To address the issue of petroleum resource depletion, it is desirable to develop recyclable materials from biobased compounds. In addition, low -energy recycling methods such as light irradiation and hydrolysis should be considered. In this paper, bio-based materials, cinnamic acid (CA) derivatives, are introduced as repeating units in polyester main -chain, because CA derivatives undergo reversible [2 + 2] cycloaddition reactions to form dimers under light exposure. Photopolymerization of the monomer with CA moieties at both ends failed, probably because it was difficult to bring the two CA moieties closer together intermolecularly. Polycondensation between the CA dimer with two carboxylic acid moieties and diol compounds successfully provided the polyesters containing CA dimers as repeating units. Furthermore, orthogonal degradation methods, such as light exposure and hydrolysis, of the obtained polyester were investigated.

Heat-resistant ABS resin, an industrial polymer material, is generally prepared by mixing AN/MS bipolymer and/or AN/ST/MS terpolymer with the matrix of ABS resin, where AN, ST and MS denote acrylonitrile, styrene and α-methylstyrene, respectively. In order to predict the thermal properties of ABS resins, it is important to know which copolymers are blended and in what ratio. In this study, statistical structural analysis was performed on polymer blends consisting of AN/ST bipolymer, AN/MS bipolymer and AN/ST/MS terpolymer to predict blending parameters for heat-resistant ABS resin. Nuclear magnetic resonance (NMR) spectral data of the polymer blends were used as explanatory variables to determine the chemical composition and mole fraction of the component copolymers. Partial least-squares (PLS) regression and least absolute shrinkage and selection operator (LASSO) regression were used as the exploratory techniques. The use of 1H NMR spectral data showed poor prediction, probably because of low resolution due to the narrow spectral width. Accordingly, 13C NMR spectra, which have wider spectral widths, were used, resulting in the successful prediction of the blending parameters of the ternary blends containing a terpolymer as a component. It should be noted that it was not necessary to obtain the NMR spectra of all the polymer blends as the explanatory variables, i.e., linear combinations of the NMR spectra of the component copolymers were sufficient.

Copolymers of [2-(acryloyloxy)ethyl]trimethylammonium chloride (AETAC) and acrylamide (AAm) (AETAC- co -AAm) are polyelectrolytes used as flocculants in wastewater purification. Diffusion-ordered two-dimensional NMR spectroscopy (DOSY) experiments for AETAC- co -AAm samples with M w ranging from 1.9 to 3.9 million and a polyacrylamide sample with M w of 1.3 million were carried out in pure D 2 O and in D 2 O containing 0.1 or 1 M NaCl using an inverse-geometry diffusion probe system. Projections of the DOSY contour plots onto the diffusion coefficient ( D ) dimension gave distributions of D for the AETAC and AAm units in the samples. The D values at the maximum point of the distribution ( D p ) agreed fairly well with those determined by dynamic light scattering.

The isoalloxazine ring system, called flavin, was successfully immobilized on poly(methacrylic acid)s, PMAAs, with different tacticity via post-polymerization modification under suitable conditions. The resulting flavin-containing polymers showed catalytic activity for aerobic oxidation reactions, in which the polymer stereoregularity clearly influenced their catalytic activity.

Statistical 1 H nuclear magnetic resonance (NMR) analyses were conducted with ternary copolymer blends. Two out of the three monomers, acrylonitrile, styrene, and α-methylstyrene, were subjected to radical copolymerization to synthesize three kinds of copolymers that were mixed to prepare binary and ternary copolymer blends. The 1 H NMR spectral matrix for the copolymers and their blends (explanatory variables) was combined with the blending parameter matrix (objective variables). Cross-validation with the least absolute shrinkage and selection operator regression confirmed that excellent regression models were constructed with a dataset composed of data for eight copolymers and forty-five binary blends; these were used to predict the blending parameters for the binary blends, such as the chemical compositions and mole fractions of the component copolymers. Accordingly, the models were then used to predict the blending parameters for the ternary blends, which resulted in successful and highly accurate predictions. Other regularized regression models, such as Ridge regression and Elastic Net, were also examined.

The anionic polymerization of methyl methacrylate (MMA) was investigated using dilithium tetra-tert-butylzincate (TBZL), which is a bulky zincate, as an initiator. Poly(methyl methacrylate) (PMMA) with a narrow molecular weight distribution was obtained by conducting the polymerization in toluene at -80 degrees C. Chain-end analysis revealed the formation of PMMA with a tert-butyl group at the alpha-end and a hydrogen atom at the te-end. These results suggest the living nature of the present polymerization. However, a prolonged polymerization time or elevated temperature caused backbiting reactions. Postpolymerization modification of the formed PMMA was also investigated using TBZL as a transesterification catalyst. Chain-end analysis revealed that terminal-selective transesterification occurred only at the monomeric unit at the terminating chain end. Therefore, TBZL appears to play dual roles in the production of chain-end-modified PMMA: an initiator for anionic polymerization and a catalyst for terminal-selective transesterification.

The development of novel effective antibacterial agents is crucial due to increasing antibiotic resistance in various bacteria. Poly (alkyl cyanoacrylate) nanoparticles (PACA-NPs) are promising novel antibacterial agents as they have shown antibacterial activity against several Gram-positive and Gram-negative bacteria. However, the antibacterial mechanism remains unclear. Here, we compared the antibacterial efficacy of ethyl cyanoacrylate nanoparticles (ECA-NPs), isobutyl cyanoacrylate NPs (iBCA-NPs), and ethoxyethyl cyanoacrylate NPs (EECA-NPs) using five Gram-positive and five Gram-negative bacteria. Among these resin nanoparticles, ECA-NPs showed the highest growth inhibitory effect against all the examined bacterial species, and this effect was higher against Gram-positive bacteria than Gram-negative. While iBCA-NP could inhibit the cell growth only in two Gram-positive bacteria, i.e., Bacillus subtilis and Staphylococcus aureus, it had negligible inhibitory effect against all five Gram-negative bacteria examined. Irrespective of the differences in growth inhibition induced by these three NPs, N-acetyl-L-cysteine (NAC), a well-known reactive oxygen species (ROS) scavenger, efficiently restored growth in all the bacterial strains to that similar to untreated cells. This strongly suggests that the exposure to NPs generates ROS, which mainly induces cell growth inhibition irrespective of the difference in bacterial species and cyanoacrylate NPs used.

Multivariate analysis was applied to nuclear magnetic resonance (NMR) spectra of methacrylate copolymers. Principal component analysis (PCA) of C-13 NMR spectra of linear copolymers of methyl methacrylate (MMA) and tert-butyl methacrylate (TBMA) successfully extracted information on chemical compositions and monomer sequences. Quantitative analysis of the chemical composition and monomer sequence was achieved by partial least -squares (PLS) regression using NMR spectra of the corresponding homopolymers and their blends as a training dataset. PCA was also useful for the extraction of information on chemical composition in branched copolymers prepared by initiator-fragment incorporation radical copolymerization of TBMA and ethylene glycol dimethacrylate with dimethyl 2,2'-azobis(isobutyrate). The chemical compositions and degree of branching were predicted by PLS regression using NMR spectra of the corresponding homopolymers, their blends and branched copolymers as a training dataset. In addition, PCA was found to be a good measure to evaluate the monomer sequence distribution in linear copolymers of MMA and benzyl methacrylate (BnMA) prepared by various polymer reactions. Furthermore, PCA of H-1 NMR spectra of linear copolymers of MMA and BnMA was applied to extract information on chemical compositions and monomer sequences. Monomer reactivity ratios were reasonably estimated from a single sample using the diad sequence distributions predicted by PLS regression.

We describe a new way of understanding enhanced molecular recognition through substrate-additive complex formation and the development of the first catalytic kinetic resolution of alpha-hydroxythioamides, which are versatile synthetic building blocks, using chiral N-heterocyclic carbene-catalyzed enantioselective acylation assisted by a carboxylate additive. Mass spectrometry provided evidence for the role of the additive, which forms a hydrogen-bonded complex with alpha-hydroxythioamide, resulting in both rate and selectivity enhancements. The synthetic applications of the resolved alpha-hydroxythioamides highlight the usefulness of the developed method.

Cationic homopolymerization of a biomass-derived monomer, trans-4-methoxy-beta-methylstyrene (trans-anethole: Ane), was achieved with a combination of bis(trifluoromethylsulfonyl)imide and solvate ionic liquid comprising lithium bis(trifluoromethylsulfonyl)imide and a Lewis base, such as ethyl acetate and diisopropyl ether (iPr(2)O). The number-average molecular weight (M-n) of the obtained poly(Ane) reached 15.6 x 103 by adding iPr(2)O in toluene at -10 degrees C. The solubility of poly(Ane) varied drastically with a change of solvent: the polymers obtained in CH2Cl2 were not completely soluble in common organic solvents such as toluene, chloroform, and tetrahydrofuran, except for 1,1,2,2,-tetrachloroethane (C2H(2)Cl(4)) at 140 degrees C, whereas the polymers obtained in toluene were soluble in these solvents. The 1H NMR spectrum measured in C2D2Cl4 at 140 degrees C revealed that the stereo structure of poly(Ane) depended significantly on the solvent and the temperature: a polymer with a more regulated stereostructure was obtained from polymerization in CH2Cl2 at-40 degrees C than those obtained by polymerization in toluene at-10 degrees C.

A chemometric approach for the quantitative structural analysis of binary blends of copolymers was conducted. Three types of copolymers were synthesized by radical emulsion copolymerization of two out of three monomers—acrylonitrile, styrene, and α-methylstyrene—to prepare three series of binary blends of these copolymers. Partial least-squares (PLS) regression and least absolute shrinkage and selection operator (LASSO) regression were conducted with datasets in which the 1H nuclear magnetic resonance (NMR) spectral matrix of the binary blends (explanatory variables) is combined with the blending parameter matrix (objective variables) of the binary blends. The blending parameters, such as chemical compositions and mole fractions of the component copolymers, were successfully predicted without any assignments of the 1H NMR signals through stepwise optimization of the objective and explanatory variables. LASSO regression exhibited higher accuracy than PLS regression, suggesting that the variable selection in LASSO regression was responsible for the improvement in the quantitative prediction.

Copolymers of methyl methacrylate (MMA) and benzyl methacrylate (BnMA) were prepared by conventional radical copolymerization in toluene at 70 °C. The 1 H nuclear magnetic resonance (NMR) spectra of these copolymers were measured in various solvents at different temperatures. The signals of the methoxy protons in the MMA units and the benzyl protons in the BnMA units showed splitting mainly because of the triad monomer sequences when the temperature was increased to 150 °C in deuterated dimethyl sulfoxide. However, the splitting was not sufficient to determine the molar ratios of the triad sequences. Therefore, multivariate analysis was applied to the 1 H NMR spectra of copolymers with various chemical compositions. Principal component analysis successfully extracted information on the polymer microstructures. Partial least-squares (PLS) regression successfully predicted the mole fractions of the diad monomer sequences. Then, the fractions of the diad sequences in an unknown sample prepared in benzene at 60 °C were predicted using PLS regression to determine the monomer reactivity ratios. Thus, the monomer reactivity ratios were successfully determined from a single sample using multivariate analysis of the 1 H NMR spectra of copolymers of MMA and BnMA.

Low-temperature radical polymerization of achiral N-allyl-N-tert-butylacrylamide (AltBAAm) was conducted in toluene in the presence of chiral tartrates, such as diethyl L-tartrate (L-EtTar) and di-n-butyl L-tartrate. The H-1 NMR spectra of the polymers obtained indicated progress of cyclopolymerization at low temperatures such as -80 degrees C. Optical properties of the poly(AltBAAm)s examined by optical rotation and circular dichroism measurements indicated asymmetric induction in the cyclopolymerization of achiral AltBAAm. For example, addition of L-EtTar at -80 degrees C provided the polymer with specific rotation of - 4.8 degrees. The tert-butyl groups of poly(AltBAAm)s were removed by treatment with CF3SO3H, transforming into poly(N-allylacrylamide)s [poly(AlAAm)s]. Then, stereochemistry in the stereorepeating unit was investigated by comparing H-1 NMR signals of the poly (AlAAm)s with those of model compounds, cis- and trans-3-ethyl-4-methyl-2-pyrrolidones. Taking the negative specific rotation values of the poly(AltBAAm)s obtained with L-tartrates into account, it was revealed that (3S,4S)-trans-unit was predominantly formed through the hydrogen-bond-assisted complex formation of AltBAAm with L-tartrates.

Radical copolymerizations of N-ethylacrylamide (NEAAm) and N-isopropylacrylamide (NIPAAm) at various ratios were conducted in N-ethylacetamide at -40 degrees C to prepare isotactic copolymers with mm triad contents of 48.7%-50.8%. The temperature-induced phase transition behaviors of their aqueous solutions were investigated using light transmittance (500 nm) and dynamic light scattering. Reversible and sharp phase transitions were observed in the transmittance of aqueous solutions (1.0 wt%) of copolymers with NIPAAm compositions of <= 9.1 mol%. The phase transition temperatures in both the heating and cooling processes gradually decreased with increasing hydrophobic NIPAAm composition. However, copolymers with NIPAAm compositions of 13.9-28.0 mol% exhibited large hystereses (ca. 40 degrees C) in which the phase transition temperature in the cooling process dramatically decreased. Furthermore, the copolymer with NIPAAm composition of 37.8 mol% was insoluble in water. Syndiotactic poly(NEAAm-co-NIPAAm)s were soluble in water and showed reversible and sharp phase transitions regardless of the NIPAAm composition, which indicates that stereostructure plays an important role in the induction of unusually large hysteresis. Dynamic light scattering analysis suggested that the dehydrated polymers were swollen in the cooling process, even below the phase transition temperature in the heating process, likely because of the cross-linking domain formed by isotactic NIPAAm segments with hydrophobic interaction in the dehydrated state.

Radical polymerization of N-allylmethacrylamide (NAlMAAm) was conducted in CH3CN in the presence or absence of lithium bis(trifluoromethanesulfonyl)imide (LiNTf2). The addition of LiNTf2 accelerated the polymerization and affected the molecular weight distribution of the polymers obtained. Polymers with unimodal molecular weight distributions were obtained in the presence of LiNTf2, whereas those with multimodal distributions were obtained in the absence of LiNTf2. This suggested that LiNTf2 suppressed side reactions such as cross-linking reaction, commonly observed in polymerization of divinyl monomers, and allylic hydrogen abstraction reaction. The 1H NMR, IR and MALDI-TOF mass analyses of the polymers obtained suggested that the radical polymerization proceeded in a chemoselective manner, leading to preferential formation of linear polymers having pendant allyl groups.

The stereochemical analysis of polymers derived fromN,N-disubstituted acrylamides is usually difficult. The diad tacticity can be determined from the(1)H nuclear magnetic resonance (NMR) signals of the main-chain methylene groups. However, the splitting because of the configurational sequences is poor, even in(13)C NMR, which does not allow determination of the tacticity at the triad level. In contrast, the stereochemical analysis of polymers derived fromN-monosubstituted acrylamides is easily conducted and the triad tacticity can be determined from the(13)C signals of the main-chain methine groups. Thus, stereochemical analysis ofN,N-disubstituted polymers should be able to be conducted if the polymers are transformed intoN-monosubstituted polymers with retention of the configurational sequence. Poly(N-tert-butyl-N-n-propylacrylamide) was radically prepared, and de-tert-butylation was conducted by treatment with scandium triflate in a mixed solvent of CH3CN and 1,4-dioxane at 50, 80, and 110 degrees C.H-1 NMR analysis of the resulting polymers indicated quantitative conversion after 72 hr, regardless of the temperature.C-13 NMR analysis of the transformed polymers confirmed that the configurational sequences were retained during the reaction. Thus, the triad stereochemical analysis ofN,N-disubstituted polymers was successfully conducted by de-tert-butylation as a polymer reaction, followed by(13)C NMR analysis of the transformed polymers.

Most practical synthetic polymers are copolymers. The copolymerization of monomers with different reactivities proceeds through a complicated reaction process, and it is therefore not uncommon that the chemical composition of the resulting copolymer varies between a high molecular weight region and a low molecular weight region. SEC-NMR and DOSY are useful methods for investigating the molecular weight dependence of the composition of a copolymer. In this chapter, SEC-NMR and DOSY experiments on ethylene–propylene–diene rubbers and acrylate copolymers are described and the characteristic features of each measurement method are explained. Applications of SEC-NMR and DOSY using new hardware such as cryogenically cooled probe technology or high field-gradient systems to the analysis of copolymers are also described.

The physical properties of poly(lactic acid) (PLA) are influenced by its stereoregularity and stereosequence distribution, and its polymer stereochemistry can be effectively studied by NMR spectroscopy. In previously published NMR studies of PLA tacticity, the NMR data were fitted to pair-addition Bernoullian models. In this work, we prepared several PLA samples with a tin catalyst at different L,L-lactide and D,D-lactide ratios. Upon analysis of the tetrad intensities with the pair-addition Bernoullian model, we found substantial deviations between observed and calculated intensities due to the presence of transesterification and racemization during the polymerization processes. We formulated a two-state (pair-addition Bernoullian and single-addition Bernoullian) model, and it gave a better fit to the observed data. The use of the two-state model provides a quantitative measure of the extent of transesterification and racemization, and potentially yields useful information on the polymerization mechanism.

The solution-state NMR measurement of a synthetic polymer in sub-critical fluids has been accomplished by taking advantage of the specially-designed high-pressure and high-temperature NMR probe. The purpose here is to overcome the signal broadening typically occurring in conventional solution-state NMR due to the slow dynamics of polymers at room temperature. A remarkable sharpening of the 1H NMR signal was observed for poly (N-vinyl-2-pyrrolidone) dissolved in D2O at 250°C. This result has encouraged us to apply high-temperature NMR methods to polymers, such as copolymers, whose spectra were too complicated to be deconvoluted by means of conventional procedures.