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Investigations into the optimization of the structural parameters of the macromolecular matrix with a view to designing efficient polymer supports for peptide synthesis are reported. The dependence on the chemical nature of the monomers, nature and extent of crosslinking, the method of polymerization, hydrophobic-hydrophilic balance of the matrix, its chemical and mechanical stability, ease of functionalization,...
A new route for the synthesis of high glass transition temperature, thermally stable polymer foams with pore sizes in the nanometre regime has been developed, using compositionally asymmetric microphase-separated block copolymers where the minor component (poly(α-methylstyrene)) is thermally labile and the major component (polyimide) is thermally stable. The minor component can unzip to its monomer...
4-Hydroxybenzaldehyde or 3-methoxy-4-hydroxybenzaldehyde was condensed with cyanoacetic acid to afford 1-hydroxy-4-(2-cyano-2-carboxyvinyl)benzene (1) and 1-hydroxy-2-methoxy-4-(2-cyano-2-carboxyvinyl)benzene (2) respectively. They were converted to the corresponding acid chlorides by reacting with thionyl chloride and polycondensed in the presence of pyridine to afford unsaturated cyano-substituted...
A series of polycaprolactone (PCL)/poly(methyl methacrylate) (PMMA) AB crosslinked polymers (ABCP) in the form of latexes were prepared via the concentrated emulsion polymerization method. PCL diols were first reacted with acryloyl chloride in toluene to form a solution of vinyl-terminated PCL. Dissolving the methyl methacrylate monomer and a suitable initiator in this solution, the solution was...
The pregelation period of free-radical methyl methacrylate/ethylene glycol dimethacrylate (MMA/EGDM) and acrylamide/N,N -methylenebisacrylamide (AAm/BAAm) copolymerization systems was studied by means of the dilatometric technique. The amount of cyclization in MMA/EGDM copolymers was estimated using proton nuclear magnetic resonance and analytical titration methods. The results suggest that, in...
The preparation and hydrosilylation crosslinking of well-defined vinyl and allyl polydiethylsiloxane (PDES) telechelics are described. End functionalization has been achieved by using divinyltetramethyldisiloxane as a chain stopper during the cationic polymerization of hexaethylcyclotrisiloxane or by anionic polymerization of hexaethylcyclotrisiloxane with allyllithium followed by end capping with...
Methanol transport in crosslinked poly(methyl methacrylate) (PMMA) was studied. Four thicknesses were considered: 0.6, 1.0, 1.5 and 1.9 mm. The front velocity is independent of thickness. The front velocity obeys the Arrhenius equation and the activation energy is 20 kcal mol -1 . Comparing the crosslinked and uncrosslinked PMMA, the front velocity of the crosslinked PMMA is smaller...
Cyclic aryl ether oligomers containing the trans-1,2-diphenylcyclopropane moiety were synthesized in high yield from 1,2-bis(p-hydroxyphenyl)cyclopropane and 1-(3-hydroxyphenyl)-2-(4′-hydroxyphenyl)cyclopropane by reaction with 1,2-bis(4-fluorobenzoyl)benzene or 1,2-di(4-fluorobenzoyl)-3,6-diphenylbenzene. These oligomers undergo melt polymerization readily to give a crosslinked polymer in the presence...
Crosslinkable poly(phenylene oxide)s containing pendent 1,2-diphenylcyclopropane groups have been synthesized by oxidative polymerization from four new phenols containing the 1,2-diphenylcyclopropane group. The monomers were prepared by base-catalysed decomposition of the corresponding hydroxy-substituted 3,5-diphenyl-2-pyrazolines, which were the products of the reaction between hydroxy-substituted...
We have studied the reactions occurring in the solid state in phenol-formaldehyde systems crosslinked by a base. The results obtained with chemically defined models with Fourier transform infra-red spectroscopy and solid-state 13 C nuclear magnetic resonance spectroscopy (cross-polarization/magic angle spinning) applied the study of different resoles with variable formaldehyde/phenol...
Several methods of introducing crosslinks into poly(l-lactide) (PLLA) were studied. Electron beam irradiation was not effective in crosslinking PLLA, and, moreover, caused severe polymer degradation and embrittlement of the material. Peroxide crosslinking of PLLA with dicumyl peroxide (DCP), however, resulted in gelation. At high peroxide concentrations (13–25 wt%) and high curing temperatures (192°C),...
Anisotropic networks were prepared by photoinitiated cationic bulk polymerization of aligned liquid crystalline mixtures of mono- and bifunctional vinyl ethers. The thermal reversibility of the macroscopic order of the networks was assessed by infra-red spectroscopy measuring the dichroic ratio of the oriented samples at different temperatures between 20°C and 200°C. The order parameter gradually...
The peroxide crosslinking of plasticized poly(vinyl chloride), PVC, blended with trimethylolpropane trimethacrylate, TMPTMA, has been studied by following gel formation and changes in mechanical properties. By applying the right preparation conditions and peroxide type, it was possible to avoid crosslinking while dry-blending the materials. During compression moulding, gel yield was found to increase...
The objective of this paper is to study the crosslinking copolymerization of styrene (S) with a mixture of para- and meta-divinylbenzenes (mixed-DVBs). The crosslinking copolymerization, initiated with benzoyl peroxide (BPO), was performed at temperatures of 70, 80, and 90°C. The mole ratio of DVB to S was kept small, i.e. within 4–8%. At various stages of the polymerization the overall conversion...
A novel idea relating to the selective barrier layer of a composite membrane is described. The effective interface of the composite membrane could act as a barrier layer which could be controlled to an ideally ultrathin thickness. A new type of polyamide composite membrane was prepared according to this idea, which possessed permeability and chemical resistance more than one magnitude greater than...
Bisphenol-A-bis(2-hydroxypropyl methacrylate) (BisGMA) was copolymerized with methyl derivatives of styrene initiated by di-tert-butyl peroxide in the presence of 76 wt% of silica filler at 150 o -200 o C. The Raman bands of the C=C stretching vibrations at 1630 and 1637 cm -1 were found to be suitable for determining the conversion of C=C double bonds of the styrene...
The multiple waveform rheological technique was used to study the crosslinking behaviour of a filled elastomeric system at various temperatures. The gel point could be precisely determined from a single experiment at each temperature using this technique. At the instant of gelation, the storage (G ) and loss (G ) moduli scale with frequency in an identical manner, i.e. ∼ ω n . The relaxation...
The unsaturated polyesters derived from maleic anhydride and 2,2-di(4-hydroxypropoxyphenyl)propane were copolymerized with styrene in order to obtain the crosslinked materials. They were studied by means of high resolution 13 C n.m.r. in the solid state (CP/MAS). The structural changes upon crosslinking were followed by analysing proton spin-lattice relaxation time, T H1 ...
The kinetics of formation of epoxy resin composites was studied using an epoxy matrix of diglycidylether of bisphenol-A (DGEBA) and 4,4 -diaminodiphenylmethane (DDM) as curing agent in the presence of quartz flour as filler. The curing reactions of these systems were kinetically followed by differential scanning calorimetry (d.s.c.) at different scanning rates. The activation energies of the curing...
The melt-processible sulfonyl fluoride precursor of a Nafion ionomer was utilized as a sol-gel reaction medium for 3-aminopropyltriethoxysilane (APrTEOS). The diffusion-mediated reaction of APrTEOS with SO 2 F groups can be controlled with high degree of reaction. Fourier transform infra-red/attenuated total reflection studies show that sulfonamide linkages are formed and condensation...
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