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

Adhikari, Raju; Gunatillake, Pathiraja A.; McCarthy, Simon J.; Meijs, Gordon F.

doi:10.1002/1097-4628(19991213)74:12<2979::aid-app25>3.0.co;2-f

Cited by 20 publications

(28 citation statements)

References 14 publications

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“…The molecular weights of the polymers synthesized in the PU and PUU series ranged from 114,300 to 124,500 and 78,400 to 103,300, respectively, whereas their respective polydispersities were 1.89–1.98 and 1.35–1.61 (Table I). The molecular weights observed are typical of what is normally achieved with this class of polymers and should not have significantly affected their mechanical properties 12…”

Section: Resultsmentioning

confidence: 99%

“…Tan δ peak temperatures and glass‐transition temperatures estimated from E ′‐versus‐temperature plots are summarized in Table VI. As we previously observed for other systems,12 the T g values estimated from DMTA were higher than those determined by DSC. However, the general trend was similar.…”

Section: Resultsmentioning

confidence: 99%

“…The molecular weights observed are typical of what is normally achieved with this class of polymers and should not have significantly affected their mechanical properties. 12 The films cast from polymers in each series showed different degrees of transparency, as measured using a Gardner UX10 Hazemeter with a PG5500 digital photometer attachment. The results are summarized in Figure 1.…”

Section: Polymer Synthesismentioning

confidence: 99%

“…This macrodiol has ethoxypropyl end groups, which may also contribute both to its improved compatibility with the hard segment and its improved mechanical properties. The influence of the amount of the comacrodiol as well as the effect of the chain extender composition on polyurethane properties and morphology has been investigated 10–12. However, no previous article has reported a detailed study of the effect of PDMS molecular weight on polyurethane properties and morphology.…”

Section: Introductionmentioning

confidence: 99%

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Effect of polydimethylsiloxane macrodiol molecular weight on properties and morphology of polyurethane and polyurethaneurea

Adhikari

Gunatillake

Bown

2003

J of Applied Polymer Sci

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Two series of polyurethanes and polyurethaneureas were prepared using a two-step bulk-solution polymerization procedure. Each series consisted of three polymers based on three molecular weights of ␣,-bis(6-hydroxyethoxypropyl) polydimethylsiloxane (PDMS): 940, 1913, and 2955. The soft segment in all cases was an 80:20 mixture of PDMS and poly(hexamethylene oxide) (MW 700), and the hard segment was based on 4,4Ј-methylenediphenyl diisocyanate and mixed chain extenders (40 wt %). In the polyurethane (PU) series the chain extender was a 60:40 (mol) mixture of BDO and 1,3-bis(4-hydroxybutyl)1,1,3,3-tetramethyldisiloxane (BHTD), whereas in the polyurethaneurea (PUU) series it was a 60:40 (mol) mixture of BHTD and 1,2-ethylenediamine. The polymerization was carried out by preparing a prepolymer using a bulk polymerization procedure followed by chain extension in a solution of N,Ndimethylacetamide. Polymers were characterized by sizeexclusion chromatography, tensile testing, differential scanning calorimetry (DSC), and dynamic mechanical thermal analysis (DMTA). The number-average molecular weights of the polymers in the PU series were in the range of 114,300 -124,500, whereas they were in the 78,400 -103,300 range for the PUU series. Polymers with good clarity and mechanical properties were obtained with PDMS-940 and PDMS-1913, but those obtained from PDMS-2955, despite having good tensile strength, had a low percentage of elongation, high modulus, and poor clarity. DSC and DMTA results indicated that regardless of the PDMS molecular weight, the siloxane segments existed as a highly phaseseparated state. This poor compatibility was consistent with the low solubility of PDMS compared to that of the hardsegment-forming components. The polymers in the polyurethane series exhibited multiple melting endotherms, attributed to the melting of ordered domains from different hard segments. The combined heats of fusion were similar for the materials in the PU series. In contrast, the polymers in the PUU series showed a hard-segment order that was significantly less defined, with the heat of fusion approximately a third to a half that of the materials in the polyurethane series.

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Section: Resultsmentioning

confidence: 99%

Section: Resultsmentioning

confidence: 99%

Section: Polymer Synthesismentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

See 2 more Smart Citations

Effect of polydimethylsiloxane macrodiol molecular weight on properties and morphology of polyurethane and polyurethaneurea

Adhikari

Gunatillake

Bown

2003

J of Applied Polymer Sci

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“…Microphase separation depends on several factors such as molecular weight of the SS, structure of comacrodiol, chain extender composition, intermolecular hydrogen bonding between hard and SS, compatibility between hard and SS, and processing conditions . A thorough understanding of these attributes will be needed to optimize for target biomedical applications.…”

Section: Introductionmentioning

confidence: 99%

Morphology and surface properties of high strength siloxane poly(urethane‐urea)s developed for heart valve application

et al. 2018

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A series of siloxane poly(urethane-urea) (SiPUU) were developed by incorporating a macrodiol linked with a diisocyanate to enhance mixing of hard and soft segments (SS). The effect of this modification on morphology, surface properties, surface elemental composition, and creep resistance was investigated. The linked macrodiol was prepared by reacting α,ω-bis(6-hydroxyethoxypropyl) poly(dimethylsiloxane)(PDMS) or poly(hexamethylene oxide) (PHMO) with either 4,4'-methylenediphenyl diisocyanate (MDI), hexamethylene diisocyanate (HDI), or isophorone diisocyanate (IPDI). SiPUU with PHMO-MDI-PHMO and PHMO-IPDI-PHMO linked macrodiols showed enhanced creep resistance and recovery when compared with a commercial biostable polyurethane, Elast-Eon™ 2A. Small and wide-angle X-ray scattering data were consistent with significant increase of hydrogen bonding between hard and SS with linked-macrodiols, which improved SiPUU's tensile stress and tear strengths. These SiPUU were hydrophobic with contact angle higher than 101° and they had low water uptake (0.7%·w/w of dry mass). They also had much higher siloxane concentration on the surface compared to that in the bulk. © 2018 Wiley Periodicals, Inc. J Biomed Mater Res Part B: Appl Biomater, 2018.

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Low‐modulus siloxane–polyurethanes. Part II. Effect of chain extender structure on properties and morphology

Adhikari

Gunatillake

McCarthy

et al. 2002

J of Applied Polymer Sci

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A series of six polyurethanes were prepared to study the effect of silicon chain extender structure on properties and morphology of siloxane-polyurethanes. Polyurethanes were prepared by a two-step bulk polymerization without a catalyst. The soft segment of the polyurethanes was based on an 80:20 (w/w) mixture of ␣,-bis(6-hydroxyethoxypropyl) polydimethylsiloxane (PDMS, MW 966) and poly(hexamethylene) oxide (MW 714). The hard segment was based on 4,4Ј-methylenediphenyl diisocyanate (MDI) and a 60:40 molar mixture of 1,4-butanediol (BDO) and a silicon chain extender. Silicon chain extenders (SCE) investigated were 1,3-bis(4-hydroxybutyl)1,1,3,3-tetramethyldisiloxane (BHTD), 1,3-bis(3-hydroxypropyl)1,1,3,3-tetramethyldisiloxane (BPTD), 1,4-bis(3-hydroxypropyl)1,1,3,3-tetramethyldisilylethylene (HTDE), 1,3-bis(6-hydroxyethoxypropyl)1,1,3,3-tetramethyldisiloxane (BETD). All polyurethanes were clear and transparent with number average molecular weights between 72,000 to 116,000. Incorporation of the silicon chain extender resulted in polyurethanes with low-modulus and high elongation. This was achieved without significant compromise in ultimate tensile strength in all cases, except BETD. Differential scanning calorimetry (DSC) results showed that the silicon chain extenders did not significantly disrupt the hard segment crystallinity, but exhibited a unique morphological feature where SCE-based hard segments formed separate domains, which may be the primary reason for achieving low modulus without significant compromise in strength.

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

Cited by 20 publications

References 14 publications

Effect of polydimethylsiloxane macrodiol molecular weight on properties and morphology of polyurethane and polyurethaneurea

Effect of polydimethylsiloxane macrodiol molecular weight on properties and morphology of polyurethane and polyurethaneurea

Morphology and surface properties of high strength siloxane poly(urethane‐urea)s developed for heart valve application

Low‐modulus siloxane–polyurethanes. Part II. Effect of chain extender structure on properties and morphology

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