發(fā)布時間：2019-02-26 08:37

【摘要】：采用動態(tài)蒙特卡洛分子模擬研究了環(huán)形高分子單鏈在不良溶劑中發(fā)生塌縮轉(zhuǎn)變時可逆地出現(xiàn)具有核-殼結(jié)構(gòu)特征的熔球中間態(tài),發(fā)現(xiàn)該結(jié)構(gòu)特征與相同鏈長的線形單鏈基本相同,表明其只與鏈的長短有關(guān),而與鏈端基的特殊效應(yīng)無關(guān).本工作將這一現(xiàn)象與單鏈單晶在其平衡熔點附近出現(xiàn)的類似現(xiàn)象相互關(guān)聯(lián),采用表面預(yù)溶模型來解釋單鏈塌縮出現(xiàn)熔球中間態(tài)的熱力學(xué)機理.分子量越低,熔球越小,表面預(yù)溶現(xiàn)象就越顯著,塌縮轉(zhuǎn)變隨熱力學(xué)條件變化就越緩慢.實際的高分子體系由于鏈內(nèi)拓撲纏結(jié),在表面未必能充分釋放片段鏈,達不到理論預(yù)期的平衡態(tài).表面預(yù)溶使得相分離臨界點或晶體熔點附近在界面厚度方向上存在鏈單元能量狀態(tài)不連續(xù)分布,這在微觀分子水平上與臨界界面連續(xù)濃度梯度的傳統(tǒng)理論處理不一致,為我們深入理解高分子流體界面的微觀結(jié)構(gòu)帶來幫助.
[Abstract]:In this paper, dynamic Monte Carlo molecular simulation was used to study the reversible intermediate state of core-shell structure in the core-shell structure of circular polymer single chain during collapse transition in bad solvent. It is found that the structure is basically the same as the linear single chain with the same chain length, indicating that it is only related to the length of the chain, but has nothing to do with the special effect of the end group of the chain. In this paper, this phenomenon is related to the similar phenomenon of single-chain single crystal near its equilibrium melting point, and the thermodynamic mechanism of the intermediate state of single-chain collapse is explained by surface pre-dissolving model. The lower the molecular weight is, the smaller the melting ball is, the more obvious the surface pre-dissolution phenomenon is, and the slower the collapse transition changes with the thermodynamic conditions. Because of the topological entanglement in the chain, the actual polymer system may not release the fragment chain sufficiently on the surface, which can not reach the equilibrium state expected by the theory. The surface pre-dissolution results in the discontinuous distribution of the chain element energy in the direction of interface thickness near the critical point of phase separation or near the melting point of the crystal, which is inconsistent with the traditional theoretical treatment of the continuous concentration gradient at the critical interface at the micro-molecular level. It is helpful for us to understand the microstructure of polymer fluid interface.
【作者單位】： 南京大學(xué)化學(xué)化工學(xué)院高分子系;
【基金】：國家自然科學(xué)基金(基金號21474050)資助項目
【分類號】：O631.11

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1 樊克,吳大誠;端基附壁高分子模型鏈的塌縮轉(zhuǎn)變[J];高分子學(xué)報;2001年01期

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本文編號：2430614