控制/活性自由基聚合溫度敏感型高分子：聚N-異丙基丙烯醯胺及其團聯共聚物之相變化研究

Thermosensitive polymer of controlled-living radical polymerization:Phase behavior of diblock copolymers by poly(N-isopropylacrylamide)

莊曜瑛(Yao-Ying Chuang)

指導教授 ： 芮祥鵬

國立臺北科技大學/工程學院/有機高分子研究所/碩士(2012年)

摘要

本研究利用控制/活性自由基聚合技術(Control/Living Free Radical Polymerization Techniques)中的穩定自由基聚合反應-氮氧自由基系統（Stable Free Radical Polymerization； SFRP；Nitroxide-mediated　Controlled Radical Polymerization; NMCRP； NMRP），以單體：N-tert-butylacrylamide (NTBA)、N-isopropylacrylamide (NIPAAm)；穩定氮氧自由基：2,2,6,6,-tetramethyl-1- piperdinyloxy nitroxide (TEMPO)以及起始劑：2,2’-Azobis(isobutyronitrile) (AIBN)進行一系列聚合反應，可以有效控制形成之聚合物具有低的聚分散度(Polydispersity；PDI)的特性，以及保有高分子之活性，以利進行二次聚合。
藉由NMCRP方法，在設定NTBA/AIBN/TEMPO = 20 mmol/0.24 mmol/0.216 mmol 的比例下，氮氣系統、125 ℃恆溫條件中進行第一次聚合反應，得到白色活性聚合物Poly(N-tert-butylacrylamide)（PNTBA-TEMPO），由1H-NMR圖譜顯示，在δ=5.5~6.2 ppm(-CH=CH2)處雙鍵訊號消失，顯示NTBA單體中的雙鍵已斷鍵聚合成高分子，藉由膠體滲透層析儀(Gel Permeation Chromatography；GPC) 鑑定結果顯示，隨著不同反應時間(10 min–24 hr)，其分子量略微上升的趨勢 (Mw = 11667-16854)，且各樣品的聚分散度(PDI)皆在2以下。以透光度儀測得PNTBA-TEMPO在不同濃度（1%-30%）下，最高臨界溶液溫度(Upper Critical Solution Temperature; UCST)之轉換溫度介於27.5 ℃到33.1 ℃之間。
在二次聚合團聯聚合反應中，選定NIPAAm/AIBN/TEMPO = 20 mmol/0.24 mmol/0.216 mmol為比例，在氮氣系統、125 ℃下反應24小時後，加入不同比例NTBA(0.2826 g (2.22 mmol)和2.5438 g (20 mmole))，升溫至135 ℃，再反應24小時，得到PNIPAAm-block-PNTBA白色固體。由1H-NMR圖譜顯示，在δ=5.5~6.3 ppm (-CH=CH2, NTBA and NIPAAm)處雙鍵訊號消失以及在δ=1.2 ppm(CH3, NTBA)有甲基訊號產生，證實PNIPAAm-block-PNTBA成功聚合。其中 PNIPAAm-block-PNTBA(mole ratio = 1：1)藉由雷射透光度計測得最低臨界溶液溫度(Lower Critical Solution Temperature; LCST)為27.69 ℃，此外PNIPAAm-block-PNTBA(mole ratio = 9：1)若在5%的溶液中其相轉換溫度則接近人體體溫37.43 ℃。

關鍵字

控制/活性自由基聚合 ； 穩定自由基聚合 ； 氮氧自由基 ； TEMPO ； 溫度敏感型 ； 聚N-異丙基丙烯醯胺 ； 聚N-叔丁基丙烯醯胺 ； 最低臨界溶液溫度

並列摘要

In this study, we used Nitroxide-mediated Controlled Radical Polymerization (NMCRP; NMRP) to prepare the active polymer - PNTBA-TEMPO. NMCRP; NMCRP;NMRP is a Stable Free Radical Polymerization (SFRP) of Control/Living Free Radical Polymerization method. The monomers we proceeded for the series of polymerization are N-tert-butylacrylamide (NTBA), N-isopropylacrylamide (NIPAAm), stable nitroxide free radical, 2,2,6,6-tetramethyl-1-piperdinyloxy nitroxide (TEMPO). The initiator is 2,2’-Azobis(isobutyronitrile) (AIBN). This method can effectively control the formation polymers to have low polydispersity (PDI) property, and it can also maintain the active of polymer in order to facilitate the second polymerization.
By NMCRP method, we set the ratio of NTBA / AIBN / TEMPO equal to 20 mmol/0.24 mmol/0.216 mmol. In nitrogen condition and constant temperature at 125℃ to proceed first polymerization, and we obtained white active polymer – Poly(N-tert-butylacrylamide) (PNTBA-TEMPO). From 1H-NMR spectrum, the double bond signal at δ=5.5-6.2 ppm (-CH=CH2) is disappeared. It shows that the double bond of NTBA monomers were broken to use for polymerization. According to the analysis from GPC (Gel Permeation Chromatography), the molecular weight (Mw = 11667 to 16854) will slightly increased with increase of reaction time (10 min to 24 hr). The samples’ PDI degree all below 2. Otherwise, using Free Radical Polymerization Techniques. Under same reaction time (24 hr), the samples’ molecular weight is 48700; PDI ratio is 4.7. Measuring by light transmission instrument, we had discovered that under different concentration (1% - 30%), the UCST (Upper Critical Solution Temperature) transition temperature region of PNTBA-TEMPO was between 27.5℃ to 33.13 ℃.
In the secondary copolymerization, we selected the ratio for NIPAAm / AIBN / TEMPO equal to 20 mmol / 0.24 mmol / 0.216 mmol. In nitrogen condition and temperature at 125℃ to proceed 24 hr, we added different percentage of NTBA (0.2826 g (2.22 mmol) and 2.5438 g (20 mmole) ). We raised the temperature to 135℃ and repeated reaction for 24 hr, then we obtained the white polymer of PNIPAAm-block-PNTBA. Measuring by 1H-NMR spectrum, the double bond signal at δ=5.5-6.2 ppm (-CH=CH2, NTBA and NIPAAm) is disappeared and there is another methyl group signal at δ=1.2 ppm (CH3, NTBA). As a conclusion, we had proved that PNIPAAm-block-PNTBA polymer was successfully created. Based on the testing from light transmission instrument, we had figured out the LCST (Lower Critical Solution Temperature) temperature of PNIPAAm-block-PNTBA (mole ratio = 1:1) is 27.69℃. Furthermore, if we added 5% of PNIPAAm-block-PNTBA (mole ratio = 9:1) in solution, the phase transition temperature was close to human body temperature (37.43℃).

並列關鍵字

Living ； SFRP ； NMCRP ； TEMPO ； Thermosensitive ； PNIPAAm ； PNTBA ； LCST

參考文獻

[28] 楊恩伉，聚(氮-異丙基丙烯醯胺)衍生溫度感應性共聚微乳膠之低臨界溶液溫度之研究，碩士論文，國立台灣大學材料科學與工程學研究所，台北，2006 年。

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