HUANG Huahua, DONG Jinyong. SYNTHESIS OF STYRYLCAPPED ISOTACTIC POLYPROPYLENES AND THEIR APPLICATION IN SYNTHESIS OF POLYPROPYLENES WITH TOPOLOGICAL STRUCTURE[J]. Acta Polymerica Sinica, 2010,(1):87-95.
HUANG Huahua, DONG Jinyong. SYNTHESIS OF STYRYLCAPPED ISOTACTIC POLYPROPYLENES AND THEIR APPLICATION IN SYNTHESIS OF POLYPROPYLENES WITH TOPOLOGICAL STRUCTURE[J]. Acta Polymerica Sinica, 2010,(1):87-95. DOI: 10.3724/SP.J.1105.2010.00087.
This paper demonstrates the successful synthesis of reactive isotacticpolypropylene terminated with styryl groups.The styryl group was introduced into the iPP chain end via chain transfer reaction to 1
4-divinylbenzene or 1
2-bis(4-vinylphenyl)ethane
during metallocenecatalyzed propylene polymerization by rac-Me2Si[2-Me-4-Ph(Ind)]2ZrCl2/MAO complex in the presence of hydrogen.Although hydrogen does not influence the polymer molecular weight
it greatly affects the catalyst activity.The iPP molecular weight is strongly dependent on the concentration of chain transfer agent.The isotacticity (mmmm) of iPP macromonomers is quite high ( 70%).The polymerization mechanism was also studied by using deuterium as labelled molecule of hydrogen in combination with 13C-NMR technique
and it is clear that the existent double enchainment of chain transfer agent is because the styryl-capped polymer chain would spontaneously insert into ZrH species with the unique 1
2-manner.The reactive iPP obtained was used as building block
and two kinds of topological structural polymers were synthesized.Styryl-capped iPP was copolymerized with styrene using CpTiCl3/MAO complex to produce sPS-g-iPP copolymer.Crude copolymer was subjected to extraction with chloroform which resulted in pure graft copolymer free of styryl-capped iPP.DSC results show thatTm
Xc
and Tc of sPS main chains and iPP side chains are all lower than those of the sPS and iPP homopolymers
separately.The appearance of extremely large supercoolings in sPS main chains is attributed to crystallization starting from homogeneous nuclei in isolated microdomains of graft copolymers which are generated by phase segregation.In addition
the terminal styryl groups of iPP were effectively transformed to azido groups through chlorination and substitutional reaction
and azidocapped iPP was obtained.Then
the click reaction between azido-capped iPP and trialkyne-containing couple agent was conducted in the presence of CuBr/PMDETA.1H-NMR results indicated that the click reaction was fast and highly efficient