Photochemical Activation of Extremely Weak Nucleophiles: Highly Fluorinated Urethanes and Polyurethanes from Polyfluoro Alcohols

Abstract

An efficient and environmentally friendly photoreaction between phenyl isocyanate or pentafluorophenyl isocyanate and polyfluorinated alcohols and diols is described for the first time. New highly fluorinated urethanes and diurethanes, derived from aromatic isocyanates, are produced in good yields in a photoreaction that is apparently governed by the acidic properties of the polyfluoro alcohols and diols. The wettability properties of the new polyfluorinated diurethanes have been tested, some of them showing significantly high values of hydrophobicity and oleophobicity. This new photoreaction has also been tested in the production of a model polyfluorinated polyurethane, establishing the influence of the irradiation power in the outcome of the process, and directly achieving a molecular weight distribution corresponding to a number-average DP(n) = 12 and a highest DP(n) = 20 after 4 h of irradiation (DP(n): "number-average degree of polymerization").

Bis(thiocarbamates): Synthesis and Substituent Effects on the Barrier to N‐CO Rotation

“…As in the case of amides and carbamates [, ], bis(thiocarbamates) are characterized by the presence of N–CO bond having a partially double bond character, which results in the presence of the two s‐cis and s‐trans conformations. In our case and as can be seen from Table , the benzyl and phenyl derivatives show the coexistence of the two conformers (i.e., two NH NMR signals), while only one signal was observed in the 1 H NMR spectra for the other derivatives at room temperature (Fig.…”

“…Among the different routes used for their synthesis, the addition of thiols or alcohols to isocyanates is the most common method [24][25][26][27][28][29][30]. Recently, the synthesis of polythiourethanes has shown an increasing expansion primarily due to their successful industrial and commercial applications as high refractive index optical materials [29][30][31][32]. Despite the enormous work carried out on polyurethane and polythiourethane [23][24][25][26][27][28][29], studies on monomer analogs (i.e., urethanes or diurethanes) are much less reported in the literature [33][34][35].…”

“…Recently, the synthesis of polythiourethanes has shown an increasing expansion primarily due to their successful industrial and commercial applications as high refractive index optical materials [29][30][31][32]. Despite the enormous work carried out on polyurethane and polythiourethane [23][24][25][26][27][28][29], studies on monomer analogs (i.e., urethanes or diurethanes) are much less reported in the literature [33][34][35]. This seems to be surprising since investigation of the structure and properties of the latter simple molecules would be much easier before polymerization than that undertaken on the more complicated polymer counterparts.…”

Reviewing of General Polymer Types, Properties and Application in Medical Field

“…Several forms of 3D printing, including layer by layer stereolithography and two-photon absorption 3D photopolymerization , use photopolymerization. (Soto et al, 2014).…”

Finite Element Modeling of Multilayer Orthogonal Auxetic Composites under Low-Velocity Impact

“…Since the first auxetic polyurethane (PU) foam with a re-entrant structure was made by Lakes in 1987, a number of auxetic materials have been proposed and fabricated, ranging from macroscopic and micro-structural levels to a molecular level, including auxetic polymeric foams and micro-porous polymers [ 1 , 2 , 3 , 4 , 5 , 6 , 7 ], auxetic fibers [ 8 , 9 ] and fabrics [ 10 , 11 , 12 , 13 ], auxetic honeycombs [ 14 ] and composites [ 15 , 16 , 17 , 18 ], and so on. Auxetic materials have aroused much interest due to their counterintuitive deformation behavior and improved mechanical properties, such as enhanced shear resistance [ 19 , 20 , 21 ], increased indentation resistance [ 22 , 23 , 24 , 25 ], and improved crashworthiness [ 26 , 27 ]. These feature advantages have made auxetic materials very attractive for many potential applications such as automobile, aerospace and defense, and sport equipments, etc.…”