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Smart Paints
Published in Asit Baran Samui, Smart Polymers, 2022
Asit Baran Samui, Sushil S. Pawar
The optimal interaction of the immobilized antimicrobial agents with the bacterial membrane depends on the spacer length, along with the accessibility of the antimicrobial agent. Coatings based on polymer brushes offer various advantages, such as: (1) sufficient conformational freedom for the immobilized biocidal agent due to the flexibility of the grafted chains to interact with the bacterial membrane; (2) a non-fouling polymer brush coating together with a fouling polymer brush reduces the bacterial adhesion and also prevents dead bacteria from being deposited on the surface; and (3) the hydrophilic nature of the polymer brush coating is responsible for the biocompatibility of the surfaces.40
Silicon/polymer composite nanopost arrays
Published in Klaus D. Sattler, Silicon Nanomaterials Sourcebook, 2017
Xueyao Liu, Wendong Liu, Bai Yang
In this section, we will discuss the methods to grow polymer brush on the silicon nanopost arrays. Polymer brush is attached to the substrate surface on one end, and the other end is suspended in the solvents. Owing to its composition, density, and length-control advantages, polymer brush is widely applied to build functional surfaces. Either by covalently attaching or physical adsorption, polymer brush can be grafted onto the surface. The physical adsorption includes electrostatic interactions, hydrophobic or hydrophilic interactions, and hydrogen bonding, which suffer instability problems. Covalent attachment embraces “grafting to” and “grafting from” two pathways. The former one is conducted by grafting the prepared polymer (end-functionalized) to the modified surface. The latter one is performed by growing polymer directly from the initialized surface.
Controlled biointerfaces with biomimetic phosphorus-containing polymers
Published in Science and Technology of Advanced Materials, 2021
Suphatra Hiranphinyophat, Yasuhiko Iwasaki
In addition to the antifouling property, lubricity is another interesting property of surfaces modified with zwitterionic MPC polymers [72]. To achieve super-low-friction phenomena, comb-like graft chains of the MPC homopolymer (P(MPC)) should be formed on the surface [73,74]. Therefore, surface-initiated graft polymerization of MPC is the most effective way for surface modification [75]. Moro et al. and Ishihara et al. were pioneers of improving the lubricity of the surface of cross-linked ultra-high-molecular weight polyethylene (CLPE) to prolong the lifetime of the artificial hip joint [23,76]. For graft polymerization, the photo-initiator benzophenone (BP) was coated on CLPE from the acetone solution. BP-coated CLPE was soaked in an aqueous solution containing MPC. Finally, graft polymerization of MPC was performed under UV (≈350 nm) photo-irradiation. Surface modification with P(MPC) significantly reduced the surface friction of CLPE. Lubrication of the modified surface was due to hydration lubrication [77]. A P(MPC) graft layer of ~100 nm thickness accumulated water molecules, which play an important role in lubrication. Even under load, the water molecules might be preserved in the polymer layer and superior lubrication could be observed. The molecular motion of P(MPC) chains is also an important factor in high lubricity. Surface-initiated graft polymerization is a suitable way to generate a polymer brush structure having flexible free chain ends. Currently, an innovative hip joint system with a P(MPC)-grafted CLPE liner, Aquala® (Kyocera Co, Kyoto, Japan), was used in Japan; the hip joint is expected to last longer than conventional artificial hip joints [24].
Concentrated Polymer Brush as Reciprocating Seal Material for Low Leakage and Low Friction
Published in Tribology Transactions, 2020
Chiharu Tadokoro, Kosuke Sato, Takuo Nagamine, Ken Nakano, Shinya Sasaki, Takaya Sato, Keita Sakakibara, Yoshinobu Tsujii
A polymer brush is an assembly of polymer chains densely end-grafted on a solid surface (Napper (14); Parnas and Cohen (15); Klein and Kumacheva (16); Klein (17)). Surface-initiated living radical polymerization (Edmondson, et al. (18); Tsujii, et al. (19); Barbey, et al. (20)) has recently afforded an exceptional increase in the graft density more than one order of magnitude higher than that of typical semidilute polymer brushes (Ejaz, et al. (21)). Such high-density polymer brushes reasonably fall in the regime of the concentrated state, or CPB.
Biomimetic materials based on zwitterionic polymers toward human-friendly medical devices
Published in Science and Technology of Advanced Materials, 2022
Recently, zwitterionic polymers were investigated for the preparation of lubricating surfaces on substrates [198,201,213–218]. They successfully controlled the state of the polymer layer at the interface, thus making it multifunctional. For example, in Figure 12(a), an interpenetrating network structure is formed, which is considered one of the most promising ways to generate a robust hydrogel and improve the load-carrying properties of the sliding interface [198]. Research has been conducted to enhance the durability of polymer brushes by introducing photoreactivity into the polymer brush layer, which achieves high lubrication through a hydration lubrication mechanism and by bridging the polymer brushes (Figure 12(b)) [213]. Silica nanoparticles covered with a zwitterionic polymer brush layer can act as a lubricant that stores drugs to decrease inflammation in joints (Figure 12(c)) [214]. As shown in Figure 12(d), this study mimicked the conditions at the joint interface, focusing on polysaccharide molecules present in the joints and utilizing hybrids with zwitterionic polymers [215]. The aforementioned studies have created materials based on a detailed understanding of the biological properties of joints and the low-friction properties they exhibit and used biomimetic concepts to fabricate these materials. A high-density polymer brush layer was prepared by fixing the zwitterionic polymer to the surface using terminal functional groups or applying surface-initiated polymerization. Suitable solvents expand the polymer chains and the surface achieves fluid lubrication. From these studies, it is expected that new technologies that contribute to mechanical engineering, such as the improvement of energy efficiency owing to low friction and durability by reducing material wear, will be created regardless of medical devices.