Synthesis of an ABCD 4-Miktoarm Star Quaterpolymer Through a Diels–Alder Click Reaction

Electrospinning can produce tissue-engineering scaffolds possessing appropriate strength, biomimetic structure, economic appeal, and biocompatibility. To investigate how microstructural changes could potentially affect adherent mammalian cells, tensile samples were strained to 10, 40, and 80% extension, and adhered to double-sided carbon tape to maintain specific states of strain. While establishing the stress-strain response, we invoked polymer sintering to help verify that the ''point bonding'' concept is more significant than previously realized at both the macroscopic and microscopic length scales. Sintering successfully established the effects of deliberate, extensive point bonding/localized ''notch'' generation on mechanical properties and microstructural response without requiring chemical changes within the structure. We also found that fibers experience significant hysteresis in terms of their orientation following exposure to high values of strain. Aligned fibers provide higher strengths (s ave ¼ 2.8 6 0.3 MPa vs. s ave ¼ 1.29 6 0.04 MPa for unaligned fibers) but considerably lower elongation [e ave ¼ (30 6 2)% vs. e ave ¼ (102 6 6)%]. Conversely, when strain occurs perpendicular to the aligned fiber direction total strain increases [e ave ¼ (188 6 6)%] while strength decreases (s ave ¼ 0.38 6 0.01 MPa). Elastic response to low strains appears to estimate ultimate tensile strength. In many ways, electrospun fibers behave similarly to classic interpretations of polymer chains in that when strained in both cases elements can rearrange and translate to align along the direction of loading.

Section: Methodsmentioning

confidence: 99%

Microstructure‐property relationships in a tissue‐engineering scaffold

Johnson

Ghosh

Lannutti

2007

“…Anthracen‐9‐ylmethyl 3‐hydroxy‐2‐(hydroxymethyl)‐2‐methylpropanoate 1 ,17 TU,18 and 2‐bromo‐2‐methyl propionic acid 2‐(3,5‐dioxo‐10‐oxa‐4‐azatricyclo[5.2.1.02,6]dec‐8‐en‐4‐yl) ethyl ester 3 19 were prepared according to published procedures.…”

Section: Methodsmentioning

confidence: 99%

Foams based on low density polyethylene/hectorite nanocomposites: Thermal stability and thermo‐mechanical properties

Velasco¹,

Antunes²,

Ayyad³

et al. 2007

Novel polymer nanocomposite foams made by a two step compression molding method are analyzed in this article. Nanocomposites of low density polyethylene and an organo-modified hectorite were first melt compounded and then foamed using a compression molding method. To study the influence of the presence and the amount of hectorite in both mechanical and thermal properties, samples with 3% and 7% content of hectorite were prepared. Polyethylene crystalline characteristics and thermal stability of the samples were studied by differential scanning calorimetry (DSC) and thermogravimetric analysis (TGA), respectively. Mechanical properties of foams and solid nanocomposites were analyzed by using dynamical mechanical analysis (DMA). Thermal expansion of the samples was analyzed by thermomechanical analysis. The results indicate that the exfoliation of hectorite platelets was achieved after the foaming process, but not during the melt mixing step. Foams with hectorite nanoparticles exhibit improved thermal stability and mechanical properties when compared with neat polymeric foams.

“…32,33 They have less entanglement in the solid state, high solubility in various organic solvents, as well as lower solution and bulk viscosities compared to linear ones having similar molecular weights. 38,39 In this study, we are reporting synthesis, characterization, and metal ion sensing application of novel hexa-armed dansyl endcapped poly(e-caprolactone) star polymer with phosphazene core (P2) (Scheme 1). 37 Besides, well-defined miktoarm star-shaped polymers have been prepared using multifunctional core compounds having different polymerization initiating and click coupling sites.…”

Section: And Zhongmentioning

confidence: 99%

Synthesis, characterization, and Pb²⁺ ion sensing application of hexa‐armed dansyl end‐capped poly(ε‐caprolactone) star polymer with phosphazene core

Görür

Doğancı

Yılmaz

et al. 2015

Novel hexa-armed dansyl end-capped poly(e-caprolactone) (PCL) star polymer with phosphazene core (P2) was prepared via ring opening polymerization (ROP) and esterification reactions. P2 showed dual fluorescence emission when excited at 328 nm in acetonitrile : water (6 : 4) due to twisted intramolecular charge transfer (TICT) between dimethylamino and naphthalene units in the dansyl moiety. TICT emission band (A band) in the emission spectra red-shifted with increasing solvent polarity. P2 responded to the addition of Pb 21 , Hg 21 , Co 21 , Cd 21 , Mn 21 , and Zn 21 metal ions by decreasing TICT emission band with slight bathochromic shifts. The highest quenching efficiency was observed for Pb 21 ion with Stern-Volmer constant of 324.74M 21 . The Stern-Volmer plot for Pb 21 was rather linear with the increasing concentration of the quencher, indicating a dynamic (collisional) quenching mechanism. Stern-Volmer constants for Hg 21 , Co 21 , Cd 21 , Mn 21 , and Zn 21 ions were found to be 212. 33, 189.21, 36.24, 20.84, and 20.69, respectively. Besides, the highest quenching efficiency (94.24%) was attained in the presence of Pb 21 , suggesting that P2 could be employed as a potential Pb 21 chemical probe.