Aggregation of poly

Stork, M., Giese, A., Kretzschmar, H. A., and Tavan, P. (2005). Molecular dynamics simulations indicate a possible role of parallel beta-helices in seeded aggregation of poly-Gln. Biophys. J. 88, 2442-2451. 

Rosenbaum VM, Dekhtyar ML (1993) A simple model for formation of aggregate of poly-methine dye molecules. Ukr J Phys 38 1296-1299... 

The introduction at the C- or N-terminal position of a crown ether unit has been used as a strategy to control the aggregation of poly(benzyl glutamate) derivatives 19 The incorporation of the crown unit at the C-terminal position is performed using (benzo-15-crown-5)-4-amine as initiator of the polymerization of l-G1u(OBz1)-NCA. Physical properties of such crown derivatives can be modulated by the formation of sandwich 2 1 complexes driven by the addition of specific alkali metal ions. In the reported case, the formation of K+ sandwich complex between two C-terminal benzo-15-crown-5 modified helical polypeptides induced aggregation. In a similar approach,f20 addition of Cs+ to 18-crown-6 terminated helical peptides results in the formation of supramolecular assemblies having membrane ion conductivity activities. 

Remarkably few systematic studies have been made of the kinetics of anionic polymerization in non-polar solvents containing small amounts of ethers in contrast, studies of bulk ether systems abound. Several studies have appeared 156 158) in which the propagation reactions involving styryllithium were measured in mixtures of benzene or toluene with ethers. The kinetic orders, in some cases, of the reactions were identical to those observed in the absence of the ether. Thus, in part, the conclusion was reached 157,1581 that the ethers did not disrupt the dimeric degree of aggregation of poly(styryl)lithium. The ethers used were tetrahydrofuran 156), anisole 157), diphenyl ether 158), and the ortho and para isomers of ethylanisole157). 

Hemker DJ, Frank CW (1990) Dynamic light-scattering studies of the fractal aggregation of poly(methacrylic acid) and poly(ethylene glycol). Macromolecules 23(20) 4404-4410... 

Fig. 21 Assembly of polymers via triple-hydrogen bonds, a Formula of the flavine/2,6-diamino-triazine and thymine/2,6-diaminotriazine interactions, b Formation of nanopar-ticles/polymer aggregates, c Polymersome formation by aggregation of poly(norbornenes) and poly(styrenes) bearing N-bisacyl-2,6-diamino-pyridine and thymine side-chains, respectively. Reprinted with permission from [104,105]...

Fig. 34 Formation and aggregation of poly(hexenes) via ureidopyrimidones. Redrawn after [135]...

Vasilescu, M. Caragheorgheopol, A. Caldararu, H. Aggregation numbers and micro structure characterization of self-assembled aggregates of poly(ethylene oxide) surfactants and related block-copolymers, studied by spectroscopic methods. Adv. Colloid Interf Sci. 2001, 89, 169-194. 

S. Ito, Phase transition of aqueous solution of poly(/V-alkylacrylamide) derivatives, Kobunshi Ronbunshu, 1989, 46, 437 H. Hachisako and R. Murakami, Thermosensitive telomer aggregates of poly(/V-substituted acrylamide), Kobunshi Kako (Polymer Processing), 1998, 47, 21. 

Dynamic mechanical and NMR investigations of crystals grown from dilute solutions for polymers other than linear polyethylene have been much less extensive. Studies have been reported for the linear polymers polyoxy methylene (3, 40, 94), poly (ethylene oxide) (3, 78), and nylon 6 (42), and the branched polymers polypropylene (40), poly-l-butene (19, 95), poly(4-methyl-l-pentene) (33), poly (vinyl alcohol) (78), and branched polyethylene (78). In addition, dielectric loss measurements have been made on crystal aggregates of poly (ethylene oxide) (23), poly (vinyl alcohol) (68), and polyoxymethylene (3) and mechanical loss measurements have been carried out on polyoxymethylene formed by solid state polymerization (94). 

TA Otake, K., Karaki, R., Ebina, T., Yokoyama, C., and Takahashi, S., Pressure effects on the aggregation of poly(A-isopropylacrylamide) and poly(A-isopropylaciylamide-co-acrylic acid) in aqueous solutions, Mocro/wo/ecM/es, 26, 2194, 1993. 

The temperature interval for aggregation of poly(GVGVP) begins just above room temperature in water, that is, above 25° C, and ends at about 37° C (see Figure 5.1C and Figure 5.5A). Addition of salt (NaCI) at 25° C lowers the temperature for aggregation and causes the solution to go cloudy. As discussed below, salt drives contraction by lowering the temperature interval for heat-driven contraction. 

Polymer solvent interactions determine several properties, sueh as, solubility, solvent retention, plastieizer aetion, wettability, adsorption and adhesion. The solubility parameter is an important eriterion for the choice of solvents. However, acid-basic characters of bofli solvent and polymer are also determinant parameters, which can affect the solution and final film properties. This part, devoted to the influence of acid-base interactions on the aggregation of poly(methyl methacrylate) will first present some recent concepts in acid-base interactions, followed by two practical examples based on experimental results obtained for PMMA/solvent systems. 

Chu, Q. and Y. Pang. 2003. Molecular aggregation of poly[(l,3-phenyleneethynylene)-flfr-oligo(2,5-dialkoxy-l,4-phenyleneethynylene)] Effects of solvent, temperature, and polymer conformation. Macromolecules 36 4614. 

Breitenkamp, R.B. and G.N. Tew. 2004. Aggregation of poly(p-phenyleneethynylene)s containing nonpolar and amine side chains. Macromolecules 37 1163. 

KUM Kumar, A.C., Erothu, H., Bohidar, H.B., and Mishra, A.K., Bile-salt-induced aggregation of poly(A-isopropylacrylamide) and lowering of the lower critical solution temperature in aqueous solutions, J. Phys. Chem. B, 115, 433,2011. 

Cuniberti, C. Evidence for aggregation of Poly(ethylene-oxide). Polymer 16 (1975) 306-307... 

Gohy J-F, Antoun S, Jerome R (2001) Self-aggregation of poly(methyl methacrylale)-Wock-poly(sulfonated glycidyl metharrylate) copolymers. Polymer 42 8637-8645... 

The aggregation of poly(methacrylic acid) derivatives with mesogenic side groups in solution and in solid takes place by stereo-association, i.e. the formation of microcrystallites. These aggregates are relatively stable and can only be destroyed by melting in solution. The rate of crystallization is enhanced by subjecting the solution to shear stress by capillary flow. A structural model of the aggregates is proposed and discussed. 

---