Polymer Science and Engineering and NSF Materials Research Science & Engineering Center, University of Massachusetts, Amherst, Massachusetts 01003, USA.
J Phys Chem B. 2012 Jun 21;116(24):7379-88. doi: 10.1021/jp3043494. Epub 2012 Jun 13.
The effect of the surface charge of nucleation agents on the crystallization behavior of poly(vinylidene fluoride) (PVDF) has been investigated. Ion-dipole interaction between the positive surface of nucleation agents and the partially negative CF(2) dipoles of PVDF is established as a main factor for further lowering the free energy barrier for nucleation, and thus increasing significantly the crystallization kinetics. This is in contrast to the behavior observed for nucleation agents possessing either negative surface or neutral charges. Positive nucleation agents led to a remarkable increase in the crystallization temperature of PVDF (lower supercooling) as compared with that of neat PVDF. The dispersion of each type of nucleation agent is also important. The melting temperatures of nucleation agents need to be higher than the melting temperature of PVDF. The melting point and degree of crystallinity of PVDF can also be raised by using specific nucleation agents. The detailed crystallization kinetics and conformational changes of the PVDF chain have been investigated. With the addition of positive nucleation agents, the γ and β chain conformations, instead of the α phase, dominate.
研究了成核剂表面电荷对聚偏氟乙烯（PVDF）结晶行为的影响。成核剂表面的离子偶极子与 PVDF 部分负的 CF(2)偶极子之间的离子-偶极相互作用被确立为进一步降低成核自由能势垒的主要因素，从而显著提高结晶动力学。这与具有负表面或中性电荷的成核剂的行为形成对比。与纯 PVDF 相比，正成核剂导致 PVDF 的结晶温度显著升高（过冷度降低）。每种成核剂的分散性也很重要。成核剂的熔点需要高于 PVDF 的熔点。使用特定的成核剂还可以提高 PVDF 的熔点和结晶度。详细的结晶动力学和 PVDF 链的构象变化也得到了研究。随着正成核剂的加入，γ和β链构象而不是α相占主导地位。
