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Polylactide (PLA) stereocomplexes (SCs) formed by poly(L,L-lactide) (PLLA) and poly(D,D-lactide) (PDLA) are well known, and their derivatives and copolymers have also been reported. However, little research has been conducted on SCs with a combination of one enantiomer of a copolymer and a homopolymer. In this study, we selected a PLA copolymer with poly(ethylene glycol) (PEG) and a urethane capping PLA bearing almost the same molecular weights as PLA segments and prepared various SC samples. Depending on the combination of L-isomers and D-isomers, the SCs were classified as a Homo-SC, Co-SC, and Multi-SC: the Homo-SC had the same polymer chain ends and copolymers, the Co-SC had different polymer chain ends and copolymers, and the Multi-SC had a mixture of various polymer chain ends and copolymers. Depending on the chain end structures, the melting points of the SCs changed in the case of Homo-SC and Co-SC, but Multi-SC showed two broad melting points at ~200 °C. We propose that these findings are the results of the various combinations of polymer–polymer interactions in the case of Multi-SC. We selected a polylactide (PLA) copolymer with poly(ethylene glycol) (PEG) and a urethane capping PLA and prepared various stereocomplex (SC). Depending on the combination of L-isomers and D-isomers, the SCs were classified as Homo-SC, Co-SC, and Multi-SC: Homo-SC by the same polymer chain ends and copolymers, Co-SC by different polymer chain ends and copolymers, and Multi-SC by a mixture of various polymer chain ends and copolymers. Multi-SC showed two broad melting points at around 200 °C, suggesting the various combinations of polymer–polymer interaction in the case of Multi-SC.

Poly(N-vinylamide) derivatives were synthesized to improve the performance of kinetic hydrate inhibitors (KHIs). In this work, we synthesized poly(N-vinylformamide) (PNVF) and poly(N-vinylcaprolactam) (PVCap) by free radical polymerization with several commercial chain transfer agents (CTAs), which afforded a few thousand Mn. The structures of synthesized PNVF and PVCap were then investigated by 1H NMR and MALDI-TOF/MS spectrograms. KHI properties of the synthesized PNVF and PVCap polymers were also evaluated by the high-pressure slow constant cooling KHI test method. Some of the tested polymers showed a better KHI effect than PVCap.

To modify the flexibility of chitosan (CS), poly(trimethylene carbonate) (PTMC) and its derivatives and copolymers were blended with a chitosan derivative, N,N,N-trimethylchitosan (TM-CS). The tensile strength of the CS and TM-CS films blended with PTMC was found to cause brittleness, but a PTMC derivative copolymer bearing carboxylic acid improved the elongation properties of TM-CS. A softer film was obtained for a blend film composed of TM-CS with 25% consisting of an added PTMC derivative copolymer bearing a 10% carboxylic acid moiety on the side chain. This film showed an elongation at break of 20.6 ± 9.3% with a tensile strength of 2.2 ± 0.83 MPa, while the original CS and TM-CS films showed an elongation at break of 7.4 ± 3.4% and 9.2 ± 1.6% with a tensile strength of 13.6 ± 1.0 MPa and 3.7 ± 0.35 MPa, respectively. This is the first report of the modification of CS using polymers with a PTMC backbone. Poly(trimethylene carbonate) (PTMC) based polymers were blended with N,N,N-trimethylchitosan (TM-CS). The tensile strength of the chitosan (CS) and TM-CS films blended with PTMC was found to cause brittleness, but a PTMC derivative copolymer bearing carboxylic acid improved the elongation properties of TM-CS. A softer film was obtained for a blend film composed of TM-CS with 25% consisting of an added PTMC derivative copolymer bearing a 10% carboxylic acid moiety on the side chain. This is the first report of the modification of CS using polymers with a PTMC backbone.

The radical copolymerization on α-substituted fluoroalkyl acrylate (FA) monomer bearing C4, C6, and C8 as perfluoroalkyl (Rf) groups, as well as the variation of α-substituents, hydrogen, methyl, and chlorine with styrene was investigated. Q-e values and monomer reactivity ratio of FA monomers were estimated. When the alpha position of FA monomer of C6 as Rf group was changed from −H to −CH3, the e value decreased from 0.85 to 0.60. The substituent of −Cl resulted in an e value of 1.06. The Q values were also markedly changed. When the alpha position was changed from −H to −CH3, the Q value increased from 0.38 to 0.79. The substituent of −Cl resulted in a Q value of 2.90. The copolymer composition of α-substituted FA monomers with stearyl acrylate (C18A) was simulated. The obtained results revealed that a chlorine substituent at the alpha position emphasizes the polymerization which would contribute to a novel material design containing a fluorine side chain in a monomer structure.

Novel poly(e-caprolactone) (PCL)–glycerol polyester was synthesized in one step in the presence of Novozym 435 under mild reaction conditions. The objective of the study was to investigate the feasibility of enhancing the hydrophilicity of PCL by condensing it with glycerol through biocatalytic approach. Effect of reaction time, glycerol-to-CL ratio and CL-to-toluene ratio was studied. The 1H NMR and GPC results established that self-condensation of CL units and condensation of CL with glycerol units take place simultaneously. When the glycerol content was 10 and 20 mol% with regard to CL, condensation continued for 6 h; further extension of reaction time resulted in the cleavage of ester linkages. When the glycerol content was increased to 40 mol%, the condensation of CL–glycerol units was accomplished in 4 h; however, the reaction had to get extended beyond 6 h for complete condensation of CL–CL units. The study revealed that the crystallinity and the melting temperature (Tm) of the products altered with an increase in the glycerol content. Furthermore, TGA and contact angle values of water on PCL and its glycerol derivative films revealed that the water uptake capacity of PCL too increased significantly with the increase in glycerol content, rendering PCL more hydrophilic.

The organogels poly(styrene-co-divinylbenzene), PS gel (1); poly(styrene-co-divinylbenzene-co-vinylpyridine), PS-VP gel (2); poly(styrene-co-divinylbenzene-co-vinylbenzoic acid), PS-VBA gel (3); and poly(styrene-co-divinylbenzene-co-styrenesulfonate), PS-SS gel (4) were prepared with limonene by varying the concentration of cross-linker and comonomer to control the properties of the gels. Limonene was used as the swelling solvent due to its low toxicity and environmental friendliness. Additionally, 4-vinylpyridine (VP), 4-vinylbenzoic acid, and 4-styrenesulfonate were introduced as cationic and anionic moieties to act as interaction units. An increase in the divinylbenzene ratio improved the mechanical strength, as evidenced by an increase in the G′ value; for example, the G′ of gel 3 improved from 15,000 Pa with 5% cross-linking to 93,000 Pa with 10% cross-linking. However, the increased cross-linking reduced the solubility in limonene, resulting in a decrease in the swelling ratio from 1.5 to 0.7. Cationic gel 2 can adsorb anionic compounds, while anionic gel 4 can adsorb cationic compounds. Gel 2 with 5 mol% VP was able to adsorb approximately 4.4 mg/g of an anionic dye, while gel 4 with 5 mol% SS was able to adsorb approximately 6.6 mg/g of a cationic dye. The limonene organogels were used for lipophilic drug storage and the controlled release of testosterone due to their dense polymer network.

In this paper, we present a different approach of coating a phase change material (PCM) for a possible use in thermal energy storage. We focused on layer-by-layer coating of pentaerythritol (PE) particles, which was achieved through stereocomplex formation of isotactic (it-)poly(methyl methacrylate) (PMMA) and syndiotactic (st-)PMMA as coating materials. As a model system, a quartz crystal microbalance (QCM) was covered by PE and subsequently coated by alternated dipping into solutions of it-PMMA and st-PMMA in hexane/acetonitrile (1/9, v/v). Frequency shifts in each step were calculated using Sauerbrey’s equation and specific peaks of PE, PMMA, and PMMA stereocomplex were detected by FT-IR. The results indicate a stepwise formation of PMMA stereocomplex onto the PE substrate covering the QCM. Furthermore, PE particles were prepared by homogenization and coated by alternating submersion in solutions of it-PMMA and st-PMMA in hexane/acetonitrile (1/9, v/v). After 20 cycles resulting in 40 PMMA layers, IR measurements of the particles showed the specific peaks for PE, PMMA, and PMMA stereocomplex. SEM pictures of uncoated PE particles and of residues of the coated particles after washing out the PE by water/methanol (water/MeOH) were compared to confirm the successful coating. With this basic demonstration of the processes feasibility for the abovementioned materials, the enhanced PCMs could be developed for the use in thermal energy storage.

Poly(methacrylic acid-co-2-aminoethyl methacrylate) (MAA-AMA) was simply synthesized by free radical polymerization. Immobilization of 2,4-dihydroxybenzaldehyde on MAA-AMA was done via Schiff base formation to obtain MAA-AMA(BZ). The qualitative and quantitative analyses of immobilization were done by nuclear magnetic resonance spectroscopy. The degree of immobilization of 2,4-dihydroxybenzaldehyde on MAA-AMA was 16–18%. Surface charge and particle size of MAA-AMA(BZ) is pH sensitive. In addition, intermolecular amidation provided cross-link structure at pH 12. The MAA-AMA(BZ) acted as an antifungal against Aspergillus genus with a percentage efficiency up to 25% against A. fumigatus.

The inkjet printing technique is potentially applicable for the formation of polymer stereocomplexes and can control the amount, thickness and structure of the printed polymers. Stereocomplexes of polylactides (PLAs) with both terminals conjugated to aromatic groups were easily formed via casting or inkjet printing methods based on even layer-by-layer assembly and solution mixing, indicating that the stereocomplex formation was not influenced by the conjugation groups at both chain ends of the PLAs. Their formation was confirmed through Fourier transform infrared (FT-IR), X-ray diffraction (XRD) and differential scanning calorimetry (DSC) analyses as well as direct observation of melting behavior using a hot plate. The 10% weight loss thermal decomposition temperature (T10) of the stereocomplexes showed an increase of more than 90 °C compared with those of the corresponding original PLAs. PLA stereocomplexes with conjugation of both terminals that are formed via inkjet printing may be useful as highly thermally stable materials in various fields, especially in nanoscale situations. Inkjet printing is a facile method for covering substrates with thermally resistant PLA stereocomplexes with conjugation of both terminals. Stereocomplexes of polylactide with both terminals conjugated to bio-based aromatic compounds, with benzyl alcohol (b1) as an initiator and 3,4-diacetoxycinnamic acid (DACA) as a protection group, were easily formed via inkjet printing techniques based on even layer-by-layer assembly (DACA-SCb1-LbL) and solution mixing (DACA-SCb1-mix). The thermal properties of the stereocomplexes were superior to those of the original PLAs. Inkjet printing is a powerful method of forming functional, thermally stable PLA stereocomplexes with both terminals conjugated.

This review focused on the various polymers composed of trimethylene carbonate (TMC) units and ethylene glycol (EG) units. Poly(TMC) is a biodegradable polymer that is used in biomedical materials. It has been reported that its combination with oligo(EG) and poly(EG) would offer a useful approach. In addition, monomer design and polymer reactions are available. These polymers, including TMC and EG units, are useful in preparing various nanostructures and they have the potential for application in biomedical materials.

The androgen testosterone is less expensive than bone morphogenetic proteins and has been shown to effectively repair bone fractures. However, testosterone is lipophilic and insoluble in water, making it difficult to load into hydrogels, which are common drug carriers. In this study, we prepared a novel oil gel composed of poly(L-lactide) and a poly(trimethylene carbonate) derivative and studied the release of testosterone from the gel. Dimethyl sulfoxide and dimethyl carbonate, which are organic solvents with relatively low toxicities, were used as dispersion media. The oil gel in dimethyl sulfoxide released testosterone faster than that in dimethyl carbonate. In addition, the dimethyl carbonate oil gel was vacuum-dried to reduce the gel porosity and thus slow testosterone release. Therefore, oil gel is a promising substrate for lipophilic drugs, including testosterone. In this study, we prepared a novel oil gel composed of poly(L-lactide) and a poly(trimethylene carbonate) derivative. We investigated the release of testosterone, an inexpensive therapeutic drug for the segmental defect of bones, from the gel. Dimethyl sulfoxide and dimethyl carbonate, which are organic solvents with relatively low toxicities, were used as dispersion media. The oil gel in dimethyl sulfoxide released testosterone faster than that in dimethyl carbonate. In addition, the dimethyl carbonate oil gel was vacuum-dried to reduce the gel porosity and resulted in slow testosterone release.

Thermal and photo responsive copolymer based on N-vinylamide backbone was designed. Methoxyethyl group and azobenzene were selected to improve hydrophilicity and photoresponsive moieties, respectively. The N-(methoxyethyl)-N-vinylformamide was synthesized and copolymerized with N-vinylformamide by free radical polymerization. In order to control the nanosized structures, poly(N-vinylformamide) derivatives bearing azobenzene at the N-position near to the vinyl polymer main chain were synthesized by polymer reaction with the poly(N-vinylformamide-co-N-(methoxyethyl)-N-vinylformamide) and azobenzene. Aggregation size of the multi-stimuli-responsive polymer was controlled by preparation of the hydrophobic interaction at around N-position. Electronic supplementary material The online version of this article (doi:10.1186/s11671-017-2221-7) contains supplementary material, which is available to authorized users.

Using the syndiotactic-rich poly(methacrylic acid) (PMAA), the stereocomplex formation and template effect were investigated. The partially irregular porous isotactic poly(methyl methacrylate) (PMMA) film, which was prepared by syndiotactic-rich PMAA and isotactic PMMA with layer-by-layer method, incorporated the large amount of syndiotactic PMAA, while the template polymerization of methacrylic acid in the porous film did not achieve high syndiotactic PMMA synthesis. The present results suggested the difference of the monomer–polymer interaction and polymer–polymer interaction of PMMA stereocomplex.

The novel thermoresponsive polycations poly(N-vinylbutyramide-co-vinylamide) (poly(NVBA-co-VAm)), with different mole ratios of poly(VAm) (PVAm):poly(NVBA) (PNVBA), were synthesized as a biomaterial by free radical copolymerization of poly(N-vinylbutyramide-co-N-vinylformamide) (poly(NVBA-co-NVF), followed by acid hydrolysis. Such poly(N-vinylamide)s do not generate toxic low-molecular-weight amine compounds by hydrolysis, although the poly(acrylamide) structural isomers do. The mole ratio of PVAm and PNVBA was varied by adjusting the NVF:NVBA mol% feeding ratio used in the copolymerization. The lower critical solution temperature (LCST) of the obtained copolymers was investigated and compared with that of PNVBA. PNVBA showed an LCST of 32 °C, while that for poly(NVBA-co-VAm) increased as the VAm mole ratio increased (due to the increasing hydrophilicity), and the more physiologically relevant temperature (for humans) of 36.5 °C was obtained at a VAm mole ratio of 5%. Furthermore, the LCST of these copolymers not only depended on the VAm mole ratios but also on the pH, the concentration of the copolymer solution and ionic strength. Variation in the copolymer LCST could lead to several applications, especially for copolymers with an LCST value around physiological temperature that would potentially be of merit for a controlled drug or biomolecule delivery system. The novel thermoresponsive polycation, poly(N-vinylbutyramide-co-vinylamide) (poly(NVBA-co-VAm)), was synthesized by free radical copolymerization of poly(N-vinylbutyramide-co-N-vinylformamide) (poly(NVBA-co-NVF), followed by acid hydrolysis. The mole ratio of PVAm and PNVBA was varied by adjusting the feeding ratio of NVF and NVBA. PNVBA showed a lower critical solution temperature of 32 °C, while that for poly(NVBA-co-VAm) increased as the VAm mole ratio increased owing to the increasing hydrophilicity, and the more physiologically relevant temperature of 36.5 °C was obtained at a VAm mole ratio of 5%.

Copolymerization of polydimethylsiloxane (PDMS) macromer having two molecular weight (Mn), two types of methacrylate and crosslinker was conducted. The crosslinked copolymer was analyzed with 13C solid-state NMR to investigate the relationship between copolymers compositions and physical properies by molecular level approach. The T1H, T1ρH, and T1ρc values suggested the influence of PDMS Mn and methacrylate type on microstructure, mobility, and morphology change. Thus the present analysis contributes to a better understanding of the physical characteristics on the crosslinked methacrylates-siloxane copolymers.

Morphological changes of macromolecularly porous thin films during isotactic (it) poly(methyl methacrylate) (PMMA) crystallization and the subsequent syndiotactic (st) poly(methacrylic acid) (PMAA) incorporation are described herein. Porous it-PMMA thin films were prepared on a gold substrate by the selective extraction of st-PMAA from stereocomplex films composed of it-PMMA/st-PMAA using layer-by-layer assembly. it-PMMA crystallization occurred when the porous it-PMMA films were immersed in a mixed solvent of acetonitrile/water (4/6, v/v). Surface analyses of films were performed by scanning electron microscopy, atomic force microscopy, X-ray photoelectron spectroscopy (XPS) and static contact angles. Dotted aggregates of it-PMMA appeared on crystallized films, whereas networks composed of crystallized it-PMMA and the stereocomplex were observed on st-PMAA incorporated films. Gold substrate peaks were observed not on porous it-PMMA films, but on crystallized it-PMMA films by XPS, indicating that homogeneously broadened it-PMMA in porous films was localized because of its crystallization. The static contact angle of crystallized it-PMMA films was 36.5±1.6°, which was smaller than that of porous it-PMMA films (49.2±1.9°). This difference resulted from the surface morphology of the thin films. Dotted it-PMMA aggregates were also observed when spin-coated films were immersed in the mixed solvent. Morphological changes of macromolecularly porous thin films in it-PMMA crystallization and subsequent st-PMAA incorporation

Macroporous Silicagel Substrate for Stereoregular Template Polymerization of Methacrylic Acid Using Stereocomplex Assembled Thin Films

The novel styrene derivatives bearing various amino groups at ortho-position, 2-(1-indolinyl)methylstyrene (2), 2-(9-carbazolyl)methylstyrene (3), 2-(N,N-diphenylamino)methylstyrene (4), 2-(N-3-methoxyphenyl-N-phenylamino)methylstyrene (5), and 2-(N-3-methylphenyl-N-phenylamino)methylstyrene (6), were synthesized and polymerized with radical and anionic initiations. As the bulkiness of the substituents at the ortho-position increased, the polymerizabilities of these monomers during the radical and anionic methods significantly decreased. The anionic polymerization of 4–6 with the n-butyllithium (−)-sparteine complex in toluene at 0 °C afforded the optically active polymers ([α]25365 +48° to +22°), whereas no optical activity was observed for the polymers of 2 and 3 obtained under the same conditions. The optically active polymers likely have a chiral helical conformation which is related to a high stereoregularity.

The asymmetric oxidative coupling polymerization of (R)- and (S)-3,3’-dihydroxy-2,2’-dimethoxy-1,1’-binaphthalene 1 and (S,S)-, (R,R)-, and (S,R)-3,3”-dihydroxy-2,2’,3’,2”-tetramethoxy-1,1’ : 4’,1”-ternaphthyl with the CuCl-2,2’-isopropylidenebis(4-phenyl-2-oxazoline) (Phbox) catalyst was performed to stereoselectively obtain poly(2,3-dihydroxy-1,4-naphthylene) derivatives. The polymerization with the bisoxazoline proceeded in a ligand controlled manner regardless of the monomer stereostructure in contrast to that using diamines, such as N,N,N’,N’-tetramethylethylenediamine, which afforded polymers under substrate control. For example, the polymerization of (R)- and (S)-1 with (S)Phbox produced the polymers with preferential …SSSS… and …RSRS… chain structures, respectively.

Three ortho-substituted styrenes, 2-[(S)-2-(1-pyrrolidinylmethyl)-1-pyrrolidinylmethyl]styrene (1), 2-[(S)-2-(methoxymethyl)-1-pyrrolidinylmethyl]styrene (2), and 2-[(S)-2-(N,N-diethylaminomethyl)-1-pyrrolidinylmethyl]styrene (3), were synthesized, and the effects of the ortho-substituents on polymerizability and the stereoregularity and chiroptical property of the polymers obtained by anionic method were examined. The anionic polymerization of 1–3 with n-BuLi in toluene at 0°C gave optically active polymers in good yields. Although the polymer obtained from 2 with n-BuLi at 0°C showed a low stereoregularity, the anionic polymerization of 1 and 3 gave the polymers with a high stereoregularity, which was supported by 13C NMR analysis. The poly(1) and poly(3) are likely to have regular conformation. Enantioselective oxidative coupling of a naphthol derivative was carried out using poly(1)s as a chiral ligand to obtain a corresponding 2,2’-binaphthol derivative.

Surface Structure Control of Macroporous Silica Gel by Atom Transfer Radical Polymerization