本實驗利用活性開環聚合反應(living ring-opening polymerization)與活性自由基聚合反應(living free radical polymerization)，製備聚丙烯腈─聚己內酯共聚物(poly(acrylonitrile)-block-poly(ε-caprolactone)，PAN-PCL)。其中PAN為一碳化之前置材料，而PCL為一可生物分解之結晶性材料。將發展許久之碳化製程應用於高分子團聯共聚合物系統中，由傅立葉轉換紅外光譜儀(Fourier transform infrared, FTIR)及掃描式探針顯微鏡(scanning probe microscopy, SPM)觀察其化學反應變化及其形態之改變，且結合熱重分析儀(thermal gravimetric analysis, TGA)分析，初步推論在奈米空間下，對PAN-PCL高分子團聯共聚合物而言，於微相分離時，其PAN鏈段形態並非如以往所認定為不規則形(random coil)，而是有具有分子拉伸排列特性之鏈段；由於分子拉伸排列性質之故，PAN-PCL高分子團聯共聚合物中之PAN鏈段其碳化過程將因為此特性而減少分子鏈斷裂(chain scission)的情形，使其碳化率遠高於一般未經拉伸處理之PAN碳纖前置材料。
本實驗同時印証，可利用水解及熱裂解方式移除PCL鏈段，達到多樣化的方式建構奈米圖案成形(nanopatterned template)技術。水解方式是以利用NaOH (0.5M)水溶液及NaOH (0.5M):CH3OH=3:2(v/v)的溶液於PCL熔點以上進行水解反應；而熱裂解則利用PCL高溫熱裂解之性質進行熱裂解反應。而因應不同需求下，本系統可提供不同之方法以應用於奈米材料之製備。如：製造奈米規則圖案碳列陣時，為了避免在PAN碳化過程中因為高溫而使得原有的微觀相分離結構遭到破壞，可先以水解移除PCL鏈段。而相反地在製造奈米尺寸多孔性碳材時，可以熱裂解方式移除PCL鏈段並保留其微觀相分離形態。

In this study, we present a new approach to well-organized nanostructured carbon materials, based on the carbonization of block copolymers containing poly(acrylonitrile) (PAN). The distinguishing feature of the method presented here is that it relies on the use of block copolymers, PAN-PCL, in which the carbonization precursor (PAN) is pre-organized into a well-defined nanostructure through self-assembly, induced by the presence of a immiscible block, poly(ε-caprolactone) (PCL), which could be removed by various ways (i.e. hydrolysis). The copolymer was prepared by Atom Transfer Radical Polymerization (ATRP). The first step was the preparation of ε-caprolactone based macroinitiators by ring-opening polymerization and then ATRP was used for PAN-b-PCL.
The nanostructured precursor phase serves then as a template of the target carbon material, which is obtained by pyrolysis accompanied by volatilization of sacrificial phase. The key to success of such a strategy is the survival of the original nanostructure through pyrolysis. This might appear extremely challenging, since a high extent of graphitization typically requires heating the material to temperatures as high as 800oC and above. Herein we demonstrate that this can be accomplished utilizing the process of thermal stabilization used in the manufacturing of carbon fibers. During this step the material is heated to 260 oC in the presence of air, which leads to conversion of PAN into a cross-linked, ladder polymer and to stabilization of the nanostructure.
In order to identify the microphase-separated structure of PAN-b-PCL and the reaction mechanism of carbonization procedure, scanning probe microscope (SPM) and Fourier transform infrared (FTIR) are used, respectively. The detail carbonization procedure condition would be identified by Thermal Gravimetric Analysis (TGA) and FTIR. Interestingly, the final remaining weight is relative to the stretching ratio and the degree of orientation of PAN molecules in microphase-separated PAN-PCL from TGA results. Comparison of without pre-stretched PAN homopolymer which is random-coil, the microphase-separated PAN possesses much more orientated molecules and lower degree of chain scission. Therefore, microphase-separated PAN molecules have better stability and more remaining weight of carbon nanofiber during carbonization procedure than PAN homopolymers.
Furthermore we also prove that this system has various ways to remove the PCL crystal domain high selectively. Since PCL is a degradable polymer, we could remove PCL via hydrolytic degradation by NaOH/Methanol mixed solution or thermal degradation at high temperature. PCL domain could be hydrolytic degraded by NaOH(0.5M):CH3OH=3:2 (V/V) solutions at above PCL melting point temperature, or thermal degradation with pyrolysis of PAN. For different procedure requirements, there are different ways to be chosen, i.e. when manufacturing carbon nanoarray structure, in order to prevent the microstructure disappearing at higher treatment temperature, hydrolytic degradation of PCL domain is necessary, otherwise when manufacturing a mesoporous carbon template, thermal degradation of PCL domain after stabilization could improve the stability of template.

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