Tuning the chain helicity and organizational morphology of an L-valine-containing polyacetylene by pH change
文献类型：期刊论文
| 作者 | Li, BS; Cheuk, KKL; Salhi, F; Lam, JWY; Cha, JAK; Xiao, XD; Bai, CL; Tang, BZ |
| 刊名 | NANO LETTERS
 |
| 出版日期 | 2001-06-01 |
| 卷号 | 1期号:6页码:323-328 |
| ISSN号 | 1530-6984 |
| DOI | 10.1021/nl015540o |
| 英文摘要 | The helical chirality and self-assembling structures of an unnatural polymer, poly(p-ethynylbenzoyl-L-valine)(1), are readily manipulated by a simple environmental perturbation of pH change. The amino acid appendages of L-valine create an asymmetric force field, inducing the polyacetylene backbones to helically rotate, and form intra- and interchain hydrogen bonds, stabilizing the screw-sense conformation of the polymer chains. The polymer exhibits a large Cotton effect in methanol, which decreases with an increase in pH upon addition of KOH into the polymer solution. The change in the chain helicity is reversible: the unfolded polymer chains refold back to their original helical conformations when the solutions are neutralized. Natural evaporation of the methanol solutions of 1 on mica gives long, bundled nanofibers of macromolecular assemblies; in contrast, evaporation of the methanol/KOH solutions yields short, unraveled nanofibers with sizes of roughly single macromolecular chains. The ionization of the carboxy groups of the valine moieties by KOH breaks the hydrogen bonds, and the entropy-driven randomization leads to the observed chain helicity attenuation. The electrical repulsion between the polyelectrolyte chains carrying the negatively charged carboxylate ions disassembles the macromolecular association, resulting in the formation of the nanofibers of single chain dimension. |
| 语种 | 英语 |
| WOS记录号 | WOS:000173721200010 |
| 出版者 | AMER CHEMICAL SOC |
| 源URL | [http://ir.iccas.ac.cn/handle/121111/76795]  |
| 专题 | 中国科学院化学研究所 |
| 通讯作者 | Tang, BZ |
| 作者单位 | 1.Hong Kong Univ Sci & Technol, Dept Chem, Kowloon, Hong Kong, Peoples R China 2.Hong Kong Univ Sci & Technol, Inst Nanosci & Technol, Kowloon, Hong Kong, Peoples R China 3.Chinese Acad Sci, Inst Chem, Ctr Mol Sci, Beijing 100080, Peoples R China |
| 推荐引用方式 GB/T 7714 | Li, BS,Cheuk, KKL,Salhi, F,et al. Tuning the chain helicity and organizational morphology of an L-valine-containing polyacetylene by pH change[J]. NANO LETTERS,2001,1(6):323-328. |
| APA | Li, BS.,Cheuk, KKL.,Salhi, F.,Lam, JWY.,Cha, JAK.,...&Tang, BZ.(2001).Tuning the chain helicity and organizational morphology of an L-valine-containing polyacetylene by pH change.NANO LETTERS,1(6),323-328. |
| MLA | Li, BS,et al."Tuning the chain helicity and organizational morphology of an L-valine-containing polyacetylene by pH change".NANO LETTERS 1.6(2001):323-328. |
入库方式： OAI收割
来源：化学研究所
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