Syndiotactic Polystyrene Physical Gels:  Guest Influence on Structural Order in Molecular Complex Domains and Gel Transparency

Daniel, Christophe; Avallone, and Antonio; Guerra, Gaetano

doi:10.1021/ma061124k

Cited by 40 publications

(40 citation statements)

References 31 publications

(28 reference statements)

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“…For example, Hou et al reported ES block copolymer having 56–87 mol % of styrene with melting points of 214–245 °C 19 and Grassi and coworkers reported melting temperatures of 200–242 °C for sPS‐ block ‐PE copolymers (43–93 mol % styrene) prepared by hydrogenation of syndiotactic styrene‐butadiene block copolymers 51. Thus, although the data from this work and that of Yokota23 are consistent with blocky sPS/ES copolymers derived from B (or its tetramethyl analogue), the similar solubility of ES copolymers and low‐melting sPS in THF and the well‐known ability of sPS to form clathrates and gels52 illustrate the challenges of distinguishing sPS/ES block copolymers from their blends.…”

Section: Resultssupporting

confidence: 63%

Bone mineral density in young adult survivors of acute lymphoblastic leukemia

Thomas

Donohue

Ness

et al. 2008

Cancer

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BACKGROUND.The purpose of the current study was to determine the prevalence of low bone mineral density (BMD) (ie, osteopenia) and identify factors associated with low BMD in young adult survivors of childhood acute lymphoblastic leukemia (ALL).METHODS.Dual energy x‐ray absorptiometry was used to evaluate BMD in 74 randomly selected, long‐term childhood ALL survivors initially treated in Minneapolis/St. Paul, Minnesota. Growth hormone (GH)‐releasing hormone–arginine stimulation testing was conducted to evaluate peak GH level, and insulin‐like growth factor I (IGF‐I) and other markers of endocrine functioning were also evaluated in relation to BMD.RESULTS.The mean age at the time of interview was 30 years, and the mean time since diagnosis was 24 years. Low BMD (Z‐score, ≤−1) was present in 24% of subjects, including 1 with osteoporosis. Low BMD was substantially more prevalent in men than in women and was strongly associated with short height. The mean height Z‐score for those with low BMD was −1.44, compared with a height Z‐score of −0.39 (P < .01) for those with normal BMD. GH insufficiency, low IGF‐I Z‐score, and current smoking were also suggestive risk factors for low BMD.CONCLUSIONS.In this long‐term follow‐up study of childhood ALL survivors, low BMD was found to be more prevalent than expected based on population normative data, specifically in men. The health consequences of early‐onset BMD problems in childhood ALL survivors need to be carefully monitored. Cancer 2008. © 2008 American Cancer Society.

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Section: Resultssupporting

confidence: 63%

Bone mineral density in young adult survivors of acute lymphoblastic leukemia

Thomas

Donohue

Ness

et al. 2008

Cancer

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“…The average crystalline size was calculated by the Scherrer formula:43, 44 where L hkl is the crystalline domain size (nm), λ is 0.1542 nm, and θ is the diffraction angle (rad). L hkl was considered as an average dimension perpendicular to the reflecting planes ( hkl ).…”

Section: Resultsmentioning

confidence: 99%

“…where I 300 is the intensity of the b-phase reflection, which was located at 2y % 16.0 , and I 110 , I 040 , and I 130 are the intensities of the corresponding monoclinic diffraction peaks. The average crystalline size was calculated by the Scherrer formula: 43,44…”

Section: Crystal Structures Of Pp and Its Nanocompositesmentioning

confidence: 99%

Mechanical properties, morphology, and crystal structure of polypropylene/chemically modified attapulgite nanocomposites

Chen

Zhu

et al. 2011

J of Applied Polymer Sci

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Atactic polypropylene (aPP) was chemically grafted onto attapulgite (ATP) via the bridge linking of a polymerizable cationic surfactant and poly(octadecyl acrylate) in the presence of ultrasonic oscillation and dicumyl peroxide, and then, the modified ATP was added to a polypropylene (PP) matrix to obtain PP nanocomposites by melt blending. The results of Fourier transform infrared spectroscopy and X-ray photoelectron spectroscopy confirmed that aPP and poly(octadecyl acrylate) were chemically grafted onto ATP through a graft polymerization reaction. The results of the mechanical properties testing showed that the addition of modified ATP improved the toughness and strength of PP remarkably. The dynamic mechanical analysis indicated that the modified ATP significantly increased the storage modulus and decreased the glasstransition temperature of PP. The results of scanning electron microscopy and transmission electron microscopy showed that the modified ATP was uniformly dispersed into the PP matrix as crystal needles; this proved the presence of strong interactions between modified ATP and PP. The crystal structure analysis revealed that the b-form crystalline of PP was formed within the modified ATP.

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“…Dried gels for X‐ray diffraction measurements were prepared from the slowly‐crystallized as‐prepared gels by supercritical drying using a CO 2 critical‐point dryer (SPI Supplies). This method generally allows for interface‐free removal of the solvent, thereby preventing the collapse of the swollen as‐prepared gel due to the absence of surface tension and resulting in minimal associated changes to the microstructure of the polymer‐rich phase . The sealed DSC crucibles containing the gel samples were opened and immediately flushed with liquid CO 2 at ∼15 °C; the samples were then left for 2 h allowing solvent exchange to take place.…”

Section: Methodsmentioning

confidence: 99%

Solution‐crystallization and related phenomena in 9,9‐dialkyl‐fluorene polymers. I. Crystalline polymer‐solvent compound formation for poly(9,9‐dioctylfluorene)

Perevedentsev

Stavrinou

Bradley

et al. 2015

J. Polym. Sci. Part B: Polym. Phys.

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Polymer-solvent compound formation, occurring via co-crystallization of polymer chains and selected small-molecular species, is demonstrated for the conjugated polymer poly(9,9-dioctylfluorene) (PFO) and a range of organic solvents. The resulting crystallization and gelation processes in PFO solutions are studied by differential scanning calorimetry, with X-ray diffraction providing additional information on the resulting microstructure. It is shown that PFO-solvent compounds comprise an ultra-regular molecular-level arrangement of the semiconducting polymer host and small-molecular solvent guest. Crystals form following adoption of the planar-zigzag β-phase chain conformation, which, due to its geometry, creates periodic cavities that accommodate the ordered inclusion of solvent molecules of matching volume. The findings are formalized in terms of nonequilibrium temperature–composition phase diagrams. The potential applications of these compounds and the new functionalities that they might enable are also discussed. © 2015 The Authors. Journal of Polymer Science Part B: Polymer Physics published by Wiley Periodicals, Inc. J. Polym. Sci., Part B: Polym. Phys. 2015, 53, 1481–1491

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Syndiotactic Polystyrene Physical Gels: Guest Influence on Structural Order in Molecular Complex Domains and Gel Transparency

Cited by 40 publications

References 31 publications

Bone mineral density in young adult survivors of acute lymphoblastic leukemia

Bone mineral density in young adult survivors of acute lymphoblastic leukemia

Mechanical properties, morphology, and crystal structure of polypropylene/chemically modified attapulgite nanocomposites

Solution‐crystallization and related phenomena in 9,9‐dialkyl‐fluorene polymers. I. Crystalline polymer‐solvent compound formation for poly(9,9‐dioctylfluorene)

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