The effect of varying soft and hard segment length on the structure–property relationships of segmented polyurethanes based on a linear symmetric diisocyanate, 1,4-butanediol and PTMO soft segments

Abstract 1. Densities of elastomers with crystallizing soft segments were higher than that of the noncrystallizing ones. However, the effect of the soft segment length is not regular and may reflect some specific interactions between two phases as well as instantaneous morphology. 2. Phase inversion as judged by drop of hardness takes place at about ssc=60° or more; a shift to higher ssc gives a greater segment length. 3. Tg of the soft segment in samples with well separated phases is independent of ssc, e.g., the presence of hard phase does not change mobility of the soft phase in samples with ssc=50° or more, in all series. However, Tg is strongly dependent on the soft-segment length. Tg for the soft segment of Mn=650 was −43°C, for Mn=1000 was −62°C, and for Mn=2000, Tg was −75°C. The effect of the presence of the hard phase on mobility of the soft phase seems to vanish for M>2500. 4. Tg of the hard segment at 77°C was clearly observed only in quenched samples with a high hard-segment concentration (80%) and at 93°C in a pure hard segment. 5. Melting of both phases were observed in polymers with long soft segments (Mn=2000). Soft segments of Mn=650 and 1000 do not crystallize. The hard phase crystallizes if its Mn is about 1000 or more or if the degree of polymerization of the hard segment is 3 or above, although exceptions were found in the A series. 6. Spherulitic structures were observed in polymers with low ssc (20% and 40%) polymers and in one with ssc=80°. Thus, both hard and soft phases can form spherulitic structures.

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Study on the Influences of Domain Structure of Hydrophilic Polyurethane with Partially Crystalline on its Moisture Permeability

Advanced Materials Research ◽

10.4028/www.scientific.net/amr.233-235.281 ◽

2011 ◽

Vol 233-235 ◽

pp. 281-287

Author(s):

Heng Quan ◽

Zhen Ya Gu

Keyword(s):

Chemical Structure ◽

Hard Segment ◽

Microphase Separation ◽

Soft Segment ◽

Moisture Permeability ◽

Soft Segments ◽

Separation Degree ◽

Polyethylene Glycol 1000 ◽

Segmented Polyurethanes ◽

Hydrophilic Polyurethane

Multiphase, segmented polyurethanes with mixed soft segment phase were prepared from 4,4’- diphenylmethane diisocyanate (Pure MDI), polybutylene adipate (glycol) 2000 (PBA2000) and polyethylene glycol 1000 (PEG1000) with 1,4-butanediol (BDO) as the chain extender. Further more, the relationships between domain separation structure, crystallizability of soft segment and moisture permeability, hydrophilic property, phase inversion temperature (PIT) of the polyurethanes were investigated. The studies show that the chemical structure, concentration of hydrophilic soft monomers and the microphase separation degree of the mixed soft segments from hard segment domain have remarkable effects on the application properties of polyurethane.

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Study of the Effect of Soft-Segment Length and Concentration on Properties of Polyetherurethanes. II. The Effect on Mechanical Properties

Rubber Chemistry and Technology ◽

10.5254/1.3536087 ◽

1985 ◽

Vol 58 (4) ◽

pp. 701-712 ◽

Cited By ~ 11

Author(s):

Zoran S. Petrović ◽

Jaroslava Budinski-Simendić

Keyword(s):

Mechanical Properties ◽

Chain Length ◽

Plastic Flow ◽

Soft Segment ◽

Maximum Strength ◽

Segment Length ◽

Elongation At Break ◽

Mechanical Methods ◽

Soft Segments ◽

Segmented Polyurethanes

Abstract Three series of segmented polyurethanes with different soft segment lengths and concentrations were examined by TMA, DMA, and mechanical methods. Maximum tensile strengths were obtained when ssc was 40–50%, which was explained by a specific interlocking morphology. No significant effect of soft-segment chain length on maximum strength was found, but higher values were found in the C series when ssc was 60%. Elongation at break increases linearly with ssc but indications that shorter soft segments produce higher extensions was attributed to plastic flow. TMA showed that Tg was independent of ssc in the C and, to a degree, in the B series, while temperature of α-transition in DMA was independent of ssc only in the C series at ssc above 50%.

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Novel Water Loving Coatings (WLC) Lubricious and Durable Guidewires

2017 Design of Medical Devices Conference ◽

10.1115/dmd2017-3434 ◽

2017 ◽

Author(s):

Peter A. Edwards ◽

Michael Price ◽

Nick Nimchuk ◽

Jeff Mahon

Keyword(s):

Phenyl Isocyanate ◽

Structure Property ◽

Poly Ethylene Glycol ◽

Water Dispersible ◽

Structure Property Relationships ◽

Soft Segments ◽

Hard Segments ◽

Poly Ethylene ◽

Hydrophilic Coatings ◽

Glycol Methyl Ether

Hydrophilic coatings applied to guidewires or catheters, lower friction of the device thus improves handling and reduces damage to the vessel walls during access, delivery and retrieval. Peripheral guidewires typically consist of a polymer jacket, basecoat and topcoat. The polymer jacket is highly radiopaque for fluoroscopy visualization. Basecoat adheres to the polymer jacket and hydrophilic topcoat. Basecoat and topcoat play important roles towards coating device durability and lubricity. Water Loving Coatings (WLC) are the first developed 510(k) clearance guidewires utilizing epoxy polyurethane technology. Coatings are non-hemolytic and non-cytotoxic. WLC are advances toward glycidyl carbamate (GC) resins. Linear Glycidyl Carbamates have shown excellent flexibility based off structure property relationships [1]. Water dispersible GC (WD-GC) oligomers have been prepared by additions of poly(ethylene glycol) methyl ether (m-peg) to isocyanurate and biuret, then end capped with glycidol [2]. WLC technologies are lubricious and durable water dispersible polyurethane or polyurea glycidyl carbamates [3]. Modified Hyaluronate with WD-GC oligomers have shown increases in lubricity of Guidewires when used with a catheter [4]. WLC coatings have been applied to a micro-wire to reduce endothelial mechanical lining damage [5]. Common thermoplastic urethanes (TPU), similar to WLC morphology, used in the medical industry, are: Biomer and Lubrizol’s Pellethane®, Tecoflex™ and Estane™. Biomer consists of 4,4′-Methylenebis(phenyl isocyanate) (MDI), Ethylenediamine (EDA), and Polytetramethylene diol (Poly THF). Pellethane consists of MDI, 1,4-Butanediol (BDO) and Poly THF. Tecoflex consists of 4-4′-methylenebis (cyclohexyl isocyanate) (H12MDI), BDO and Poly THF. Medical grade Estane is an ester of adipic acid with BDO for soft segments and MDI and BDO for hard segments. TPU structure and morphology dictates polymeric properties.

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