Amplification of surface-initiated ring-opening metathesis polymerization of 5-(perfluoro-n-alkyl)norbornenes by macroinitiation

Simultaneous Spin Coating and Ring-Opening Metathesis Polymerization for the Rapid Synthesis of Polymer Films

We report a highly controlled technique for the synthesis of polymer films atop a substrate by combining spin coating with ring-opening metathesis polymerization (ROMP), herein termed spin coating ROMP (scROMP). The scROMP approach combines polymer synthesis and deposition into one process, fabricating films of up to 36 cm2 in under 3 min with orders-of-magnitude reduction in solvent usage. This method can convert numerous norbornene-type molecules into homopolymers and random copolymers as uniform films on both porous and nonporous substrates. Film thickness can be varied from a few hundred nanometers to a few tens of micrometers based on spin speed and monomer concentration. The resulting polymers possess high MW (>100 kDa) and low polydispersity (PDI) (<1.2) values that are similar to ROMP polymers made in solution. We also devise a model to investigate the balance between convective monomer spin-off and polymer growth from the surface, which allows the determination of critical kinetic parameters for scROMP. Finally, translation of scROMP to porous supports enables the synthesis of thin film composite membranes that demonstrate the ability to dehydrate ethanol by pervaporation.

Hydrophobic and antifouling modification of graphene oxide with functionalized polynorbornene by surface-initiated ring-opening metathesis polymerization

Surface-initiated ring-opening metathesis polymerization (SI-ROMP), based on the design of hydrophobic and antifouling monomers, was employed for the synthesis of grafting-modified graphene oxide (GO).

Surface-Initiated Ring-Opening Metathesis Polymerization (SI-ROMP): History, General Features, and Applications in Surface Engineering with Polymer Brushes

Surface-Initiated Ring-Opening Metathesis Polymerization (SI-ROMP) has attracted great attention in the past two decades because of its high efficiency in decorating material surfaces with functional polymer brushes. To fill the vacancy of review articles in SI-ROMP, this article is aimed at giving an overview of the history, the general features and procedures, and applications of SI-ROMP, guiding future researchers in this field. In general, SI-ROMP consists of three main steps: surface functionalization with olefin anchors, attachment of catalyst to the surface, and polymerization from the surface. Several metal-based catalysts for ROMP in solution have been developed, but most SI-ROMP reactions use the ruthenium-based Grubbs catalysts. SI-ROMP enables the rapid growth of polymer films on a large variety of substrates such as silica, gold, graphene oxides, carbon nanotubes, metal oxide nanowires, and composite polymer membranes. There are many methods to characterize these polymer brushes. In addition, some novel techniques have been developed to precisely control the surface polymer growth and lead to polymer films with unique structures and functions. Up to this day, SI-ROMP can be applied to the surface engineering of many novel materials, including ultrahydrophobic surfaces, microfluidic channels, electric devices, ion exchange media, and responsive surfaces.

pH-Responsive Copolymer Films Prepared by Surface-Initiated Polymerization and Simple Modification

We report the preparation of pH-responsive, ester/carboxylic acid random copolymer films via simple modification of poly(norbornene diacyl chloride) (pNBDAC), prepared via surface-initiated ring-opening metathesis polymerization, with mixtures of water and ethanol to form carboxylic acid and ethyl ester side groups. The pNBDAC film serves as a compositionally versatile platform to controllably obtain copolymers with multiple functionalities. In modifying the pNBDAC to form the copolymer film, ethanol exhibits a significantly higher reactivity with acyl chloride groups within the film than does water. The magnitude and range of the pH-responsive performance are highly dependent on the carboxylic acid content in the copolymer films, which demonstrates the effect of film hydrophilicity on the pH-responsive switching of ionic barrier properties. The resistance of the film against ion transfer can be decreased by a factor of 10⁴ through pH change, demonstrating pH-induced switching from hydrophobic and insulating to swollen and ion-permeable films. The interactions of the copolymer films with water at different pH values were also explored. When the copolymer contains 34% carboxylic acids, a 4× greater film thickness is obtained in high pH solution than in low pH solution due to ionically driven water swelling. The reversibility of the pH-responsive performance of these copolymer films is high based on measurements using quartz crystal microbalance with dissipation (QCM-D).

Polymer brush on surface with tunable hydrophilicity using SAM formation of zwitterionic 4-vinylpyridine-based polymer

A zwitterionic vinylpyridine-based polymeric SAM was assembled on different surfaces to obtain tunable hydrophilicity.

Surface-Initiated Ring-Opening Metathesis Polymerization of Dicyclopentadiene from the Vapor Phase

Surface-attached polydicyclopentadiene (pDCPD) films were prepared on gold and silicon substrates via surface-initiated ring-opening metathesis polymerization (SI-ROMP) of dicyclopentadiene (DCPD). The films were grown utilizing monomer in both the vapor phase and the solution phase with the former process exhibiting rapid kinetics, producing ∼400-nm-thick pDCPD films in less than 1 min of polymerization. No significant differences in thickness were observed for films grown from monomer in the vapor phase with the different isomers (exo and endo) of DCPD. Decane was used as an inert additive to control the concentration of DCPD monomer in the vapor phase enabling the preparation of pDCPD films with thickness ranging from tens of nanometers to hundreds of nanometers. The thickness of pDCPD films polymerized using monomer in the vapor phase was enhanced by the presence of a rinse solvent on the surface of the ROMP-active gold substrates. The choice of ROMP catalyst was found to be an important consideration when SI-ROMP was conducted on different substrates. Electrochemical impedance spectroscopy was used to reveal that the films provide effective barriers to the diffusion of aqueous ions in excess of 1 × 10⁶ Ω·cm². The mechanical properties of the surface-tethered pDCPD films were quantified with AFM PeakForce quantitative nanomechanical mapping (QNM) with a measured reduced Young's modulus (E_r) of 15 GPa. The measured E_r was greater than that of a non-cross-linked surface-tethered polymer, pNB, indicating that the pDCPD films are stiffer.

Surface-Initiated Controlled Radical Polymerization: State-of-the-Art, Opportunities, and Challenges in Surface and Interface Engineering with Polymer Brushes

The generation of polymer brushes by surface-initiated controlled radical polymerization (SI-CRP) techniques has become a powerful approach to tailor the chemical and physical properties of interfaces and has given rise to great advances in surface and interface engineering. Polymer brushes are defined as thin polymer films in which the individual polymer chains are tethered by one chain end to a solid interface. Significant advances have been made over the past years in the field of polymer brushes. This includes novel developments in SI-CRP, as well as the emergence of novel applications such as catalysis, electronics, nanomaterial synthesis and biosensing. Additionally, polymer brushes prepared via SI-CRP have been utilized to modify the surface of novel substrates such as natural fibers, polymer nanofibers, mesoporous materials, graphene, viruses and protein nanoparticles. The last years have also seen exciting advances in the chemical and physical characterization of polymer brushes, as well as an ever increasing set of computational and simulation tools that allow understanding and predictions of these surface-grafted polymer architectures. The aim of this contribution is to provide a comprehensive review that critically assesses recent advances in the field and highlights the opportunities and challenges for future work.

Controlled decoration of the surface with macromolecules: polymerization on a self-assembled monolayer (SAM)

Polymer functionalized surfaces are important components of various sensors, solar cells and molecular electronic devices. In this context, the use of self-assembled monolayer (SAM) formation and subsequent reactions on the surface have attracted a lot of interest due to its stability, reliability and excellent control over orientation of functional groups. The chemical reactions to be employed on a SAM must ensure an effective functional group conversion while the reaction conditions must be mild enough to retain the structural integrity. This synthetic constraint has no universal solution; specific strategies such as "graft from", "graft to", "graft through" or "direct" immobilization approaches are employed depending on the nature of the substrate, polymer and its area of applications. We have reviewed current developments in the methodology of immobilization of a polymer in the first part of the article. Special emphasis has been given to the merits and demerits of certain methods. Another issue concerns the utility - demonstrated or perceived - of conjugated or non-conjugated macromolecules anchored on a functionally decorated SAM in the areas of material science and biotechnology. In the last part of the review article, we looked at the collective research efforts towards SAM-based polymer devices and identified major pointers of progress (236 references).