Bridging-type bonding

Conversely, we have also confirmed that the presence of bridge-type bonds in po I y (/i-a I ky I am i n oboraz i nes) confer flexibility and improve processability, thus leading to the conclusion that melt spinnability increases going from polymers derived from 1 to polymers derived from 4. 

It has been confirmed that the presence of bridge-type bonds in such poly (B-alkylaminoborazines) confers flexibility and an inaeased melt-spirmability, thus leading to the conclusions that melt-spinnability inaeases from 1- to 4-daived polymers. In addition, the ceramic yield is reduced with the increased proportion of -NlCHj) in the B-(alkylamino)borazine leading to important shrinkages during the furlha- polymer-to-ceramic conversion of green fibers derived therefrom. Hence, it is relevant to assume... 

To obtain polyrotaxanes of Type 5, a dinitrophenyl-based BG was also introduced by reaction of the end groups. Polyrotaxane 40 further reacted with epi-chlorohydrin in basic solution to give a tubular structure (48) in which the adjacent CDs were linked together by bridges (chemical bonds). Upon cleavage of the BG, the linear polymer was removed to afford a molecular nanotube (49) [81]. 

The saturated rubbers such as butyl or EPDM cannot be cross linked by sulphur and accelerators. Organic peroxides are necessary for the vulcanization of these rubbers. When the peroxides decompose, free radicals are formed on the polymer chains and these chains can then combine to form cross links of the type where only carbon-carbon bonds are formed, unlike in sulphur vulcanization. These carbon-carbon bonds are quite stable ones. Such bonds are also formed by vulcanization using gamma or x-ray radiation of compounded rubbers. Some rubbers can be vulcanized by the use of certain bisfunctional compounds which form bridge type cross... 

Around 3400 cm 1 a band could be observed characteristic of axial deformation of hydroxyl groups that participate in interactions of bridge-type hydrogenbonds. Close to 2900 cm-1 another band appeared characteristic of axial deformation of a C-H bond. At 1246 cm4, a band indicating an axial deformation of ester C-O bonds could also be detected (9). 

Just the atoms in vertexes of first type bonds take part in forming bridge like intermolecular bonds in clusters on base of C2s-... 

Strong hydrogen bonds are formed by charged side-chains and by main-chain termini. These interactions are of the general hydrogen-bonded salt-bridge types... 

R n Mn Polyhedra Bridge Type Comments (Mn—0 Bond Lengths in A)... 

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