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URN etd-0223105-164115 Statistics This thesis had been viewed 3603 times. Download 1638 times. Author Yuan-An Ku Author's Email Address firstname.lastname@example.org Department Materials Engineering Year 2004 Semester 1 Degree Ph.D. Type of Document Doctoral Dissertation Language English Page Count 128 Title In Situ Preparation of Smart Hydrogels and Composites with Plasma Modified Materials Keyword ultra-violet (UV) induced surface modification smart hydrogels PET nonwoven graft polymerization cold plasma cold plasma graft polymerization PET nonwoven smart hydrogels surface modification ultra-violet (UV) induced Abstract Stimuil-sensitive hydrogels change their physical properties in response to their surrounding environment such as pH, temperature and electrical potentials. Poly(N-isopropylacrylamide) (Poly(NIPAAm)) hydrogels in aqueous solution exhibits a rapid and reversible hydration-dehydration change in response to small temperature changes around its low critical solution temperature (LCST). Poly(NIPAAm) hydrogels have recently been of increasing interest in the field of controlled drug delivery, immobilization of enzymes, and artificial muscles. However, they have poor mechanical strength, especially after swelling, which limits their applications. Its can be improve by graft polymers onto surface of substrates.
Poly(N-vinyl 2-pyrrolidone) (PVP) is widely used in medicine due to its high biocompatibility. In this study, itaconic acid (IA) was co-polymerized with N-vinyl 2-pyrrolidone (NVP) monomer to prepare the pH sensitive hydrogels. These copolymer hydrogels were prepared using ultra-violet (UV) induced methods at ambient temperature. Monomer and cross-linking agent (N, N’-methylene-bisacrylamide (MBAAm)) concentration effects on preparation of this copolymer hydrogel were investigated using swelling, FT-IR, and SEM. The prepared copolymer hydrogel is highly pH sensitive. The percentage swell of the copolymer hydrogels was found to increase from 150% to 3011% as the pH value of the swelling solution varied from 4 to 10.
Hydroxyapatide (HAp)-contained hydrogel composite, analogous to bone structurally and biotical, will not only be easy to make desired shapes in workplace, but also have better mechanical strength to meet the requirements of bone substitute. The influences of polymerization and gel react factors on the characteristics of the fabriced composites hydrogel were investigated. The swelling ratios of composites hydrogel decreased from 16 to 10 as the ratio of HAp powder increased. The compressive strength of HAp/Poly(AAm/IA) composites hydrogel also increases from 7.0 (N/cm2) to 25.8 (N/cm2). HAp/Poly(AAm/IA) composites hydrogel with swelling capabilities in the range 800%~1000% were obtained.
Modification of surface properties (such as wettability, electricity, adhesion and dyeing activity) of materials had become an important object to study, because they can maintain the bulk’s properties without any destruction. There are lots of modification methods such as acidic or alkaline treatment, plasma or corona exposure, polymer deposit or coating, metal vapor deposit or ion planting and additive blending. Among them, plasma polymerization is a fairly excellent method because it can produce the uniform activated surface and has low environmental pollution. In addition, using refined plasma equipment, the kinds of samples will not be restricted even if the samples are particles, fabric cloth, sheet or scaffold. However, the surface property of the plasma activating materials would decayed followed by the longer exposure in air due to the exhaust of activation sites. Therefore, in order to throughout change the surface property, subsequently UV light irradiated graft polymerization has been employed to form a stable and functional surface that had been proved to keep the surface properties for a long time.
Another develop a novel method to formation of swelling and deswelling nonwoven PET/Poly(NIPAAm-co-different monomers) composite hydrogel by combined of surface graft and crossling polymerization reactions. The effect of change different monomer content of composite hydrogels on swelling/deswelling kinetics, and porous sizes will be investigated. The nonwoven PET/Poly (NIPAAm-co-NVP) composite hydrogels exhibit faster deswelling and reswelling rates.
The hydrophobic surface of nonwoven poly(ethylene terephthalate) (PET) with surface inertia has limited the practical bio-applications. The objective of the present research was to surface graft polymerization of biocompatibility monomer onto plasma-treated nonwoven PET substrate utilizing ultra-violet (UV) induced methods. N-vinyl 2-pyrrolidone (NVP) was successfully grafted onto nonwoven PET surfaces. After the plasma activation and/or grafting, the hydrophobic surface of nonwoven was modified into a hydrophilic surface. Effects of various parameters such as monomer concentration, reaction time, initiator (ammonium peroxodisulfate (APS)) concentration and crosslinking agents (N, N’-methylene-bisacrylamide (MBAAm)) concentration on percentage grafting were studied. The grafting efficiency of the modified nonwoven PET surfaces reached maximum at 50 min UV irradiative time and 30wt% aqueous NPV solution. The surface wettability shows water absorption of NVP-grafted nonwoven PET (NVP-g-Nonwoven PET) increased with increasing grafting time. The NVP-g-Nonwoven PET was verified by FT-IR spectra and SEM measurements. The test of antibacterial assessment using Anti-Staphylococcus Aureus test indicated that the Staphylococcus Aureus has been restrained from growing in NVP-g-Nonwoven PET.
Advisor Committee Ko-Shao Chen - advisor
Chi-Yuan Huang - co-chair
Feng-Huei Lin - co-chair
Hong-Ru Lin - co-chair
Jen-Ming Yang - co-chair
Wen-Fu Lee - co-chair
Files Date of Defense 2005-01-28 Date of Submission 2005-02-23