Enhancement of mechanical and optical performance of commercial polystyrenes by blending with siloxane‐based copolymers

Abstract

Well‐defined poly(styrene‐block‐dimethylsiloxane) copolymers (PS‐b‐PDMS) with low polydispersity index (Mw/Mn) and different compositions were synthesized by sequential anionic polymerization of styrene (S) and hexamethyl(ciclotrisiloxane) (D3) monomers. Synthesized PS‐b‐PDMS copolymers were characterized by 1H‐nuclear magnetic resonance, size exclusion chromatography, Fourier transform infrared spectroscopy, and transmission electron microscopy. The physicochemical characterization determined that block copolymers have molar mass values close to ∼135,000 g mol−1, narrow Mw/Mn < 1.3, and chemical composition ranging from low to intermediate PDMS content. Blends of these copolymers with a commercial polystyrene (PS) were obtained by melt mixing and subsequently injection. Films obtained were flexible, and showed lower transparency than the original PS matrix. On the other hand, a 10 wt % incorporation of PS‐b‐PDMS copolymers leads to better mechanical performance by enhancing elongation at break (∼8.8 times higher) and opacity values (∼18 times higher). In addition, UV–Vis barrier capacity of the resulting blends is also increased (up to 400% higher). © 2017 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2017, 134, 45122.

Tailor-Made, Linear, and “Comb-Like” Polyester-Based Copolymers: Synthesis, Characterization, and Thermal Behavior of Potential 3D-Printing/Electrospinning Candidates

“…At 1261 cm −1 , the out-of-phase vibrations of Si-(CH 3 ) 2 and O-Si-OR are also detected [1]. Besides, at 1093 cm −1 and 1024 cm −1 , absorption bands associated to the vibration of Si-O-Si and C-Si-C bonds, respectively, can be observed [3,32]. The PCL spectrum shows an absorption band at 1724 cm −1 associated to the stretching vibrations from carbonyl >C=O groups, as well as at 1240 cm −1 (vibrations of O-C=O) [33,42].…”

“…Polymerizations were carried out in two steps. First, a model poly(dimethylsiloxane) hydroxyl-ended homopolymer (PDMS-OH) was synthesized by employing anionic polymerization and hand-made polymerization apparatuses (glass-blowing techniques), by a vacuum manifold (VM), and by following the methodology reported in our previous works [3,39,40]. Briefly, the reactor was attached to the VM and checked for pinholes.…”

“…During the last decades, the development of new polymerization techniques (which involve less sophisticated procedures from a practical point of view) has noticeably increased the potential of polymer materials to expand their uses [1]. Complex macromolecular structures are now easily achieved, and a broad range of applications for new polymeric materials can be proposed at levels scarcely envisioned a few decades ago [2,3]. Reversible deactivation radical polymerization (RDRP) techniques, such as atom transfer polymerization (ATRP), nitroxide-mediated polymerization (NMP), and reversible addition-fragmentation chain-transfer (RAFT) polymerization, are now well-established, and their uses in the synthesis of macromolecules are widely employed in synthetic laboratories worldwide.…”

Hydroxyapatite Growth on Poly(Dimethylsiloxane-Block-ε-Caprolactone)/Tricalcium Phosphate Coatings Obtained by Electrophoretic Deposition

“…The poly(dimethylsiloxane) (PDMS-OH) homopolymer was synthesized by anionic polymerization, employing hand-made polymerization reactors and high-vacuum techniques (Scheme 1) (Ninago et al, 2017;Redondo, 2018). In brief, the sealed ampoule of the D 3 monomer (12.5 g, previously dissolved in 40-50 ml of dry cyclohexane) was gently broken and poured into the reactor flask, followed by the addition of the sec-Bu -Li + ampoule (2.9 ml, 0.28 M).…”

“…Figure 2 shows the FTIR-ATR spectra of the TCP precursor, PDMS-OH macroinitiator, and PDMS-b-PCL copolymer. PDMS-OH macroinitiator exhibits the typical absorption bands detected at 2,963 cm −1 (associated with C-H vibration bonds attached to Si atoms) (Liang and Ruckenstein, 1996;Wu et al, 2006;Redondo, 2018); 1,261 cm −1 (associated with out-ofphase vibrations of -Si(CH 3 ) 2 -and O-Si-O groups) (Agudelo and Pérez, 2016); and 1,094, 1,024, and 801 cm −1 (bands associated with the vibration of the Si-O-Si and C-Si-C bonds, respectively) (Agudelo and Pérez, 2016;Ninago et al, 2017;Redondo, 2018). Regarding to PDMS-b-PCL copolymer, absorption bands associated to the PCL block are observed at 2,960 and 2,865 cm −1 (vibration bands from methylene, -CH 2 , groups) and 1,724 cm −1 (a pronounced signal attributed to the stretching vibrations from carbonyl groups, >C O) (Redondo, 2018).…”