A facile end-functionalization of polystyrene by ATRP and click chemistry: Chain end effect on the glass transition temperature

Abstract The present work describes the detailed macromolecular design, synthesis, and characterization of a series of mono- and bi-terminal functionalized polystyrenes (PSs) by the combination of atom transfer radical polymerization (ATRP) and copper(I)-catalyzed alkyne-azide cycloaddition (CuAAC) reaction. We further study the effect of the incorporated end groups on the glass transition behavior of the resulting polymers. The mono and bi functionalized polystyrenes were synthesized by using 1-phenylethyl bromide and 1,4-bis(bromomethyl)benzene as the initiators to form bromo mono-end functionalized PS (PS-Br) and bromo bi-terminal functionalized PS (Br-PS-Br), respectively. PS-Br and Br-PS-Br were then transformed to azido mono- and bi-terminal functionalized PSs (PS-N3 and N3-PS-N3) by SN2-type reaction with sodium azide. PS-N3 and N3-PS-N3 were then subjected to CuAAC reactions with various alkynes like 1-decyne, 1-hexyne, trimethylsilylacetylene, phenylacetylene, and 4-ethynyl-1,1′-biphenyl respectively to give a series of alkyl or aromatic mono- and bi-terminal functionalized PSs (PS-Rs and R-PS-Rs), such as PS-Rs of PS-C8H17, PS-C4H9, PS-SiMe3, PS-Ph, PS-biPh, and R-PS-Rs of C8H17-PS-C8H17, C4H9-PS-C4H9, SiMe3-PS-SiMe3, Ph-PS-Ph, and biPh-PS-biPh. PS-SiMe3 and SiMe3-PS-SiMe3 were then transformed to the corresponding PS-H and H-PS-H through the detrimetylsilylation reaction with tetra-n-butylammonium fluoride (TBAF). Among the five end groups, -C8H17 and -C4H9 were with great flexibility; -H was viewed as a standard; and -Ph and -biPh groups represented the typical rigid moieties. The effect of these end groups on glass transition behavior was thoroughly investigated based on the above macromolecular design.