Amphiphilic Gradient Copolymers Shape Composition Influence on the Surface/Bulk Properties

Abstract

Nitroxide-mediated radical polymerization (NMP) combined with the semibatch process was used to synthesize poly(N, N-dimethylacrylamide-grad-butylacrylate), called poly(DMA-grad-BuA), in the presence of SG1 as a control agent and the alkoxyamine (MAMA) as an initiator. The pseudo-instantaneous composition was used to characterize the gradient copolymers. The variation of the addition rate of DMA influences the incorporation of DMA in the macromolecular chains. The preliminary surface characterization by the measure of the static water contact angle of the gradient copolymers films indicated that the monomer unit sequence in the polymer chain strongly influences the surface properties. The rheological properties of gradient copolymers in bulk were also studied and discussed in relation to their local structure.

Semicrystalline Macromolecular Design by Nitroxide‐Mediated Polymerization

“…A typical ''S'' curve is obtained as described by Karaky for styrene/butylacrylate and butylacrylate/dimethylacrylamide systems. [28,29] In the present study, we observe in the first segment rich in ODA units (%90%) up to 0.3 of the apparent normalized chain length. This block is rapidly followed by a strong increase of MA, characteristic of a gradient-shape composition, which tends to a plateau, characteristic of a blocky structure, for apparent normalized chain lengths from 0.7.…”

“…In fact, semi-batch nitroxide-mediated polymerization provides a facile route to synthesize gradient copolymers as demonstrated by Karaky et al [28,29] In this work, ODA and MA were selected as monomers for synthesizing gradient copolymers. To form gradient copolymers it is also necessary that the relative incorporation of the monomers into polymer chains gradually changes throughout the polymerization process.…”

“…[26] Recently, our group was interested in synthesizing gradient copolymers by batch and semi-batch nitroxidemediated radical polymerization, demonstrating the effect of the synthetic methodology on the molecular architecture. [27][28][29] In this paper, the synthesis of PODA homopolymers, diblock, triblock and gradient copolymers composed of the crystallizable ODA monomer (T f % 34 8C) and methyl acrylate (MA) units by NMP is shown for the first time. These gradient copolymers synthesized by the semi-batch process were obtained by continuous addition of MA during the ODA-polymerization reaction in solution.…”

“…After 4 h 45 min, the flask was cooled down to room temperature and exposed to air: 51% conversion ( 1 H NMR spectroscopy); M n ¼ 16 300 g Á mol À1 and polydispersity index, I p ¼ 1. 29. The polymer was precipitated in a methanol/ water mixture (80/20 v/v); the resulting solid was isolated by vacuum filtration and dried for 48 h under vacuum.…”

“…[27] A pseudo-instantaneous composition is used to describe the profile of the gradient copolymer, as we recently described. [28,29] It was calculated by monitoring the conversion of each component as the copolymerization progressed. The experimental data were estimated using 1 H NMR spectroscopy from the relationship between the relative areas of the proton signals of the OCH 2 group of ODA and the OCH 3 group of MA, which appeared at d ¼ 4.05 ppm and d ¼ 3.7 ppm, respectively.…”