1 / 16

Polymers: 1. Introduction 2. The variety of Polymeric Materials

Polymers: 1. Introduction 2. The variety of Polymeric Materials. Dept. Phys., Tunghai Univ. C. T. Shih. Introduction. Polymers: a giant molecule, made up of many repeat units covalently joined together Common characteristics: long, string-like molecules

kkelley
Download Presentation

Polymers: 1. Introduction 2. The variety of Polymeric Materials

An Image/Link below is provided (as is) to download presentation Download Policy: Content on the Website is provided to you AS IS for your information and personal use and may not be sold / licensed / shared on other websites without getting consent from its author. Content is provided to you AS IS for your information and personal use only. Download presentation by click this link. While downloading, if for some reason you are not able to download a presentation, the publisher may have deleted the file from their server. During download, if you can't get a presentation, the file might be deleted by the publisher.

E N D

Presentation Transcript

  1. Polymers:1. Introduction2. The variety of Polymeric Materials Dept. Phys., Tunghai Univ. C. T. Shih

  2. Introduction • Polymers: a giant molecule, made up of many repeat units covalently joined together • Common characteristics: long, string-like molecules • Living polymers: long-chain objects whose subunits are joined by physical bonds, e.g., actin filaments

  3. Variety of Polymeric Materials • Polymer chemistry • Stereochemistry • Architecture • Homopolymers and Copolymers • Physical state

  4. Polymer chemistry • Most polymers contains carbon atoms. Simplest polymer: polyethylene （聚乙烯）

  5. Polymer chemistry (conti.) • The main chain can have different side groups: polymethyl methacrylate（聚甲基丙烯酸甲酯）

  6. Polymer chemistry (conti.) • The main chain can incorporate non-carbon atoms, e.g., Nylon

  7. Polymer chemistry (conti.) • The main chain can involve loops, e.g., amylose （澱粉）

  8. Polymer chemistry (conti.) • The polymer can be multiply connected, forming a ladder structure, e.g., poly(dioctyl fluorene)

  9. Polymer chemistry (conti.) • The main chain can contain no carbon atoms at all, e.g., PDMS (silicone oil)

  10. Stereochemistry • If a polymer has more than one type of chemical group attached to each main chain (carbon) atom, then different arrangement of the groups in 3D are possible: isotactic, syndiotactic, and atactic.

  11. Quenched disorder → Glasses

  12. Architecture • Linear vs. Branched polymers • Linear polymers can be characterized by N, the number of repeated units: degree of polymerization • N is proportional to the relative molecular mass M • Degree of polymerization is not a constant for a group of polymers – a distribution • PDI: polydispersity index ≡ (weight average)/(number average)

  13. PDI=Mw/Mn • Number average: • Weight average: • Standard error:

  14. Branched Polymer • The polymers may be branched • The branched points introduce quenched disorder, and hinder the formation of crystals • A lot of branch points – a network

  15. Copolymers • The building units are all the same – homopolymers • Different building units – copolymers • Phase separation and microphase separation • DNA and proteins are copolymers

  16. Physical States • Liquid – melts and solutions, usually very viscous/viscoelastic • Glass – is common because of the difficulty of crystallization • Crystalline – usually incomplete/small due to quenched disorder • Liquid crystal

More Related