Block Copolymer Adsorption at the Polymer Melt/Substrate Interface: The Effect of Matrix Competition

Abstract

Using low-energy forward recoil spectrometry (LE-FRES) and neutron reflectivity (NR), the interfacial excess, z*, of an asymmetric poly(deuterated styrene-block-methyl methacrylate) (dPS-b-PMMA) at the polymer matrix/silicon oxide interface was found to decrease as the bromostyrene mole fraction, x, in a poly(styrene-ran-4-bromostyrene) (PBr x S) matrix systematically increased. For matrix degrees of polymerization, P = 480 and 3846, z* decreased by 15% and 33%, respectively, as x increased. Neglecting the matrix−substrate interaction energy, , self-consistent mean-field (SCMF) calculations predicted an increase in z* with x, consistent with an increase in unfavorable matrix−dPS interactions, χ. By including a small attractive interaction ( = −0.01k B T) between the matrix and substrate, the SCMF z* decreased by ca. 50%, in qualitative agreement with experiments. Thus, as x increased (and therefore ), matrix chain competition for silicon oxide counteracts the expected increased adsorption due to χ. Furthermore, the dPS volume fraction profile in PBr0.136S had a lower z* and was thinner than for the neutral matrix case.

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

“…Our focus here is to utilize the retention of the polymers as a quantitative measure of the polymer affinity to the surface in solution and to delineate the effects of the comonomer distribution in 4-BrS segments in the PBr x S RCPs on surface adsorption from solution. While the 4-BrS segments are attracted toward silica (interaction energy % À0.07 kT Á monomer [15] ), at the same time they experience unfavorable interaction with non-polar solvents (i.e., IO [16] ).…”

Effect of Block Copolymer Adsorption on Thin Film Dewetting Kinetics

“…The adsorption of dPS- b -MMA to silicon oxide from a matrix polymer has been studied as a function of matrix degree of polymerization, P , , and matrix composition . As P increases, the interfacial excess, z *, increases rapidly and then becomes constant for P larger than 2 N , where N is the dPS block length.…”

Block Copolymer Adsorption from a Homopolymer Melt to Silicon Oxide: Effects of Nonadsorbing Block Length and Anchoring Block−Substrate Interaction

“…For the PS:dPS-b-PMMA system, the values are PMMA-dPS ) 0.0371, 2,33,34 PMMA-hPS ) 0.0282, 33,34 and hPS-dPS ∼ 0.0001. 9 For the case of PS:dPS-b-PDMAEMA, the between PDMAEMA and the dPS block, PDMAEMA-dPS , as well as PDMAEMA and PS, PDMAEMA-PS , are unknown. Because a DMAEMA segment is more polar than MMA, the values for PDMAEMA-dPS and PDMAEMA-PS are expected to be greater than PMMA-dPS and PMMA-PS , respectively.…”

“…In fact, few experimental studies attempt to measure the strength of these interactions. [1][2][3][4][5][6][7][8][9] However, the polymer conformation near interfaces has been studied theoretically 2,9-11 and experimentally. [12][13][14][15][16] The goals of our study are to investigate the effects of the nonadsorbing block length on the conformation of adsorbed molecules at the polymer/substrate interface and to understand how these interfacial characteristics depend on the polymer-substrate interaction by changing the adsorbing block type.…”