Boué François, Combet Jérôme, Demé Bruno, Heinrich Martine, Zilliox Jean-Georges, Rawiso Michel
Laboratoire Léon Brillouin (CEA-CNRS), CE Saclay, 91191 Gif-sur-Yvette Cedex, France.
Génie Microbiologique et Procédés Alimentaires, INRA-AgroParisTech-UPSay, 1 rue Lucien Brétignières, 78850 Thiverval-Grignon, France.
Polymers (Basel). 2016 Jun 8;8(6):228. doi: 10.3390/polym8060228.
Scattering functions of sodium sulfonated polystyrene (NaPSS) star-branched polyelectrolytes with high sulfonation degrees were measured from their salt-free aqueous solutions, using the Small Angle Neutron Scattering (SANS) technique. Whatever the concentration , they display two maxima. The first, of abscissa ₁*, is related to a position order between star cores and scales as ₁* ∝ . The second, of abscissa ₂*, is also observed in the scattering function of a semi-dilute solution of NaPSS linear polyelectrolytes. In the dilute regime ( < , non-overlapping stars), peak abscissa does not depend on concentration and is just an intramolecular characteristic associated with the electrostatic repulsion between arms of the same star. In the semi-dilute regime, due to the star interpenetration, the scattering function ⁻ through the peak position, reflects repulsion between arms of the same star or of different stars. The threshold between these distinct -dependencies of ₂ in the dilute and semi-dilute regimes is estimated as . Just as simple is the measurement of the geometrical radius of the star obtained from the ₁ value at * through the relation 2 = 2π/₁*. By considering NaPSS stars of the same functionality with different degrees of polymerization per arm , we find scaling linearly with , suggesting an elongated average conformation of the arms. This is in agreement with theoretical predictions and simulations. Meanwhile the value of ₂* measured in the dilute regime does not allow any inhomogeneous counterion distribution inside the stars to be revealed.
使用小角中子散射（SANS）技术，从无盐水溶液中测量了高磺化度的磺化聚苯乙烯钠（NaPSS）星型支化聚电解质的散射函数。无论浓度如何，它们都显示出两个最大值。第一个最大值的横坐标为₁*，与星型核之间的位置有序性有关，且₁* ∝ 。第二个最大值的横坐标为₂*，在NaPSS线性聚电解质的半稀溶液的散射函数中也能观察到。在稀溶液区域（< ，不重叠的星型），峰横坐标不依赖于浓度 ，只是与同一星型臂之间的静电排斥相关的分子内特征。在半稀溶液区域，由于星型的相互渗透，穿过峰位置的散射函数 ⁻ 反映了同一星型或不同星型臂之间的排斥。稀溶液和半稀溶液区域中₂的这些不同 - 依赖性之间的 阈值估计为*。通过关系2 = 2π/₁*，从处的₁值获得的星型几何半径 的测量同样简单。通过考虑具有不同每臂聚合度的相同官能度的NaPSS星型，我们发现 与 呈线性比例关系，这表明臂的平均构象是拉长的。这与理论预测和模拟结果一致。同时，在稀溶液区域中测量的₂*值无法揭示星型内部任何不均匀的抗衡离子分布。
