An official website of the United States government
ABSTRACT Cobaltocenium‐containing polyelectrolyte block copolymer nanoparticles were prepared via polymerization‐induced self‐assembly (PISA) using aqueous dispersion RAFT polymerization. The cationic steric stabilizer was a macromolecular chain‐transfer agent (macro‐CTA) based on poly(2‐cobaltocenium amidoethyl methacrylate chloride) (PCoAEMACl), and the core‐forming block was poly(2‐hydroxypropyl methacrylate) (PHPMA). Stable cationic spherical nanoparticles were formed in aqueous solution with low dispersity without adding any salts. The chain extension of macro‐CTA with HPMA was efficient and fast. The effects of block copolymer compositions, solid content, charge density, and addition of salts were studied. It was found that the degree of polymerization of both the stabilizer PCoAEMACl and the core‐forming PHPMA had a strong influence on the size of nanoparticles. © 2019 Wiley Periodicals, Inc. J. Polym. Sci.2020,58, 77–83
more »
« less
Hybrid Photoiniferter and Ring‐Opening Polymerization Yields One‐Pot Anisotropic Nanorods
Abstract Polymerization‐induced self‐assembly (PISA) has emerged as a scalable one‐pot technique to prepare block copolymer (BCP) nanoparticles. Recently, a PISA process, that results in poly(l‐lactide)‐b‐poly(ethylene glycol) BCP nanoparticles coined ring‐opening polymerization (ROP)‐induced crystallization‐driven self‐assembly (ROPI‐CDSA), was developed. The resulting nanorods demonstrate a strong propensity for aggregation, resulting in the formation of 2D sheets and 3D networks. This article reports the synthesis of poly(N,N‐dimethyl acrylamide)‐b‐poly(l)‐lactide BCP nanoparticles by ROPI‐CDSA, utilizing a two‐step, one‐pot approach. A dual‐functionalized photoiniferter is first used for controlled radical polymerization of the acrylamido‐based monomer, and the resulting polymer serves as a macroinitiator for organocatalyzed ROP to form the solvophobic polyester block. The resulting nanorods are highly stable and display anisotropy at higher molecular weights (>12k Da) and concentrations (>20% solids) than the previous report. This development expands the chemical scope of ROPI‐CDSA BCPs and provides readily accessible nanorods made with biocompatible materials.
more »
« less
- Award ID(s):
- 2238834
- PAR ID:
- 10500064
- Publisher / Repository:
- Wiley Blackwell (John Wiley & Sons)
- Date Published:
- Journal Name:
- Macromolecular Rapid Communications
- ISSN:
- 1022-1336
- Format(s):
- Medium: X
- Sponsoring Org:
- National Science Foundation
More Like this
-
-
Abstract This work develops the Polyolefin Active‐Ester Exchange (PACE) process to afford well‐defined polyolefin–polyvinyl block copolymers. α‐Diimine PdII‐catalyzed olefin polymerizations were investigated through in‐depth kinetic studies in comparison to an analog to establish the critical design that facilitates catalyst activation. Simple transformations lead to a diversity of functional groups forming polyolefin macroinitiators or macro‐mediators for various subsequent controlled polymerization techniques. Preparation of block copolymers with different architectures, molecular weights, and compositions was demonstrated with ring‐opening polymerization (ROP), nitroxide‐mediated polymerization (NMP), and photoiniferter reversible addition–fragmentation chain transfer (PI‐RAFT). The significant difference in the properties of polyolefin–polyacrylamide block copolymers was harnessed to carry out polymerization‐induced self‐assembly (PISA) and study the nanostructure behaviors.more » « less
-
Abstract Access to block copolymers from monomers that do not polymerize via a common mechanism requires initiation from a multifunctional species that allows orthogonal polymerization chemistries. We disclose a strategy to provide well‐defined polyacrylamido‐b‐polyether block copolymers by a one‐pot combination of photoiniferter polymerization and organocatalytic ring‐opening polymerization (ROP) using a hydroxy‐functionalized trithiocarbonate photoiniferter as the dual initiator at ambient temperature. Our results reveal good compatibility between the two polymerization systems and highlight that they can be performed in arbitrary order or simultaneously with good retention of the thiocarbonylthio functionality. We also demonstrate selective temporal control over the photoiniferter polymerization during concurrent ROP. We harnessed the efficiency of combining these polymerization systems to provide tailor‐made block copolymers from chemically distinct monomers.more » « less
-
Preparation of multiblock copolymers via step-wise addition of l -lactide and trimethylene carbonatePoly( l -lactide) (PLA) is a bioderived and biodegradable polymer that has limited applications due to its hard and brittle nature. Incorporation of 1,3-trimethylene carbonate into PLA, in a block copolymer fashion, improves the mechanical properties, while retaining the biodegradability of the polymer, and broadens its range of applications. However, the preparation of 1,3-trimethylene carbonate (TMC)/ l -lactide (LA) copolymers beyond diblock and triblock structures has not been reported, with explanations focusing mostly on thermodynamic reasons that impede the copolymerization of TMC after lactide. We discuss the preparation of multiblock copolymers via the ring opening polymerization (ROP) of LA and TMC, in a step-wise addition, by a ferrocene-chelating heteroscorpionate zinc complex, {[fc(PPh 2 )(BH[(3,5-Me) 2 pz] 2 )]Zn(μ-OCH 2 Ph)} 2 ([(fc P,B )Zn(μ-OCH 2 Ph)] 2 , fc = 1,1′-ferrocenediyl, pz = pyrazole). The synthesis of up to pentablock copolymers, from various combinations of LA and TMC, was accomplished and the physical, thermal, and mechanical properties of the resulting copolymers evaluated.more » « less
