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Title: Mechanical Material Characterization of PDMS/PDPS Copolymers.

Abstract

Abstract not provided.

Authors:
Publication Date:
Research Org.:
Sandia National Lab. (SNL-NM), Albuquerque, NM (United States)
Sponsoring Org.:
USDOE National Nuclear Security Administration (NNSA)
OSTI Identifier:
1365518
Report Number(s):
SAND2017-4282T
652716
DOE Contract Number:
AC04-94AL85000
Resource Type:
Thesis/Dissertation
Country of Publication:
United States
Language:
English

Citation Formats

Small, Mark E. Mechanical Material Characterization of PDMS/PDPS Copolymers.. United States: N. p., 2017. Web.
Small, Mark E. Mechanical Material Characterization of PDMS/PDPS Copolymers.. United States.
Small, Mark E. Sat . "Mechanical Material Characterization of PDMS/PDPS Copolymers.". United States. doi:.
@article{osti_1365518,
title = {Mechanical Material Characterization of PDMS/PDPS Copolymers.},
author = {Small, Mark E.},
abstractNote = {Abstract not provided.},
doi = {},
journal = {},
number = ,
volume = ,
place = {United States},
year = {Sat Apr 01 00:00:00 EDT 2017},
month = {Sat Apr 01 00:00:00 EDT 2017}
}

Thesis/Dissertation:
Other availability
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  • Abstract not provided.
  • The effects of gamma radiation on a series of characterized copolymers, synthesized from different molar ratios of glycidyl methacrylate (GMA) and ethyl methacrylate (EMA), have been studied using a variety of techniques. Polymers were characterized using IR, NMR, GPC, and viscosity measurements. The analysis of radiation G values suggests that at glycidyl methacrylate concentrations below 10%, crosslinking does not predominate. However, at higher GMA concentrations, G values for crosslinking increase, and at GMA concentration over 60%, G values approach 10, a value only reached by chain reactions. Spectroscopic evidence is presented for the participation of the glycidyl group in radiation-inducedmore » reactions. FTIR studies on irradiated thin films of COP show decreases in the epoxide functional group regions, ca. 908 and 1250 cm/sup -1/. EPR results suggest that a paramagnetic species, possibly due to the epoxide group, is produced by irradiating the polymer. The EPR spectral parameters of V(CO)/sub 6/, a stable paramagnetic species have been resolved using the experimental technique of Partial Orientation. Slow-cooling an EPR sample of V(CO)/sub 6/ in cyclohexane produces crystallites containing the solute. When these crystallites are of sufficient size, resolution of the broadened EPR spectrum into the individual g tensors is observed. This induced resolution allows the precise assignment of the hyperfine coupling constants and g tensor values.« less
  • The central theme of this thesis work is to develop new block copolymer materials for biomedical applications. While there are many reports of stimuli-responsive amphiphilic [19-21] and crosslinked hydrogel materials [22], the development of an in situ gel forming, pH responsive pentablock copolymer is a novel contribution to the field, Figure 1.1 is a sketch of an ABCBA pentablock copolymer. The A blocks are cationic tertiary amine methacrylates blocked to a central Pluronic F127 triblock copolymer. In addition to the prerequisite synthetic and macromolecular characterization of these new materials, the self-assembled supramolecular structures formed by the pentablock were experimentally evaluated.more » This synthesis and characterization process serves to elucidate the important structure property relationships of these novel materials, The pH and temperature responsive behavior of the pentablock copolymer were explored especially with consideration towards injectable drug delivery applications. Future synthesis work will focus on enhancing and tuning the cell specific targeting of DNA/pentablock copolymer polyplexes. The specific goals of this research are: (1) Develop a synthetic route for gel forming pentablock block copolymers with pH and temperature sensitive properties. Synthesis of these novel copolymers is accomplished with ATRP, yielding low polydispersity and control of the block copolymer architecture. Well defined macromolecular characteristics are required to tailor the phase behavior of these materials. (2) Characterize relationship between the size and shape of pentablock copolymer micelles and gel structure and the pH and temperature of the copolymer solutions with SAXS, SANS and CryoTEM. (3) Evaluate the temperature and pH induced phase separation and macroscopic self-assembly phenomenon of the pentablock copolymer. (4) Utilize the knowledge gained from first three goals to design and formulate drug delivery formulations based on the multi-responsive properties of the pentablock copolymer. Demonstrate potential biomedical applications of these materials with in vitro drug release studies from pentablock copolymer hydrogels. The intent of this work is to contribute to the knowledge necessary for further tailoring of these, and other functional block copolymer materials for biomedical applications.« less
  • Self-assembly is a powerful tool in forming structures with nanoscale dimensions. Self-assembly of macromolecules provides an efficient and rapid pathway for the formation of structures from the nanometer to micrometer range that are difficult, if not impossible to obtain by conventional lithographic techniques [1]. Depending on the morphologies obtained (size, shape, periodicity, etc.) these self-assembled systems have already been applied or shown to be useful for a number of applications in nanotechnology [2], biomineralization [3, 4], drug delivery [5, 6] and gene therapy [7]. In this respect, amphiphilic block copolymers that self-organize in solution have been found to be verymore » versatile [1]. In recent years, polymer-micellar systems have been designed that are adaptable to their environment and able to respond in a controlled manner to external stimuli. In short, synthesis of 'nanoscale objects' that exhibit 'stimulus-responsive' properties is a topic gathering momentum, because their behavior is reminiscent of that exhibited by proteins [8]. By integrating environmentally sensitive homopolymers into amphiphilic block copolymers, smart block copolymers with self assembled supramolecular structures that exhibit stimuli or environmentally responsive properties can be obtained [1]. Several synthetic polymers are known to have environmentally responsive properties. Changes in the physical, chemical or biochemical environment of these polymers results in modulation of the solubility or chain conformation of the polymer [9]. There are many common schemes of engineering stimuli responsive properties into materials [8, 9]. Polymers exhibiting lower critical solution temperature (LCST) are soluble in solvent below a specific temperature and phase separate from solvent above that temperature while polymers exhibiting upper critical solution temperatures (UCST) phase separate below a certain temperature. The solubility of polymers with ionizable moieties depends on the pH of the solution. Polymers with polyzwitterions, anions and cations have been shown to exhibit pH responsive self assembly. Other stimuli responsive polymers include glucose sensitive polymers, calcium ion-sensitive polymers and so on. Progress in living radical polymerization (LRP) methods [10] has made it possible for the facile synthesis of these block copolymer systems with controlled molecular weights and well defined architectures. The overall theme of this work is to develop novel smart block copolymers for biomineralization and biomedical applications. Synthesis and characterization of self-assembling thermoreversible ionic block copolymers as templates in biomimetic nanocomposite synthesis using a bottom-up approach is a novel contribution in this respect. Further, we have extended these families of copolymers to include block copolymer-peptide conjugates to enhance biological specificity. Future directions on this work will focus on enhancing the polymer templating properties for biomineralization by expanding the family of block copolymers with organic polypeptides and biological polypeptide scaffolds as well as a detailed understanding of the polymer-inorganic nanocomposites at the molecular level using small angle scattering analysis. Glucose responsive polymer hydrogels for drug delivery, polymer-ligand conjugates for non-viral therapy and thermoresponsive injectable photocrosslinkable hydrogels for posttraumatic arthritis cartilage healing are other applications of these novel copolymers synthesized in our work.« less
  • The overall theme of this work is to develop novel smart block copolymers for biomineralization and biomedical applications.