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URN etd-0905113-164932 Statistics This thesis had been viewed 1250 times. Download 55 times. Author Yu-Xuan Chen Author's Email Address No Public. Department Chemical Engineering Year 2012 Semester 2 Degree Master Type of Document Master's Thesis Language English Page Count 107 Title Preparation and Properties of Surface Modification and Catalytic Applications on Gel Keyword reduction reaction Hydrogel hydrophobicity BSA thermosensitive gold nanoparticles gold nanoparticles thermosensitive BSA hydrophobicity Hydrogel reduction reaction Abstract Abstract
This thesis is divided into two parts. The first part is preparation and properties of surface modification on poly(HEMA) hydrogel. And the second part is preparation and properties of poly(NIPAAm) hydrogel as the carrier of gold nanoparticles on catalytic application.
In the first part, we prepared poly(2-Hydroxyethyl methacrylate ) [poly（HEMA）] hydrogel whose inside and surface contained siloxane structure by introducing the hydrophobic tetraethyl orthosilicate (TEOS) and 3-(trimethoxysilyl) propyl methacrylate(TMSPMA). This measure improved the hydrophobic property of poly(HEMA) hydrogel and reduced the adsorption of BSA protein, then the self-cleaning hydrogel was manufactured. The effects of TEOS and TMSPMA to the gel properties like mechanical properties and swell ratio were also investigated.
Pure poly(HEMA) hydrogels were prepared first. Then the gels were dipped into the TEOS and ethyl alcohol (EtOH) mixing solution with different ratios to carry out the sol-gel reaction. As a result, the hydrophobic poly(siloxane) structure was formed at the surface of poly(HEMA) hydrogel. The second step was preparing the poly(TM-co-HEMA) hydrogel by crosslinking the TMSPMA with poly(HEMA). And the gels were also dipped into the TEOS/(EtOH) solution mentioned above. These two kinds of hydrogel are the semi- and fully- interpenetrating polymer network (IPN) structure respectively. The effects of sol-gel in different ratios of TEOS/EtOH mixing solution and crosslinking with TMSPMA to the hydrogel properties: conversion rate, swelling ratio, mechanical strength, water contact angle, gel exterior morphology and adsorption to the bovine serum albumin (BSA) protein were investigated in this study.
The results showed that the hydrogels which TEOS was introduced to had lower swelling ratio with higher TEOS content. It was attributed to the formation of IPN structure. However, the mechanical strength was improved since the structure became more closed due to the formation of IPN. And because TEOS is hydrophobic, the poly(HEMA) hydrogels after sol-gel reaction have the raising water contact angle with higher TEOS content. The adsorbed amount of BSA protein was measured by UV spectrophotometer. And the result showed that the adsorbed amount decreased with the increased hydrophobicity. According to this result, the poly(HEMA) hydrogels could be provided the self-cleaning feature after sol-gel reaction with TEOS/EtOH mixing solution. The gel which TMSPMA was added to has the same result. And the effect of poly(HEMA-coTMSPMA) sol-gel with TEOS is the best.
Second part used the poly(N-isopropylacrylamide) [poly (NIPAAm)] as the mainly monomer. Poly(NIPAAm) hydrogel is a thermoreversible gel material. Since the gel properties could be change with the temperature change and the hydrogel does not have catalytic activity. Poly(NIPAAm) hydrogel could be used as a carrier for colloidal gold.
Gold has great catalytic effect. Here we used the colloidal gold water solution as the catalyst (gold-particle size less than 100nm). The poly(NIPAAm) hydrogel was dipped into the colloidal gold water solution. Then the colloidal gold was introduced into the poly(NIPAAm) hydrogel by swelling adsorption. After well adsorption, put the gel into the 4-nitrophenol (4-NP) and sodium tetrahydridoborate (NaBH4) mixing solution to reduce the 4-NP to 4-aminophenol (4-AP). The great catalytic effect of colloidal gold was expected. And the poly(NIPAAm) would help to improve the recycle of colloidal gold. The gel contained colloidal gold could be reuse. In addition, reducing the environmental pollution after catalyzing could be reduced, too.
Then the thermoreversibility of poly(NIPAAm) was investigated. The effect of different gelling temperature to the swelling ratio、mechanical strength、reaction rate and activation energy was measured after adsorbing colloidal gold. And the reaction rate and activation energy were controlled by different reaction temperature and gelling temperature.
Advisor Committee Wen-Fu Lee - advisor
Hong-Ru Lin - co-chair
Ko-Shao Chen - co-chair
Files Date of Defense 2013-07-29 Date of Submission 2013-09-09