Side-chain branching

The short side chain branching frequency is inversely proportional to polymer crystallinity. Short branches occur at frequencies of 2—50 per 1000 carbons in chain length their corresponding crystallinity varies from 35 to 75%. Directiy proportional to the polymer density, crystallinity can be calculated by the following formula,... 

As shown in Table 3, the glass-transition temperatures of the amorphous straight-chain alkyl vinyl ether homopolymers decrease with increasing length of the side chain. Also, the melting points of the semicrystalline poly(alkyl vinyl ether)s increase with increasing side-chain branching. 

Figure 11.13. Effect of side-chain branching on the melting point and glass transition temperature of...

Tab. 2.4 Effect of salt bridge orientation and side-chain branching at C y) on 3i4-helicity in water as investigated by CD > [177]...

The true tricyclics are often subdivided into tertiary and secondary amine groups. Structurally, the difference lies in the length of side chains branching off the basic three-ringed hub of the molecule. Clinically, side effects are most common and most severe with the tertiary amine medications such as amitriptyline, imipramine, and doxepin. The secondary amines are generally better tolerated. It should be added that two of the tertiary amine TCAs, amitriptyline and imipramine, are metabolized... 

Fig. 3. Conventions used to define the numbering of bonds in side chains branching at a tetrahedral carbon atom as seen (a) perpendicularly to and (b) looking along the bond leading to the Branch point. If the bonds leading from the branching carbon atom toward the backbone and toward Branch 1 are in the plane of the drawing, the bond leading to Branch 2 is below this plane, and the hydrogen atom is above this plane (a). (Edsall etal., 1966).

Discussion Point DPS The previously unexpected observation of side-chain branches in diimine-nickel catalyzed polyethylene formation is explained by the reaction scheme represented in Figure 15. Propose related chain migration schemes which explain i) the chain straightening , i.e. the incorporation of propylene methyl substituents into the backbone of polypropylene chains produced by these catalysts, ii) the 2,co-concatenation of higher a-olefins by some Ni-based catalysts, and Hi) the introduction of stereoerrors in isotactic polypropylene by chain-migration of chiral ansa-zirconocene catalysts. 

The side chain dihedral angle Xi is important for high-resolution definition of protein structures as it determines the angle at which each amino acid side chain branches out from the protein backbone. Moreover, in combination with certain types of NOEs, it can allow stereospecific assignment of prochiral /3-methylene protons, which improves the precision of NMR structures by obviating the need to include pseudoatom distance corrections.140-142... 

Carter and coworkers studied how side-chain branching in PFs affects device performance with and without an additional HTL of cross-linkable polymer 2 [ 19]. They found that the device efficiency is affected more by the position of the exciton recombination zone than by variations of polymer morphology induced by side-chain branching, which mainly controls the relative emission between vibrational energy levels and has a minimal effect on polymer charge transport properties. For double-layer devices (ITO/PEDOT PSS/2/3,4, or 5/Ca), a typical brightness of 100 cdm 2 at 0.8 MV cm-1, maximum luminance of 10 000 cd m-2 at 1.5 MV cm x, and device efficiencies between 1.3 and 1.8 cd A 1 for 3 and 5 branching can be achieved. 

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