Copper-free azide-alkyne click chemistry is utilized to covalently modify polyvinyl chloride(PVC). Phthalate plasticizer mimics di(2-ethylhexyl)-1H-triazole-4,5 dicarboxylate (DEHT), di(nbutyl)-1H-1,2,3-triazole-4,5-dicarboxylate (DBT), and dimethyl-1H-triazole-4,5-dicarboxylate(DMT) are covalently attached to PVC. DEHT, DBT, and DMT have similar chemical structures to traditional plasticizers di(2-ethylhexyl) phthalate (DEHP), di(n-butyl) phthalate (DBP), and dimethyl phthalate (DMP), but pose no danger of leaching from the polymer matrix and forming small endocrine disrupting chemicals. The synthesis of these covalent plasticizers is expected to be scalable, providing a viable alternative to the use of phthalates, thus mitigating dangers to human health and the environment.

Plasticization of PVC was carried out by covalently linking phthalate derivatives via copper-free (thermal) or copper catalyzed azide-alkyne cycloadditions. Di(2-ethylhexyl) phthalate derivatives (DEHPether and DEHP-ester) were synthesized and appended to PVC at two different densities. The glass transition temperatures of the modified PVC decreased with increasing content of plasticizer. PVC-DEHP-ether gave lower glass transition temperatures than PVC-DEHP-ester, reflecting the enhanced flexibility of the ether versus ester linker.

was found to give reasonably controlled/living nitroxide-mediated (NMP) precipitation polymerizations of styrene in supercritical carbon dioxide (scCO 2 ). In contrast under the same conditions, the analogous SG1 (N-tert-butyl-N-(1-diethylphosphono-2,2-dimethylpropyl) nitroxide)-alkoxyamine gave higher rates of polymerization and inferior controlled/living character. The circumvention of the requirement for excess free [nitroxide] 0 allowed the study of nitroxide partitioning effects in scCO 2 for three newly synthesized fluorinated alkoxyamines. Two alkoxyamines dissociated into scCO 2 -philic fluorinated TIPNO-nitroxide derivatives, while another contains a similar sized fluorinated "foot". Despite the increase steric bulk about the N-O bond for the novel fluorinated alkoxyamines, all polymerizations proceeded at a similar rate and level of control to the TIPNO system in solution (toluene). PREDICI simulations for the styrene/TIPNO system are used to support extensive partitioning effects observed in scCO 2 for the fluorinated alkoxyamines. IntroductionSupercritical carbon dioxide (scCO 2 ) is a benign solvent used to circumvent the requirement for environmentally damaging volatile organic solvents. [1][2][3] Advantages include a readily accessible critical point (31 °C and 7.4 MPa), 4 variable solubility by subtle changes in pressure and temperature, 5 and the lack of chain transfer to solvent in radical polymerizations. 6,7 It is particularly well-suited for heterogeneous radical polymerizations, since reagents such as the monomer, initiator and controlling agent are generally soluble in scCO 2 , but the resultant polymer is insoluble and precipitates. 2,3 If the precipitation system is carried out in the presence of a colloidal stabilizer to prevent coagulation of particles, then dispersion polymerization results giving polymer of narrow particle size distributions and well-defined particles (d ≈ 100 nm to 15 μm). 1-3The monomer is not always soluble in the reaction medium, such as in the controlled/living nitroxide-mediated radical polymerization (NMP) of N-isopropylacrylamide (NIPAM) in scCO 2 , where an inverse suspension system is generated. 8,9 In recent years, there has been a proliferation in the numbers of reported controlled/living precipitation and dispersion polymerizations in scCO 2 with NMP, [9][10][11][12][13][14][15][16][17][18][19][20][21] atom transfer radical polymerization (ATRP), 22-29 reversible addition-fragmentation chain transfer (RAFT) 3, 30-39 and iodine transfer polymerization (ITP). 40,41 The slow build up in molecular weight (MW) in a controlled/living system by virtue of the equilibrium between active propagating radicals and dormant polymer chains allows measurement of the critical degree of polymerization (J crit ) before polymer chains precipitate from solution or the continuous phase (containing monomer and scCO 2 ). After J crit , the polymerization continues in the monomer-rich particle phase. For controlled/living precipitation/dispersion polymerizations, J crit can be ...

The synthesis of 4-vinyl-1,2-phthalate esters via Suzuki coupling is described, followed by nitroxide-mediated polymerization to prepare short homopolymers (degree of polymerization [DP] ¼ 10-40, polydispersity index [PDI] ¼ 1.1-1.3). Random copolymers with n-butyl acrylate (NBA) were prepared. Copolymers rich in phthalate ester residues of medium lengths (DP ¼ 16-48, PDI ¼ 1.2-1.8) and of shorter lengths (DP ¼ 8-17, PDI ¼ 1.2-1.3) were prepared. Copolymers rich in NBA residues were also prepared (DP ¼ 13-19, PDI ¼ 1.2-1.3). All polymers were oily liquids, with glass transitions temperatures undetected between 75 and À40 C, indicating these polymeric phthalates hold promise as potential nonmigratory phthalate plasticizers.

Polystyrene supported fluorinated cyclic nitrone spin-traps: Resin-2-HFDMPO (2-hydroxymethyl-2-methyl-5-(trifluoromethyl)-3,4-dihydro-2H-pyrrole-1-oxide) and Resin-2-PFDMPO (2-(3-hydroxypropyl)-2-methyl-5-(trifluoromethyl)-3,4dihydro-2Hpyrrole 1-oxide) containing a trifluoromethyl pyrroline-N-oxide core were developed to detect free radicals under flow conditions. A continuous flow EPR technique was used to evaluate the spin trapping properties of these tethered nitrones. While both resins trapped radicals, polymer supported nitrone Resin-2-PFDMPO with a longer and more flexible linker showed a more information rich spectrum than Resin-2-HFDMPO.

Copper-free azide-alkyne click chemistry is utilized to covalently modify polyvinyl chloride(PVC). Phthalate plasticizer mimics di(2-ethylhexyl)-1H-triazole-4,5 dicarboxylate (DEHT), di(nbutyl)-1H-1,2,3-triazole-4,5-dicarboxylate (DBT), and dimethyl-1H-triazole-4,5-dicarboxylate(DMT) are covalently attached to PVC. DEHT, DBT, and DMT have similar chemical structures to traditional plasticizers di(2-ethylhexyl) phthalate (DEHP), di(n-butyl) phthalate (DBP), and dimethyl phthalate (DMP), but pose no danger of leaching from the polymer matrix and forming small endocrine disrupting chemicals. The synthesis of these covalent plasticizers is expected to be scalable, providing a viable alternative to the use of phthalates, thus mitigating dangers to human health and the environment.