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How does tacticity affect polymer properties?
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Michel Paul
How does tacticity affect polymer properties?
The tacticity allows to synthesize a polymer having macromolecular chains more regular. This regularity allows the polymer chains to parallelize in a more compact manner so as to create greater Van der Walls forces, making the polymer more performing in terms of mechanical characteristics; in practice they allow the polymer to create more crystalline parts.
I can better explain youthe question using as example polypropylene which was the polymer on which the possibility of obtaining stereoregular polymers and therefore the phenomenon of stereoregularity was studied first.
Before to discover stereospecific catalysts, polypropylene was a practically unused polymer since in the radical polymerization the methyl groups on the chain were placed randomly in the direction of the observer or in the opposite direction. The polymer did not crystallize and had very low mechanical properties. Furthermore branched polymers were formed which disadvantaged the possibility of parallelizing the chains and to form crystalline zones.
The polymerizations with stereospecific catalysts have allowed to obtain regular polymers that in the case of polypropylene could be of two types: (a) isotactic, placing the methyls of the polymeric chain all on the same side (towards the observer as in Fig. 1) ; (b) syndiotactic, placing the methyls alternately and regularly towards the observer and in the opposite direction (Fig. 2).
The tacticity allows to synthesize a polymer having macromolecular chains more regular. This regularity allows the polymer chains to parallelize in a more compact manner so as to create greater Van der Walls forces, making the polymer more performing in terms of mechanical characteristics; in practice they allow the polymer to create more crystalline parts.
I can better explain youthe question using as example polypropylene which was the polymer on which the possibility of obtaining stereoregular polymers and therefore the phenomenon of stereoregularity was studied first.
Before to discover stereospecific catalysts, polypropylene was a practically unused polymer since in the radical polymerization the methyl groups on the chain were placed randomly in the direction of the observer or in the opposite direction. The polymer did not crystallize and had very low mechanical properties. Furthermore branched polymers were formed which disadvantaged the possibility of parallelizing the chains and to form crystalline zones.
The polymerizations with stereospecific catalysts have allowed to obtain regular polymers that in the case of polypropylene could be of two types: (a) isotactic, placing the methyls of the polymeric chain all on the same side (towards the observer as in Fig. 1) ; (b) syndiotactic, placing the methyls alternately and regularly towards the observer and in the opposite direction (Fig. 2).
Sorry Christopher I’m going to answer this fairly brief:
You’ve probably heard of PMMA; Poly(methyl methacrylate) or - if you wish - Poly(methyl 2-methylpropenoate) . (The trade name Plexiglass might ring a bell.)
Sorry Christopher I’m going to answer this fairly brief:
You’ve probably heard of PMMA; Poly(methyl methacrylate) or - if you wish - Poly(methyl 2-methylpropenoate) . (The trade name Plexiglass might ring a bell.)
The tacticity allows to synthesize a polymer having macromolecular chains more regular. This regularity allows the polymer chains to parallelize in a more compact manner so as to create greater Van der Walls forces, making the polymer more performing in terms of mechanical characteristics; in practice they allow the polymer to create more crystalline parts.
I can better explain youthe question using as example polypropylene which was the polymer on which the possibility of obtaining stereoregular polymers and therefore the phenomenon of stereoregularity was studied first.
Before to discover stereospecific catalysts, polypropylene was a practically unused polymer since in the radical polymerization the methyl groups on the chain were placed randomly in the direction of the observer or in the opposite direction. The polymer did not crystallize and had very low mechanical properties. Furthermore branched polymers were formed which disadvantaged the possibility of parallelizing the chains and to form crystalline zones.
The polymerizations with stereospecific catalysts have allowed to obtain regular polymers that in the case of polypropylene could be of two types: (a) isotactic, placing the methyls of the polymeric chain all on the same side (towards the observer as in Fig. 1) ; (b) syndiotactic, placing the methyls alternately and regularly towards the observer and in the opposite direction (Fig. 2).
The tacticity allows to synthesize a polymer having macromolecular chains more regular. This regularity allows the polymer chains to parallelize in a more compact manner so as to create greater Van der Walls forces, making the polymer more performing in terms of mechanical characteristics; in practice they allow the polymer to create more crystalline parts.
I can better explain youthe question using as example polypropylene which was the polymer on which the possibility of obtaining stereoregular polymers and therefore the phenomenon of stereoregularity was studied first.
Before to discover stereospecific catalysts, polypropylene was a practically unused polymer since in the radical polymerization the methyl groups on the chain were placed randomly in the direction of the observer or in the opposite direction. The polymer did not crystallize and had very low mechanical properties. Furthermore branched polymers were formed which disadvantaged the possibility of parallelizing the chains and to form crystalline zones.
The polymerizations with stereospecific catalysts have allowed to obtain regular polymers that in the case of polypropylene could be of two types: (a) isotactic, placing the methyls of the polymeric chain all on the same side (towards the observer as in Fig. 1) ; (b) syndiotactic, placing the methyls alternately and regularly towards the observer and in the opposite direction (Fig. 2).
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Sorry Christopher I’m going to answer this fairly brief:
You’ve probably heard of PMMA; Poly(methyl methacrylate) or - if you wish - Poly(methyl 2-methylpropenoate) . (The trade name Plexiglass might ring a bell.)
Sorry Christopher I’m going to answer this fairly brief:
You’ve probably heard of PMMA; Poly(methyl methacrylate) or - if you wish - Poly(methyl 2-methylpropenoate) . (The trade name Plexiglass might ring a bell.)
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