Abstract
摘要由於苯乙烯一丁二烯一苯乙烯團聯共聚物(SBS) ，具有橡膠高氣體透過性之性質，因此本研究嘗試以此為研究基本材料。以輻射接枝法將4-乙烯□啶接枝至SBS 基材，形成SBS-g-VP接枝共聚物，利用4-烯□啶對氧的高親和性與SBS 的高氣體滲透性，以期製備較佳的富氧膜。而在製備SBS-g-VP接枝共聚物的過程，順便對4-乙烯□啶輻射接枝至SBS 之動力學進行詳實的研究。在SBS 的結構中由於丁二烯團聯具有不飽和雙鍵，在適當的條件下能予以反應，所以本研究亦嘗試以過甲酸將其環氧化，使SBS 極性化，探討其溶解度參數，交聯度及玻璃轉移溫度的變化，然後以這些因素來探討環氧化的SBS（ 簡稱ESBS）對氣體透過之性質。在4-乙烯□啶的結構上，由於其環上的氮原子具有成對的未鍵結電子能與具有空價軌域的金屬錯合物產生錯合鍵結，因此在本研究中亦嘗試將SBS 與4-乙烯□啶之接枝共聚物(SBS-g-VP)，與具有氧載體特性的(N,N`-disalicylideneethylene-diamine)cobalt(Ⅱ) (CoS)形成錯合鍵結，利用(CoS) 對氧具有可逆的吸脫附特性，探討含有CoS 的SBS-g-VP膜對氧透過性質，並嘗試以Dual Mode 的理論處理。當SBS 被環氧基(oxirane) 。由於環氧基上的氧原子帶有二對的未鍵結電子，依錯合鍵結之理論具有成對未鍵結電子之分子可與具有空價軌域的金屬錯合物產生錯合鍵結，因此本研究亦嘗試探討ESBS與CoS 在氯仿溶液中之錯合鍵結之可能性，並經由溶液鑄膜法成膜，研究含氧載體之ESBS膜對氧之氣體透過性。今將研究成果依一、SBS-g-VP接枝共聚物之研究。二、SBS 環氧化之研究。三、含氧載體之改質SBS 及其對氧透過性之研究。闡述如下：一、SBS-g-VP接枝共聚物之研究(A) 當SBS 均相輻射接枝法製備SBS-g-VP接枝共聚物，由於在均相溶液中的溶氧參與反應抑制了乙烯□啶接枝至SBS 的接枝量，因此在本研究中最高的接枝量僅為8.4 ％。(B) 改用異相輻射接枝法製備SBS-g-VP接枝共聚物，如使用甲醇當溶劑時，接枝量可達到21％，以乙醇╱水當混合溶劑時接枝量可達到26％。(C) 將SBS 製成薄馱，探討異相輻射接枝之動力學。顯示接枝率與照射劑量平方根成正比，符合均一聚合反應的理論。接枝聚合反應進行時，接枝量的大小與高分子基質的分子鏈節運動能力有關。當分子鏈節運動能力較容易時，成長鏈節末諯易進行終止反應。反應系統中溶劑的選擇對接枝量的影響很大，此乃因溶劑會影響高分子成長鏈節末端分子運動能力，因此影響接枝的進行。(D) 經由DSC 測試玻璃轉移溫度，萬能拉力機測試應力，及偏光顯微鏡對形態學之研究結果顯示，當乙烯□啶接枝至SBS 時，由於乙烯□啶與SBS 基材之不相溶性，乙烯□啶是以微小區域(domain)分佈在SBS 的基材內，因此造成第二個玻璃轉移溫度的存在。而此種結構如同物理的擬交聯點，提高了高分子材料的交聯密度，使玻璃轉移溫度往較高溫移動。(E) 因為接枝乙烯□啶使SBS 基材之物性改變使得氣體在高分子薄馱內的溶解度減低，擴散係數變小，不利氣體的透過性。對14％的SBS-g-VP膜而言當其在(273, 283,293, 303, K)的不同測試溫度時，氧氮氣體的透過性較未接枝的SBS 膜小，其下降量分別為(30%, 41%, 37.8%, 28.8 %)(O2) ，(32.3 %, 45.8%, 39.7%, 31.3%)(N2) 。但氧氮的分離效果則增加。在測試溫度由273K變化至303K時，氣體的透過性對未接枝的SBS 膜及14％的SBS-g-VP膜分別增加(341% 與348%)(N2)及(250%與256%) (O2)。在SBS-g-VP對氧氮氣體透過性之研究顯示壓力效應對氣體透過性沒有影響，能以Craham所提出之Solution-diffusion model解釋。二、SBS 環氧化的研究(A) 以低分子量過氧酸(H2O2+formic acie)對SBS 進行環氧化時，由於酸的效應造成開環的副反應。以元素分析法及化學滴定法定量的求出總含氧量及環氧量的多寡，顯示反應時間的增長，開環的副反應較顯著。在NMR 的光譜研究，顯示環氧化的反應主要發生在1 ，4 乙烯式結構的雙鍵上，其中又以順式的1 ，4 結構的反應性較反式的為高。(B) 由於環氧基含氧的存在，使環氧化的SBS 凝聚能溶解度參數及極性增加。由DSC的測試研究顯示玻璃轉移溫度與總含氧量有如下關係。Tg=Tg。+5.74ΦTg。= 純SBS 之玻璃轉移溫度Tg= 環氧化SBS 之玻璃轉移溫度Φ= 總含氧量亦即環氧量的增加，提高玻璃轉移溫度，另由抗張強度，應力的測試亦顯示交聯密度隨環氧化程度而提高。經由環氧化反應後SBS 的物性改變，極性的增加造成氣體溶解度的減低，並由於玻璃轉移溫度的提高與分子鏈節間的交聯度增加，減小氣體的透過性但增加了分離效果。對總含氧量為7.35wt% 的環氧化SBS 膜對氧氣的滲透活化能為9kcal/mole，對氮氣的滲透活化能為12.2kcal/mole ，分別較純SBS 膜增加了36%(O2) ，所以溫度效應對氮氣的透過性影響較氧大，因此在較高溫時不利氧氮分離。含氧載體之改質SBS 膜及其對氧透過性之研究在本研究中進一步的利用改質的SBS 在結構上具有成對的未鍵結電子之特性（在SBS-g-VP是乙烯□啶分子上的氮原子，在ESBS是環氧基上的氧原子），將具有氧載體特性的CoS 與其在氯仿溶液中相互混合，以溶液鑄膜法成膜。經由UV光譜的測試及Miller方法的定量探討得知改質SBS 與CoS 是以化學錯合狀態存在，並求得其錯合配位數及錯合平衡常數，更進而提出SBS-g-VP及ESBS分別與CoS 形成錯合之可能結構。對於含氧載體的改質SBS 膜，經由UV光譜測試與Miller方法的定量研究，確定此類型錯合膜對氧具有可逆的吸附能力。在DSC 熱學性質之研究亦可佐證錯合膜對氧具有可逆吸附之能力。由於含氧載體的改質SBS 膜對氧具有可逆的吸附能力，因此對氧的透過性測試研究，不能單純的以Henry law 處理而需以Dual Mode 方式處理。在含氧載體的錯合膜，雖然氧載體對氧具有可逆吸附特性在較低壓下有利於氣體的透過，但由於氧載體布測試的溫度範圍為一硬質材料故其分佈在錯合膜內時，相對的會使膜的有效自由體積減低，因此不利於氣體的透過，例如對ESBS膜而言氧的透過性為1.78 ×10-9cm3(STP)cm/cm2-sec-cmHg，氮為6.2×10-10cm(STP)cm/cm2-sec-cmHg，但對ESBS-CoS膜而言則氮為5×10-10cm3(STP)cm/cm2-sec-cmHg ，氧的透過性雖隨壓力的減低會增加，但在測試範圍內亦小於1.78×10-9cm3(STP)cm/cm2-sec-cmHg 亦即氧載體的添加可能會造成透過性的降低，但由於氧載體具有促進輸送的能力則對分離效果有顯著的助益。///////ABSTRACTBy using the properties of high flux of styrene-butadiene-styrene blockcopolymer (SBS) and high O2/N2 selectivity of poly (vinyl pyridine), theperformance of gas permeation of 4-vinylpyridine grafted to SBS (SBS-g-VP)was studied. In the study of radiation-induced graft polymerization of4-vinyl pyridine to SBS, a discussion of the mechanism of graftpolymerization was presented and the effect of solvent was also studied.SBS is an unsaturated compound, so it can be modified by some chemicalmethods. In this study, the epoxidation of SBS in toluene solution withperoxyfformic acid generated in situ was discussed. Then the epoxidied SBS(ESBS) was cast into membranes and the gas permeability was also studied.Using the properties of forming oxygen adducts reversibly of metalcomplexs, such as cobalt schiff base complex and iron porphyrin,(N,N`-disalicylideneethylenediamine) cobalt (II) (COS) was mixed with themodified SBS (SBS-g-VP and ESBS) in chloroform solution to form thepolymeric complex (SBS-g-VP-CoS and ESBS-CoS). Then the membranes weremade by solution casting method and the performance of gas permeation wasstudied. From this study, the following results were found.1. The study of SBS-g-VP copolymer(A) Since the dissolved oxygen reacted with SBS polymer to form peroxide,the degree of grafting of 4-vinyl pyridine to SBS by homografting methodhad a largest value of about 8.4% and then decreased with the increasingof the irradiation time.(B) From the radiation induceed graft copolymerization of heterogeneoustype, the degree of grafting initially increased with total irradiationdosage and then levelled off at 21% for SBS-VP-MeOH system and at 26% forSBS-VP-EtOH-H2O system.(C) From the kinetic study of radiation induced graft polymerization of4-vinyl pyridine to SBS, it was found the rate of grafting is seen to beproportional to the half power of the irradiation dose rate. And thedegree of grafting is affected by the molecular chain mobility, and thisis related to the solubility of molecules in the graft polymerizationsystem. If the grafted monomer has a better solubility with the polymer,the degree of grafting will be smaller. When the solvent system is a goodsolvent for the grafted polymer or homopolymer, the degree of graftingwill be small.(D) The glass transition temperature (Tg) and tensile strength of SBS-g-VPincreased with the degree og grafting. And there was second Tg for 14%grafting SBS-g-VP, that was due to the incompatibility between poly(4-vinyl pyridine) and polybutadiene, which caused microphase separation.(E) Thi O2/N2 selectivity of SBS-g-VP membrane increased with theincreasing of degree of grafting, but it could be done at the expense of adecrease in the gas permeability. Comparing the results of 14%degree ofgrafting membrane to those of ungrafted membrane, the gas permeabilitydecreased at various operating temperature, (273, 283, 293, and 303 K).The decreasing ratios were 30%, 41%, 37.8% and 28.8% for oxygen, and were32.3%, 45.8%, 39.7% and 31.3% for nitrogen. The decreasing ratio ofnitrogen was higher than that of oxygen, so the O2/N2 selectivityincreased. When operating temperature was changed from 273 to 303 K gaspermeation increased 341% for ungrafted membrane and 348% for 14% graftingdegree membrane. The permeability of oxygen increased 250% and 256% forungrafted and 14% grafting degree SBS-g-VP membrane. The pressure does nothave any effect on the permeability of oxygen and nitrogen in SBS-g-VPmembrane that can be explained by solution-diffusion mode.2. The Study of Epoxidation of SBSThe epoxidation of SBS by an in situ generated p eracid method wasdiscussed. The presence of an acid acting as catalyst led to sidereaction. The reactivities of internal double bonds (the 1,4 structure)were higher than those of the vinyl bonds (the 1,2 structure). In the 1,4structure, the reactivities of cis-structure were higher than those oftrans-structure. The oxirane weight content and total oxygen weightcontent were determined by titration and element analysis, respectively.The solubility parameter, cohesire energy and the glass transitiontemperature of epoxidized SBS increased with increasing total oxygenweight content. But the molar volume and molecular weight betweencrosslinking points decreased resulting in an increase of crosslinkingdensity with increasing total oxygen weight content. The changes ofproperties of epoxidized SBS reduced the gas permeability of oxygen andnitrogen through epoxidized SBS membrane, but increased the gasselectivity between oxygen and nitrogen. When the operating temperature ofgas permeation increased, the permeability of oxygen and nitrogenincreased but the selectivity decreased. For epoxidized SBS containing7.35 wt% oxygen content, the activation energy were 9 kcal/mole and 12.2kcal/mole for oxygen and nitrogen, respectively.3. The Study of Modified SBS Complexing with Oxygen Carrier and Use forOxygen Permeation.The complex formation reaction of modified SBS (SBS-g-VP and ESBS) with(N,N`-disalicylideneethylenedialine) cobalt (II) (CoS) in chloroformsolution was studied. The coordination numbers and formation constants aredetermined by Miller method. The membranes of SBS-g-VP-CoS and ESBS-CoSare made by solution casting method. The kinetics of oxygen binding toSBS-g-VP-CoS and ESBS-CoS membrane were studied and the equilibriumconstants, association and dissociation constants were determined. Theconversion of oxygen binding to SBS-g-VP-CoS and ESBS-CoS membrane atequillibrium were also determined. The membranes of SBS-g-VP-CoS andESBS-CoS have the affinity to absorb oxygen with reversibility and that isconfirmed by DSC study. Due to the reversible absorption of oxygen toSBS-g-VP-CoS and ESBS-CoS, the permeation of oxygen through SBS-g-VP-CoSand ESBS-CoS membranes can be explained by Dual Mode. From the viewpointof free volume theory, CoS in the polymeric complex membrane was veryrigid and dispersed in the matrix of modified SBS (SBS-g-VP or ESBS). Sothe diffusivities of O2 and N2 through the membrane might decrease andresult in the decrease of permeability of O2 and N2. For example, thepermeability of O2 and N2 are 1.78×10-9cm3(STP)cm/cm2-sec-cmHg and6.2×10-10cm3(STP)cm/cm2-sec-cmHg for ESBS membrane respectively. But thepermeability of N2 is only 5×10-10cm3(STP)cm/cm2-sec-cmHg for ESBS-CoSmembrane and the permeability of O2 is smaller than1.78×10-9cm3(STP)cm/cm2-sec-cmHg. Although the decrease in permeabilityof O2 and N2 in polymeric complex membrane, the selectivity increase dueto the affinity of oxygen transport of CoS.