Synthesis, Characterization, and Properties of Starlike Poly(n-butyl acrylate)-b-poly(methyl methacrylate) Block Copolymers

Abstract

A series of 10- and 20-arm starlike block copolymers containing inner soft poly(n-butyl acrylate) (PBA) block and outer hard poly(methyl methacrylate) (PMMA) block were synthesized by atom transfer radical polymerization (ATRP). Short macroinitiators for preparation of starlike copolymers, poly(2-bromoisobutyryloxyethyl acrylate) (PBiBEA) with degree of polymerization DP = 10 and 20, was prepared by ATRP of trimethylsilyloxyethyl acrylate (HEATMS) and subsequently esterified. Partial star coupling during the star extension with PMMA blocks was observed, and the coupling increased with increasing number of arms and arm length. Phase-separated morphologies of cylindrical hard PMMA block domains arranged in the soft PBA matrix were observed by atomic force microscopy and small-angle X-ray scattering. The mechanical and thermal properties of the copolymers were also thoroughly characterized, and their thermoplastic elastomer behavior was studied. Tensile strength of the starlike copolymers was considerably higher compared to linear and three-arm stars with similar compositions.

Sustainable thermoplastic elastomers derived from renewable cellulose, rosin and fatty acids

“…All of these TPE materials based on ABA triblock copolymers and some star block copolymers 19,25 are derived from fossil fuel sources.…”

“…The T g values for these samples (Fig. 4(A)) are about [10][11][12][13][14][15][16][17][18][19][20] C below ambient temperature. These observations suggest an optimal DAEMA content between 25 and 40 mol% leads to gra copolymers with a suitable balance between side-chain attraction (imparting elastic character and ability to support tensile stress) and chain disentanglement (enabling large strain deformation and postponing failure to higher strains).…”

Synthesis of Photoactuating Acrylic Thermoplastic Elastomers Containing Diblock Copolymer-Grafted Carbon Nanotubes

“…8−10 ATRP has been successfully employed for the synthesis of a wide range of block copolymers with TPE properties. 11,12 In addition to linear block copolymers, block copolymers with star-like, 11−13 brush, 14 or branched 15 architectures have been synthesized. The properties of these copolymers differ from those of their linear analogues.…”

“…For example, star-like copolymers exhibit better tensile strength and elongation at break than three-arm and linear copolymers with similar compositions. 11,12 The incorporation of carbon nanotubes (CNTs) into a TPE matrix can lead to the improvement of certain material characteristics, such as electrical conductivity, mechanical properties, or photoactuation performance. 16−19 The dispersion and distribution of CNT in a polymer matrix remain key factors in the preparation of nanocomposites.…”

Synthesis of Poly(vinyl acetate) Molecular Brushes by a Combination of Atom Transfer Radical Polymerization (ATRP) and Reversible Addition−Fragmentation Chain Transfer (RAFT) Polymerization

“…Indeed, when poly-(vinyl alcohol) (PVA) was functionalized with xanthate moieties to form a macro-CTA for the subsequent growth of PVOAc side chains by RAFT, a limited control was observed. 38 In fact, the obtained polymers should be regarded more as starlike (rather than comblike), 39 since the side chains were longer than the backbone. The molecular weight distribution of the obtained molecular brushes was multimodal, and control of molecular architecture was relatively limited.…”