Influence of Hydrophobic Polystyrene Blocks on the Rehydration of Polystyrene-block-poly(methoxy diethylene glycol acrylate)-block-polystyrene Films Investigated by in Situ Neutron Reflectivity

Abstract

The rehydration of thermoresponsive polystyrene-block-poly-(methoxy diethylene glycol acrylate)-block-polystyrene (PS-b-PMDEGA-b-PS) films forming a lamellar microphase-separated structure is investigated by in situ neutron reflectivity in a D 2 O vapor atmosphere. The rehydration of collapsed PS-b-PMDEGA-b-PS films is realized by a temperature change from 45 to 23 °C and comprises (1) condensation and absorption of D 2 O, (2) evaporation of D 2 O, and (3) reswelling of the film due to internal rearrangement. The hydrophobic PS layers hinder the absorption of condensed D 2 O, and a redistribution of embedded D 2 O between the hydrophobic PS layers and the hydrophilic PMDEGA layers is observed. In contrast, the rehydration of semiswollen PS-b-PMDEGA-b-PS films (temperature change from 35 to 23 °C) shows two prominent differences: A thicker D 2 O layer condenses on the surface, causing a more enhanced evaporation of D 2 O. The rehydrated films differ in film thickness and volume fraction of D 2 O, which is due to the different thermal protocols, although the final temperature is identical.

Determination of the Thin-Film Structure of Zwitterion-Doped Poly(3,4-ethylenedioxythiophene):Poly(styrenesulfonate): A Neutron Reflectivity Study

“…The SLD was 3.15 × 10 −6 Å -2 which is similar to the well known value of 3.47 × 10 −6 Å -2 reported in literature, [40][41][42] confirming that this layer is a native oxide. Out of the two models used the bi-layer model had the best fit with a χ According to the two layer model for the 10 mM sample, there is a 10.1 nm thick layer on top of the SiO 2 with a σ RM S of 8.1 nm.…”

Amyloid Beta Aggregation in the Presence of Temperature-Sensitive Polymers

“…In a similar manner, LCST data were obtained via turbidimetric measurements for the polyacrylates 3 as explained in the experimental part, showing the same unexpected influence of the molecular weight on the LCST as described in the literature [ 59 , 61 , 62 ] (see Table 1 ). Thus, LCSTs ranging from 34.4 °C (polymer 3a ) to 45.1 °C (polymer 3c ) could be determined, demonstrating a strong increase ofthe T CP with increasing molecular weight [ 62 ].…”

“…In preparation of the subsequent fibrillation experiments (amyloid aggregation in the presence of polymers), first-hand experimental information on the LCST influence of the molecular weight and the addition of salts (buffer solutions are required for respective fibrillation conditions), the concentration of the polymer via appropriate extensive turbidimetric measurements was accomplished. First experiments were done with P i PrOx ( 6 , 7 and 8 ), whose LCST behavior is well documented in the literature [ 41 , 42 , 47 , 50 ], followed by poly(methoxy diethylene glycol)acrylate, which is less intensely studied in the literature [ 45 , 61 , 62 ]. The results of the turbidimetric measurements are given in Table 1 .…”

Controlled Hydration, Transition, and Drug Release Realized by Adjusting Layer Thickness in Alginate-Ca2+/poly(N-isopropylacrylamide) Interpenetrating Polymeric Network Hydrogels on Cotton Fabrics

“…The used cotton fabric behaves similarly to the formerly investigated Si substrates in the case of thermoresponsive polymer films on Si. Thereby, it can be concluded that the substrate has an important role in the hydration of the polymer films even in the case of rather thick films. − The relatively hydrophobic cotton fabrics hinder the absorption of water in the IPN hydrogels. This effect is more prominent in thinner layers.…”