How do cross linked branched polymers compare to cross linked linear polymers?
Cross-linked branched polymers and cross-linked linear polymers both involve the formation of chemical bonds between polymer chains, resulting in a three-dimensional network structure. However, there are some key differences between the two.
To understand these differences, let's first review what branched and linear polymers are.
A linear polymer consists of a long chain of repeating monomer units connected end-to-end in a straight line. It has a single backbone, and its structure resembles a string of beads. On the other hand, a branched polymer has multiple branches or side chains attached to the main polymer chain, resulting in a more complex structure.
Now, let's break down how cross-linking is achieved in both types of polymers:
1. Cross-linked branched polymers: In this case, the branches or side chains of the polymer become connected with neighboring polymer chains through covalent bonds. Cross-linking can occur between the branches of adjacent polymer chains, as well as between the branches and the main polymer backbone. This creates a highly interlinked and three-dimensional network.
2. Cross-linked linear polymers: In cross-linked linear polymers, the cross-linking occurs between the main polymer chains, rather than the branches or side chains. This means that the linear chains are bound together through covalent bonds, forming a network structure.
Now, let's compare the properties and characteristics of cross-linked branched polymers and cross-linked linear polymers:
1. Structure: Cross-linked branched polymers have a more complex structure due to the presence of side chains, resulting in a more heterogeneous network. In contrast, cross-linked linear polymers have a simpler structure with uniformly connected linear chains.
2. Mechanical properties: Cross-linked branched polymers tend to be more flexible and elastic due to the presence of side chains, which can act as movable hinges within the network. On the other hand, cross-linked linear polymers are generally stiffer and more rigid.
3. Solvent absorption: Cross-linked branched polymers often have a higher degree of solvent absorption due to the increased surface area provided by the side chains. In contrast, cross-linked linear polymers tend to have lower solvent absorption capacity.
4. Swelling behavior: In terms of swelling behavior, cross-linked branched polymers typically exhibit higher swelling ratios compared to cross-linked linear polymers. This is again due to the presence of side chains, which can create additional free volume for solvent absorption.
Overall, the differences between cross-linked branched polymers and cross-linked linear polymers lie in their structural complexity, mechanical properties, solvent absorption, and swelling behavior. By understanding the fundamental characteristics of these two types of polymers and how cross-linking occurs, you can better comprehend their similarities and differences.