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Preparation and Characterization of Shape Memory Biocompatible Nanocomposites of Polyurethane/Carbon-magnetic Hybrid Nanoparticles

Salkhi Khasraghi, Samaneh | 2020

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  1. Type of Document: Ph.D. Dissertation
  2. Language: Farsi
  3. Document No: 52944 (06)
  4. University: Sharif University of Technology
  5. Department: Chemical and Petroleum Engineering
  6. Advisor(s): Shojaei, Akbar
  7. Abstract:
  8. Smart bio-based shape memory polymers with high performance and fast response have the exciting potential to meet the growing need in biomedical applications. A fascinating approach in SMP categories in biomedical field is the development of noncontact activation without increasing the environmental temperature through remote triggering methods, such as magnetic triggering. Magnetically responsive SMPs have received lots of attention in the biomedical applications, especially the non-contact triggering of medical equipment and implants inside the body. In this study, the biocompatible nanocomposite based on shape memory polyurethane acrylates (SMPUAs)/ hybrid carbon-magnetic nanoparticles, as magneto-responsive SMPs for the biomedical application, were synthesized using in-situ polymerization.The biocompatible polyurethane acrylates (PUAs) comprising polycaprolactone diols (PCL-Diol), hexamethylene diisocyanate (HDI) and hydroxy-methyl methacrylate (HEMA) were synthesized by two-step bulk polymerization. At the first phase of this study, novel fast response UV-curable shape memory polyurethane acrylates (SMPUAs) were synthesized. Two series of PUAs with the almost same amount of hard segment content (HSC) were prepared with varying soft-segment molecular weight (2000, 3000, and 4000 g/mol) and different molar ratios of constituents. A mono-functional reactive diluent was used to control HSC and reduce the viscosity. Morphological characterization revealed nanoscale phase separation in SMPUAs. Increase in soft segment molecular weight was accompanied by an increase in the degree of microphase separation, crystallinity, and stiffness. The results indicated that shape memory behavior of PUAs was affected substantially by soft segment crystallinity and formation of stable ordered hard domains. The versatility of our SMPUAs was further reflected in good shape memory performance (higher than 97% fixity and recovery) with fast response as well as tunable transition temperature.In the next step, the multifunctional nanostructures of oxidized nanodiamond (Ox-ND)/ Fe3O4 nanoparticles were synthesized through a one-step modified co-precipitation method. Subsequently, the as-prepared Ox-ND/Fe3O4 (NDF) hybrid nanoparticle was surface functionalized with vinyltrimethoxysilane (VTMS) to enhance its compatibility with organic media. The silanaized-NDF (S-NDF) nanoparticles contribute in crosslinking and network formation during the curing process. The structure, morphology, magnetic and optical properties, and biocompatibility of the nanohybrid were systematically investigated. The results confirmed that synthesized nanoparticles with crystalline nature present the core diameter of the particles between 5 and 25 nm, strong superparamagnetic properties, and photoluminescence properties (blue emission). PrestoBlue assay indicated great biocompatibility of S-NDF in MCF-7 cells.In the final step, the thermally cured PUA and magnetic PUA/S-NDF nanocomposite were synthesized through in-situ polymerization. The PCL-diol with the molecular weight of 4000 g/mol and two different molar ratios of constituents were used to synthesize PUA and PUA/S-NDF. The morphology, thermal and mechanical properties, shape memory properties, and biocompatibility of PUA and PUA/S-NDF with the loading of 2 and 9% of were investigated. The morphological analysis suggested homogeneous distribution of S-NDF in the polymer matrix at the loading of 2 wt% and small agglomeration for nanocomposites with 9 wt% loading were observed. The base polymer and nanocomposites presented excellent shape fixity ratios (above 97%) and shape recovery ratios (above 99.5%) in hot water. PUA/S-NDF nanocomposites with the loading of 9 wt% exhibited excellent shape recovery rate (above 96%) in a very small magnetic field (H = 0.76 kA.m-1) as well as faster magnetic responsiveness compared to the chemically dispersed Fe3O4 nanocomposites. Further, the PrestoBlue cell viability assay has suggested the biocompatibility of base polymers and nanocomposites
  9. Keywords:
  10. Acrylated Polyurethane ; Polycaprolactone Composite ; Nano Diamond/Graphite ; Thermal Annealing ; Biomedical Applications ; Shape Memory Polymer (SMP)Naocomposite ; Noncontact Magnetic Triggering ; Shape Memory Polymers ; Biocompatible Polymer

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