Synthesis Of Network Polymers Research Articles

Synthesis of network polymers by means of ring-opening addition reaction of a tri-aziridine and dicarboxylic acid compounds

Polyethylenimine (PEI) is widely used in various products. Development of PEI network polymers would expand the application of the PEI. Ring-opening homo-polymerization of tri-aziridine compounds yielded the PEI-based hard network polymers derived from high dense crosslinking structure. Introduction of the flexible unit in the polymer network should be effective to control the mechanical properties of the resulting network polymers. In the present study, ring-opening addition reactions between a tri-aziridine, 2,2-bishydroxymethylbutanol-tris[3-(1-aziridinyl)propionate] (3AZ), and α,ω-dicarboxylic acid, RCAn (HOOC-(CH2)n-COOH): succinic acid (RCA2), adipic acid (RCA4), dodecanedioic acid (RCA10), or α,ω-dicarboxylic acid with ether linkage, ECAm (HOOC-(CH2OCH2)m-COOH); diglycolic acid (ECA1), 3,6,9-triocaundecanedionic acid (ECA3), poly(ethylene glycol) bis(carboxymethyl) ether (ECA4) were conducted to yield the polymers with controlled network structure. The reactions at room temperature in N,N-dimethylformamide successfully yielded gels. Young's modulus of the gel decreased with increasing in the chain length of the dicarboxylic acid used. The reaction of 3AZ with RCA4 in acetone or ethanol (EtOH) induced phase separation and produced porous polymers. The reactions with oxalic acid (RCA0), glutaric acid (RCA3), suberic acid (RCA6), ECA1, ECA3, or ECA4 in EtOH also yielded the porous polymers. The morphology in the porous polymers was formed by connected particles. The Young's modulus of the porous polymer also decreased with increasing in the chain length of the dicarboxylic acid used. The resulting porous polymers absorbed various solvents, such as acetone, water, dichloromethane, and chloroform. Hydrophobicity and hydrophilicity of the porous polymers can be controlled by the molecular structure of the dicarboxylic acid in the polymer networks.

Synthesis of network polymers by ring-opening addition reaction of multi-functional epoxy and dithiol compounds

Synthesis of network polymers by ring-opening addition reaction of multi-functional epoxy and dithiol compounds

Synthesis of network polymers by photo-initiated thiol–ene reaction between multi-functional thiol and poly(ethylene glycol) diacrylate

Network polymers have been synthesized by thiol–ene reaction of multi-functional thiol, 1,3,4-tris(3-mercaptobutyloxethyl)-1,3,5-triazine-2,4,6- (1H,3H,5H)-trione (TEMBIC), pentaerythritol tetrakis(3-mercaptobutylate) (PTMB), tris[(3-mercaptopropionyloxy)-ethyl]-isocyanurate (TEMPIC), pentaerythritol tetrakis(3-mecaptopropionate) (PEMP), dipentaerythritol hexakis(3-mercaptpropionate) (DPMP), and poly(ethylene glycol) diacrylate (PEGDA) in toluene using a photo-radical initiator. All the reactions in toluene successfully yielded gels. Mechanical properties of the gels were investigated by compression test, and Young’s modulus of the gels increased with an increase in the number of thiol group in the multi-functional thiol compound due to high cross-linking density in the gels. The gels were also synthesized in some organic solvents including dimethyl sulfoxide (DMSO), propylene carbonate (PC), and tetrahydrofuran. Solvent affected mechanical properties of the resultant gels, and the gels prepared in DMSO or PC showed high Young’s modulus and breaking stress. The reaction systems of TEMBIC, TEMPIC, PEMP, or DPMP and high-molar-mass PEGDA in EtOH yielded porous polymers induced by phase separation during the network formation. All the porous polymers showed morphology formed by connected spheres. The porous polymers were soft and flexible, and not breakable by compression at the force of up to 500 kPa.

Computer Synthesis of Network Polymers

A model and the principle of constructing a corresponding computer program are proposed for the electronic synthesis of polymer networks with a specified range of glass transition temperatures have been proposed for the first time. A repeating fragment of the network is synthesized from the smallest basic fragments, which are connected to each other using a control matrix of interactions. As an example, there are presented 27 chemical structures of the cross-linked points, 26 basic fragments for constructing polymer chains connecting the cross-linked points, and five repeating fragments of polymer networks with glass transition temperatures falling within the range 450–480 K.

Synthesis of Network Polymers by Means of Addition Reactions of Multifunctional-Amine and Poly(ethylene glycol) Diglycidyl Ether or Diacrylate Compounds.

Addition reactions of multi-functional amine, polyethylene imine (PEI) or diethylenetriamine (DETA), and poly(ethylene glycol) diglycidyl ether (PEGDE) or poly(ethylene glycol) diacrylate (PEGDA), have been investigated to obtain network polymers in H2O, dimethyl sulfoxide (DMSO), and ethanol (EtOH). Ring opening addition reaction of the multi-functional amine and PEGDE in H2O at room temperature or in DMSO at 90 °C using triphenylphosphine as a catalyst yielded gels. Aza-Michael addition reaction of the multi-functional amine and PEGDA in DMSO or EtOH at room temperature also yielded corresponding gels. Compression test of the gels obtained with PEI showed higher Young’s modulus than those with DETA. The reactions of the multi-functional amine and low molecular weight PEGDA in EtOH under the specific conditions yielded porous polymers induced by phase separation during the network formation. The morphology of the porous polymers could be controlled by the reaction conditions, especially monomer concentration and feed ratio of the multi-functional amine to PEGDA of the reaction system. The porous structure was formed by connected spheres or a co-continuous monolithic structure. The porous polymers were unbreakable by compression, and their Young’s modulus increased with the increase in the monomer concentration of the reaction systems. The porous polymers absorbed various solvents derived from high affinity between the polyethylene glycol units in the network structure and the solvents.

Synthesis of Network Polymers from Multifunctional Aromatic Thiol Compounds

Network polymers have been synthesized by means of catalyst free thiol-yne reaction of multi-functional aromatic ethynyle and thiol compounds, 1,3,5-triethynylbenzenen (TEB), 1,4-diethynylbenzene (DEB), 1,4-benzenedithiol (BDT) and benzenethiol (BT). The network polymers of TEB/DEB-BDT or TEB-BDT/BT were obtained in good yields. The feed ratio of DEB or BT increased the chloroform solution, fragments, of the network polymers. The fragments of the network polymers showed optical properties derived from conjugation units of phenyl-ethynyl-sulfide. The network polymers have been synthesized by oxidation reaction of multi-functional aromatic thiol compounds, 1,3,5-benzene trithiol (BTT) with BDT or 4,4’-biphenyl dithiol (BPDT), accompanied by formation of disulfide bonds. The BTT network was degradable by a reductant, tris(2-caboxyethyl)phosphine hydrochloride.

Synthesis of Network Polymers Containing Si-Vinylene Units by Mizoroki-Heck Reaction

Network polymers containing Si-vinylene units have been synthesized by Mizoroki-Heck reaction of cyclic siloxane or cubic silsesquioxane compounds with vinyl groups, as joint molecules, and dibromo aryl compounds, as linker molecules, using a Pd catalyst. The reaction of 1,3,5,7-tetravinyltetramethylcyclotetrasiloxane (TVMCTS) or octavinyloctasilsesquioxane (PVOSS) with o, m, p-dibromobenzene (DBB) or 4,4'-dibromobiphenyl (DBBP) yielded the corresponding network polymers, except TVMCTS-oDBB system. Optical properties of the network polymers were studied by UV-vis and photoluminescence spectroscopy, and absorption and emission derived from s-p conjugation of the Si-vinylene units were detected. Copolymerization of TVMCTS-DBB/bromobenzene yielded CHCl3 soluble fraction due to formation of the network fragments. The network polymers of TVMCTS or PVOSS with 2,7-dibromofluorene (BFl) or 9,9-dihexyl-2,7-dibromofluorene were synthesized by the same procedures. Scanning electron microscope image of TVMCTS-BFl network polymer indicated formation of porous structure. The network polymers have been also synthesized by the reactions of multifunctional aryl bromide, as the joint molecules, with divinyl or dially silane compounds, as the linker molecules. The molecular structure of the multifunctional aryl bromide affected the emission wavelengths of the network polymers. In the case of the 2,2’,7,7’-tetrabromo-9,9’-spirobifluorene-based network polymers, the emission spectra widely ranged from 450 to 500 nm, which were sensitive to molecular structure of the divinyl or dially silane compounds.