化学の見かた・考えかた

2023/06/28 総⼈のミカタ @京都⼤学 吉⽥南キャンパス 化学の⾒かた・考えかた 京都⼤学 2023/06/28 ⼈間・環境学研究科 森⽵将之 津江研究室

⽬次 本⽇のスケジュール • ⾃⼰紹介(5分) • 科学と化学(5分) • 化学と研究(30分) • 化学の⽅法論(20分) 2

科学と化学 4 物理・化学・⽣物・地学の違うところ同じところ 地球、気象、岩⽯ ⽣体、細胞、遺伝⼦ 地学 物質、分⼦、電⼦ ⽣物 宇宙 素粒⼦ 化学 物理 109m 物理 106m 103m m 10-3m 10-6m 化学 → 物質、分⼦、電⼦を対象にする⾃然科学 10-9m 10-12m

化学の研究 5 化学の研究って何をするのか︖~概念図~ つくる 合成 抽出 結晶作成 加⼯ 社会への応⽤ ⾯⽩い現象 ⾯⽩いもの 構造測定 組成測定 物性測定 はかる 理論研究 機構解明 シミュレーション かんがえる

化学の研究 6 化学の研究って何をするのか︖~スライムを例に~ つくる ・スライムとは ・材料 2) ホウ砂 1) PVA OH OH n 洗濯糊 3) ⽔ B OH HO OH ⽬薬 H O H

化学の研究 7 化学の研究って何をするのか︖~スライムを例に~ 注意) 安全な実施のために ⼿袋着⽤、⾶沫に注意、異変があれば教えてください つくる ・実験⼿順 2. 攪拌する 3. 混合する B 1. 材料を計り取る ホウ砂⽔溶液 A B PVA⽔溶液 ホウ砂⽔溶液 薄(B: 0.1 g/L) 濃(B’: 0.2 g/L) A A PVA⽔溶液 PVA⽔溶液

化学の研究 8 化学の研究って何をするのか︖~スライムを例に~ はかる その1 硬さと濃さの関係 お箸で持ち上げてみると… その2 酸性にしてみよう + クエン酸⽔溶液

化学の研究 9 化学の研究って何をするのか︖~スライムを例に~ かんがえる ホウ砂の量の変化 → 硬さの違い 酸性条件 → スライムが溶ける ホウ砂 少ない 多い 柔らかさ 柔らかい 硬い 中性 酸性 溶ける

m 化学の研究 化学の研究って何をするのか︖~スライムを例に~ Journal of Sol-Gel Science and Technology (2022) 101:103–113 a 107 20 μm かんがえる その1 100 μm 硬さと濃さの関係 b その2 酸性にしてみよう 20 μm PVA ホウ砂 OH 20 μm m m 10 100 μm 20 μm 100 μm 20 μm OH OH OH + OH HO B OH OH O O B O O 架橋構造 c ホウ砂 d 20 μm 100 μm PVA 20 μm ⽔ 架橋構造 Fig. 3 SEM images of the hydrogels formed by cross-linking PVA with different mass fractions of borax (scale bar: 100 μm) and enlarged image (scale bar: 20 μm). a 1.0-Borax-PVA. b 2.0-Borax-PVA. c 3.0-Borax-PVA. d 5.0-Borax-PVA 酸性 中性 B(OH)3 B(OH)4- 架橋できる ホウ砂の状態が変化

化学の研究 11 化学の研究って何をするのか︖~スライムを例に~ Journal of Sol-Gel Science and Technology (2022) 101:103–113 107 a つくる 100 μm 20 μm 社会への応⽤ ホウ砂⽔溶液 b A PVA⽔溶液 100 μm スライムの 硬さと組成 c 形成機構 100 μm 20 μm スライムの構造 20 μm d はかる かんがえる

化学の研究 12 化学の研究って何をするのか︖~スライムを例に~ 社会への応⽤ ゴムと加硫 輪ゴム PVA等を⽤いた新規材料 タイヤ 架橋 少ない 多い 弾性 柔軟 硬い I. Kajal et al, Prog. Org. Coat., 174 107268 (2023). 難燃材料、電導性複合材料、⽣体材料…

化学の研究 14 化学の研究って何をするのか︖~まとめ~ つくる 合成 抽出 結晶作成 加⼯ 社会への応⽤ ⾯⽩い現象 ⾯⽩いもの 構造測定 組成測定 物性測定 はかる 理論研究 機構解明 シミュレーション かんがえる

化学の⽅法論 内容 実験データについて • ⾃分の実験データは正しいのか︖ • 先⾏研究の実験データは正しいのか︖ 理論について • 恣意的に決められた基準・単位 15

化学の⽅法論 16 ⾃分の実験データは正しいのか︖ 加熱した試料の温度を知りたい 温度計 試料の温度分布︖ 試料の温度の時間変化︖ 試料 測定⽅法は正しいか︖ 温度計は正しい温度を⽰すか︖

化学の⽅法論 17 ⾃分の実験データは正しいのか︖~精度と正確度~ 実験データが正しいとは 精度 測定⼿法の改善 エラーバーで表⽰ https://www.hitachi-hightech.com/jp/ja/knowledge/semiconductor/room/manufacturing/accuracy-precision.html 正確度 校正

• https://www.hitachi-hightech.com/jp/ja/knowledge/semiconductor/room/manufacturing/accuracy-precision.html

化学の⽅法論 18 ⾃分の実験データは正しいのか︖ 加熱した試料の温度を知りたい 温度計 試料の温度分布︖ 測定⽅法は正しいか︖ 試料を⼩さく 複数位置の測定 マニュアル 試料の温度の時間変化︖ 試料 温度計は正しい温度を⽰すか︖ 校正 時間平均をとる 平衡状態をつくる 何のために温度を知りたいのか︖ 測定装置と原理を理解しているか︖

化学の⽅法論 19 ⾃分の実験データは正しいのか︖~校正~ 温度コントローラ 測定装置 冷却装置 試料 光源 検出機 PC 50 0 -200 校正温度[℃] X線構造解析装置 Rigaku Saturn 724+ -温度校正 試料部の温度測定 →設定温度との差異確認 -150 -100 -50 0 -50 -100 -150 設定温度[℃] 校正温度 設定温度 -200 50

化学の⽅法論 20 先⾏研究の実験データは正しいのか︖ ・論⽂の章⽴て Introduction 導⼊ Journal of Sol-Gel Science and Technology (2022) 101:103–113 105 References Experimental Results and discussion Conclusions microscopy (FEI G2 F20 S-TWIN, USA) under 200 kV from Aladdin company (Shanghai, China). All solutions 参考⽂献 実験 結果と考察 結論 accelerating voltage. were prepared in deionized water. All reagents were analytically pure. Journal of Sol-Gel Science and Technology (2022) 101:103–113 from Aladdin company (Shanghai, China). All solutions were prepared in deionized water. All reagents were analytically pure. 2.3.5 Swelling properties of hydrogels 105 microscopy (FEI G2 F20 S-TWIN, USA) under 200 kV accelerating voltage. 2.2 Experimental methods 2.3.5 Swelling properties of hydrogels 2.2 Experimental methods PVA (3 g) was dissolved in deionized water (97 mL), stirred at 90 °C for 45 min, and placed at room temperature. Borax (4 g) was dissolved in deionized water (96 mL). Different quantities of borax and PVA were mixed and stirred until uniform and stable Borax-PVA hydrogels were formed. In this study, the hydrogels with 1.0, 2.0, 3.0, and 5.0 wt% borax were designated as 1.0-Borax-PVA, 2.0-Borax-PVA, 3.0-Borax-PVA, and 5.0-Borax-PVA, respectively. The swelling properties of the hydrogels were studied by measuring their weight change during the uptake of water. Hydrogel samples were immersed in distilled water at 25 °C until equilibrium was reached. In order to determine the weight changes of the hydrogel at different time intervals, the hydrogel was weighed every three minutes with any excess surface moisture removed with filter paper prior to weighing. 2.3.6 Analysis of viscoelastic properties 2.3 Analytical methods 2.3.1 FT-IR analysis The hydrogel samples were dried for 12 h in an oven at 70 °C to remove moisture and were then ground to form a powder. Then the hydrogel powder and KBr were mixed in a mass ratio of 1:300 and pressed. Infrared spectra of the dried hydrogels were recorded using a Bruker VECTOR-22 spectrometer, ranging from 4000 to 500 cm−1. 2.3.2 XRD analysis of crystal form The hydrogel samples were dried for 24 h in an oven at 50 °C to remove moisture and were then ground to form a powder. X-ray diffraction (XRD) powder patterns were obtained with a Rigaku MiniFlex 600 (Cu Kα source, λ = 0.154 nm; tube voltage, 40 kV; tube current, 30 mA) operating in reflection mode over the range 2θ = 5–80° at a scanning speed of 8.0/min. 2.3.3 SEM The hydrogel samples were freeze-dried and treated in a vacuum. A suitable quantity of dry hydrogel was then placed on conductive adhesive using tweezers and the samples were sputtered with gold under vacuum. SEM images were then acquired using a TESCAN Vega3 SBH microscope to characterize the microstructure of the hydrogels. 2.3.4 Transmission electron microscope analysis The hydrogel samples were ultrasonicated for 15 min in an ethanol solution, and a droplet of the suspension was dripped onto a carbon film copper mesh with a liquid transfer gun. After drying at ambient temperature, the morphology was observed by transmission electron The viscoelastic properties of hydrogels were measured using a Thermo Haake rheometer (Thermo Haake, RS150L) using a 25 mm parallel plate cell. The storage modulus (G′) and loss modulus (G″) of the samples were measured over a frequency range ω = 0.1–100 Hz and amplitude A = 1 mm at 25 °C. 2.3.7 Tensile property analysis The hydrogel samples were placed on a 100 N load cell tester (Instron Machine 5300) for tensile tests. The hydrogel sample was placed on a cylindrical cylinder with a height of 20 mm and a diameter of 5 mm and was compressed at a speed of 3 mm min−1 to 85% of its original height. PVA (3 g) was dissolved in deionized water (97 mL), stirred at 90 °C for 45 min, and placed at room temperature. Borax (4 g) was dissolved in deionized water (96 mL). Different quantities of borax and PVA were mixed and stirred until uniform and stable Borax-PVA hydrogels were formed. In this study, the hydrogels with 1.0, 2.0, 3.0, and 5.0 wt% borax were designated as 1.0-Borax-PVA, 2.0-Borax-PVA, 3.0-Borax-PVA, and 5.0-Borax-PVA, respectively. 2.3.6 Analysis of viscoelastic properties 2.3 Analytical methods 2.3.1 FT-IR analysis 2.3.8 Self-repairing properties of hydrogel Cut the hydrogel into two pieces. After the butt of the two parts has healed, the hydrogel was subjected to the rheological measurements before and after the self-healing process. The storage modulus (G′) and loss modulus (G″) of the samples were measured over a frequency range ω = 0.1–100 Hz and amplitude A = 1 mm at 25 °C. 2.3.9 Thermal and pH response analysis of hydrogel To test the self-healing properties of the hydrogels, 6 mL of the 3.0-Borax-PVA hydrogel samples were placed in plastic bottles, immersed in an ice water bath at 10 °C for 15 min, and then placed in an oven at 50 °C for 15 min. HCl solution (1 mL, 0.1 M) was added to the hydrogel bottle and the resulting sample was shaken for 5 min. NaOH solution (1 mL, 0.1 M) was then added, and the resulting sample was agitated for an additional 5 min. The heating and pHchange-induced gel–sol transformation processes were repeated in five circles. 試料の作り⽅ 量、濃度、温度… The swelling properties of the hydrogels were studied by measuring their weight change during the uptake of water. Hydrogel samples were immersed in distilled water at 25 °C until equilibrium was reached. In order to determine the weight changes of the hydrogel at different time intervals, the hydrogel was weighed every three minutes with any excess surface moisture removed with filter paper prior to weighing. The hydrogel samples were dried for 12 h in an oven at 70 °C to remove moisture and were then ground to form a powder. Then the hydrogel powder and KBr were mixed in a mass ratio of 1:300 and pressed. Infrared spectra of the dried hydrogels were recorded using a Bruker VECTOR-22 spectrometer, ranging from 4000 to 500 cm−1. 2.3.2 XRD analysis of crystal form The hydrogel samples were dried for 24 h in an oven at 50 °C to remove moisture and were then ground to form a powder. X-ray diffraction (XRD) powder patterns were 測定⽅法 処理、条件、装置… The viscoelastic properties of hydrogels were measured using a Thermo Haake rheometer (Thermo Haake, RS150L) using a 25 mm parallel plate cell. The storage modulus (G′) and loss modulus (G″) of the samples were measured over a frequency range ω = 0.1–100 Hz and amplitude A = 1 mm at 25 °C. 2.3.7 Tensile property analysis The hydrogel samples were placed on a 100 N load cell tester (Instron Machine 5300) for tensile tests. The hydrogel sample was placed on a cylindrical cylinder with a height of 20 mm and a diameter of 5 mm and was compressed at a speed of https://www.niu.edu/clas/chembio/research/analyti 3 mm min−1 to 85% of its original height. cal-lab/ftir/bruker.shtml

• https://www.niu.edu/clas/chembio/research/analyti

化学の⽅法論 21 恣意的に決められた単位・基準 単位系の任意性 cgs単位系 MKS単位系 同⼀の結論が導かれる 物理法則は単位系には依存しない (のではないか)

化学の⽅法論 22 恣意的に決められた単位・基準 化学的に重要な概念・定数 →熱⼒学の議論から導⼊される エントロピー: S エネルギー: E 熱⼒学第⼀法則 エネルギー保存則 ギブスの⾃由エネルギー: G 熱⼒学第⼆法則 エントロピーの導⼊ 熱⼒学…三つの法則をもとに成り⽴つ https://ja.wikipedia.org/wiki/%E7%86%B1%E5%8A%9B%E5%AD%A6%E7%AC %AC%E4%B8%80%E6%B3%95%E5%89%87 実験事実を説明できることが重要 熱⼒学第三法則 S>0

化学の⽅法論 23 恣意的に決められた単位・基準 法則が破綻する？ →新たな学問分野の発展 -量⼦⼒学 ニュートン⼒学 →微⼩領域での破綻 -相対性理論 ニュートン⼒学 + 電磁気学 →光速領域での破綻 科学の未解決問題 気体吸着特性の特異的な温度依存性 他にも ⾼温超伝導、ダークマター… まだまだたくさんの未知の現象！

化学の⽅法論 まとめ • ⾃分の実験データは正しいのか︖ →測定装置と原理を理解する 校正を⾏う →⾃分の測定の精度と正確度を知る • 先⾏研究の実験データは正しいのか︖ →実験項を⾒る 24