Facile Method of Controlling Monomer Sequence Distributions in Random Copolymers

Abstract

Copolymers of poly(styrene‐co‐4‐bromostyrene) (PBrxS) with adjustable monomer sequence distribution of styrene (S) and 4‐bromostyrene (4‐BrS) and composition (x = content of 4‐BrS) are prepared by brominating parent polystyrene (PS). While bromination reaction carried out above the theta temperature (Θ) leads to PBrxS with random monomer distribution, bromination of PS performed at temperatures below Θ produces PBrxS having a random‐blocky character.

Discriminating Among Co‐monomer Sequence Distributions in Random Copolymers Using Interaction Chromatography

“…Kerr effect measurements were employed as an independent technique to determine the average blocky length of the 4-BrS consecutive units (h 4-BrS ) in three PBr x S samples. [4] The values of h 4-BrS are given in Figure 1; they confirm that the blockiness in PBr x S made at temperatures below Q is higher relative to the specimens formed above Q. Finally, truly random PBr x S RCPs have been prepared by brominating the same parent PS chains in NB [13] and used to study quantitatively the polymer HPLC retention and surface adsorption due to the segment blockiness in PBr x S RCPs made in CUD.…”

“…These results are in a very good qualitative agreement with the trends reported previously. [4] Second, the co-monomer distribution in r-PBr x S-CUD is more random than that in the b-PBr x S-CUD samples. It is also important to notice that r-PBr x S-CUD possesses less random character than PBr x S-NB, which is close to truly RCP.…”

“…[4] The synthetic scheme was based on a series of computer simulation studies reported by Khokhlov and Khalatur, [5][6][7] who suggested that ''proteinlike'' RCPs with tunable co-monomer sequence distributions could be produced by adjusting the dimension of a parent homopolymer made of A-type monomers and reacting the exposed A segments of the homopolymer chains with ''coloring'' moieties B in solution. While bromination of PS in good solvents, where PS coils expanded, yielded RCPs with random distributions of 4-BrS segments, random-blocky sequences of 4-BrS in PBr x S were realized by brominating PS in poor solvents, in which PS adopted collapsed chain conformations.…”

“…While bromination of PS in good solvents, where PS coils expanded, yielded RCPs with random distributions of 4-BrS segments, random-blocky sequences of 4-BrS in PBr x S were realized by brominating PS in poor solvents, in which PS adopted collapsed chain conformations. [4] The differences in the monomer sequence distributions between the two RCPs were elucidated from electro-optical Kerr effect measurements and conformed by studying dewetting rates of thin PBr x S films on solid substrates [4] and adsorption onto solid substrates from solutions. [8] Here we utilize IC to discriminate among both chemical composition and co-monomer sequence distributions in synthetic PBr x S RCPs by tailoring the RCP solubility in the mobile phase and adsorption-based retention inside a chromatographic column.…”

“…The Kerr effect experiments were performed by following the protocols described earlier. [4] Chromatographic Analysis…”