Dataset Information

Blue Light-Initiated Alcoholic RAFT Dispersion Polymerization of Benzyl Methacrylate: A Detailed Study.

ABSTRACT: Blue light-initiated alcoholic reversible addition-fragmentation chain transfer (RAFT) dispersion polymerization of benzyl methacrylate (BzMA) using bis (acyl) phosphane oxide (BAPO) as the photo-initiator is developed to prepare diblock copolymer nano-objects. High monomer conversion (95%) was achieved within 2 h of blue light irradiation in an isopropanol/water mixture. Effects of solvent, light intensity, and reaction temperature on the polymerization kinetics were evaluated. Finally, the effect of reaction temperature on the morphologies of diblock copolymer nano-objects was investigated and two morphological phase diagrams were constructed at 25 and 70 °C. Transmission electron microscopy (TEM) measurement confirmed that increasing the reaction temperature promoted the evolution of higher order morphology. We believe this study will provide more mechanistic insights into alcoholic RAFT dispersion polymerization for the creation of diblock copolymer nano-objects with well-defined structures.

SUBMITTER: Liu D

PROVIDER: S-EPMC6723682 | biostudies-literature | 2019 Aug

REPOSITORIES: biostudies-literature

ACCESS DATA

Publications

Blue Light-Initiated Alcoholic RAFT Dispersion Polymerization of Benzyl Methacrylate: A Detailed Study.

Liu Dongdong D Zeng Ruiming R Sun Hao H Zhang Li L Tan Jianbo J

Polymers 20190801 8

Blue light-initiated alcoholic reversible addition-fragmentation chain transfer (RAFT) dispersion polymerization of benzyl methacrylate (BzMA) using bis (acyl) phosphane oxide (BAPO) as the photo-initiator is developed to prepare diblock copolymer nano-objects. High monomer conversion (95%) was achieved within 2 h of blue light irradiation in an isopropanol/water mixture. Effects of solvent, light intensity, and reaction temperature on the polymerization kinetics were evaluated. Finally, the eff ...[more]

PMID: 31374884

Similar Datasets

Project description:A poly(2-(dimethylamino)ethyl methacrylate) (PDMA) chain transfer agent (CTA) is used for the reversible addition-fragmentation chain transfer (RAFT) alcoholic dispersion polymerization of benzyl methacrylate (BzMA) in ethanol at 70 °C. THF GPC analysis indicated a well-controlled polymerization with molecular weight increasing linearly with conversion. GPC traces also showed high blocking efficiency with no homopolymer contamination apparent and Mw/Mn values below 1.35 in all cases. 1H NMR studies confirmed greater than 98% BzMA conversion for a target PBzMA degree of polymerization (DP) of up to 600. The PBzMA block becomes insoluble as it grows, leading to the in situ formation of sterically stabilized diblock copolymer nanoparticles via polymerization-induced self-assembly (PISA). Fixing the mean DP of the PDMA stabilizer block at 94 units and systematically varying the DP of the PBzMA block enabled a series of spherical nanoparticles of tunable diameter to be obtained. These nanoparticles were characterized by TEM, DLS, MALLS, and SAXS, with mean diameters ranging from 35 to 100 nm. The latter technique was particularly informative: data fits to a spherical micelle model enabled calculation of the core diameter, surface area occupied per copolymer chain, and the mean aggregation number (Nagg). The scaling exponent derived from a double-logarithmic plot of core diameter vs PBzMA DP suggests that the conformation of the PBzMA chains is intermediate between the collapsed and fully extended state. This is in good agreement with 1H NMR studies, which suggest that only 5-13% of the BzMA residues of the core-forming chains are solvated. The Nagg values calculated from SAXS and MALLS are in good agreement and scale approximately linearly with PBzMA DP. This suggests that spherical micelles grow in size not only as a result of the increase in copolymer molecular weight during the PISA synthesis but also by exchange of individual copolymer chains between micelles and/or by sphere-sphere fusion events.

Project description:RAFT dispersion polymerization of 2,2,2-trifluoroethyl methacrylate (TFEMA) is performed in n-dodecane at 90 °C using a relatively short poly(stearyl methacrylate) (PSMA) precursor and 2-cyano-2-propyl dithiobenzoate (CPDB). The growing insoluble poly(2,2,2-trifluoroethyl methacrylate) (PTFEMA) block results in the formation of PSMA-PTFEMA diblock copolymer nano-objects via polymerization-induced self-assembly (PISA). GPC analysis indicated narrow molecular weight distributions (M w/M n ≤ 1.34) for all copolymers, with 19F NMR studies indicating high TFEMA conversions (≥95%) for all syntheses. A pseudo-phase diagram was constructed to enable reproducible targeting of pure spheres, worms, or vesicles by varying the target degree of polymerization of the PTFEMA block at 15-25% w/w solids. Nano-objects were characterized using dynamic light scattering, transmission electron microscopy, and small-angle X-ray scattering. Importantly, the near-identical refractive indices for PTFEMA (1.418) and n-dodecane (1.421) enable the first example of highly transparent vesicles to be prepared. The turbidity of such dispersions was examined between 20 and 90 °C. The highest transmittance (97% at 600 nm) was observed for PSMA9-PTFEMA294 vesicles (237 ± 24 nm diameter; prepared at 25% w/w solids) in n-dodecane at 20 °C. Interestingly, targeting the same diblock composition in n-hexadecane produced a vesicle dispersion with minimal turbidity at a synthesis temperature of 90 °C. This solvent enabled in situ visible absorption spectra to be recorded during the synthesis of PSMA16-PTFEMA86 spheres at 15% w/w solids, which allowed the relatively weak n→π* band at 515 nm assigned to the dithiobenzoate chain-ends to be monitored. Unfortunately, the premature loss of this RAFT chain-end occurred during the RAFT dispersion polymerization of TFEMA at 90 °C, so meaningful kinetic data could not be obtained. Furthermore, the dithiobenzoate chain-ends exhibited a λmax shift of 8 nm relative to that of the dithiobenzoate-capped PSMA9 precursor. This solvatochromatic effect suggests that the problem of thermally labile dithiobenzoate chain-ends cannot be addressed by performing the TFEMA polymerization at lower temperatures.

Dataset Information

Blue Light-Initiated Alcoholic RAFT Dispersion Polymerization of Benzyl Methacrylate: A Detailed Study.

Publications

Blue Light-Initiated Alcoholic RAFT Dispersion Polymerization of Benzyl Methacrylate: A Detailed Study.

Similar Datasets

OmicsDI is part of the ELIXIR infrastructure

Tweets