Phase Behavior of Poly(4-hydroxystyrene-block-styrene) Synthesized by Living Anionic Polymerization of an Acetal Protected Monomer

Abstract

We have synthesized a series of poly(4-(2-tetrahydropyranyloxy)styrene) [P(OTHPSt)] homopolymers by living anionic polymerization of the protected monomer (OTHPSt) in tetrahydrofuran at −78 °C, with excellent control over molecular weight and dispersity. The high T g of P(OTHPSt) led to facile purification and isolation of the polymer as a powder. Characterization of the POTHPSt homopolymer by nuclear Overhauser effect spectroscopy confirms the strong preference for the axial position of the relatively sterically demanding alkoxy phenyl group. By sequential monomer addition, a series of low to high molecular weight P(OTHPSt-b-styrene) BCPs with narrow dispersities were synthesized. Quantitative deprotection of the THP groups yielded poly(4-hydroxystyrene-b-styrene) with tunable molecular weights and compositions. The solid-state and melt-phase self-assembly of these diblocks was investigated using synchrotron small-angle X-ray scattering (SAXS) and transmission electron microscopy (TEM). Mean-field theory analysis of the temperature-dependent correlation-hole scattering for a disordered diblock was used to determine the interaction parameter as χ HS/S (T) = (4.39 ± 0.83)/T + (0.109 ± 0.002), which is approximately 4 times larger than that of poly(styrene-b-methyl methacrylate) with the same disproportionately high contribution of entropy to the free energy of mixing.

RETRACTED: Controlled Light Cross-Linking Technique to Prepare Healable Materials

“…This broad peak is present in the scattering pattern of X#P ON as well as in P and is therefore not a characteristic of the network. The presence of such a peak is well known for concentrated polymer systems that display micro-phase separation such as block copolymers in the amorphous state [28,29]. The underlying physical effect is referred to as "correlation-hole" effect.…”

Artificial membranes with selective nanochannels for protein transport

“…The Flory--Huggins interaction parameter is !"/! "# = 0.124 43 . The morphology of symmetric ABA triblock copolymers has been examined by self--consistent field theory.…”

Isomeric Effect Enabled Thermally Driven Self-Assembly of Hydroxystyrene-Based Block Copolymers

“…As a result, P(4HS-b-S) can form self-assembled lamellae with periodicities (L 0 ) as small as 12 nm, which is about a factor of 2 smaller than the minimum periodicities achievable with P(S-b-MMA). 29 Furthermore, the modification of the phenolic group to introduce metal or oxide precursors can result in a robust hard mask that can be used for subsequent pattern transfer to the underlying substrate. By utilizing protected or deprotected phenol groups, a variety of nanopatterning strategies that combine top-down and bottom-up approaches are possible.…”

“…29 In order to make the copolymer chains mobile to rapidly drive the assembly process within several minutes, typically annealing at temperatures far above T g is required. For example, annealing P(S-b-MMA) thin film at temperatures higher than T g + 120°C is required for complete assembly within 5 min.…”

“…34 However, thermal annealing at 220°C (∼T g + 40°C) for a P(4HS)-based BCP is difficult, 35 as the highly reactive phenol group undergoes side reactions such as selfcross-linking or degradation of second block before complete phase separation can occur. 29,36,37 We recently published the synthesis and chemical characterization of a 4HS-based BCP, 38 Upon thermal annealing of this BCP thin-film at 220°C, ill-defined microphase-separated morphology resulted due to self-crosslinking reaction in the P(4HS) block ( Figure 1a). However, solvent vapor annealing worked quite well (Figure 1b), leading to well-defined morphology.…”