Thermoplastic elastomer gels. I. Effects of composition and processing on morphology and gel behavior

Laurer, Jonathan H.; Mulling, James; Khan, Saad A.; Spontak, Richard J.; Bukovnik, Rudy

doi:10.1002/(sici)1099-0488(19980930)36:13<2379::aid-polb13>3.0.co;2-0

Cited by 97 publications

(99 citation statements)

References 37 publications

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“…They also examined the impact of this dilution on the rheological response. The dependence of the gel modulus on the polymer content, along with the gel microdomain structure, was also studied in detail by Spontak and coworkers [11][12][13][14] for several styrenic triblock copolymers, all of which showed a strong power-law dependence of the modulus on the triblock content in the gels.…”

Section: Introductionsupporting

confidence: 86%

“…Moreover, similar exponents were found previously by Laurer and coworkers for several styrenic triblock copolymers in a midblock-selective solvent (aliphatic oil): styrene-(ethylene-co-butene)-styrene (SEBS) 11 (exponent ϭ 2.43), SEPS 13 (exponent ϭ 2.68), and SIS 13 (exponent ϭ 1.77). Exponents of approximately 2 have also been found for a variety of SEBS triblocks in tetradecane.…”

Section: Viscoelastic Properties and Plateau Moduli (G 0 )mentioning

confidence: 99%

“…1(b)], the bridging chains produce an association, which can lead to phase-separated solutions at low polymer contents 2,4 and physical networks at high polymer contents. [5][6][7][8][9][10][11][12][13][14] Watanabe and coworkers 9,10 conducted extensive investigations of styrene-isoprene-styrene (SIS) triblocks in the midblock-selective solvent tetradecane at various polymer concentrations. The fraction of bridges was directly determined by an elegant dielectric technique and was shown to decrease as the triblock was diluted.…”

Section: Introductionmentioning

confidence: 99%

See 2 more Smart Citations

Phase behavior and viscoelastic properties of entangled block copolymer gels

Vega

Sebastian

Loo

et al. 2001

J Polym Sci B Polym Phys

131

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Triblock copolymers in midblock-selective solvents can form physical gels. However, at low triblock contents (near the percolation threshold), the bridging of chains between micelles can lead to macrophase separation. Adding a styrene-isoprene diblock to a styrene-isoprene-styrene triblock copolymer in squalane can eliminate macrophase separation, yielding a wide range of stable, single-phase gels with a disordered arrangement of micelles. The plateau modulus of these triblock gels scales with the 2.2 power of polymer content, indicating the importance of entanglements in dictating the modulus. Comparing gels made from the midblock-saturated derivative of the same polymer [styrene-(ethylene-alt-propylene)-styrene] in squalane reveals that the modulus differences in the gels are a direct consequence of the difference in the entanglement molecular weight of the midblock homopolymer in bulk. Finally, the broad relaxation spectrum of these triblocks is well-described by a recent theory for the dynamics of entangled star polymers, with the breadth of the relaxation spectrum dictated by the number of entanglements per midblock in the gel.

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Section: Introductionsupporting

confidence: 86%

Section: Viscoelastic Properties and Plateau Moduli (G 0 )mentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

See 1 more Smart Citation

Phase behavior and viscoelastic properties of entangled block copolymer gels

Vega

Sebastian

Loo

et al. 2001

J Polym Sci B Polym Phys

131

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“…Small-angle scattering studies [1-2 ; 21-26] and TEM studies [27][28][29] proved that ABA-block copolymers, when mixed with a solvent or an extender oil selective for the midblock, but incompatible with the outerblocks, aggregate into microdomains. This results in a nanophase separation between the endblocks and the matrix, containing the (dissolved) midblock and the solvent.…”

Section: Introductionmentioning

confidence: 97%

Silica reinforced triblock copolymer gels

Theunissen

Overbergh

Reynaers

et al. 2004

Polymer

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The effect of silica and polymer coated silica particles as reinforcing agents on the structural and mechanical properties of polystyrene-poly(ethylene/butylene)-polystyrene (PS-PEB-PS) triblock gel has been investigated. Different types of chemically modified silica have been compared in order to evaluate the influence of the compatibility between gel and filler.Time-resolved SANS and small-angle X-ray scattering (SAXS) shows that the presence of silica particles affects the ordering of the polystyrene domains during gelsetting. The scattering pattern of silica-reinforced gels reveals strong scattering at very low q, but no structure and formfactor information. However, on heating above the viscoelastic to plastic transition, the 'typical' scattering pattern of the copolymer gel builds-up. All reinforced gels are strengthened by the addition of the reinforcing agent. The transitions from a viscoelastic rubber to a plastic fluid and from a plastic fluid to a viscoelastic liquid are shifted to more elevated temperatures when silica is added to the triblock copolymer gel.

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“…The mechanical properties of a variety of ABA type gels have been extensively evaluated in the literature. [13][14][15][16][17][18] A triblock copolymer gel serves as an excellent starting point for a surrogate material because these gels exhibit predictable mechanical behavior over a known temperature range, the mechanical properties are relatively stable over time, and the gel mechanical properties may be tuned by changing solvent selectivity, triblock copolymer composition, and temperature.…”

Section: Introductionmentioning

confidence: 99%

Multiscale mechanical characterization of biomimetic physically associating gels

et al. 2006

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Public reporting burden for this collection of information is estimated to average 1 hour per response, including the time for reviewing instructions, searching existing data sources, gathering and maintaining the data needed, and completing and reviewing the collection information. Send comments regarding this burden estimate or any other aspect of this collection of information, including suggestions for reducing the burden, to Department of Defense, Washington Headquarters Services, Directorate for Information Operations and Reports (0704-0188), 1215 Jefferson Davis Highway, Suite 1204, Arlington, VA 22202-4302. Respondents should be aware that notwithstanding any other provision of law, no person shall be subject to any penalty for failing to comply with a collection of information if it does not display a currently valid OMB control number. PLEASE DO NOT RETURN YOUR FORM TO THE ABOVE ADDRESS. REPORT DATE (DD-MM-YYYY) ARL-RP-134 SPONSOR/MONITOR'S ACRONYM(S) 9. SPONSORING/MONITORING AGENCY NAME(S) AND ADDRESS(ES) SPONSOR/MONITOR'S REPORT NUMBER(S) DISTRIBUTION/AVAILABILITY STATEMENTApproved for public release; distribution is unlimited. SUPPLEMENTARY NOTES ABSTRACTThe mechanical response of living tissue is important to understanding the injury-risk associated with impact events. Often, ballistic gelatin or synthetic materials are developed to serve as tissue surrogates in mechanical testing. Unfortunately, current materials are not optimal and present several experimental challenges. Bulk measurement techniques, such as compression and shear testing geometries, do not fully represent the stress states and rate of loading experienced in an actual impact event.Indentation testing induces deviatoric stress states as well as strain rates not typically available to bulk measurement equipment. In this work, a ballistic gelatin and two styrene-isoprene triblock copolymer gels are tested and compared using both macroscale and microscale measurements. A methodology is presented to conduct instrumented indentation experiments on materials with a modulus far below 1 MPa. The synthetic triblock copolymer gels were much easier to test than the ballistic gelatin. Compared to ballistic gelatin, both copolymer gels were found to have a greater degree of thermal stability. All of the materials exhibit strain-rate dependence, although the magnitude of dependence was a function of the loading rate and testing method. The mechanical response of living tissue is important to understanding the injury-risk associated with impact events. Often, ballistic gelatin or synthetic materials are developed to serve as tissue surrogates in mechanical testing. Unfortunately, current materials are not optimal and present several experimental challenges. Bulk measurement techniques, such as compression and shear testing geometries, do not fully represent the stress states and rate of loading experienced in an actual impact event. Indentation testing induces deviatoric stress states as well as strain rates not typically available to bulk meas...

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Thermoplastic elastomer gels. I. Effects of composition and processing on morphology and gel behavior

Cited by 97 publications

References 37 publications

Phase behavior and viscoelastic properties of entangled block copolymer gels

Phase behavior and viscoelastic properties of entangled block copolymer gels

Silica reinforced triblock copolymer gels

Multiscale mechanical characterization of biomimetic physically associating gels

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