`[NH(CH_2)_6NHCO(CH_2)_4CO]_n` is a

Options

A. addition polymer
B. thermosetting polymer
C. homopolymer
D. copolymer

Explanation

To determine the type of polymer represented by the formula `[NH(CH_2)_6NHCO(CH_2)_4CO]_n`, we can follow these steps:

### Step 1: Identify the Structure of the Polymer
The given formula can be broken down as follows:
- The repeating unit contains an amine group (`NH`), a long hydrocarbon chain (`(CH_2)_6`), and a carbonyl group (`CO`), followed by another hydrocarbon chain (`(CH_2)_4`) and another carbonyl group (`CO`).

### Step 2: Recognize the Monomers
The polymer is formed from two types of monomers:
1. **Hexamethylenediamine**: This contains the `NH(CH_2)_6NH` part.
2. **Adipic acid**: This contains the `CO(CH_2)_4CO` part.

### Step 3: Determine the Type of Polymerization
The polymerization process involves the reaction between the amine and the carboxylic acid, resulting in the formation of amide bonds and the release of water as a by-product. This indicates that the polymer is formed through a condensation reaction.

### Step 4: Classify the Polymer
- **Addition Polymer**: This type does not involve the formation of by-products. Since water is released during the formation of this polymer, it cannot be classified as an addition polymer.
- **Thermosetting Polymer**: These polymers are characterized by irreversible hardening and cross-linking. The given polymer does not exhibit cross-linking, so it is not a thermosetting polymer.
- **Homopolymer**: This consists of only one type of monomer. Since our polymer is made from two different monomers, it is not a homopolymer.
- **Copolymers**: Since the polymer is made from two different types of monomers (hexamethylenediamine and adipic acid), it qualifies as a copolymer.

### Conclusion
The polymer `[NH(CH_2)_6NHCO(CH_2)_4CO]_n` is a **copolymer**.

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