MATRIX EFFECTS ON THE DIFFUSION OF LONG POLYMER-CHAINS
MATRIX EFFECTS ON THE DIFFUSION OF LONG POLYMER-CHAINS
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DOI：
10.1021/ma00158a029
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发表时间：
1986-04-01
期刊：
影响因子：
5.5
通讯作者：
KRAMER, EJ
中科院分区：
文献类型：
--
作者：
GREEN, PF;KRAMER, EJ
用正反冲光谱法研究了分子量为M的长链（M链）在分子量为P的基质中的扩散。基质分子量P从低于纠缠临界分子量Mc的极短未纠缠链到高度纠缠的长链不等。而M链的示踪剂扩散系数D*与P无关，当P在纠缠态中足够大时（D*~ M™2），当P小于特征分子量P*时，随着P的减小，示踪剂扩散系数D*迅速增加，P*随M缓慢增加，这与理论预测D*= Drep+ Da一致。这里Drep是由于m链的扩散而产生的扩散系数，Da是由于周围p链的同时扩散（约束释放）而产生的m链扩散的附加矩阵贡献。我们发现DCI的尺度近似为M-1P ' 3。在未纠缠状态下（P< Mc），研究在不同温度下进行，其中每个矩阵的分数自由体积等于常数0.042。示踪剂扩散系数约为D*~ jVf~< 0-5~-6) P~ 1，这一结果与链在黏度为P的粘性环境中作为流体动力半径为R~ M~（a5~’6）的线圈扩散相一致。
The diffusion of long chains of molecular weight M (M-chains) into matrices of molecular weight P is studied by forward-recoil spectrometry. The matrix molecular weight P ranged from very short unentangled chains below the critical molecular weight for entanglement Mc to long highly entangledchains. Whereas the tracer diffusion coefficient D* of the M-chains is independent of P for sufficiently large P in the entangled regime (D*~ M™ 2), it rapidly increases with decreasing Pfor P less than a characteristic molecular weight P* which increases slowly with M. This behavior is consistent with theoretical predictions that D*= Drep+ Da. Here Drep is thediffusion coefficient due to thereptation of the M-chain, and Da is an additional matrix contribution to the diffusion of the M-chain that arises from the simultaneous diffusion of the surrounding P-chains (constraint release). We find that DCI scales approximately as M-1P “3. In the unentangled regime (P< Mc) studies were conducted at different temperatureswhere the fractional free volume of each matrix was equal to a constant, 0.042. Here the tracer diffusion coefficient scales approximately as D*~ jVf~< 0-5~-6) P~ 1, a result that is consistent with the chain diffusing as a coil of hydrodynamic radius R~ M~(a5~'6) in a viscous environment whose viscosity scales as P.