Thermoplastic polyurethane elastomers based on aliphatic diisocyanates: thermal transitions

Aitken, R. R.; Jeffs, G.M.F.

doi:10.1016/0032-3861(77)90039-8

Cited by 34 publications

(15 citation statements)

References 3 publications

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“…In polyurethanes based on aliphatic diisocyanates, the factors affecting T g include the crystallization of soft-and hard-segment components, the steric hindrance of the hard-segment unit in a hydrogenbonding process, and the inherent solubility of the hard and soft components. 45 For the poly(ester urethane)s synthesized in this study, T g increased with the decreasing content and molecular weight of the soft segment, that is, the increasing content of hard segments due to phase mixing. For poly(ester ether urethane)s, the influence of the soft-segment chemical structure on T g was minimal.…”

Section: Discussionmentioning

confidence: 70%

Biodegradable polyurethanes for implants. II. In vitro degradation and calcification of materials from poly(ϵ‐caprolactone)–poly(ethylene oxide) diols and various chain extenders

Górna

Gogolewski

2002

J. Biomed. Mater. Res.

137

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Linear, biodegradable, aliphatic polyurethanes with various degrees of hydrophilicity were synthesized in bulk at 50-100 degrees C. The ratios between the hydrophilic and hydrophobic segments were 0:100, 30:70, 40:60, 50:50, and 70:30, respectively. The hydrophilic segment consisted of poly(ethylene oxide) (PEO) diol (molecular weight = 600 or 2000) or the poly(ethylene-propylene-ethylene oxide) (PEO-PPO-PEO) diol Pluronic F-68 (molecular weight = 8000). The hydrophobic segment was made of poly(epsilon-caprolactone) diol (molecular weight = 530, 1250, or 2000). The chain extenders were 1,4-butane diol and 2-amino-1-butanol. The diisocyanate was aliphatic hexamethylene diisocyanate. The polymers absorbed water in an amount that increased with the increasing content of the PEO segment in the polymer chain. The total amount of absorbed water did not exceed 2% for the poly(ester urethane)s and was as high as 212% for some poly(ester ether urethane)s that behaved in water like hydrogels. The polymers were subjected to in vitro degradation at 37 +/- 0.1 degrees C in phosphate buffer solutions for up to 76 weeks. The poly(ester urethane)s showed 1-2% mass loss at 48 weeks and 1.1-3.8% mass loss at 76 weeks. The poly(ester ether urethane)s manifested 1.6-76% mass loss at 48 weeks and 1.6-96% mass loss at 76 weeks. The increasing content and molecular weight of the PEO segment enhanced the rate of mass loss. Similar relations were also observed for polyurethanes from PEO-PPO-PEO (Pluronic) diols. Materials obtained with 2-amino-1-butanol as the chain extender degraded at a slower rate than similar materials synthesized with 1,4-butane diol. All the materials already manifested a progressive decrease in the molecular weight in the first month of in vitro aging. The rate of molecular weight loss was higher for poly(ester ether urethane)s than for poly(ester urethane)s. For poly(ester ether urethane)s, the rate of molecular weight loss was higher for materials containing Pluronic than for those containing PEO segments. All polymers calcified in vitro. The susceptibility to calcification increased with material hydrophilicity. The progressive deposition of calcium salt on the film surfaces resulted in the formation of large crystal aggregates, the structure of which depended on the chemical composition of the calcified material. Needle-like aggregates, resembling brushite, formed on the hydrophobic polyurethane, and plate-like crystals formed on the highly hydrophilic material. The calcium-to-phosphorus atomic ratio of the crystals growing on the samples was dependent on the chemical composition of the material and varied from 0.94 to 1.55.

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Section: Discussionmentioning

confidence: 70%

Biodegradable polyurethanes for implants. II. In vitro degradation and calcification of materials from poly(ϵ‐caprolactone)–poly(ethylene oxide) diols and various chain extenders

Górna

Gogolewski

2002

J. Biomed. Mater. Res.

137

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“…A series of poly(ether urethane)s and poly(carbonate urethane)s containing various amounts of chain extender with fluorinated side chains were synthesized with methylenebis(phenylene isocyanate) (MDI), polytetramethyleneoxide (PTMO), or poly(1,6-hexyl-1,5-pentylcarbonate) diol (PHPCD), 1,4-butandiol (BDO) and 3- (2,2,3,3,4,4,5,5,6,6,7,7,8,8,8-pentadecafluoro-octyloxy)-propane-1,2-diol (PFOP-DOL). The details of the fluorinated polyurethanes synthesis were reported in Ref [35] and the detailed information of these samples is listed in Table 1, and the structure is shown in Fig.…”

Section: Synthesis Of Materialsmentioning

confidence: 99%

“…These desirable bulk properties mainly derive from the two-phase structure of hard and soft domains: hard domains, composed of aromatic (or aliphatic) urethane or urea segments, and soft domains, composed of aliphatic polyether, polycarbonate, polyester or poly(methylsiloxane) segments [2,3]. Factors that control the phase separation include composition, such as the symmetry of diisocyanate, the type of chain extender, the number of carbons in linear low molecular weight chain extender [4], the type and the chain lengths of soft segments [2,[4][5][6], crystallizability of either segment [7], the thermal history of the polyurethanes [5,8,9] and the method of synthesis [10].…”

Section: Introductionmentioning

confidence: 99%

The effect of fluorinated side chain attached on hard segment on the phase separation and surface topography of polyurethanes

Tan

Guo

et al. 2004

Polymer

108

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“…Typically, polyurethanes based on H 12 MDI (a configurational isomeric mixture of cis-cis, cis-trans, trans-trans) are transparent with good flexibility and set but generally have poor biostability. [15][16][17][18] It is envisaged that by the incorporation of PDMS-based soft segments, the degradation resistance of H 12 MDI based polyurethanes could be improved. Further, the use of chain extender mixtures would allow one to control the level of phase mixing to overcome any incompatibility associated with PDMS macrodiol.…”

Section: Introductionmentioning

confidence: 99%

Effect of chain extender structure on the properties and morphology of polyurethanes based on H12MDI and mixed macrodiols (PDMS–PHMO)

Adhikari

Gunatillake

McCarthy

et al. 1999

J. Appl. Polym. Sci.

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ABSTRACT:The effect of chain extender structure on properties and morphology of ␣,-bis(6-hydroxyethoxypropyl) polydimethylsiloxane (PDMS) and poly(hexamethylene oxide) (PHMO) mixed macrodiol-based aliphatic polyurethane elastomers was investigated using tensile testing, differential scanning calorimetry (DSC), and dynamic mechanical thermal analysis (DMTA). All polyurethanes were based on 50 wt % of hard segment derived from 4,4Ј-methylenecyclohexyl diisocyanate (H 12 MDI) and a chain extender mixture. 1,4-Butanediol was the primary chain extender, while one of 1,3-bis(4-hydroxybutyl)tetramethyldisiloxane (BHTD), 1,3-bis(3-hydroxypropyl)tetramethyldisiloxane (BPTD), hydroquinonebis(2-hydroxyethyl)ether (HQHE), 1,3-bis(3-hydroxypropyl)tetramethyldisilylethylene (HTDE), or 2,2,3,3,4,4-hexafluoro-1,5-pentanediol (HFPD) each was used as a secondary chain extender. Two series of polyurethanes containing 80 : 20 (Series A) and 60 : 40 (Series B) molar ratios of primary and secondary chain extenders were prepared using one-step bulk polymerization. All polyurethanes were clear and transparent and had number-average molecular weights between 56,000 and 122,100. Incorporation of the secondary chain extender resulted in polyurethanes with low flexural modulus and high elongation. Good ultimate tensile strength was achieved in most cases. DSC and DMTA analyses showed that the incorporation of a secondary chain extender disrupted the hard segment order in all cases. The highest disruption was observed with HFPD, while the silicon-based chain extenders gave less disruption, particularly in Series A. Further, the silicon chain extenders improved the compatibility of the PDMS soft segment phase with the hard segment, whereas with HFPD and HQHE, this was not observed.

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Thermoplastic polyurethane elastomers based on aliphatic diisocyanates: thermal transitions

Cited by 34 publications

References 3 publications

Biodegradable polyurethanes for implants. II. In vitro degradation and calcification of materials from poly(ϵ‐caprolactone)–poly(ethylene oxide) diols and various chain extenders

Biodegradable polyurethanes for implants. II. In vitro degradation and calcification of materials from poly(ϵ‐caprolactone)–poly(ethylene oxide) diols and various chain extenders

The effect of fluorinated side chain attached on hard segment on the phase separation and surface topography of polyurethanes

Effect of chain extender structure on the properties and morphology of polyurethanes based on H12MDI and mixed macrodiols (PDMS–PHMO)

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