Functional Mechanism of Polymers for Papermaking : Fundamental Research Using Fluorescently Labeled Polymers.

在PAM水溶液中加入氯化胆碱，根据Hofmann反应制备了含伯胺和季胺的阳离子聚丙烯酰胺（C-PAM）。在20c条件下，60 min后反应完成率为90%。通过控制NaOH、NaOCl和氯化胆碱的相对浓度，可以广泛地改变伯胺和季胺的比例。以二甲基甲酰胺水溶液为溶剂，在均相体系中对c - pam进行了丹基化（荧光标记）。丹桂化C-PAM （DC-PAM）在水中的最佳激发波长为333 nm，对应的发射波长为540 nm。分别制备了(a)分子量（MW）恒定（4x10*5）、电荷密度（CD）变化（0.65、1.4和2.5 meq/g）和(b) CD恒定（1.4 meq/g）、电荷密度变化（2x10*4、4x10*5和8x10*6）的系列c - pam。无论分子量和CD大小如何，这些c - pam在单硅片聚苯乙烯乳胶（PSL）上的吸附速度都非常快，但由于纤维素纤维的多孔性，分子量和CD对其吸附速率有显著影响。然而，在纤维的情况下，也迅速实现了相当程度的吸附。根据所得的吸附等温线，讨论了被吸附聚合物的电荷与底物的电荷之比。荧光标记对C-PAM在PSL或纤维上的吸附性能影响不大，可能是因为其取代度较低。用相同的分子量和CD研究了c - pam在PSL和纤维素纤维上的交换反应，只是预吸附的聚合物被荧光标记。对于最高MW的C-PAM，在PSL和纤维上没有检测到明显的交换。当使用CD最高的C-PAM时，PSL和纤维上都发生了轻微的交换。在PSL上，交换水平仅受位移开始前时间（预吸附时间）的轻微影响，2小时后脱吸没有进一步减少。另一方面，在纤维上，交换水平受预吸收时间的显著影响，即使在3周后交换程度仍在继续。对不同分子量的DC-PAM， 1小时预吸附时间内从纤维到PSL的转移速率依次为：中等>高>低。有趣的是，考虑到如此高MW的交换反应不会对PSL或上述纤维产生影响，考虑到具有最高MW的DC-PAM相当容易转移。聚合物的CD对聚合物转移的影响不大。聚合物转移时，聚合物链发生解理。传递的分数近似于光纤和PSL电荷的比值。少

Cationic polyacrylamides (C-PAM) which contain both primary and quaternary amines were prepared according to the Hofmann reaction by adding choline chloride to a solution of PAM in water. The reaction was 90 % complete after 60 min at 20ﾟC. The degree of aniNation was over 70 % and the proportion of primary and quaternary amines could be altered widely by controlling the relative concentrations of NaOH, NaOCl and choline chloride.C-PAM was dansylated (fluorescently labeled) in a homogeneous system using aqueous dimethylformamide as solvent. The optimum excitation wavelength for dansylated C-PAM (DC-PAM) in water was 333 nm and the corresponding emission wavelength 540 nm.Series of C-PAMs in which (a) the molecular weight (MW) was constant (4x10*5) and the charge densities (CD) varied (0.65, 1.4 and 2.5 meq/g) and (b) the CD was constant (1.4 meq/g) and MWs varied (2x10*4, 4x10*5 and 8x10*6) were prepared with and without a fluorescent label.The adsorption of these C-PAMs onto monodispe … More rse polystyrene latex (PSL) was very rapid regardless of MW and CD, but the adsorption rate onto cellulose fibers were significantly influenced by MW and CD due to the porous nature of fibers. A considerable degree of adsorption was, however, also rapidlyachieved in the case of fibers. The ratio of the charge of the adsorbed polymer to the charge of the substrate is discussed on the basis of the adsorption isotherms obtained. The fluorescent labeling had little effect on the adsorptivity of C-PAM on either PSL or fibers, probably because of the low degree of substitution.The exchange reaction of C-PAMs on PSL and cellulose fibers have been studied using with the same MW and CD except that the pre-adsorbed polymers were fluorescently labeled. For C-PAM with the highest MW no significant exchange could be detected on PSL or on fibers. When C-PAM with the highest CD was used a slight exchange occurred on both PSL and fibers. On PSL the level of exchange was influenced only slightly by the time before displacement started (pre-adsorption time), and after 2 hr there was no further reduction in deabsorption. On fibers, on the other hand, the levels of exchange were affected significantly by the pre-absorption time, and the degree in exchange continued even after 3 weeks. The rates and levels of exchange were also influenced by the MW and CD.For DC-PAM with different MWs, the rate of transfer from fibers to PSL 1 hr pre-adsorption time was in the following order, medium > high > low. It is interesting to note that DC-PAM with highest MW is transfered fairly easily considering that an exchange reaction for such a high MW does not take ple on PSL or on fibers described above. The effects of the CD of the polymer on polymer transfer were not great. When polymers transferred the cleavage of polymer chain occurred. The transferred fraction converged approximately to the ratio of charges of fibers and PSL. Less