博⼠論⽂要旨
論文題名：液相還元法による金属ナノ粒子分散 ポリイミド樹脂フィルムの合成に関する研究
⽴命館⼤学⼤学院⽣命科学研究科
⽣命科学専攻博⼠課程後期課程 フジオカ ダイキ 藤岡 ⼤毅
本研究においては，⽔素化ホウ素カリウム（KBH4）⽔溶液を⽤いた液相還元法により，⾦属 ナノ粒⼦分散ポリイミド樹脂フィルムの合成について検討した．合成プロセスは，（1）⽔酸化 カリウム⽔溶液処理による，カチオン交換⽤カルボキシル基のポリイミド樹脂への導⼊，（2）
カルボキシル基のイオン交換反応による、カリウムイオンと⾦属イオンを置換させた前駆体フ ィルムの合成，（3）KBH4⽔溶液を⽤いた液相還元による⾦属の析出，からなる．
このプロセスは，イオン交換能を利⽤する表⾯めっきで使⽤されている⽅法の⼀つであるが，
今回，新しいナノ粒⼦合成への応⽤に成功した．本研究の重要な点は，⽔素還元法を⽤いた先
⾏研究とは異なり，⾦属イオンを樹脂フィルム中に再導⼊できたことである．
Ni ナノ粒⼦分散ポリイミド樹脂フィルムを，Ni2+イオンの液相還元によって合成した．Ni2+
イオンを再導⼊しない（1回の吸着/還元）場合，粒⼦サイズが10〜20 nmのアモルファス状態 の⾦属 Niナノ粒⼦が得られ，KBH4濃度が⾼くなると粒⼦サイズは減少した．これは核⽣成が 核成⻑よりも優先したためと考えられる．還元温度が⾼いと，⾯⼼⽴⽅晶の⾦属Niナノ粒⼦が 得られた．⼀⽅，多数回の吸着/還元を⾏った場合，ナノ粒⼦の数とNi 含有量はともに増加し，
ホウ化Niナノ粒⼦が⽣成した．このように，ナノ粒⼦のサイズ，粒⼦数，結晶性などを決定す る要因として還元条件が重要であることが明らかとなった．
Ni-Co 合⾦ナノ粒⼦分散ポリイミド樹脂フィルムは，Ni2+と Co2+イオンの液相還元によって 合成された．得られたナノ粒⼦は，直径 6〜20 nm の，アモルファス構造の⾦属合⾦であり，
Ni と Co の組成⽐は，両イオンの仕込み濃度⽐にほぼ⼀致した．ナノ粒⼦数の増加には，吸着/
還元処理の繰り返しが有効であった．
本研究で得られた⾦属ナノ粒⼦分散ポリイミド樹脂フィルムは，今後，触媒や磁性材料など への応⽤が期待される．
Abstract of Doctoral Thesis
Title: Study on the synthesis of metal nanoparticle dispersed polyimide resin films by liquid-phase reduction method
Doctoral Program in Advanced Life Sciences Graduate School of Life Sciences Ritsumeikan University
フジオカ ダイキ FUJIOKA Daiki
In this study, the synthesis of metal nanoparticle dispersed polyimide resin films was investigated by a liquid-phase reduction method using aqueous solutions of potassium borohydride (KBH4).The synthesis process was as follows: (1) Introduction of carboxyl groups into polyimide resin films for cation exchange by treatment in aqueous potassium hydroxide solutions, (2) synthesis of precursor films in which potassium ions and metal ions were replaced by ion exchange reaction of carboxyl groups, and (3) precipitation of the metal by liquid-phase reduction using aqueous KBH4 solutions.
Although this process is one of the methods conventionally used in the surface plating using ion exchange capability, we succeeded in applying it to new nanoparticle synthesis.The important point of this study is that metal ions can be reintroduced into the resin films, unlike the preceding studies using the hydrogen reduction method.
Ni nanoparticle dispersed polyimide resin films were synthesized by liquid-phase reduction of Ni2+
ions. When Ni2+ ions were not reintroduced (namely, single adsorption/reduction), amorphous metallic Ni nanoparticles with the size of 10 to 20 nm were obtained, and the particle size was decreased with increasing reducing KBH4 concentration. This is probably because nucleation occurred in preference to nuclear growth. When the reduction temperature was high, face-centered cubic metallic Ni nanoparticles were obtained. On the other hand, when adsorption/reduction was repeated many times, both the number of nanoparticles and Ni amounts increased, and Ni boride nanoparticles were also formed. Thus, it becomes clear that reducing conditions are important factors that determine the size, the number, and crystallinity of nanoparticles.
Ni-Co alloy nanoparticle dispersed polyimide resin films were synthesized by liquid-phase reduction of Ni2+ and Co2+ ions. The resulting nanoparticles are metal alloys having amorphous structures with the size of 6 to 20 nm, and the composition ratio of Ni to Co was approximately coincident with the starting concentration ratio of both ions. Repeated adsorption/reduction treatment was found to be effective for increasing the number of nanoparticles.
The metal nanoparticle dispersed polyimide resin films obtained in this study is expected to be applicable to catalysts and magnetic materials in the future.
