the PUs prepared from MDI showed only grained texture for all the compositions. Elastomeric behavior was observed in the polymers from PTMG 2000 and H 12 MDI with mesogen content 20-49 mol%.

Studies on thermotropic main chain liquid crystalline segmented polyurethanes I. Synthesis and properties of polyurethanes from high aspect ratio mesogenic diol as chain extender

Thermotropic main chain liquid crystalline polyurethanes were prepared from 4-{[4-(6-hydroxyhexyloxy)phenylimino]methyl}benzoic acid 4-{[4-(6-hydroxyhexyloxy)phenylimino]methyl}phenyl ester (mesogenic diol) and 1,6-hexamethylene di-isocyanate. The effects of partial replacement of the mesogenic diol by 20-50 mol% of poly(tetramethylene oxide)glycol (PTMG) of varying molecular mass (M n =650, 1000, 2000) on the liquid crystalline properties were studied. Structural characterization was carried out by FTIR spectroscopy and the molecular mass distribution was determined by GPC. Differential scanning calorimetry and hot stage polarizing optical microscopy were used to study the mesomorphic properties. It was observed that the partial replacement of the mesogenic diol by PTMG of varying molecular masses influenced the phase transitions and the occurrence of mesophase textures. When the molecular mass of PTMG was enhanced, a higher content of mesogenic agent was needed to obtain liquid crystalline properties.

Blends of thermoplastic polyurethane and polyether–polyimide: preparation and properties

A series of blends of thermoplastic polyurethane(PU) and polyether–polyimide (PI) were prepared in two steps. The first step was the preparation of polyether–amic acid by the reaction of an oligmer based on polytetramethylene oxide glycol di-p-aminobenzoate (APTMO) of different molecular weight (650, 1000, and 2000) with benzenetetracarboxylic acid dianhydride (PMDA). The second step was mixing polyether–polyurethane and polyether–polyamic acid solution at room temperature in various weight ratios, and the blend films were obtained by casting and then heat imidization. Infrared spectroscopy (IR), dynamic mechanical analysis (DMA), differential scanning calorimetry (DSC), small-angle X-ray scattering (SACS) and wide-angle X-ray diffraction(WAXD) were used to study this family of blends. DSC analysis of the films showed that glass transition temperature (Tg) of PU–PI 650 and PU–PI 1000 series shifted depending on the ratio of PU and PI components. The shift of Tg, along with the transparency of the films, gave the evidence that soft segments of PU and PI were miscible to some extent in the PU–PI 650 and PU–PI 1000 series. DMA results indicated that the blends exhibited a well phase-separated structure and had a broad rubbery plateau from about −30 to 200°C, which varied with the PU content. Thermal stability of PU was found to increase by the incorporation of PI. The excellent tensile properties of the blends suggested that they could be potentially used as heat resistant thermoplastic elastomers.

Study on shape-memory behavior of polyether-based polyurethanes. II. Influence of soft-segment molecular weight

Polyurethanes (PUs) of a suitable molar ratio of monomers were found to have shape-memory behavior. In this study, four series of PUs were synthesized by 4,4′-diphenylmethane diisocyanate (MDI), 1,4-butanediol (BD), and various molecular weights of poly(tetramethylene oxide)glycol (PTMO) to study the influence of the soft segment (PTMO) on the shape-memory behavior of PUs. The investigation on thermal and dynamic mechanical properties was performed using DSC and DMA; then, the morphology of the PUs was directly observed by TEM. At the range of the individual glass transition, a similar recovering behavior was found from the deformed specimen that contained the same composition but different molecular weights of PTMO. However, the phase separation between the soft and the hard segments of the PUs would influence their shape-memory behavior. On the other hand, a large number of the dispersed phase of the PUs would delay the recovery rate of the deformed specimens using a high molecular weight PTMO. © 1998 John Wiley & Sons, Inc. J Appl Polym Sci 69: 1575–1586, 1998

High-Resolution NMR Study on Hydrogen Bondings in Polyether Polyurethane Zwitterionomers

Hydrogen bondings formed in polyether-polyurethane zwitterionomers based on 4,4′-diphenylmethane diisocyanate (MDI), methyl diethanolamine (MDEA), and polytetramethylene oxide glycol (PTMO) were studied in concentrated solutions with high resolution 1H NMR spectroscopy. By comparing with the results of a previous wide line NMR study, a direct relationship was found between the degree of phase separation and the amounts of various kinds of hydrogen bondings formed in the system. The formation of hard segment micelles in concentrated solution is proved and high resolution NMR is demonstrated to be a powerful tool to study the morphology of the multiphase polymers.

Investigation of interactions in polyether-polyurethanes and their mixtures with other polyurethanes by high resolution n.m.r.

The hydrogen bonds in polyether-polyurethanes based on 4,4′-diphenylmethane diisocyanate, N-methyldiethanolamine (MDEA) and poly(tetramethylene oxide) glycol (PTMG) and their zwitterionomers were investigated by high resolution 1H n.m.r. in deuterated dimethyl formamide. There are four NH peaks in each of the 1H n.m.r. spectra resulting from four kinds of hydrogen bonds. The NH groups in the hard segments may form hydrogen bonds with the CO groups of the hard segments, the N atoms of the MDEA portions, the SO groups of γ-propanesulfonates and the O atoms of PTMG. The relative amounts and chemical shifts of the NH peaks do not change with polyurethane concentration. Mixtures of polyether-polyurethanes with a polysiloxane-polyurea and a polyester-polyurethane were also studied by 1H n.m.r. There are no hydrogen-bonding interactions between the hard segments of the two different polyurethanes in these mixtures. The hard segments of the two different polyurethanes cannot be mixed at the molecular level. This is proven by nuclear Overhauser effect spectroscopy (NOESY) for a mixture of a polyether-polyurethane with a polysiloxane-polyurea. The NOESY spectrum indicates that the soft segments of the two different polyurethanes can be mixed at the molecular level. Most of the hard segments form microdomains in concentrated solution. Neither the solvent nor water can invade the microdomains rich in hard segments. Thus we can study hydrogen-bonding interactions in concentrated solution and deduce those interactions in the solid state.