Microphase Separation of Segmented Poly(urethane urea) Block Copolymers

Garrett, J. T.; Runt, James; Lin, J. S.

doi:10.1021/ma000600i

Cited by 221 publications

(185 citation statements)

References 36 publications

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“…This implies that plastic deformation had taken place well before the yield strain (at 25-66% strain). Segmented block copolymers often display significant strain-softening believed to be due to the break-up of the long crystalline ribbons [4,[10][11][12][13]. The yield strain increased with increasing PTMO length and thus also with decreasing T6A6T content (Table 1 and Fig.…”

Section: Dmtamentioning

confidence: 99%

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Tensile properties of segmented block copolymers with monodisperse hard segments

2008

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The tensile properties of segmented block copolymers with mono-disperse hard segments were studied with respect to the hard segment content (16-44 wt.%) and the temperature (20-110°C). The copolymers were comprised of poly(tetramethylene oxide) segments with the molecular weights of 650-2,900 Da and of mono-disperse bisester-tetra-amide segments (T6A6T) based on adipic acid (A), terephthalic acid (T) and hexamethylene diamine (6). An increasing content of T6A6T gave rise to an increased modulus, yield stress and fracture stress. The modulus could be modeled by a composite model. Moreover, a strain-softening was observed well below the yield stress, due to the shearing of the T6A6T crystallites. At strains [200%, a strain-hardening of the PTMO segments took place and this even for PTMO segments that were amorphous in the isotropic state. The strain hardening increased the tensile properties. An increase in temperature had little effect on the modulus of the copolymers, but was found to lower the yield and fracture stresses. At temperatures above the melting temperature of the oriented PTMO, no strain-hardening took place. The yield stress as a function of temperature could be described by the Eyring relationship, but a modulus-yield stress relationship could not be established.

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Section: Dmtamentioning

confidence: 99%

“…The hard segment (HS) crystallites have a nano-ribbonlike structure with a high aspect ratio [10][11][12][13][14], and these nano-ribbons reinforce the soft phase [3,4,15]. Upon stretching of such a copolymer, both the soft and the hard phases are deformed, and for a high enough strain, yielding of the hard phase occurs [13,[16][17][18].…”

Section: Introductionmentioning

confidence: 99%

Tensile properties of segmented block copolymers with monodisperse hard segments

2008

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“…It is well established that segmented copolymers can undergo microphase separation into soft and hard domains giving rise to hierarchically ordered structures that display a wide range of morphologies [25][26][27]. This type of self organization is thermodynamically driven (unfavorable enthalpic contribution of intersegmental mixing) with hydrogen bonding diminishing (hard-hard bridging) or even enhancing (hard-soft bridging) the compatibility of the two phases.…”

Section: Mechanical Propertiesmentioning

confidence: 99%

Fouling release nanostructured coatings based on PDMS-polyurea segmented copolymers

Fang

Kelarakis

Wang

et al. 2010

Polymer

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The bulk and surface characteristics of a series of coatings based on PDMS-polyurea segmented copolymers were correlated to their fouling release performance. Incorporation of polyurea segments to PDMS backbone gives rise to phase separation with the extensively hydrogen bonded hard domains creating an interconnected network that imparts mechanical rigidity.Increasing the compositional complexity of the system by including fluorinated or POSS functionalized chain extenders or through nanoclay intercalation, confers further thermomechanical improvements. In analogy to the bulk morphology, the surface topography also reflects the compositional complexity of the materials, displaying a wide range of motifs.Investigations on settlement and subsequent removal of Ulva sporelings on those nanostructured surfaces indicate that the work required to remove the microorganisms is significantly lower compared to coatings based on standard PDMS homopolymer. All in all, the series of materials considered in this study demonstrate advanced fouling release properties, while exhibiting superior mechanical properties and, thus, long term durability.

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“…1 The morphology of PU determines its mechanical, thermal, and water absorption properties. [2][3][4] The hard segments are formed by the addition of a chain extender to the diisocyanate, and the soft segments consist of a long flexible polyether or polyester chain that interconnects two hard segments. At temperatures lower than the order-disorder transition temperature (T ODT ), the lowmelting soft segments are incompatible with the polar and high-melting hard segments, which leads to a phase-separated microstructure.…”

Section: Introductionmentioning

confidence: 99%

Synthesis and characterization of in situ polymerized segmented thermoplastic elastomeric polyurethane/layered silicate clay nanocomposites

Choi

Anandhan

Youk

et al. 2006

J of Applied Polymer Sci

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Nanocomposites based on thermoplastic elastomeric polyurethane (TPU) and layered silicate clay were prepared by in situ synthesis. The properties of nanocomposites of TPU with unmodified clay were compared with that of organically modified clay. The nanocomposites of the TPU and organomodified clay showed better dispersion and exhibited superior properties. Exfoliation of the clay layers was observed at low organoclay contents, whereas an intercalated morphology was observed at higher clay contents. As one of major purposes of this study, the effect of the silicate layers in the nanocomposites on the order-disorder transition temperature (T ODT ) of the TPU was evaluated from the intensity change of the hydrogen-bonded and free carbonyl stretching peaks and from the peak position change of the NÀ ÀH bending peak. The presence of the organoclay increased T ODT by approximately 108C, which indicated improved stability in the phase-separated domain structure. The layered silicate clay caused a tremendous improvement in the stiffness of the TPU; meanwhile, a reduction in the ultimate elongation was observed.

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Microphase Separation of Segmented Poly(urethane urea) Block Copolymers

Cited by 221 publications

References 36 publications

Tensile properties of segmented block copolymers with monodisperse hard segments

Tensile properties of segmented block copolymers with monodisperse hard segments

Fouling release nanostructured coatings based on PDMS-polyurea segmented copolymers

Synthesis and characterization of in situ polymerized segmented thermoplastic elastomeric polyurethane/layered silicate clay nanocomposites

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