Masayoshi Oiwa

Steric effect on the radical polymerization of triallyl isocyanurate: possibility of chain length enlargement in allyl polymerization

Abstract Radical polymerizations of triallyl isocyanurate (TAIC) and its isomer triallyl cyanurate (TAC) were conducted in benzene at 60°. In the polymerization of TAIC, gelation occurred quite early and the primary chain length was quite high compared with that for TAC. Both TAIC and TAC were copolymerized in bulk with allyl benzoate (ABz); the primary chain length decreased markedly with increase in the mole fraction of ABz and the difference between TAIC and TAC copolymerizations was reduced until almost no difference was observed above 50 mol% of ABz. Gelation was delayed with increasing ABz in the feed and the gel points for both TAIC and TAC copolymerizations were reached at the same conversions above 50 mol% ABz. The telomerization behaviours of TAIC and TAC in the presence of CBr4 were explored; the difference between TAIC and TAC polymerizations was significantly reduced as monomer chain transfer was replaced by chain transfer to CBr4. The chain transfer constant CCBr4 was estimated to be 77 and 84 for TAIC and TAC, respectively. These results are discussed in connection with a steric effect in the radical polymerization of TAIC leading to increased chain length.

Solvent effect in the copolymerization of methyl methacrylate with oligoglycol dimethacrylate

Abstract Methyl methacrylate was radically copolymerized with oligoglycol dimethacrylate using dioxane or n-butyl acetate as good and poor solvents, respectively. The delay between actual gel point and the theoretical one was much larger in a good solvent. The primary chain length, closely related to gelation, was relatively shortened for the polymer obtained in a poor solvent. The occurrence of intramolecular cyclization, leading to the formation of loop structures, was reduced in a poor solvent. The relationships between intrinsic viscosity or root-mean square radius of gyration and weight-average molecular weight were found and they are discussed in terms of the solvent effect on intramolecular cyclization and crosslinking.

Mechanical properties of diallyl phthalate resins co-cured microheterogeneously with vinyl monomers having long-chain alkyl groups

SummaryDiallyl phthalate(DAP) was co-cured with vinyl monomers having long-chain alkyl groups, including vinyl laurate(VL), dioctyl fumarate(DOF), lauryl methacrylate(LMA), and stearyl methacrylate(SMA) with the intention of the improvement in mechanical properties of commercially important DAP resins. Thus the elongation and fracture energy increased with an increase in the mole fraction of comonomers and their extents were enlarged in the order VL < DOF < LMA < SMA, although a reverse tendency was observed for the tensile strength; in particular, LMA and SMA as comonomers showed a remarkable effect. These results are discussed in detail by considering the copolymerizability of DAP with comonomers and, moreover, the formation of microgel in microheterogeneous copolymerization systems.

Gelation in the copolymerization of styrene with oligoglycol dimethacrylates

Abstract The gelation behaviour in the copolymerization of styrene with oligoglycol dimethacrylates (OGMA) has been examined in benzene at 50° and compared with the thermal copolymerization results in toluene at 95°. Gelation was delayed by changing the number ( n ) of oxyethylene units of OGMA from 1 to 2, but it was accelerated at n = 9. The gel-point conversion decreased with increasing n . The rate of polymerization was almost independent of the cross-linkers and no Trommsdorff effect was observed. These results are in a remarkable contrast with those for the thermal copolymerization, but in line with the results for the copolymerization of methyl mechacrylate with OGMA.

Gelation in the Copolymerization of Diallyldimethylammonium Chloride with Acrylamide

Abstract Diallyldimethylammonium chloride (DADMAC) was free-radical copolymerized with acrylamide (AA) in water at a total monomer concentration of 4 mol/L and 40°C with different monomer feed compositions. Gelation occurred only for 20/80 DADMAC/AA monomer feed although crosslinking was observed for all monomer feed compositions. The gel point was at 51% conversion, and the swelling ratios of the resulting gels were quite high, from 1400 to 700. Addition of 2‐propanol as a chain‐transfer reagent reduced crosslinking and prevented gelation. These results are mechanistically discussed in connection with the cyclopolymerizability of DADMAC, and significant allylic hydrogen abstraction by the growing polymer radical characteristic of allyl polymerization is proposed.

Studies of the polymerization of diallyl compounds—XLIII. Microheterogeneous copolymerization of diallyl terephthalate with vinyl monomers having long-chain alkyl groups

Abstract Diallyl terephthalate (DAT) was radically copolymerized in benzene with vinyl monomers having long-chain alkyl groups, including lauryl methacrylate (LMA), stearyl methacrylate (SMA) and vinyl laurate (VL). In the DAT-LMA copolymerizations, the initial rate was quite high because of high polymerizability of LMA compared with DAT. The gel point was at a higher conversion than in DAT homopolymerization. The LMA content in the copolymer decreased rapidly with the conversion up to the gel point; beyond the gel point, the LMA content in the soluble portion increased markedly with the progress of gelation. These tendencies were more pronounced in the DAT-SMA copolymerization. The reversed conversion dependence of the composition of precopolymer and sol at the gel point and the delayed gelation were not observed in the DAT-VL copolymerization. The change of the composition distribution of copolymer with progress of copolymerization was followed by comparison of r.i.- and u.v.-monitored GPC curves. These results are discussed from the standpoint of microheterogeneous copolymerization.

Steric control of gelation in monovinyl-multivinyl polymerization leading to preparation of self-crosslinkable polymer having pendant vinyl groups

Abstract Steric effects of long-chain alkyl groups on a radical vinyl polymerization including a multivinyl monomer is discussed in connection with control of gelation. Three kinds of alkyl methacrylate (RMA) were added to the system of methyl methacrylate with ethylene dimethacrylate (EDMA) in order to examine the steric effect of the long-chain alkyl group of RMA on the gelation. Study of the significance of steric effects on gelation was extended to the copolymerization of lauryl methacrylate (LMA) with several polyethylene glycol dimethacrylates (PEGDMA); gelation depended on the number of oxyethylene units ( n ) of PEGDMA as a crosslinker and no gelation was observed up to n = 4. Finally, LMA-EDMA copolymerization behaviour was examined in detail by changing monomer concentration and the amount of EDMA; the occurrence of intermolecular crosslinking leading to gelation is obviously suppressed by the steric effect of the long-chain alkyl group, providing a new way for the preparation of novel self-crosslinkable polymers having pendant vinyl groups.

Cyclic Acetal-Photosensitized Polymerization. VI. Photopolymerization of 2-Vinyl-1,3-dioxolane

Abstract The photopolymerization of 2-vinyl-l,3-dioxolane (VDO) was carried out in benzene at 40° C without use of the usual radical initiator. VDO was decomposed by means of photoirradiation to a cyclic acetal radical which transformed instantly into the ester radical by β-scission of dioxolane ring: the vinyl polymerization could be initiated by the ester radical. Because of the degradative chain transfer by allylidene group, the rate of polymerization and the molecular weight of polymer were very small.

Radical copolymerization of ethylene glycol bis(methyl fumarate) with N-vinylcarbazole

SummaryFor the purpose of elucidating copolymerizability of ethylene glycol bis(methyl fumarate), a new multifunctional monomer, its free-radical Copolymerization with N-vinylcarbazole has been studied. The results show that free-radical Copolymerization of ethylene glycol bis(methyl fumarate) with N-vinylcarbazole produces soluble copolymers at low conversions, the compositions of which vary from 1∶1 to increasingly VCZ rich (below 2.0) with an increase in the VCZ content in the monomer feed. It is suggested that 1∶1 alternating Copolymerization proceeds and that cyclo-propagation becomes predominant when the monomer feed composition becomes rich in VCZ. Gelation occurs at relatively high conversions.

Permselective properties for aqueous ethanol solutions through copolymer membranes from benzyl methacrylate and polyethylene glycol dimethacrylate

Abstract Copolymer membranes prepared by bulk copolymerization of polyethylene glycol dimethacrylates of three different degrees of polymerization as macromonomer and benzyl methacrylate as comonomer were used for the separation of aqueous ethanol solutions in both pervaporation and evapomeation. The copolymer membranes preferentially permeated water from an aqueous ethanol solution in evapomeation. In pervaporation, ethanol was predominantly permeated from an aqueous ethanol solution through the copolymer membranes containing a long polyethylene glycol (PEG) chain above about 20 wt% PEG content in a copolymer. This result was attributed to a remarkable swelling of the copolymer membrane containing a long PEG chain by the aqueous ethanol solution in pervaporation. In evapomeation, both the separation factors and the permeation rates through these membranes are not much affected by the ethanol concentration in the feed vapor. In pervaporation, they were significantly dependent on the ethanol concentration ...