聚乙烯醇-硼酸鹽-D2O稀釋及半稀釋溶液的動態光散射及中子散射研究

Dynamic Light Scattering and Small Angle Neutron Scattering from Dilute and semi-dilute Poly(vunyl alcohol)-Borax-D2O Solution

劉正平(Cheng-Ping Liu)

指導教授 ： 余子隆

元智大學/工程學院/化學工程與材料科學學系/碩士(2000年)

摘要

聚乙烯醇-硼酸鹽- D2O稀釋及半稀釋溶液的動態光散射
及中子散射研究
研 究 生：劉正平 指導教授：余子隆
元智大學
化學工程學系
摘要
聚乙烯醇(PVA- poly (vinyl alcohol))與硼酸鈉在水溶液中經由PVA分子上兩個相鄰雙醇與硼酸離子(borate ion)結合形成〝雙－雙醇〞(di-diol)帶負電荷之錯離子。在稀釋溶液中此〝雙－雙醇〞錯離子是硼酸離子與PVA分子經由分子內(intra-molecular)交聯形成環狀化合物。當PVA濃度接近或大於重疊濃度(overlap concentration)PVA分子經由硼酸離子產生分子間(inter-molecular)及分子內交聯。PVA濃度愈高產生分子間交聯的機率就愈大。PVA分子在水溶液中亦可經由-OH基的氫鍵結合產生聚集(cluster)或交聯現象。[borax]/[PVA]比值及氫鍵濃度為決定PVA在高於重疊濃度下是否形成凝膠(gel)之重要因素。聚合體分子間交聯分子的排斥體積(excluded volume)應及聚合體分子上負電荷的排斥效應會使分子鏈產生膨脹現象。而自由鈉離子正電荷對聚合體之負電荷的遮蔽效應及分子內交聯使分子鏈產生收縮現象。本研究報告利用動態雷射光散射與小角度中子散射研究聚乙烯醇/硼酸鈉/D2O在稀釋及半稀釋水溶液中的分形維數及相關長度或粒徑。

關鍵字

聚乙烯醇 ； 硼酸鈉 ； 動態光散射 ； 小角度中子散射

並列摘要

Dynamic Light Scattering and Small Angle Neutron Scattering
from Dilute and Semi-dilute
Poly(vinyl alcohol)-Borax-D2O Solutions
Student：Cheng-Ping Liu Advisor：Dr. T.L. Yu
Institute of Chemical Engineering Yuan-Ze Iniversity
Abstract
Poly (vinyl alcohol) forms di-diol complex with borate ion in aqueous solution. In dilute solution, the di-diol complex is formed through intra-molecular crosslinking reaction. In semidilute or high PVA concentrations where the polymer molecules entangle with each other, the di-diol complex forms both through intra- and inter-molecular crosslinking. The formation of H-bond through the -OH functional group is another important factor for the formation of PVA-borax-complex in aqueous solutions. The aggregation of PVA molecules through H-bond causes the formation of clusters. The conformation of PVA-borax complex in aqueous solution is controlled by the following factors：(1) polymer excluded volume effect; (2) intra- and inter- molecuded crosslink through H-bond formation and borate ion di-diol complex formation; (3) charge repulsion among the negative charged borate ions bound on PVA molecules; (4) the screen effect of free Na+ positive ion on the negative charge of PVA-borate complex ; (5) H-bond and cluster formation through intra- and inter-molecular reaction. In this study we report the fractal dimensions, and the correlation length or radius of PVA-borate-D2O complex in dilute and semidilute solution by dynamic light scattering and small angle neutrun scattering.

並列關鍵字

Poly(vunyl alcohol) ； borax ； dynamic light scattering ； small angle neutron scattering

參考文獻

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