New hybrid polyhydroxyurethane networks were quantitatively synthesized by radical polymerization of new hydroxyurethane methacrylate (HUMA) prepolymers. These HUMAs were synthesized in several steps. First, bis(cyclic carbonate) poly(propylene oxide) was reacted with two different diamines (ethylene diamine and 2,2 0 -(ethylenedioxy)diethylamine) in excess. Then, these end-functionalized hydroxyurethane prepolymers were converted into end-functionalized hydroxyl prepolymers by ring opening of ethylene carbonate. Finally, a methacrylate function was grafted to the hydroxyl functions. All these steps were performed at room temperature. These prepolymers were thermally either homopolymerized or copolymerized using benzylmethacrylate or poly(ethylene oxide) bisphenol A dimethacrylate as comonomers, leading to new hybrid nonisocyanate polyurethane networks with various properties.Polyurethane acrylates are currently widely used for coating applications and are notably obtained by ultraviolet (UV)-light processes. They exhibit excellent mechanical and chemical properties such as high abrasion resistance, toughness, or tear strength. [18][19][20][21][22] Moreover, thanks to various reactive diluents, their properties can be easily adjusted depending on the desired requests. Furthermore, the microphase separation of the urethane segments, mainly governed by the soft segment, enables the control of the mechanical properties of the thermosets. 23 Additionally, polyurethane methacrylates were also developed in order to obtain high glass transition temperatures and to improve the stability of the prepolymers. 24 Polyurethane methacrylates are major curing agents providing solvent-resistance, mechanical strength, and UV or thermal curing ability. 22,25,26 When moving to NIPU, few literature is provided for hydroxyurethane methacrylate (HUMA) monomers having only one HU unit. They are synthesized from the ring-opening reaction of ethylene carbonate by an amine followed by the grafting of methacrylic moiety. For example, these methacrylate monomers were investigated for their ability to react under UV Additional supporting information may be found in the online version of this article.M. Decostanzi and C. Bonneaud contributed equally to this article.
Perfluoropolyalkylethers
(PFPAEs) are a class of fluorinated polymers
having −OCF2–, −OCF2CF2–, and −OCF2CF(CF3)–
as common chain units. The ether linkages distinguish them from other
famous fluorinated polymers such as poly(tetrafluoroethylene).
Their higher mobility highlighted by below zero glass transition temperatures
permit them to be noncrystalline, which makes them easy to use for
many applications. They possess interesting tribological properties,
combined with an excellent thermal and chemical stability, make them
very useful as lubricants. However, after chemical modifications,
they also demonstrated to be very useful in numerous applications
as surfactants, electrolytes, high performance coatings, vitrimers,
or microfluidic devices, to give a few examples. This Perspective
aims to summarize all the chemical modifications reported on these
PFPAEs to provide a new insight into their potential utility in emerging
fields. Indeed, the end group can modulate the properties of PFPAE-based
materials such as lubricity, superhydrophobicity, biofouling, antibacterial
activity, amphiphilicity, and the ability to react further with comonomers
under photochemical and thermal processes. It can also modulate their
intrinsic properties such as viscosity and solubility in common organic
solvents. The chemical modifications are sorted in five main parts:
the condensation reactions, the nucleophilic reactions, the click
chemistry reactions, the radical reactions, and finally reactions
going through other mechanisms or requiring a multistep process. They
can be employed as such or for further polymerization processes depending
on the targeted application. Examples of applications are thoroughly
described to demonstrate their current usefulness and to help provide
direction for their future use.
Four different films were prepared from chitosan modified with furfuryl glycidyl ether (FG) by Diels Alder reaction with different maleimide-based cross linker. At first, a preliminary study led to structural identification and better understanding of the reaction. For the first time, Diels-Alder and retro Diels-Alder reactions were evidenced by NMR spectroscopy and DSC on chitosan based systems. Then, chitosan of 30,000 g/mol and 150,000 g/mol were modified by FG with 20% substitution degree (DS). The resulting products were then crosslinked with bis and trimaleimide cross-linkers to produce films possessing interesting mechanical properties. For the first time for chitosan-based films, DMA measurement highlighted retro Diels-Alder between 110 and 130°C. Film also showed interesting hydrophobicity and fat absorption. They also exhibited resistance in acidic media whereas crude chitosan films were destroyed.
Maleimides are attractive systems for photopolymerize for two major reasons: (1) they follow a radical mechanism without requiring a photoinitiator and (2) their rate of polymerization corresponds similarly to acrylates, which are commonplace in the industry. In this work, bismaleimide polypropylene oxide was cured under UV light forming thin films. Their surface properties were modified by copolymerization them with fluorinated comonomers. To this goal, perfluoropolyalkylethers (PFPAEs) with maleimide groups were synthesized, varying their chain structure, their functionality degree and consequently their intrinsic viscosity. These PFPPAE comonomers were highlighted to segregate at the surface, assuring omniphobic properties and acting as a protective layer against oxygen inhibition. These phenomenon were observed even when added at a concentration ≤5% w/w with respect to the main polypropylene oxide monomer. XPS analyses confirmed the segregation of the fluorine atoms at the surface during the UV-curing process of the coatings.
New perfluoropolyalkylether (PFPAE) monomers, chain extended with different alkyl groups and functionalized with vinyl ether or epoxide end-groups, were employed, together with trimethylolpropane trivinyl ether or trimethylolpropane triglycidyl ether, to produce fluorinated copolymers. The photoinduced cationic polymerization was investigated, and the PFPAE-based copolymer properties were thoroughly characterized. Interesting surface properties and two different values of refractive index were observed: thus, these fluorinated copolymers can be suitable materials for the manufacture of self-cleaning coatings and optical waveguides.
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