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Preparation of Polystyrene with Higher Tg Based on Triple Hydrogen Bond Interactions

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par Jean Claude MBULU AGALIA
Beijing University of Chemical Technology - Master es Science 2008
  

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PREPARATION OF POLYSTYRENE WITH HIGHER Tg BASED ON TRIPLE HYDROGEN BOND INTERACTION

MBULU AGALIA

MATERIALS SCIENCE

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Contents

Abstract............................................................... ......... .........2

Abstract in Chinese ... ................................................................4

Chapter 1 Introduction................ ................... ......5

1.1 Glass transition temperature.............................................................5
1.2 Styrene and Maleimide copolymer....................................................14

1.3 Melamine and chemistry .............................................................23

1.4 Diaminopyridine molecule..............................................................26

1.5 the thesis work...........................................................................27

Chapter 2 Experimentation Section.............................................31

2.1 Materials.................................................................................31

2.2 Instruments..............................................................................31

2.3 Synthesis of random copolymers of styrene and maleimide......................32

2.4 Synthesis of Blends of Styrene/Maleimide copolymer and melamine...........32

2.5 Synthesis of Blends of the copolymer and 2,6-diaminopyridine.................33

Chapter 3 Results and discussion................................................34

3.1 Characterization of copolymer of styrene and maleimide..........................34

3.2 Copolymerization of styrene and maleimide........................................33

3.3 Blends of the styrene/maleimide copolymers and melamine............................38

3.4 Blends of the copolymer and 2,6-diaminopyridine..................................43

Chapter 4 Conclusion.................................................................46

Reference...................................................................................47

PREPARATION OF POLYSTYRENE WITH HIGHER Tg BASED ON HYDROGEN BOND INTERACTION

ABSTRACT

Polystyrene is one of a common polymer. But its glass transition temperature (Tg) is only 100oC which leads to limit its applications. In the thesis, improvement of its Tg was done via increase of its chain interactions to restrict the chain flexibility.

Styrene was copolymerized with maleimide, imide of which act as a hydrogen-bond interaction site in the copolymer, by free radical polymerization method in  DMSO solution at different temperature, and different ratio of styrene to maleimide, and different reaction time, using different amount of AIBN as an initiator. To make the imide distribute randomly in the chains, maleimide was dropped slowly during the polymerization. Melamine and diaminopyridine were selected to be as interaction molecule because they can form the triple hydrogen bond with imide in the copolymer. Addition of melamine or diaminopyridine into the copolymer results in a dramatic increase of Tg. Polystyrene with imide molar concentration of 5.05% has Tg of 122oC in the presence of melamine, 22 oC higher than polystyrene, which will extend application of polystyrene. At high ratio of melamine to imide, two Tgs are observed, one is higher than 122oC but another much lower. The existence of two Tg is due to the fact that free melamine is acting as plasticizer.

Diaminopyridine also increase Tg of polystyrene, but not effectively than melamine owing to lack of crosslinking. In this case, the blend of Diaminopyridine with polystyrene containing imide looks like a copolymer of styrene with a big monomer, complex of maleimide and Diaminopyridine.

The secondary interaction characteristics between melamine or Diaminopyridine with polystyrene containing imide is confirmed by their blends readily soluble in DMSO and in CH2Cl2.

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