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Photochemical fabrication of responsive block copolymer nanoparticles: a self-assembly approach for temperature-sensitive applications

Jie Zheng, Shengnan Lin, Jianlei Liu, Huanhuan Yu, Zhengbei Pan, Raojun Zheng, Hongmei Yi, and Yen Wei

The School of Chemistry and Environmental Science, Shangrao Normal University, Shangrao, China

Received: 21 August 2024 Accepted: 27 March 2025

Abstract:

Photo-initiated polymerization-induced self-assembly (PISA) offers the benefits of efficiently fabricating block polymer nanostructures with high solid content and a wide variety of morphologies at ambient temperature. In this paper, the macro-RAFT agent, poly(N,N-dimethylaminoethyl methacrylate) (PDMAEMA), was synthesized utilizing 4-(dodecylsulfanylthiocarbonyl)sulfanyl pentanoic acid as a versatile RAFT reagent, enabling the controlled preparation of polymers with tailored chain lengths and architectures. Utilizing the photo-initiated PISA technique, a series of block copolymers composed of PDMAEMA and poly(N-isopropylacrylamide) (PNIPAM), denoted as PDMAEMA-b-PNIPAM, was crafted. These copolymers boast a substantial solid content of 25 wt%, showcasing the method’s capability to produce high-concentration polymeric materials. The copolymerization process was meticulously controlled, proceeding at a remarkably swift pace. This efficiency led to an exceptionally high monomer conversion rate within a brief timeframe, coupled with the achievement of a narrowly dispersed molecular weight distribution. The results of visible spectrum and variable temperature nuclear magnetic resonance spectroscopy showed that PDMAEMA-b-PNIPAM exhibited temperature responsiveness. The incorporation of the PNIPAM segment into the copolymer resulted in a reduced cloud point compared to the PDMAEMA macro-RAFT reagent, indicating a shift in the phase transition temperature due to the presence of the PNIPAM block. Transmission electron microscopy images revealed that the PDMAEMA-b-PNIPAM nano-objects exhibited a spherical morphology. Furthermore, dynamic light scattering measurements indicated that the hydrodynamic radius (Rh) of the PDMAEMA₁₆₄-b-PNIPAM₁₁₆ copolymers peaked at 650 nm at a temperature of 34 °C, after which it diminished with the progression of temperature elevation. Block copolymer nano-objects served as a template for the in situ synthesis of nano-silver hybrid particles. The PDMAEMA block can reduce the adsorption of silver ions on the polymer surface. Consequently, nanoparticles were successfully prepared under conditions of high concentration and in an aqueous phase. This approach avoids the need for complex posttreatment processes and improves yield, making it suitable for large-scale preparation of water-soluble nanocomposite particles. The study demonstrates the potential of PISA and in situ nanoparticle preparation for large-scale nanomaterial production, representing a significant advancement in materials science with promising applications.

Keywords: Molecular Self-assembly; Nanoparticle Synthesis; Polymer Synthesis; Polymers; Self-assembly; Supramolecular Polymers; Temperature-responsive polymer; Photochemical synthesis; Responsive block copolymer; Nanoparticles

Full paper is available at www.springerlink.com.

DOI: 10.1007/s11696-025-04042-3

Chemical Papers 79 (6) 3895–3907 (2025)