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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.

Three crosslinked films with different ratios of hydrophilic and hydrophobic monomers were prepared using trimethylene carbonate backbone with ester free structure. Oligo(ethylene glycol) (OEG) was...

This study describes the long-distance diastereomeric effect on thermoresponsive properties in water-soluble diastereomeric polyurethanes (PUs) composed of an L-lysine ethyl ester diisocyanate and a trimethylene glycol L-/D-tartrate ester, which have differences in spatial arrangements of the ethyl esters in the mirror image. The PUs based on L-lysine and L-/D-tartrate ester, named L-PU and D-PU, were synthesized with various number average molecular weights from 4700 to 13 100. In turbidimetry, L-PU showed a steep phase transition from 100%T to 0%T within about 10 °C at 4 g L−1, whereas D-PU did not change completely to 0%T transmittance even at 80 °C at 4 g L−1. In addition, the thermoresponsive properties of L-PU were less affected by concentration than those of D-PU. This long-distance diastereomeric effect on thermoresponsive behavior between L-PU and D-PU appeared in common among 6 samples with 4700 to 13 100 number average molecular weight. In the dynamic light scattering experiments at each transmittance, the hydrodynamic diameter (Dh) of l-PU increased up to 1000 nm, while the Dh of D-PU remained almost at 200–300 nm. The CO stretching vibration of FT-IR spectra showed that D-PU has more hydrogen-bonded ester groups than L-PU. Thus, we speculated that the difference in the retention of polymer chains in the micelle to promote intermicellar bridging generates the long-distance diastereomeric effect.

Thermosensitive poly(N-vinylamide) derivatives bearing an oligo ethylene glycol (OEG) chain at the N-position were designed for development of a kinetic hydrate inhibitor (KHI). Novel N-vinylamide monomers bearing an OEG chain at the N-position were synthesized and copolymerized with N-vinylformamide (NVF) or methyl N-vinylacetamide (MNVA) by free radical polymerization. Then, thermosensitive behaviors, such as lower critical solution temperature (LCST), of the synthesized poly(N-vinylamide) derivatives were investigated by light transmittance and DSC measurement. The LCST values were observed over a wide temperature range from 45 to 90 °C due to the ethoxy OEG chain at the N-position. Their phase transition properties were investigated under dilute condition by light scattering measurement. Furthermore, KHI values of the synthesized polymers were evaluated by the THF hydrate crystal growth method. On the basis of these results, it is expected that the polymers of synthesized poly(N-vinylamide) derivative...

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.

Our ultimate goal is to create a library of ester-free type trimetylene carbonate derivatives, so that we can design and produce poly(trimethylene carbonate) (PTMC) derivatives that meet application needs. Herein we introduced cycloalkyl groups (cyclopentyl, cyclohexyl and cycloheptyl groups) into the side chain of an ester-free type PTMC. Previously, ester-free type PTMC derivatives with aromatic rings in the side chain have been reported from our group, but there have been no reports of aliphatic cyclic compounds introduced with ether linkage into their side chains. This research makes possible the production of more versatile ester-free PTMC derivatives using cycloalkyl groups. The effect of ring size was also investigated. All of the monomers gave homopolymers with Mn of a few thousands, improving the thermal degradation temperatures, compared to unmodified PTMC. We found a tendency towards increasing glass transition temperature with larger ring size.

In order to create a novel rigid polymer material for biomedical application, we designed the polymer structure of polyurethane, bearing oligo(ethylene glycol) (OEG) as the side chain, which was synthesized by only hard main chain using diisocyanate and short diol monomers. We investigated the effect of the graft structure of OEG units on polymer properties using pentaethylene glycol (OEG5) or propanediol (PDO) in the main chain as the other diol monomers. Furthermore, the rigid 4,4′-methylenebis(cyclohexyl isocyanate) (HMDI) and symmetric hexamethylene diisocyanate (HDI) were selected for the isocyanate monomers. As a result, there is a significant difference in various properties, depending on both the existence and the position of OEG units in the polymer structure. For example, differential scanning calorimetry (DSC) showed that the graft structure of OEG caused a decrease in the glass transition temperature from 73 to 35 °C in the case of using HMDI as well as a disappearance of the melting point in ...

Poly(trimethylene carbonate) (PTMC) is a well-known biodegradable polymer with good biocompatible properties which make it suitable for biomedical applications. Poly(5-[2-{2-(2-methoxyethoxy)ethyoxy}-ethoxymethyl]-5-methyl-1,3-dioxa-2-one) (PTMC-MOE3OM) and copolymers, bearing oligo ethylene glycol (OEG) at the side chain of PTMC backbone, were selected to investigate the cloud point behavior by solvents such as PBS, water, 10% ethanol solution and various ionic strengths. A pH-responsive copolymer, poly(TMCM-MOE3OM-co-(5-methyl-5-carboxylic-1,3-dioxane-2-one)) as carboxylic acid carbonate showed a decreased critical temperature at pH 2. Photo-responsive copolymer, poly(TMCM-MOE3OM-co-coumarin derivatives) bearing 1% and 10% of photo-induced molecules (7-[(5-(5-methyl-1,3-dioxa-2-one)methoxy)]-methoxy coumarin (TMCM-coumarin)) exhibited a low cloud point because of the hydrophobic moieties. Meanwhile, alternative coumarin polymer including 2% of 4-methyl-7-[(5-(5-methyl-1,3-dioxa-2-one)methoxy)butoxy)]-methoxy coumarin (TMCM-4-methyl-coumarin) has been successfully synthesized and copolymerized as a novel molecule. The various combinations of monomers were studied and the significant properties were determined via external triggers after copolymerization. This study showed basically synthetic progress toward designs and trivial rationalization of thermoresponsive copolymers close to body temperature. At present, various pendant groups as side part affect to the lower critical solution temperature (LCST) and biodegradable polymer in order to utilize the actual external stimuli application. © 2017 Wiley Periodicals, Inc. J. Polym. Sci., Part A: Polym. Chem. 2017, 55, 3466–3474

In the creation of controllable selective adhesive materials, we have utilized a stereocomplex (SC) on an adhesive interface. We selected poly(L,L-lactide) (PLLA) and poly(D,D-lactide) (PDLA) initiated benzyl alcohol (PLLAb and PDLAb, respectively) as a substrate and gold nanoparticle-coated PLLA and PDLA (PLLA-Au and PDLA-Au, respectively) as an injection material. Before performing measurements, SC formation was examined via Fourier Transform Infrared Spectroscopy (FT-IR), X-ray diffraction (XRD), and Differential Scanning Calorimetry (DSC). Subsequently, the force acting on the interface after drying additional chloroform between two substrates was measured using lap-shear testing by changing the molecular weight of the PLLA and PDLA adsorbed on gold nanoparticles or the gold nanoparticle concentration. As a result, it was found that optimal conditions exist to show differences. Additionally, until present SC formation has required an organic solvent such as chloroform or acetonitrile. We have discovered that SC formation can be induced using novel organic solvents approved by the Food and Drug Administration (FDA). We anticipate applications for this study in the creation of biodegradable medical adhesive materials where these materials can be released based on environmental considerations using the selective adhesion behavior and induce SC formation through the use of novel solvents.

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.

Route of preparation can be an important step in producing safe and effective controlled-release drug vehicles. We now describe a novel class of hydrogels based on biodegradable amphiphilic polymers consisting of hydrophobic poly( l -lactic acid) and hydrophilic poly(sarcosine). The hydrogels were prepared by initially dissolving the polymers in methanol, ethanol, and butanol, which are also amphiphilic. Transmission electron microscopy revealed that the hydrogels consist of self-assembled nanofibers, with a dynamic modulus greater than the loss elastic modulus over a range of stress cycles at different frequencies. Differential scanning calorimetry indicated that the hydrogels contain stable poly( l -lactic acid) crystals. Importantly, the hydrogels did not elicit irritation in a 3D model of the human corneal epithelia, and suppressed, by more than 20%, the initial drug burst typically associated with controlled-release vehicles already on the market. Hence, the hydrogels show promise as a new class of controlled-release drug delivery systems.

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.

The chemical modification of the polymer chain end group of polylactide is important for the development of nanostructural materials. Herein, the first example of dual dynamic functionality in polylactides bearing vanillin at the chain end is first demonstrated. The first function, stereocomplex formation of both enantiomeric polymers, results in an enhancement in thermal resistance, while the second creates reversibility through amine–imine transformation. This transformation self-assembles into interesting morphologies, including raindrop-like nanoparticles observed on imine formation, and spider-web-like fibrous ones observed on aldehyde formation from hydrophobic–hydrophilic stimuli by acid. These properties indicate that the present polymer shows dual dynamic building block moiety properties, composed of the natural products.

Macroporous silica gel was employed for layer-by-layer (LbL) film preparation of isotactic- (it-) poly(methyl methacrylate) (PMMA) and syndiotactic- (st-) poly(methacrylic acid) (PMAA). The extraction of macroporous silica gel by fluorine hydride resulted in macroporous replica particles, confirmed by SEM. The further extraction of st-PMAA from their particles gave the macroporous replica consisting of porous it-PMMA films. The obtained porous it-PMMA films as macroporous replica particles showed the re-incorporation of st-PMAA. Therefore, the structure of the porous it-PMMA film was stabilized by the macroporous particle structure, although they did not include substrate. The physically crosslinked network structures maintained the molecular porous structures, without a chemically crosslinked reaction.

The stereocomplex formation of poly(l,l-lactide) (PLLA) and poly(d,d-lactide) (PDLA) was selected in order to investigate the interaction of the two surfaces including hydrogen bonding and van der Waals interaction. Adhesion force measurement using surface force apparatus (SFA) equipped with an optical microscope was conducted on the PLLA and PDLA spin-coated films. The adhesion forces, Fad, phenomenologically followed the linear relation with the applied normal load, L. For the force Fad between PLLA and PDLA films with low molecular weights (PLLA, Mn = 2800; PDLA, : Mn = 2100), the slope of linear fitting of Fad vs L was significantly larger for the heterointerface (PLLA/PLDA) compared with that for the homointerface (PLLA/PLLA and PDLA/PDLA). However, when polymers with higher molecular weights (PLLA, Mn = 8500; PDLA, Mn = 8300) were measured, the slopes of linear fitting lines were almost the same for hetero- and homointerfaces. This indicated that the mobility of the lower molecular weight PLLA/PDLA films promoted the selective interaction of PLLA and PDLA under the applied normal loads. The adhesion between the outermost PLLA layer and PDLA layer prepared by layer-by-layer (LbL) assembly was also measured. It is interesting that the adhesion force was very weak in this case. This weak adhesion could be explained by the much less mobility of the polymer chain due to the stereocomplex formation within the LbL layers. This study demonstrated that the adhesion force due to the selective interaction of PLLA and PDLA between PLLA/PDLA films could be directly measured, and depended on the mobility of the outermost polymer chains, which reflected the different structures of polymer chains in the organized complex films.

Poly(trimethylene carbonate) (PTMC) is a biodegradable polymer which doesn’t generate any acidic organic compounds after hydrolysis, leading to good biocompatible properties and biomedical application. Poly(TMCM-MOE3OM) and poly(TMCE-MOE4OM), bearing oligo ethylene glycol (OEG) at the side chain of PTMC, were selected to investigate in vitro accelerating hydrolysis behaviors at pH = 7.4 in a phosphate-buffered solution (PBS) through the use of Lipase and NaOHaq. Their degradation behaviors were in contrast to that of PTMC, resulting in the fast degradation in NaOHaq. and the slow degradation by Lipase. The contrast in results of degradations are due to the side chain of hydrophilic OEG which should interact with degradation species.

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.

In order to develop functional polymers using polylactide (PLA), it has been paid attention to use various initiators for ring-opening polymerization, because the polymer backbone could not be modified if a stereocomplex formation was applied. Herein, we prepared a novel class of PLA stereocomplex with vinyl groups at chain ends, using allyl alcohol, malic acid, and citric acids. The initiators, triallyl citrate (TACA), diallyl malic acid (DAMA), and allyl alcohol (Alc), indicated that their different initiation efficiencies, depending on the number of the allyl terminated arms, influenced on their molecular weights of the polymers. The molecular weight of linear PLA-TACA reached 3,000–5,000 g/mol and formed the PLA stereocomplex. The thermal properties of the obtained PLAs were analyzed by Tm, Tg and ΔHm, resulting in the improvement of thermal properties by changing the number of allyl groups. This study suggested that it is possible to do further chemical modification with double bonds at chain ends of these PLA stereocomplexes.

Hydrogel preparations using poly(N-vinylformamide) (PNVF) and poly(N-vinylacetamide) (PNVA), which are composed of non-conjugated vinyl monomers, N-vinylformamide (NVF) and N-vinylacetamide (NVA), were investigated without chemical crosslinkers. Hydrogen bonding interaction between the polymers and poly(ethylene glycol) have been firstly attempted to result in unstable film, which is easily soluble in water. On the other hand, the simple thermal treatment of the PNVF films at 200 °C for several hours produced the hydrogels after water immersion, although PNVA did not produce any hydrogels under the same condition. The swelling ratios of the formed hydrogel ranged from 100 to 250. The analysis of the supernatant reveals the structural change at alpha proton of PNVF. Furthermore, the decrease of molecular weights were observed by SEC analysis when the hydrogels formed. The possible mechanism of the crosslinking reaction is also discussed. The present study provides the novel method to prepare PNVF hydrogels without the use of chemical crosslinkers.

In order to prepare thermoresponsive polyurethane gels, a novel polyurethane bearing oligo(ethylene glycol) (OEG) as the side chain is successfully synthesized with hexamethylene diisocyanate and OEG tartrate ester. The aqueous solution of the polyurethane shows sharp and clear lower critical solution temperature behavior at 34 °C. Furthermore, a hydrogel based on the same polyurethane is also successfully prepared using glycerol as the crosslinker. This polyurethane hydrogel including 10 mol% of glycerol presents a large swelling ratio change between 4 °C and 37 °C from 250% to 40%.

Using different type of initiators, the antibacterial moieties are introduced at the chain end of poly(L,L-lactide) (PLLA) and poly(D,D-lactide) (PDLA), and the thermal properties are simultaneously improved using the stereocomplex approach. The physical interaction of polymers and antibacterial compounds is investigated. The double bonds at the chain end are utilized for the interaction of silver ion; however, the silver ions are not detected after stereocomplexation of PLLA and PDLA. On the other hand, catechin (CT) is selected as an initiator precursor of lactide polymerization, protecting the phenolic hydroxyl groups. The linear PLLA and PDLA are obtained by the initiator, resulting in CT conjugated PLAs at the chain end groups after deprotection of phenolic hydroxyl groups. The antibacterial properties are determined by proliferation tests of staphylococcus aureus. The results suggest that the antibacterial properties of CT modified PLAs are derived from the original CT parts.

Layer-by-layer (LbL) assembly based on hydrogen-bonding interactions is generating great interest for biomedical applications because it is composed of neutral polymers, while LbL assembly based on electrostatic interaction requires polycations which may induce toxicity issues. As a neutral polymer, poly(N-vinylamide), which has low toxicity compared to poly(acrylamide), has the potential to fabricate LbL thin films via hydrogen-bonding interactions. Herein we report interpolymer complexes of poly(N-vinylamide)s and natural polyphenol tannic acid to form the multilayered thin film. Poly(N-vinylformamide) and poly(N-vinylacetamide), which are water-soluble and insoluble in acetonitrile, could not form complexes with TA in water. On the other hand, N-alkylated poly(N-vinylamide) such as poly(N-ethyl-N-vinylformamide) and poly(N-methyl-N-vinylacetamide) was soluble in acetonitrile and allowed the LbL assembly to proceed with TA. Furthermore, the QCM frequency shift with films composed of poly(N-ethyl-N-vinylformamide) and TA were stable in water, while those of poly(N-methyl-N-vinylacetamide) and TA were instable in water, possibly because formamide has lower steric hindrance compared to acetamide to allow stronger hydrogen-bonding interactions to take place. Thus, LbL assembly reactions with alkylated poly(N-vinylamide)s and TA were investigated and revealed that poly(N-ethyl-N-formamide) and TA, which are water-soluble, effectively interacted with one another to generate water-stable hydrogen-bonded multilayered films.

N-Vinylamide derivatives, such as N-n-butyl-N-vinylformamides and N-isobutyl-N-vinylformamides were synthesized and copolymerized with N-vinylformamide and N-methyl-N-vinylacetamide. Lower critical...

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.

In regenerative medicine, it has become increasingly important to collect cultured tissues using non-invasive methods. Enzymatic deadhesion is normally used to collect cells, but this method cannot be used when trying to collect whole tissues in order to avoid damaging cell–cell interactions. In order to resolve this issue, a thermoresponsive culture dish with poly(N-isopropyl acrylamide) (PNIPAAm) has been employed. This system can change its hydrophobicity depending on temperature. Thus, tissues can attach above 37 °C and be detached below 20 °C. However, the PNIPAAm system has some issues related to cost and detachment time. In this study, we developed a novel thermoresponsive detachment system using a polysaccharide derivative. We chose hydroxy butyl chitosan (HBC) as the thermoresponsive polymer because of its high biocompatibility and rapid phase transition. We developed a novel method of HBC synthesis in conditions that were milder than previously reported. We used spin-coating to make a thin coating on two kinds of culture dishes with various concentrations of HBC solution. Seeded cells attached to the surface at less than 0.5 mg/ml HBC coating concentration, and they could be successfully detached by simply lowering the temperature of the suspension dishes without enzymatic treatment; the cells took only 5–20 min to detach. To evaluate this system, we measured three metrics related to cell culturing on culture dishes: initial attachment rate, detachment rate and tissue detachment time. The study revealed that tissues could be detached faster on the suspension dishes used in this study than on PNIPAAm grafted dishes when HBC was coated at 0.5 mg/ml. We successfully developed a novel tissue detachment system using HBC. These results suggest that smart polymers may be useful in regenerative medicine.

The radical polymerization of methacrylic acid (MAA) at 0, 20, 40, and 70 °C was achieved in porous isotactic (it-) poly(methyl methacrylate) (PMMA) films on quartz crystal microbalance (QCM) substrates, which were prepared by layer-by-layer assembled stereocomplex films of it-PMMA and syndiotactic (st-) poly(methacrylic acid) (PMAA), followed by the subsequent extraction of st-PMAA. The MAA polymerization yields increased from 35 to 75%, as the polymerization temperature increased from 0 to 70 °C. Furthermore, infrared spectroscopy revealed that a higher polymerization temperature is necessary to form it-PMMA/st-PMAA stereocomplexes via stereoregular polymerization manner that resemble native it-PMMA/st-PMAA stereocomplexes. X-ray diffraction pattern of porous it-PMMA were also investigated for reaction fields. © 2014 Wiley Periodicals, Inc. J. Polym. Sci., Part A: Polym. Chem. 2014, 52, 3032–3036

Block copolymers of L-lactide (LA) and trimethylene carbonate (TMC) derivatives bearing methoxyethyl groups [poly(TMCM-MOE1OM)-block-PLLA] were employed as spin-coated films on substrates, and their hydrophilic and degradation behaviors were investigated. Changing the solvents for film preparation, film thickness, and copolymer composition ratios varied the contact angles in the range of 84.3° ± 2.8° at 269 nm thickness and 18.2° ± 2.5° at 15 nm thickness. These contact angles showed dynamic changes from hydrophobic to hydrophilic properties, probably due to the methoxyethoxyl groups connecting the flexible TMC moieties in the copolymer. Immersion into water or hexane affected the dynamic contact angles. X-ray photoelectron spectroscopy analyses revealed that a large amount of hydrophilic groups was segregated onto the surface, although both LA and TMC units existed. Such dynamic contact angle changes were delayed by the crystallization of polylactide. The hydrolyzed behaviors of these films were examined by quartz cell microbalance, showing a slow degradation process.

To approach the biodegradable materials close to clinical application, it is worthy and preferable to fabricate polymeric three-dimensional network biomaterials based on Poly(5-[2-{2-(2-methoxyethoxy)ethyoxy}-ethoxymethyl]-5-methyl-1,3-dioxa-2-one) (PTMC-MOE3OM). It has been paid attention about the presence of thermal response along biocompatible ester-free TMC derivative as gel form. To achieve adequate mechanical properties, synthetic biodegradable crosslinked agents, (CL) which undergo possessing resembling chemical structures, were introduced. Bis-TMC crosslinkers, 2,2′-bis(trimethylene carbonate-5-yl)-butylether (BTB) and 2,2′-bis(trimethylene carbonate-5-yl)-butaethylene glycol dimethyl ether (BTB-GDE) were subsequently added at least 10% crosslinker. Herein, the novel TMCM-MOE3OM hydrogels were serially prepared and characterized. In Vitro behavior, protein adsorption and platelet adhesion, hydrogel with 10% BTB-GDE cross-linker was considered a highly repelled surface of A3 gel. Obviously, the bulk TMC preparation with low% CL represented the potential hydrogel with sufficient stiffness both compressive and tensile. Regarding the design of degradable polymers, the absence of toxic residue is determined during diverse environments such as lipase, basic and acid.

Oil gels made of low-toxic components were prepared using chemically cross-linked copolymer, which was composed of a poly(trimethylene carbonate) derivative and poly(L-lactide). The poly(L-lactide) moiety in the gels could form stereocomplexes with poly(D-lactide).

In order to improve the thermal stability of polylactides (PLA), conjugation approaches have been applied to both the terminal and initiating chain end of PLA. We selected benzyl alcohol as the initiator to introduce an aromatic group at one end. The terminal hydroxyl group of the resultant PLAs was conjugated with 3,4-diacetoxycinnamic acid (DACA). The modified polymers showed a dramatic improvement in their thermal decomposing temperature (T10) from 326 to 355 °C. The stereocomplexation of the modified PLAs could be achieved by a variety of molecular weight (Mn) combination. The melting temperature (Tm) increased after stereocomplexation with any size of polymer mixture, but the best improvements on thermal properties in both Tm and T10 were obtained by a mixture of specific Mn ranges of enantiomeric PLAs (Mn = 11 400 and 9600). In contrast, the longer and shorter Mn discouraged the simultaneous improvements in the Tm and T10, suggesting that a balance of chain end groups and stereocomplexation efficien...

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%.

Kinetic hydrate inhibitors (KHIs) are water-soluble polymers that have been used for almost 20 years as a method to prevent the formation of gas hydrate plugs. Most classes of KHI polymers contain amide groups. We have now found a simple route to synthesize poly(N-vinylalkanamide)s (PVamides) from polyvinylamine. In this paper, we present results on the KHI performance of PVamides with varying alkyl chain lengths in the side group. This has been performed in tests with a structure-II-forming synthetic natural gas in high-pressure rocker cells and on tetrahydrofuran (THF) structure II hydrate crystal growth. The KHI performance of poly(N-isopropylacrylamide)s (PNIPAMs) and poly(N-vinylisobutyramide)s (PNVIBAs) at varying molecular weights was also compared, because these two polymers differ only in the orientation of the amide group.

We investigated by Transmission Electron Microscopy (TEM) the morphologies of crosslinked copolymers from methacrylate monomers from methylmethacrylate (MMA) and trifluoroethylmethacrylate (TFEMA), polydimethylsiloxane (PDMS) macromers with molecular weight (Mn) of 1,700 and 4,700 g/mol, and crosslinker. Depending on the PDMS content, we observed, spherical PMMA islands in which small PDMS domains were dispersed, PMMA continuous phase, closely packed PTFEMA islands, and homogeneously dispersed PDMS domains were observed with low or middle magnification. Fine observation at 100,000-fold magnification revealed the “fundamental” common size domain, which was determined by the Mn value of the PDMS macromer. Thus we found two microstructure types: (1) a “fundamental domain” due to the Mn of the PDMS macromer, and (2) an aggregated domain. The former was constant under all conditions, but the latter was affected by the comonomer and its ratio. The present results are essential in understanding the chemical and physical characteristics of crosslinked copolymers from PDMS macromers. © 2012 Wiley Periodicals, Inc. J. Appl. Polym. Sci., 2013

In order to improve the hydrophilicity of silicone-containing monomers, N-2-(N′,N′-dimethylcarbamoyl)ethyl-N-[3-tris(trimethylsiloxy)silylpropyl]acrylamide (SiDAAA) and N-2-(N′,N′-dimethylcarbamoyl...

To clarify the effect of the type of acrylic monomer and the molecular weight (Mn) of polydimethylsiloxane (PDMS) on the relationship among the internal structure, oxygen permeability coefficient [P(O2)] and transparency, crosslinked copolymers were prepared with two different acrylic monomers : methyl methacrylate (MMA) and trifluoroethyl methacrylate (TFEMA). PDMS macromers with Mn of 1700, 3300, 4700, and 7800 g/mol were used. DSC measurements suggested that all constituent phases were insoluble with each other. The Mn of PDMS affected both the light transmittance and P(O2). The relationship between the Mn and P(O2) over the low Mn range (1700 and 3300 g/mol), and the calculated PDMS domain size ratio, were found to support the [Mn]2/3 rule into the crosslinked copolymer. Furthermore, a 3300 g/mol Mn copolymer became transparent when the amount of PDMS was greater than PMMA. In addition, copolymerization with TFEMA drastically affected those properties, and this effect was much greater than the effect of the PDMS Mn. To clarify the mechanism of P(O2) improvement induced by TFEMA copolymerization, calculations on the relationship among the P(O2), PDMS volume fraction, and morphology model were performed, and some properties such as solubility parameters should play important roles. © 2012 Wiley Periodicals, Inc. J. Appl. Polym. Sci., 2013