MALDI/TOF/MS and SEC Study of Astromol Dendrimers Having Cyano End Groups

Bu, Ling; Nonidez, William K.; Mays, Jimmy W.; Tan, Nora Beck

doi:10.1021/ma990458p

Cited by 23 publications

(14 citation statements)

References 26 publications

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“…Linear extrapolation gives lower [η] and higher k H1 compared to second-order fitting. 35 Nevertheless, slopes of ∼0.6 reasonably support the earlier conclusion that toluene is close to a θ-solvent for copolymers 1, 2, and 4-7. The decreasing K values from pair 6-7 to 1-2 and then 4-5 indicate the decreasing chain flexibility, which parallels the increasing T g in Table 2.…”

Section: Resultssupporting

confidence: 83%

A Biodegradable and Cross-Linkable Multiblock Copolymer Consisting of Poly(propylene fumarate) and Poly(ε-caprolactone): Synthesis, Characterization, and Physical Properties

et al. 2005

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In an effort to develop various controllable biomaterials, a series of novel cross-linkable and biodegradable multiblock poly(propylene fumarate-co-caprolactone) [P(PF-co-CL)] copolymers have been synthesized via a three-step polycondensation of oligomeric polypropylene fumarate (PPF) with polycaprolactone (PCL) diols. The chemical structures of 15 copolymers with various PCL compositions and segment lengths were further characterized by FTIR, 1 H NMR, and 13 C NMR spectra. Their physical and rheological properties have been determined extensively. The composition dependences of various characteristic temperatures such as glass transition temperature T g, melting temperature Tm, and thermal degradation temperature Td were demonstrated using a phase diagram. Together with DSC results, polarized optical microscopical graphs of several copolymers with high PCL compositions show spherulite crystalline structure. Particularly a banded spherulite has been found for a copolymer with a PCL composition of 87% when it crystallizes at room temperature. When the PCL composition in these copolymers is lower than 70%, the copolymers are amorphous with a reduced T g. This is critical for an enhanced rate of biodegradation. Because of the flexibility of PCL segments in the copolymers, P(PF-co-CL) can be either self-cross-linked or photocross-linked without using any cross-linker. The unentangled characteristics have been verified by the melt viscosity's molecular weight dependence and the master curves of storage modulus G′ and loss modulus G′′. The introduction of PCL into the copolymer chain enhances the solubility in toluene. Dilute solution viscometry shows the effect of microstructure in intrinsic viscosity while this effect is insignificant in melt viscosity. Therefore, the physical properties of such a copolymer can be modulated by the composition and segment length to satisfy the needs in a variety of tissue engineering applications such as bone, cartilage, and nerve tube regenerations.

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Section: Resultssupporting

confidence: 83%

A Biodegradable and Cross-Linkable Multiblock Copolymer Consisting of Poly(propylene fumarate) and Poly(ε-caprolactone): Synthesis, Characterization, and Physical Properties

et al. 2005

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“…(2) Lescanec, R. L.; Muthukumar, M. Macromolecules 1990, 23, 2280. (3) Pesak, D. J.; Moore, J. S.; Wheat, T. E. Macromolecules 1997, 30 Charged dendrimers display properties advantageous to their possible use as model electrophoresis systems. Dynamic light scattering and viscosity studies find that the molecules behave hydrodynamically as spheres.…”

Section: Introductionmentioning

confidence: 99%

The Electrophoretic Mobility of PPI Dendrimers: Do Charged Dendrimers Behave as Linear Polyelectrolytes or Charged Spheres?

Welch

Hoagland

2003

Langmuir

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The electrophoretic mobilities µ0 of charged polypropyleneimine dendrimers were measured by capillary electrophoresis as a function of ionization R, ionic strength I, and hydrodynamic radius a. For the two generations examined, 3 and 5, µ0 trends reminiscent of a linear polyelectrolyte are found in R but not in I and a. Strikingly, all three trends accurately follow standard electrokinetic model predictions for a charged, ion-impenetrable dielectric sphere of radius a. Although the sphere depiction is physically inexact, the meshing of theory to experiment requires no fitting of parameters. For highly charged dendrimers across the accessible aκ range (0.2 < aκ < 2), the standard electrokinetic model quantitatively captures a large observed relaxation effect. No evidence for nonspecific ion binding was uncovered. Commercial availability and conformity to sphere theory suggest that charged dendrimers might serve as model electrophoresis systems. Limitations and alternatives to the sphere depiction are discussed.

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“…GPC analysis of the dendrimers was performed using as eluent dichloromethane with a 1% v/v of triethylamine to improve the elution of the PPI‐derived dendrimers through the column and try to avoid partial adsorption processes due to the amine groups, which lead to high polydispersity values 36. In general, PI values were low (between 1.2 and 1.08), but the molecular weight was overestimated in all cases.…”

Section: Resultsmentioning

confidence: 99%

“…5). Assuming that all the species have the same response to the mass detector, we can assess the relative abundance of the different species from the intensities of the peaks 36. Correlation of the calculated weights of the possible structures with the peaks observed in the spectrum allowed us to determine the molecular composition.…”

Section: Resultsmentioning

confidence: 99%

Common diabetic therapy appears to reduce risk of pancreatic cancer

Printz¹

2009

Cancer

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Cinnamate‐containing dendrimers have been prepared by peripheral functionalization of the amine groups of a poly(propyleneimine) dendrimer with 4‐methoxycinnamate‐ or 4‐(N,N‐dimethylamino)cinnamate‐derived units and/or 4‐cyanobiphenyl units in different proportions. The synthesis, full characterization in solution, thermal properties and optical properties of the novel monomers, homodendrimers and codendrimers are reported. The composition of the molecular structure of the codendrimers has been elucidated by matrix assisted laser desorption/ionization time‐of‐flight mass spectrometry (MALDI‐TOF MS). These liquid crystalline dendrimers display lamellar SmA mesophases. The codendrimers have been tailored in such a way that the photoactive units and the liquid crystal units absorb in different regions in order to allow better control over the processes induced by light. Linearly polarized UV light irradiation studies performed on thin films of the cinnamate codendrimers show that they are photoresponsive. A photoinduced anisotropy is generated with increasing exposure time, but in‐plane amplification of anisotropy by thermal annealing in the mesophase was not observed. © 2011 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem, 2011

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MALDI/TOF/MS and SEC Study of Astromol Dendrimers Having Cyano End Groups

Cited by 23 publications

References 26 publications

A Biodegradable and Cross-Linkable Multiblock Copolymer Consisting of Poly(propylene fumarate) and Poly(ε-caprolactone): Synthesis, Characterization, and Physical Properties

A Biodegradable and Cross-Linkable Multiblock Copolymer Consisting of Poly(propylene fumarate) and Poly(ε-caprolactone): Synthesis, Characterization, and Physical Properties

The Electrophoretic Mobility of PPI Dendrimers: Do Charged Dendrimers Behave as Linear Polyelectrolytes or Charged Spheres?

Common diabetic therapy appears to reduce risk of pancreatic cancer

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