Chapter 2 chain structure and configuration
This presentation is the property of its rightful owner.
Sponsored Links
1 / 39

Chapter 2. Chain Structure and Configuration PowerPoint PPT Presentation


  • 103 Views
  • Uploaded on
  • Presentation posted in: General

Chapter 2. Chain Structure and Configuration. Polymer chains have three basic properties:. The molecular weight and molecular distribution. The conformation of the chains in space. The configuration of the chain. Coil chain conformation. 2.1 Examples of configurations and conformations.

Download Presentation

Chapter 2. Chain Structure and Configuration

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.While downloading, if for some reason you are not able to download a presentation, the publisher may have deleted the file from their server.


- - - - - - - - - - - - - - - - - - - - - - - - - - E N D - - - - - - - - - - - - - - - - - - - - - - - - - -

Presentation Transcript


Chapter 2 chain structure and configuration

Chapter 2. Chain Structure and Configuration


Polymer chains have three basic properties

Polymer chains have three basic properties:

  • The molecular weight and molecular distribution.

  • The conformation of the chains in space.

  • The configuration of the chain.

Coil chain conformation


2 1 examples of configurations and conformations

2.1 Examples of configurations and conformations

2.1.1 Head-to-head and head-to-tail configurations

head-to-tail

head-to-head

Thermodynamically and spatially preferred structure is usually the head-to-tail configuration.

The H-to-H and H-to-T configurations cannot be interchanged without breaking primary chemical bonds.


2 1 2 trans gauche conformations

2.1.2 Trans-Gauche Conformations

The trans-gauche conformations of polymer chain can be interchanged by simple rotation about the single bond linking the moieties.


2 2 theory and instruments

2.2 Theory and instruments

2.1.2 Chemical methods of determining microstructure


2 3 stereochemistry of repeating units

2.3 Stereochemistry of repeating units

2.3.1 Chiral centers

*

Chemically identical but they rotated plane-polarized light in opposite directions.


2 3 2 tacticity in polymers

2.3.2 Tacticity in polymers

Polymerization of monosubstituted ethylene

Pseudochiral center


Chapter 2 chain structure and configuration

isotactic

syndiotactic

atactic


Stereo isomers

Stereo-isomers


2 4 repeating unit isomericsm

2.4 repeating unit isomericsm

2.4.1 Optical isomerism


2 4 2 geometric isomerism

2.4.2 Geometric isomerism

The cis-trans isomerism arises because rotation about double bond is impossible without disrupting the structure.


2 4 3 substitutional isomerism

2.4.3 Substitutional isomerism

Synthesis of diene type polymers

1,2

1,4

3,4

addition polymerization

isoprene


2 4 4 infrared and raman spectroscopic characterization

2.4.4 Infrared and Raman spectroscopic characterization

C-H bending823 cm-1

C-O stretching1164 & 1231 cm-1

C=O stretching1506 cm-1

Skeletal ring vibration1776 cm-1


2 5 common types of copolymers

2.5 Common types of copolymers


Chapter 2 chain structure and configuration

Copolymers

Terpolymers


Chapter 2 chain structure and configuration

Polymer blend

Graft copolymer

IPN

Block copolymer

Semi-IPN

Cross-linked


Chapter 2 chain structure and configuration

Nanoscale ‘microphase’ segregation:

cN > (cN)ODT

with (cN)ODT = f(f)

Melt state


Chapter 2 chain structure and configuration

‘Solution’ state:

Swollen micelles and

dissolved single-chains

Blends?


Chapter 2 chain structure and configuration

Crystalline state


Block copolymer microphase separation

Block Copolymer (microphase separation)

volume fraction

< 0.20

0.20 ~ 0.35

> 0.35


Transition between mesomorphic phases

Transition between mesomorphic phases


Block copolymer phase diagram

Block Copolymer phase diagram

disorder


Representative phase diagram of diblock copolymers khandpur et al macromolecules 1995 28 8796

Representative phase diagram of diblock copolymers(Khandpur et al., Macromolecules1995, 28, 8796)


Chapter 2 chain structure and configuration

3-D TEM micrographs for PS280-PLLA307 (fPLLA= 0.37) solution-cast samples sectioned along different planes. As shown, the xy plane is the basal plane normal to helical axes and the yz and zx planes are planes parallel to helical axes


Chapter 2 chain structure and configuration

‘Knitting’ pattern


2 8 conformational states in polymers

2.8 Conformational states in polymers

Arrhenius type:

Exp(-Eact/kT)

g-

g+

t


2 9 analysis of polymers during mechanical strain

2.9 Analysis of polymers during mechanical strain

Far from the neck region

In the neck region


2 10 photophysics of polymers

2.10 Photophysics of polymers

quench

A + hu = A*

A* + B = A + B*

2.10.2 Excimmer formation

A* + A = (AA)*

(AA)* = 2A + huE


2 10 3 experimental studies

2.10.3 Experimental Studies

2.10.3.1 Microstructure of polystyrene


Infrared

Infrared


  • Login