Composite chain

This chapter has shown a possible route to the free structural control of glycerol-based nonionic surfactants reverse micelles, and it is found that the solvent properties, temperature, composition, chain length of surfactant and headgroup size, and water can be the tunable parameters for the structural variation of reverse micelles. 

Recent studies (Defieuw 1989) indicate that the crystallization conditions, blend composition, chain rigidity and microstracture, and molecular weight of the components are important. Blends consisting of two crystallizable components (Sect. 3.2.2.2) can exhibit separate crystallization or concurrent crystallization (cocrystallization). 

The most topologically simple interpenetrating networks are ID -> ID parallel networks (Figure 4.35). Only two chains become threaded through holes within each other and therefore the resultant composite chain runs in the same direction... 

D) Diffusivity. The molecular mobility of penetrant molecules in a polymeric matrix is affected by at least four factors. (1) Polymer-chain segmental mobility is governed by the inherent flexibility of the polymer chain (chemical composition, chain sequence distribution, inter- and intrachain interactions, etc.), effects of crosslinking and crystalline domains, interactions with penetrant... 

If we can assume association to be an entire equilibrium and reversible, it can be decomposed into intra- and intermolecular association. In intramolecular association, each chain has a conformation carrying several inframolecular flowers along the chain [29]. The hydrophobic cores are regarded as composite associative groups. In intermolecular association, such composite chains are connected with each other by intermolecular association. Thus, the system is modeled as a polymer solution in which polymers carry many associative groups of different sizes that may form junctions of variable multiplicity. The functionality of each chain is not fixed, but is controlled by the thermodynamic requirement. 

Fig. 10.7 Mixture of petals and telechelic chains. A petal can he regarded as a monofunctional composite chain. (Reprinted with permission from Ref. [29].)...

To obtain an unambiguous characterization of a particular material, it is often essential to fractionate a material (1-3). Synthetic polymers are rarely homogeneous chemical species, but have multivariate distributions in molecular weight, chemical composition, chain architecture, and functionality (4). For a precise characterization of a synthetic polymer, all the distributions need to be determined, which is a difficult, if not virtually impossible, task. Traditionally, fractionation has allowed separation of pol5miers on the basis of molecular mass or chemical composition (2). With proper techniques it is often possible to separate and characterize complex homo- and copolymer species on the basis of chemical heterogeneity and molar mass. 

The use of responsive vectors highlights the multifaceted and complex nature of these cationic lipid vectors and the supramolecular structures they form with DNA. By varying composition, chain lengths, linkers, and various properties, the lipoplex phase can be tailored to improve gene delivery. The research featured in this chapter has shown how the use of responsive nonviral vectors can enhance endosomal escape of the lipoplex and release of DNA from the lipoplex system, subsequently affecting gene transfer. 

Wang J, Mueller M Microphase separation of mixed polymer brushes dependence of the morphology on grafting density, composition, chain-length asymmetry, solvent quality, and selectivity, J Phys Chem B 113 11384—11402, 2009. 

Fig. 2.20. Model of a composite chain with diflFerent fractal dimensions for r < t(d = 2) and r > t d = 5/3). The cross-over distance corresponds to the size of the pearls.

High-pressure processes when used with ZN catalysts, greatly expand the product range and provide control over composition, chain linearity, and short chain branching. It became the most versatile technology through the 1980s. 

Rheological behavior of reactive blends is complex due to the presence of copolymer with poorly understood chain structure and spatial distribution. Rheological differences between reactive and non-reactive blends are substantial. Key microstructural issues needed for a detailed understanding of the rheology such as the copolymer composition, chain structure, and spatial distribution within the blend are yet to be explored carefully. 

Fig. 2.20. Model of a composite chain with different fractal dimensions for r <...

All fillers were dried overnight under vacuum at 120°C to eliminate any absorbed moisture. BD and PCL were also dried overnight under vacuum at 45°C. A detailed account of the method used to prepare organoclay/SMPU nanocomposite can be found elsewhere [21, 22]. In short, prepolymer was synthesized at 80°C for 2 hours. Chain extension of prepolymer with BD was carried out in Brabender Plasticorder (model EPL 7752) at 80°C for 4 minutes with 9.8x10" mol/L of tin catalyst. Organoclay was then added and allowed to react for additional 11 minutes to produce nanocomposites. Clay content was maintained at 1 and 3 wt%. Eor other composites, chain extension step was carried out at 110°C for 2 minutes before addition of CNF, CB or SiC. Filler particles were mixed for an additional 5 minutes at 140°C. The total filler content was maintained at 1, 3 and 5 wt%. The composites were compression molded at 220°C to produce specimens with thickness of 0.5 mm for testing of mechanical, thermal, and shape memory properties. 

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