就腸胃道用顯影劑而言，其主要需求有(1)較低毒性、(2)較低黏度及(3)能增進影像的晰度。本文主要在探討交鏈型(crosslinked)聚二甲基矽氧高分子(PDMS)應用在核磁共振造影(NMRI)之顯影劑(contrast agent)上的可適性，透過乳化技術與hydrosilylation反應可將crosslinked PDMS均勻地分散在水中而形成膠體溶液(colloidal solution)，並對這些膠體溶液作FTIR、MTT、NMRI、粒徑、穩態流變性質、動態流變性質、NMR光譜、NMR T1鬆弛及NMR T2鬆弛等特性分析。經MTT實驗證實這種膠體溶液有很低之毒性，NMRI影像亦顯示這種膠體溶液可增進影像的對比效果。在NMR特性分析中發現：crosslinked PDMS的T2鬆弛、水的T2鬆弛、-(CH2CH2O)-的T1鬆弛與T2鬆弛等數據均不符合傳統上描述T1鬆弛與T2鬆弛之公式(如方程式(2-4)與(2-5))。在流變性質研究中發現：當PDMS的體積分率大於或小於某關鍵值(φc)時，其流變性質有很大不同。因此，本研究對這些特殊現象作了深入分析與討論。此外，本研究亦發現：就crosslinked PDMS膠體溶液而言，ψ The objective of this study is to research the application of crosslinked PDMS (polydimethylsiloxane) to contrast agent of NMRI (nuclear magnetic resonance imaging) for gastro-intestine. With emulsification and hydrosilylation, the crosslinked PDMS can be homogeneously dispersed in water to form colloidal solutions. The characters of these colloidal solutions are ascertained by FTIR spectra, MTT assay, NMR images, laser light scattering, steady-shear rheology, dynamic-shear rheology, NMR spectra, T1 relaxation and T2 relaxation. MTT assay indicates these colloidal solutions have low toxicity and NMR images illustrate they can intensify contrast in in-vitro gastrointestinal images. Regarding the NMR properties of the crosslinked PDMS colloidal solutions and the linear PDMS emulsions, the conventional equations for T1 relaxation and T2 relaxation (eqn.(2-4) and eqn.(2-5)) do not agree with some of experimental results such as T1 relaxation of -(CH2CH2O)- segments and T2 relaxation of crosslinked PDMS, water as well as -(CH2CH2O)- segments. For the rheology behaviors, there is a peculiar difference between the volume fraction (ψ) greater than and smaller than a critical value (ψc). These specific NMR properties and rheology behaviors are discussed in detail in chapters 4 and 5 respectively. However, ψ
