Grafting To Approach

The grafting to method was used for the preparation of composites with the polymers containing reactive functional groups. One of the first examples of the grafting to approach was published by Fu et al in 2001. In this work, carboxylic acid groups on the nanotube surface were converted into acyl chlorides by refluxing the samples in thionyl chloride. Then the acyl chloride functionalised CNTs have been reacted with hydroxyl groups of dendritic PEG polymers via esterification reactions. 

Another original example of the grafting to approach was reported by Lou et In this work, MWNTs were grafted by polystyrene, poly(s-caprolactone) (PCL) and their BCs by the addition reaction of the correspondent alkoxyamine-terminated precursors. 

The grafting to method was recently applied for the preparation of epoxy-polyamidoamine SWNT composites.In this case, carboxylic acid groups of oxidised nanotubes have been further functionalised using polyamido-amine generation-0 (PAMAM-0) dendrimer and then epoxy monomers. The 

In another grafting to procedure, four polymers [PVDF, polysulfone (PSF), poly(2,6-dimethylphenylene oxide) and poly(phthalazinone ether ketone)] were chemically bonded to MWNTs using ozone-mediated process. Compared with pristine MWCNTs and PSF-modified MWCNTs, PVDF-modified MWCNTs were more efficient as additives that enhance the mechanical strength and electrical conductivity of PVDF.  

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The synthesis of end functional polymers by NMP, ATRP and RAFT has already been discussed in Section 9.7. The "grafting to approach involves the covalent attachment of an end-funetionalized polymer with reactive surface groups on the substrate. The approach is inherently limited by the crowding of chains at the surface and the limit this places on the final graft density. 

Our group was the first to develop synthetic protocols for both grafting-from and grafting-to approaches to the modification of micrometer-sized inorganic (sihca) particles (Scheme 6) [38-40]. 

Scheme 6 Surface functionalization of silica via ROMP. Grafting-from approach (top), grafting-to approach (bottom)...

Scheme 1 Scheme of grafting to approach of carboxy-terminated polymer onto anchoring layer of GPS... 

Scheme 49. Synthesis of graft copolymers containing dendrimers via a grafting to approach [323]...

The first component PS brushes were prepared using the grafting-to approach the second component PEGMA brushes were obtained through SIP. The thickness of the brushes obtained through SIP could be tuned in the 1-65 nm range. 

Compared to the "grafting to" approach, the "grafting from" method presents an evident superiority, offering a more homogenous MIP coverage of the sensor s surface with a larger number of cavities and a 100-fold faster diffusion of analyte [45], However, the initiator s immobilization directly onto the surface is usually complex and chemically not tenable [53],... 

Table 4.1 Comparison of grafting from and grafting to approaches.

Segura and group prepared protein-targeted cationic polymers by ATRP using the grafting from approach. The application of grafting from and grafting to approaches to prepare biomolecular chimeras by LRP has... 

Each of these points is reflected in gradually decreasing number of reports on the synthesis of dendronized polymers by using the grafting-to approach. 

Due to the relative ease of control, temperature is one of the most widely used external stimuli for the synthesis of stimulus-responsive bmshes. In this case, thermoresponsive polymer bmshes from poly(N-isopropylacrylamide) (PNIPAM) are the most intensively studied responsive bmshes that display a lower critical solution temperature (LOST) in a suitable solvent. Below the critical point, the polymer chains interact preferentially with the solvent and adopt a swollen, extended conformation. Above the critical point, the polymer chains collapse as they become more solvophobic. Jayachandran et reported the synthesis of PNIPAM homopolymer and block copolymer brushes on the surface of latex particles by aqueous ATRP. Urey demonstrated that PNIPAM brushes were sensitive to temperature and salt concentration. Zhu et synthesized Au-NPs stabilized with thiol-terminated PNIPAM via the grafting to approach. These thermosensitive Au-NPs exhibit a sharp, reversible, dear opaque transition in solution between 25 and 30 °C. Shan et al. prepared PNIPAM-coated Au-NPs using both grafting to and graft from approaches. Lv et al. prepared dual-sensitive polymer by reversible addition-fragmentation chain transfer (RAFT) polymerization of N-isopropylacrylamide from trithiocarbonate groups linked to dextran and sucdnoylation of dextran after polymerization. Such dextran-based dual-sensitive polymer is employed to endow Au-NPs with stability and pH and temperature sensitivity. 

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