What Is a Random Copolymer?
Random copolymer. The monomers M1, M2 are randomly arranged on the macromolecular chain, and the two monomers are randomly distributed on the main chain. No one monomer can form a single longer segment on the molecular chain.
Random copolymer
Random copolymer
- Random copolymer form.
- M1 M1M2 M2M2 M1M2 M1M2 M2M1
- Most of the copolymers currently developed are of this type, such as butadiene-styrene random copolymers (styrene-butadiene rubber), vinyl chloride-vinyl acetate copolymers, and the like.
- Random copolymerization usually destroys the symmetry and regularity of the chain, thereby reducing the crystallization ability or even completely losing it. Whether a random copolymer can crystallize depends on the nature of the monomer components in the copolymer.
- If the homopolymer of the two copolymer units has the same type of crystal structure, the copolymer can also crystallize;
- If the homopolymers of the two copolymer units have different crystal structures, the copolymer can crystallize when one component is dominant, and the copolymer units with a small content exist as defects in the crystal structure of the other homopolymer. in. [1]
Random copolymer substance use
- Random copolymers can be used as neutral layers in directed self-assembly lithography. Taking PS-b-PMMA as an example, unlike block copolymers, PS and PMMA of random copolymers are randomly arranged along the backbone of the molecular chain, so the macroscopic surface energy is a function of its composition, and the The components of PS and PMMA can make it neutral to PS-b-PMMA. At the same time, functional groups such as OH or HEMA are often carried on the ends or branches of the random copolymer molecular chains, which are used to anchor molecules to the substrate or to cross-link between them. Under high temperature conditions, the functional groups in the random copolymer will react with the active group hydroxyl (OH) or carbonyl (C = O) groups on the surface of the silicon wafer to form a strong molecular covalent bond. The random copolymer It is connected to the surface of the substrate to form a neutral layer with a thickness of about 2-5 nm to achieve the neutralization effect of the substrate, as shown in Figure 1 [2] .