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Alternating block polyurethanes (abbreviated as PULA-alt-PEG) and random block polyurethanes (abbreviated as PULA-ran-PEG) based on biodegradable poly(lactic acid) (PLA) and poly(ethylene glycol) (PEG) were prepared. Results showed that alternating block polyurethane gives higher crystal degree, higher mechanical properties, more patterned and rougher surface than the random counterpart, due to the regular and controlled structure. Water absorptions of the polyurethanes were in the range of 620 to 780%. Cytocompatibility of the amphiphilic block polyurethanes (PU) (water static angle 41.4°-61.8°) was assessed by CCK-8 assay using human embryonic kidney (HEK293) cells. Wound healing evaluation of the PU foam scaffolds was carried out by full-thickness SD rat model experiment, with medical gauze as control. It was found that the skin of rat in PU groups was fully covered with new epithelium without any significant adverse reactions and PU dressings give much rapid and better healing than medical gauze. Histological examination revealed that PU dressings suppress the infiltration of inflammatory cells and accelerate fibroblast proliferation. It was also demonstrated that PULA-alt-PEG exhibits obvious better healing effect than PULA-ran-PEG does. This study has demonstrated that without further modification, plain alternating block polyurethane scaffold would help wound recovery efficiently. © 2016 Wiley Periodicals, Inc. J Biomed Mater Res Part B: Appl Biomater, 105B: 1200-1209, 2017.

Samples of porous foam from polyurethane/urea copolymers based on polyethylene glycol (PURPEG) were prepared in the form of 1-mm-thick discs of diameter 10 cm and exposed to ammonia plasma created by inductively coupled radiofrequency discharge in either low density (E mode) or high density (H mode). The evolution of surface composition and structure upon plasma treatment was characterized by X-ray photoelectron spectroscopy. Treatment in the H mode caused depletion of oxygen even after 2 s of treatment, whereas treatment in the E mode caused gentle functionalization with amide groups. The concentration of functional groups depended on the discharge power, and the best results were obtained at moderately high power just before the transition from E to H modes.

A novel, efficient, and facile protocol has been developed for transforming 2-hydroxybenzonitriles and bromides into a range of 3-aryl or alkyl substituted 1,2-benzisoxazoles in good to excellent yields mediated by PPh

Nerve repair scaffolds from novel alternating block polyurethanes (PUCL-alt-PEG) based on PCL and PEG without additional growth factors or proteins were prepared by a particle leaching method. The scaffolds have pore size 10−20 µm and porosity 92%. Mechanical tests showed that the polyurethane scaffolds have maximum loads of 5.97 ± 0.35 N and maximal stresses of 8.84 ± 0.5 MPa. Histocompatiblity of the nerve repair scaffolds was tested in a SD rat model for peripheral nerve defect treatment. Two types of treatments including PUCL-alt-PEG scaffolds and autografts were compared in rat model. After 32 weeks, bridging of a 12 mm defect gap by the regenerated nerve was observed in all rats. The nerve regeneration was systematically characterized by sciatic function index (SFI), electrophysiology, histological assessment including HE staining, immunohistochemistry, ammonia sliver staining, Masson's trichrome staining and TEM observation. Results revealed that nerve repair scaffolds from PUCL-alt-PEG exhibit better regeneration effects compared to autografts. Electrophysiological recovery was seen in 90% and 87% of rats in PUCL-alt-PEG and autograft groups respectively. Biodegradation in vitro and in vivo shows good degradation match of PUCL-alt-PEG scaffolds with nerve regeneration. It demonstrates that plain nerve repair scaffolds from PUCL-alt-PEG biomaterials can achieve peripheral nerve regeneration satisfactorily. © 2014 Wiley Periodicals, Inc. J Biomed Mater Res Part A: 103: 2355–2364, 2015.

Alternating and random block polyurethanes (abbreviated as PULA-alt/ran-3/4HB respectively) based on biodegradable polyester poly(lactic acid) (PLA) and poly(3-hydroxybutyrate-co-4-hydroxybutyrate) (P3/4HB) were synthesized using 4,4′-methylene bis(cyclohexylisocyanate) (HMDI) as coupling agent and stannous octanoate (Sn(Oct)2) as catalyst. The chemical structure, molecular weight and thermal properties were characterized by FTIR, 1H NMR, GPC, DSC and TGA. Hydrophilicity was investigated by static contact angle of deionized water and CH2I2, while the mechanical behaviors were studied by tensile testing. Their shape-memory behaviors were investigated as a function of PLA molecular weight. The lowest recovery and glass transition temperatures (T g) which approach body temperature, have shown considerable prospect in medical applications. A platelet adhesion study illustrated that PULA-alt-3/4HB possesses better hemocompatibility due to its evident surface microstructure. The cell culture assay demonstrated that the materials are well suited for cell growth and proliferation of rat aortic smooth muscle cells (RaSMCs) and the RaSMCs are more favorable for attachment on PLA-alt-3/4HB materials. Porous scaffold rat implantation indicates non-toxic to animals of the synthesized block polyurethanes.

Nerve guide scaffolds from block polyurethanes without any additional growth factors or protein were prepared using a particle leaching method. The scaffolds of block polyurethanes (abbreviated as PUCL-ran-EG) based on poly(ɛ-caprolactone) (PCL-diol) and poly(ethylene glycol) (PEG) possess highly surface-area porous for cell attachment, and can provide biochemical and topographic cues to enhance tissue regeneration. The nerve guide scaffolds have pore size 1–5 μm and porosity 88%. Mechanical tests showed that the polyurethane nerve guide scaffolds have maximum loads of 4.98 ± 0.35 N and maximum stresses of 6.372 ± 0.5 MPa. The histocompatibility efficacy of these nerve guide scaffolds was tested in a rat model for peripheral nerve injury treatment. Four types of guides including PUCL-ran-EG scaffolds, autograft, PCL scaffolds and silicone tubes were compared in the rat model. After 14 weeks, bridging of a 10 mm defect gap by the regenerated nerve was observed in all rats. The nerve regeneration was systematically characterized by sciatic function index (SFI), histological assessment including HE staining, immunohistochemistry, ammonia silver staining, Masson's trichrome staining and TEM observation. Results revealed that polyurethane nerve guide scaffolds exhibit much better regeneration behavior than PCL, silicone tube groups and comparable to autograft. Electrophysiological recovery was also seen in 36%, 76%, and 87% of rats in the PCL, PUCL-ran-EG, and autograft groups respectively, whilst 29.8% was observed in the silicone tube groups. Biodegradation in vitro and in vivo show proper degradation of the PUCL-ran-EG nerve guide scaffolds. This study has demonstrated that without further modification, plain PUCL-ran-EG nerve guide scaffolds can help peripheral nerve regeneration excellently.

Biocompatible and even biodegradable polymers have unique advantages in various biomedical applications. Recent years, photonic devices fabricated using biocompatible polymers have been widely studied. In this work, we manufactured an optical fiber using biodegradable polymer POC and POMC. This step index optical fiber is flexible and easy to handle. Light was coupled into this polymer fiber by directly using objective. The fiber has a good light guiding property and an approximate loss of 2db/cm. Due to the two layer structure, our fiber is able to support applications inside biological tissue. Apart from remarkable optical performance, our fiber was also found capable of performing imaging. By measuring the impulse response of this multimode polymer fiber and using the linear inversion algorithm, concept proving experiments were completed. Images input into our fiber were able to be retrieved from the intensity distribution of the light at the output end. Experiment result proves the capability of our optical fiber to be used as a fiber endoscopy no needs to remove.

Two types of biodegradable block polyurethanes based on polycaprolactone (PCL) and poly(ethylene glycol) (PEG) were prepared by controlling the regularity of block arrangements, that is, alternating block polyurethanes PUCL-alt-PEG. Traditional random block polyurethanes PUCL-ran-PEG were also prepared for comparison. Nerve repair scaffolds were prepared from these block polyurethanes. The nerve repair scaffolds were tested in a Sprague–Dawley rat peripheral nerve defect model. The nerve regeneration was evaluated by sciatic function index analysis and histological analyses. Results revealed that polyurethane nerve-guided scaffolds exhibited much greater regeneration capabilities than PCL. Particularly, PUCL-alt-PEG exhibited better nerve regeneration than the autograft. These studies warrant further studies toward optimization of the block polyurethane nerve-guided scaffolds for peripheral nerve regeneration.

Biobased non-fossil polyester poly(3-hydroxybutyrate-co-4-hydroxybutyrate) (P3/4HB) containing 4.0 mol % 4-hydroxybutyrate (4HB) was melt-mixed with short glass fibers (SGF) via a co-rotating twin-screw extruder. The compositing conditions, average glass fiber length and distribution, thermal, crystallization, and mechanical properties of the P3/4HB/SGF composites were investigated. Calcium stearate, two kinds of paraffin wax and modified ethylene bis-stearamide (TAF) were investigated as lubricants for the P3/4HB/SGF composites. It revealed that TAF is the most efficient lubricant of the P3/4HB/SGF composites. Coupling agents 2,2′-(1,3-phenylene)bis-2-oxazoline (1,3-PBO) and pyromellitic dianhydride (PMDA) were used as end-group crosslinkers to reduce the degradation of P3/4HB and increase the mechanical properties of the P3/4HB/SGF composites. It showed that 1,3-PBO is the efficient coupling agent. The optimum condition of the P3/4HB/SGF composites is 1.5 phr TAF, 1.0 phr 1,3-PBO, and 30 wt % glass fiber content. And the maximum of tensile strength, tensile modulus, and impact strength of the composites is 3.7, 6.6, 1.8 times of the neat P3/4HB polymer, respectively. © 2012 Wiley Periodicals, Inc. J Appl Polym Sci, 2012

Bacterial polyester poly(3-hydroxybutyrate-co-4-hydroxybutyrate) (P3/4HB) containing 5 mol% 4HB was composited with different calcium carbonate (CaCO3) fillers. The effect of CaCO3 contents on thermal properties, mechanical property, and crystallization kinetics was evaluated. The thermal stability of P3/4HB was reduced by mixing with CaCO3 particles. With increasing CaCO3 content, the elongation at break, tensile strength, and impact strength decrease; however, elastic modulus increases. When P3/4HB with 20 mol% 4HB was added into the P3/4HB/CaCO3 composite, the impact strength were enhanced significantly; however, the elongation at break and tensile strength were only slight to moderate improvements. However, when compared with nano- and light-CaCO3, heavy CaCO3 had the best mechanical properties. The nonisothermal and isothermal crystallization results demonstrated that the crystallization rate of P3/4HB was reduced and the highest crystallinity was obtained for all kinds of CaCO3 fillers at 40 phr content. POLYM. COMPOS., 2011. © 2011 Society of Plastics Engineers

Block copolymers with exactly controlled structures, that is, alternating block polyurethanes based on poly(3-hydroxybutyrate-co-4-hydroxybutrate) (P3/4HB-diol) and poly (propylene glycol)-poly(ethylene glycol)-poly(propylene glycol) (PPG-PEG-PPG) were synthesized by solution polymerization via specifically selective coupling reaction between terminal hydroxyl P3/4HB segment and isocyanate group end-capped PPG-PEG-PPG segment, using 1,6-hexamethylene diisocyanate (HDI) as end-capped agent. The chemical structure, molecular weight and distribution were systematically characterized by nuclear magnetic resonance spectrum (¹H NMR), Fourier transform infrared spectroscopy (FTIR) and gel permeation chromatography (GPC). The thermal property was investigated by differential scanning calorimetry (DSC) and thermogravimetric analysis. The hydrophilicity was studied by static contact angle of H₂O and CH₂I₂. DSC revealed that the PU3/4HB-alt-PPG-PEG-PPG exhibited a distinct change from amorphous to 30% crystallinity degree, T(g) from -25 to -50 °C, T(m) from 110 to 145 °C. The polyurethanes were more hydrophilic (water contact angle centers around 80 °) than the raw PHA materials. The platelet adhesion assay showed that the obtained polyurethanes had a lower platelet adhesion than the raw materials and the amount of platelet adhesion could be controlled by varying the segmental length of P3/4HB-diol. This could be explained by the inclusion of PPG-PEG-PPG between the P3/4HB segments, improving the hemocompatibility of P3/4HB. The cell culture assay revealed that the obtained polyurethanes were cell inert and unfavorable for the attachment of mouse fibroblast cell line L929 and rabbit blood vessel smooth muscle cells (RaSMCs). This suggests that these polyurethanes would be promising candidates as hemocompatibility and tissue-inert materials.

Biopolyesters poly(3-hydroxybutyrate-co-4- hydroxybutyrate) with an 11 mol % 4HB content (P(3HB- co-11%-4HB)) and a 33 mol % 4HB content (P(3HB-co-33%- 4HB)) were blended by a solvent-casting method. The ther- mal properties were investigated with differential scanning calorimetry. The single glass-transition temperature of the blends revealed that the two components were miscible when the content of P(3HB-co-33%-4HB) was less than 30% or more than 70 wt %. The blends, however, were immisci- ble when the P(3HB-co-33%-4HB) content was between 30 and 70%. The miscibility of the blends was also confirmed by scanning electron microscopy morphology observation. In the crystallite structure study, X-ray diffraction patterns demonstrated that the crystallites of the blends were mainly from poly(3-hydroxybutyrate) units. With the addition of P(3HB-co-33%-4HB), larger crystallites with lower crystalli- zation degrees were induced. Isothermal crystallization was used to analyze the melting crystallization kinetics. The Avrami exponent was kept around 2; this indicated that the crystallization mode was not affected by the blending. The equilibrium melting temperature decreased from 144 to 140 � C for the 80/20 and 70/30 blends P(3HB-co-11%-4HB)/ P(3HB-co-33%-4HB). This hinted that the crystallization tendency decreased with a higher P(3HB-co-33%-4HB) content. V C 2010 Wiley Periodicals, Inc. J Appl Polym Sci 119: 3467-3475, 2011

Poly(3-hydroxybutyrate-co-3-hydroxyvalerate)(PHBV)/poly(3-hydroxybutyrate-co-4-hydroxybutyrate) (P3/4HB) blend films were prepared by solvent-cast method. The nonisothermal crystallization results showed that PHBV and P3/4HB are miscible due to a single glass transition temperature (Tg), which is dependent on blend composition. The isothermal crystallization results demonstrate that the crystallization rate of PHBV becomes slower after adding amorphous P3/4HB with 19.2 mol% 4HB, which could be proved through depression of equilibrium melt point () from 183.7°C to 177.6°C. For pure PHBV and PHBV/P3/4HB (80/20) blend, the maximum crystallization rate appeared at 88°C and 84°C, respectively. FTIR analysis showed that PHBV/P3/4HB blend films would maintain the helical structure, similar to pure PHBV. Meanwhile, with increasing P3/4HB content, the inter- and intra-interactions of PHBV and P3/4HB decrease gradually. Besides, a lower elastic modulus and a higher elongation at break were obtained, which show that the addition of P3/4HB would make the brittle PHBV to ductile materials. © 2010 Wiley Periodicals, Inc. J Appl Polym Sci, 2010

Star block copolymers based on poly[( R )-3-hydroxybutyrate] (PHB) and poly(e-caprolactone) (PCL), termed SPHBCL, were successfully synthesized with structural variation on arm numbers and lengths via coupling reactions and ring opening polymerizations. Arm numbers 3, 4 and 6 of SPHBCL were synthesized by using different multifunctional cores, such as trimethyol propane, pentaerythiritol and dipentaerthritol, respectively. Gel permeation chromatography (GPC) and 1 H and 13 C nuclear magnetic resonance were used to characterize the structure of SPHBCL. GPC failed to produce accurate molecular weights of the SPHBCL due to the discrepancy of star copolymer structures. The melting temperature of SPHBCL decreased with increasing degree of branching. Thermal decomposition temperature was revealed to be lower than that of linear block copolymer LPHBCL counterparts based on PHB and PCL. Films made from various SPHBCL copolymers had different porous or networking surface morphology, and all possessed improved biocompatibility in terms of less blood clotting and more osteoblast cell growth compared with their corresponding homopolymers PHB and PCL. Among them, it was found, however, that the 4-arm star block copolymer 4SPHBCL-25 showed unique surface properties, i.e. a regular nanoravine structure was observed by scanning electron microscopy and atomic force microscopy. This 4-arm star copolymer also showed the best biocompatibility.

Naturally amorphous biopolyester poly (3-hydroxybutyrate-co-4-hydroxybutyrate) (P3/4HB) con- taining 21 mol % of 4HB was blended with semi-crystal poly(butylene succinate) (PBS) with an aim to improve the properties of aliphatic polyesters. The effect of PBS con- tents on miscibility, thermal properties, crystallization kinetics, and mechanical property of the blends was evaluated by DSC, TGA, FTIR, wide-angle X-ray diffrac- tometer (WAXD), Scanning Electron Microscope (SEM), and universal material testing machine. The thermal stabil- ity of P3/4HB was enhanced by blending with PBS. When PBS content is less than 30 wt %, the two polymers show better miscibility and their crystallization trend was enhanced by each other. The optimum mechanical proper- ties were observed at the 5-10 wt % PBS blends. However, when the PBS content is more than 30 wt %, phase inversion happened. And the two polymers give lower miscibility and poor mechanical properties. V C 2009 Wiley

A series of amphiphilic alternative block polyurethane copolymers based on poly(3-hydroxybutyrate-co-4-hydroxybutyrate) (P3/4HB) and poly(ethylene glycol) (PEG) were synthesized by a coupling reaction between P3/4HB-diol and PEG-diisocyanate, with different 3HB, 4HB, PEG compositions and segment lengths. Stannous octanoate was used as catalyst. The chemical structure, alternative block arrangement, molecular weight and distribution were systematically characterized by FTIR, (1)H NMR, GPC and composition analysis. The thermal property was studied by DSC and TGA. Platelet adhesion study revealed that the alternative block polyurethanes possess excellent hemocompatibility. CCK-8 assay illuminated that the non-toxic block polyurethanes maintain rat aortic smooth muscle cells (RaSMCs) good viability. The in-vitro degradation of the copolymers in PBS buffer solution and in lipase buffer medium was investigated. Results showed that the copolymer films exhibit different degradation patterns in different media from surface erosion to diffusion bulk collapsing. The synthetic methodology for the alternative block polyurethanes provides a way to control the exact structure of the biomaterials and tailor the properties to subtle requirements.

A series of block poly(ester-urethane) poly(3/4HB-HHxHO) urethanes (abbreviated as PUHO) based on poly(3-hydroxybutyrate-co-4-hydroxybutyrate) (P3/4HB-diol) and poly(3-hydroxyhexanoate-co-3-hydroxyoctanoate) (PHHxHO-diol) segments were synthesized by a facile way of melting polymerization using 1,6-hexamethylene diisocyanate (HDI) as the coupling agent, with different 3HB, 4HB, HHxHO compositions and segment lengths. The chemical structure, molecular weight and distribution were systematically characterized by (1)H, (13)C nuclear magnetic resonance spectrum (NMR), two-dimensional correlation spectroscopy (COSY ((1)H, (13)C) NMR), Fourier transform infrared spectroscopy (FTIR) and gel permeation chromatography (GPC). The thermal property was studied by differential scanning calorimetry (DSC) and thermogravimetric analysis (TGA). The hydrophilicity was investigated by static contact angle of water and CH(2)I(2). DSC revealed that the poly(3/4HB-HHxHO) urethanes are almost amorphous with a little crystallinity (less than 6%) and T(g) from -23 degrees C to -3 degrees C. The polyurethanes are more hydrophobic (water contact angle 88 degrees -117 degrees ) than the P3/4HB and PHHxHO raw materials. The lactate dehydrogenase (LDH) assay and platelet adhesion determination showed that the obtained polyurethanes have much higher platelet adhesion property than raw materials and common biodegradable polymers polylactic acid (PLA) and poly(3-hydroxybutyrate) (PHB). Hydrophobicity and crystallinity degree are important factors to affect the platelet adhesion. All the properties can be tailored by changing the composition and segment length of prepolymers P3/4HB-diol and PHHxHO-diol.

Poly (L-lactic acid) (PLA) is a biodegradable polymer with slow crystallization rate. Oligomers of 3-hydroxybutyrate (OHB) and dendrimers of hydroxyalkanoic acids with different molecular weights were blended with PLA in a hope to improve the crystallization ability and thermal stability of PLA, respectively. Four thermally-degraded PHB products oligomers termed OHB-1, OHB-2, OHB-3, and OHB-4 with various number average molecular weights (Mn) of 4000, 7400, 14,000, and 83,000, respectively, were blended with PLA. The lower cold-crystallization temperature (Tcc) and higher heat of cold crystallization (ΔHcc) for blend of PLA/OHB-1 suggested that thermally-degraded OHB-1 formed suitable crystal size during the cooling process and then acted as nucleation agents for PLA in the subsequent heating process. On the other hand, for the blending systems of PLA/dendrimers of hydroxyalkanoic acids, no obvious change on the thermal properties was observed compared with pure PLA except an improved PLA thermal stability possibly resulted from the crosslinking effects of the dendrimers © 2008 Wiley Periodicals, Inc. J Appl Polym Sci, 2009

Poly(ether-ester urethane)s (PUs) multiblock co-polymers were synthesized from telechelic hydroxylated poly(3-hydroxybutyrate-co-3-hydroxyhexanoate) (PHBHHx) and poly(ethylene glycol) (PEG) via a melting polymerization (MP) process using 1,6-hexamethylene diisocyanate (HDI) as a non-toxic coupling agent for the first time. The PHBHHx segments and PEG segments in the multiblock co-polymers behaved as a hard, hydrophobic and a soft, hydrophilic part, respectively. Their chemical structures and molecular characteristics were studied by gel-permeation chromatography (GPC), (1)H-NMR and Fourier transform infrared spectroscopy (FT-IR). The PU produced via the MP method showed a higher molecular weight than those resulting from the solvent polymerization (SP) reported previously. Thermal properties showed enhanced thermal stability with semi-crystalline morphology via incorporation of PEG. The segments compositions evaluated from thermogravimetric analysis (TGA) two-step thermal decomposition profiles suggested that MP enhanced the reactivity of PEG compared with the SP process. It was in good agreement with those calculated from (1)H-NMR, as well as the precursor feed ratio, respectively. Water contact angle measurements revealed that surface hydrophilicity of the PUs was enhanced by incorporating the PEG segment into PHBHHx polymer backbone. The mechanical properties assessment of the PUs recorded an improved and adjustable ductility and toughness than pure PHBHHx while preserving the tensile strength. Samples synthesized via MP were resistant to hydrolytic and lipase degradation, yet the multiblock co-polymers incorporating the highest amount of PEG degraded at the highest rate. SEM studies revealed that the surface of the PU films became increasingly porous as the degradation proceeded. Implantation of PU in mouse abdominal cavity indicated that tissue regeneration and tissue compatibility of PU film was better than that of PHBHHx-only film.

Novel tailor-made poly(ester urethane)s (PUs) based on microbial polyesters poly(3-hydroxybutyrate-co-4hydroxybutyrate) (P3HB4HB) and poly(3-hydroxybutyrate-co-3-hydroxyhexanoate) (PHBHHx) were synthesized by melting polymerization (MP) using 1,6-hexamethylene diisocyanate (HDI) as a coupling agent. A comprehensive characterization using (1)H-NMR, Fourier transform infrared spectroscopy (FT-IR), gel-permeation chromatography (GPC), differential scanning calorimetry (DSC), mechanical properties, static water contact angles, cell proliferation using smooth muscle cells from rabbit aorta (RaSMCs) and immortalized human keratinocytes (HaCat), and blood coagulation behavior were conducted on the synthesized PUs films. DSC showed that PU samples had a low degree of crystallinity at room temperature and became fully amorphous after a melt-quenched process. The series of tailor-made PUs based on different mass ratios of P3HB4HB and PHBHHx revealed a ductile and flexile mechanical property especially for PHBHHx-rich PU, or a hydrophobic property for 4HB-rich PU. A 4 days incubation experiment showed that all PU films had a better cell proliferation than poly(lactic acid) (PLA), polyhydroxybutyrate (PHB), P3HB4HB and PHBHHx. RaSMCs cultured on PU films had a quiescent contractile phenotype, indicating that they were fully functional. HaCat incubated on tailor-made PU films showed a proliferation approximately equal to tissue-culture plates (TCPs). Blood coagulation behavior tests revealed a strong platelet adhesion and a short coagulation time on PU films. This study demonstrated potential medical applications for P3HB4HB and PHBHHx based polyurethane as a hydrophobic wound-healing and hemostatic materials.

Poly(3-hydroxybutyrate-co-3-hydroxyhexa- noate) (PHBHHx) is a thermoplastic biopolyester with a slow crystallization rate. L-Phenylalanine (L-PH) was used to improve the crystallization rate of PHBHHx. The noni- sothermal crystallization kinetics and melting behaviors of PHBHHx and PHBHHx/L-PH samples were characterized and compared with differential scanning calorimetry. At cooling rates of 2, 5, 10, and 208C/min, PHBHHx/L-PH could crystallize at higher temperatures than pure PHBHHx. A modified Avrami equation based analysis showed that the addition of L-PH shortened the half-time of crystallization of PHBHHx from 9.6 to 8.0 min and increased the composite rate constant of PHBHHx from 0.201 to 0.283 during the nonisothermal crystallization process at a cooling rate of 108C/min. For other cooling rates, similar trends of changes were observed. These indicated a faster crystallization rate of PHBHHx in the presence of L-PH. PHBHHx/L-PH samples showed a higher melting temperature and a sharper melting peak than those of the pure PHBHHx, which suggested that L-PH as a nucleation agent improved the perfection of the PHBHHx crystals. Stress-strain measurements showed that both PHBHHx and PHBHHx/L-PH maintained their ductile and elastic properties during the 60 days of the aging study. 2008 Wiley Periodicals, Inc. J Appl Polym Sci 110: 2950-2956, 2008

Conducting polymer polyparaphenylene (PPP) was synthesized from cis-dihydrocatechol (DHCD) obtained from bacterial transformation of benzene. Results showed that the DHCD to DHCD-DA (diacetate) synthesis process produced some byproducts as impurities includ- ing trace amounts of phenol, quinone, and phenyl acetate derived from phenol. These impurities played a negative role in the polymerization process of DHCD-DA to P(DHCD-DA). In this study, a distillation fractionation method was employed to obtain monomer DHCD-DA with high purity and high yield. Four different polymer- ization methods using the purified DHCD-DA, including bulk polymerization initiated by different catalyst systems, solution polymerization as well as emulsion polymeriza- tion, were compared. A very high P(DHCD-DA) yield of 92% with a molecular weight of 84,500 was obtained under an optimized condition using the bulk polymeriza- tion process initiated by (di)benzoyl peroxide (BPO) and ferrous sulfate. A standard curve was established to evalu- ate the aromatization degree of P(DHCD-DA) to PPP under different temperatures based on the intensity of FTIR absorption and functional groups on the PPP. The glass transition temperature and the crystallinity of PPP increased with the degree of aromatization of the prepoly- mer P(DHCD-DA). Thermal analysis indicated that the PPP possessed high thermal stability both in nitrogen and in air atmospheres. All these results would help the syn- thesis of PPP. V C 2008 Wiley Periodicals, Inc. J Appl Polym Sci 110: 2085-2093, 2008

BACKGROUND: The aim of this work was to develop polyhydroxyalkanoates (PHAs) for blood contact applications, and to study their self-assembly behavior in aqueous solution when the PHAs are incorporated with hydrophilic segments. To do this, poly(ester-urethane) (PU) multiblock copolymers were prepared from hydroxyl-terminated poly(ethylene glycol) (PEG) and hydroxylated poly[(R)-3-hydroxyalkanoate] (PHA-diol) using 1,6-hexamethylene diisocyanate as a coupling reagent. The PEG segment functions as a soft, hydrophilic and crystalline portion and the poly[(R)-3-hydroxybutyrate] segment behaves as a hard, hydrophobic and crystalline portion. In another series of PU multiblock copolymers, crystalline PEG and completely amorphous poly[((R)-3hydroxybutyrate)-co-(4-hydroxybutyrate)] behaved as hydrophobic and hydrophilic segments, respectively. RESULTS: The formation of a PU series of block copolymers was confirmed by NMR, gel permeation chromatography and infrared analyses. The thermal properties showed enhanced thermal stability with semicrystalline morphology via incorporation of PEG. Interestingly, the changes of the hydrophilic/hydrophobic ratio led to different formations in oil-in-water emulsion and surface patterning behavior when cast into films. Blood compatibility was also increased with increasing PEG content compared with PHA-only polymers. CONCLUSION: For the first time, PHA-based PU block copolymers have been investigated in terms of their blood compatibility and aggregation behavior in aqueous solution. Novel amphiphilic materials with good biocompatibility for possible blood contact applications with hydrogel properties were obtained.  2008 Society of Chemical Industry Supplementary electronic material for this paper is available in Wiley InterScience at http://www.interscience.wiley.com/jpages/ 0959-8103/suppmat/

BACKGROUND: Biodegradable block copolymers have attracted particular attention in both fundamental and applied research because of their unique chain architecture, biodegradability and biocompatibility. Hence, biodegradable poly[((R)-3-hydroxybutyrate)-block-(D,L-lactide)-block-(e-caprolactone)] (PHB-PLA-PCL) triblock copolymers were synthesized, characterized and evaluated for their biocompatibility. RESULTS: The results from nuclear magnetic resonance spectroscopy, gel permeation chromatography and thermogravimetric analysis showed that the novel triblock copolymers were successfully synthesized. Differential scanning calorimetry and wide-angle X-ray diffraction showed that the crystallinity of PHB in the copolymers decreased compared with methyl-PHB (LMPHB) oligomer precursor. Blood compatibility experiments showed that the blood coagulation time became longer accompanied by a reduced number of platelets adhering to films of the copolymers with decreasing PHB content in the triblocks. Murine osteoblast MC3T3-E1 cells cultured on the triblock copolymer films spread and proliferated significantly better compared with their growth on homopolymers of PHB, PLA and PCL, respectively. CONCLUSION: For the first time, PHB-PLA-PCL triblock copolymers were synthesized using low molecular weight LMPHB oligomer as the macroinitiator through ring-opening polymerization with D,L-lactide and e-caprolactone. The triblock copolymers exhibited flexible properties with good biocompatibility; they could be developed into promising biomedical materials for in vivo applications. Copyright © 2008 Society of Chemical Industry

Natural amorphous polymer poly(3-hydroxybutyrate-co-4-hydroxybutyrate) (P3HB4HB) containing 41 mol % of 4HB was blended with poly(3-hydroxybutyrate) (PHB) with an aim to improve the properties of PHB. The influence of P3HB4HB contents on thermal and mechanical properties of the blends was evaluated with differential scanning calorimetry (DSC), Fourier transform infrared (FTIR) spectroscopy, stress–strain measurement and thermo gravimetric analyzer. Miscibility of PHB/P3HB4HB blends was mainly decided by the contents of P3HB4HB. When P3HB4HB exceeded 50 wt %, the two polymer phases separated and showed immiscibility. The addition of P3HB4HB did not alter the crystallinity of PHB, yet it diluted the PHB crystalline phase as revealed by DSC studies. DSC and FTIR results showed that the overall crystallinity of the blends decreased remarkably with increasing of P3HB4HB contents. Decreased glass transition temperature and crystallinity imparted desired flexibility for the blends. The ductility of the blends increased progressively with increasing of P3HB4HB content. Thus, the PHB mechanical properties can be modulated by changing the blend composition. P3HB4HB did not significantly improve the thermal stability of PHB, yet it is possible to melt process PHB without much molecular weights loss via blending it with suitable amounts of P3HB4HB. © 2007 Wiley Periodicals, Inc. J Appl Polym Sci 2007

Poly(3-hydroxybutyrate) (PHB) was plasti- cized with dioctyl (o-)phthalate, dioctyl sebacate, and ace- tyl tributyl citrate (ATBC). The thermal properties, me- chanical properties, and melt flow ability were studied with differential scanning calorimetry, thermogravimetric analysis, a universal material testing machine, and a melt flow indexer. ATBC was revealed to be an efficient plasti- cizer, reducing the glass-transition temperature and increasing the thermoplasticization ability of PHB. We also blended poly(3-hydroxybutyrate-co-hydroxyhexanoate) (PHBHHx) and poly(3-hydroxybutyrate-co-4-hydroxybuty- rate) (P(3/4HB)) with PHB, ATBC, and antioxidant 1010 to overcome the brittleness of PHB and improve the melt flow stability of the materials. PHBHHx did little to improve the thermal processing but increased the fluidity of PHB, and P(3/4HB) toned the toughness of PHB. The addition of antioxidant 1010 enhanced the thermal stabili- zation of PHB. 2007 Wiley Periodicals, Inc. J Appl Polym Sci 107: 166-173, 2008

Alternating block polyurethanes (abbreviated as PULA-alt-PEG) and random block polyurethanes (abbreviated as PULA-ran-PEG) based on biodegradable poly(lactic acid) (PLA) and poly(ethylene glycol) (PEG) were prepared. Results showed that alternating block polyurethane gives higher crystal degree, higher mechanical properties, more patterned and rougher surface than the random counterpart, due to the regular and controlled structure. Water absorptions of the polyurethanes were in the range of 620 to 780%. Cytocompatibility of the amphiphilic block polyurethanes (PU) (water static angle 41.4°-61.8°) was assessed by CCK-8 assay using human embryonic kidney (HEK293) cells. Wound healing evaluation of the PU foam scaffolds was carried out by full-thickness SD rat model experiment, with medical gauze as control. It was found that the skin of rat in PU groups was fully covered with new epithelium without any significant adverse reactions and PU dressings give much rapid and better healing than medical gauze. Histological examination revealed that PU dressings suppress the infiltration of inflammatory cells and accelerate fibroblast proliferation. It was also demonstrated that PULA-alt-PEG exhibits obvious better healing effect than PULA-ran-PEG does. This study has demonstrated that without further modification, plain alternating block polyurethane scaffold would help wound recovery efficiently. © 2016 Wiley Periodicals, Inc. J Biomed Mater Res Part B: Appl Biomater, 105B: 1200-1209, 2017.

Blending of microbial polyester poly(3-hydroxybutyrate) (PHB) with various dendritic polyester oligomers or dendrimers was achieved by solution casting to improve the film forming ability of PHB. Films of the blends were characterized by differential scanning calorimetry (DSC), thermogravimetric analysis (TGA), scanning electron micrograph (SEM), and Fourier transform infrared spectroscopy (FTIR). It was revealed that there were mainly two types of interactions in the blending system: the plasticizing or lubricating effect of the low melting spherical dendrimers molecules improved the polymer chain mobility through the suppression of PHB crystallization in the blends; The dendrimers also functioned as crosslinking agents or antiplasticizing agents via weak hydrogen bonding to enhance the overall intermolecular interactions which decrease the chain mobility and thus cause the increase of glass transition temperature (Tg) of PHB. TGA results concluded that incorporating the dendrimers could retard the thermal decomposition of PHB and enhanced its thermal stability accordingly. With the above blend processes, the so-obtained PHB possessed better film forming ability and even patterned surface structures. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 102:3782–3790, 2006

A pure amphiphilic macrocrown ether (MC-12) was obtained by removing linear oligomers and larger macrocycles at the macrocyclization step, before proceeding with an established synthetic procedure. This pure MC-12 was used to synthesize a rotaxane composed of one MC-12 ring threaded with one end-capped poly(tetrahydrofuran) (PTHF) oligomer by equilibrating half an equivalent of the thread with an organized solution of MC-12 and end-capping the threads with excess 2-p-[tris(p-tert-butylphenyl)methyl]phenoxymethyl-4,4-dimethylazlactone. The rotaxane was positively identified by matrix-assisted laser desorption/ionization time-of-flight (MALDI-ToF) mass spectrometry (MS), although the spectra showed a low abundance of the rotaxane ions and high abundances of unthreaded MC-12 and end-capped thread ions in the product isolated from the threading experiment. Analysis by GPC was inconclusive because both the rotaxane and a one-to-one complex elute at the same retention volume. MALDI-ToF and electrospray ionizati...

A series of hyperbranched poly(ferrocenylene)s containing elements (E) of groups 14 [E=Si (hb-1), Ge (hb-2)] and 15 [E=P (hb-3), Sb (hb-4)] are prepared in good isolation yields (up to 82wt%) by the salt-eliminative polycoupling of dilithioferrocene with tri-(RECl3) or tetrachlorides of the elements (ECl4). While the polymers with no or small R groups are insoluble or partially soluble, those with long alkyl chains (R=C n H2n+1 with n ≥ 8) are completely soluble and film forming. The polymers exhibit solution properties characteristic of hyperbranched macromolecules: e.g. hb-1(18) shows a low intrinsic viscosity ([η]=0.02dL/g) despite its high absolute molecular weight (Mw=5 × 105). Spectroscopic analyses reveal that the polymers possess rigid skeleton structures with extended conjugations, with their absorption spectra tailing into the infrared region (>700nm). The polymers show good thermal stability with Td up to ~400°C and can be graphitized into iron-containing ceramics when pyrolyzed at high temperatures, with char yields up to ~60wt%. While calcinations of the Si-containing polymers (hb-1) at 1000°C under nitrogen give ceramics containing mostly α-Fe nanoparticles, those of Ge-(hb-2) and Sb-containing polymers (hb-4) are completely transformed into their iron-alloys. The ceramics from the P-containing polymers (hb-3) show diffraction patterns of iron phosphides. Iron silicide nanocrystals of “large” sizes are obtained when the pyrolysis of hb-1 is conducted at a high temperature of 1200°C under argon. This ceramic is highly magnetizable (Ms up to ~51emu/g) and shows near-zero remanence and coercivity; in other words, it is an outstanding soft ferromagnet with a high magnetic susceptibility and practically nil hysteresis loss.

A series of hyperbranched poly(ferrocenylenesilyne)s, [(η5-C5H4)2FeSi(R)]n {R = CH3 [1(1)], CHCH2 [1(V)], n-C8H17 [1(8)], n-C12H25 [1(12)], n-C16H33 [1(16)], n-C18H37 [1(18)]}, was prepared in good isolation yields (up to 77 wt %) by one-pot coupling reactions of dilithioferrocene with trichlorosilanes. While the polymers with small R groups [1(1) and 1(V)] were partially soluble, those with long alkyl chains [1(m) with m ≥ 8] were completely soluble and readily film forming. The polymers exhibited diagnostic solution properties of hyperbranched macromolecules; for example, 1(18) had a high absolute molecular weight (Mw = 5 × 105 Da) but a low intrinsic viscosity ([η] = 0.02 dL/g). Spectroscopic analyses revealed that the polymers possessed rigid skeleton structures with extended conjugations, with their absorption spectra tailed into the infrared region (>700 nm). With an increase in the alkyl chain length, the polymer changed from glassy to rubbery state. The polymers lost little of their weights when h...

High molecular weight, hyperbranched polyarylenes were synthesized in high isolation yields by the copolycyclotrimerizations of 2,5-diethynylthiophene (1), 4,4′-biphenyldiyne (2), and 2,7-diethynylfluorenes (3) with 1-heptyne (4) and 1-dodecyne (5) using TaCl5–Ph4Sn as the catalyst in toluene. The structures of the polymers were characterized by IR, NMR, TGA, and UV analyses. All the polymers exhibited outstanding thermal stability and emitted strong blue light, whose intensities are higher than that of poly(1-phenyl-1-octyne), a well-known highly emissive polyacetylene. Little red shift was observed in the photoluminescence of the polymer thin films. The polymers strongly attenuated intense pulses of 532 nm laser pulses.

Diyne polycyclotrimerizations initiated by transition-metal catalysts afforded hyperbranched polyphenylenes, which exhibited low viscosity, outstanding thermal stability, and small optical dispersion. Under optimized reaction conditions, polycyclotrimerizations of 1,8-nonadiyne (1) and 1,9-decadiyne (2) catalyzed by TaCl5−Ph4Sn produced hyperbranched poly(1,2,4-benzenetriyl-1,5-pentanediyl) (3) and poly(1,2,4-benzenetriyl-1,6-hexanediyl) (4),1-5 respectively, in high yields (up to 93%). The polymers were completely soluble and film-forming, and possessed high molecular weights (Mw up to ∼1.4 × 106) but low intrinsic viscosities ([η] down to 0.13 dL/g). Their structures and properties were analyzed and evaluated by IR, UV, NMR, SEC, TGA, DSC, spectrofluorometry, light scattering, and spectroellipsometry. The structural characterizations confirmed the expected hyperbranched molecular architectures of 3 and 4 (comprising of 1,2,4-benzene rings and α,ω-alkyl spacers) and revealed the regioselective feature of...

Nerve repair scaffolds from novel alternating block polyurethanes (PUCL-alt-PEG) based on PCL and PEG without additional growth factors or proteins were prepared by a particle leaching method. The scaffolds have pore size 10-20 µm and porosity 92%. Mechanical tests showed that the polyurethane scaffolds have maximum loads of 5.97 ± 0.35 N and maximal stresses of 8.84 ± 0.5 MPa. Histocompatiblity of the nerve repair scaffolds was tested in a SD rat model for peripheral nerve defect treatment. Two types of treatments including PUCL-alt-PEG scaffolds and autografts were compared in rat model. After 32 weeks, bridging of a 12 mm defect gap by the regenerated nerve was observed in all rats. The nerve regeneration was systematically characterized by sciatic function index (SFI), electrophysiology, histological assessment including HE staining, immunohistochemistry, ammonia sliver staining, Masson's trichrome staining and TEM observation. Results revealed that nerve repair scaffolds from PUCL-alt-PEG exhibit better regeneration effects compared to autografts. Electrophysiological recovery was seen in 90% and 87% of rats in PUCL-alt-PEG and autograft groups respectively. Biodegradation in vitro and in vivo shows good degradation match of PUCL-alt-PEG scaffolds with nerve regeneration. It demonstrates that plain nerve repair scaffolds from PUCL-alt-PEG biomaterials can achieve peripheral nerve regeneration satisfactorily.

Most of the existing metal carbonyl catalysts for acetylene polymerizations need to be preactivated by chlorine-containing additives or by UV irradiation in halogenated solvents. In this work, we developed a series of “simple” metal carbonyl catalysts of general structure M(CO)xLy (M = Mo, W), none of which require additives or pre-photoirradiation, most of which are air- and moisture-stable, and some of which work well in nonhalogenated solvents. The acetonitrile complexes M(CO)3(NCCH3)3 initiated polymerizations of a variety of mono- and disubstituted acetylenes at room temperature. The arene and diene complexes W(CO)3(mes) and Mo(CO)3(nbd) (mes = mesitylene, nbd = 2,5-norbornadiene) are tolerant of polar groups and effected polymerizations of functional acetylenes containing ester, ether, and cyano groups. The halogenated complexes MI2(CO)3(NCCH3)2 catalyzed polymerizations of phenylacetylene in toluene. The chlorine-containing acetylene monomers ClC⋮CC6H5 and ClC⋮CC6H13 were readily polymerized by the...

Pyrolysis of hyperbranched poly[1,1'-ferrocenylene(methyl)silyne] (5) yields mesoporous, conductive, and magnetic ceramics (6). Sintering at high temperatures (1000-1200 degrees C) under nitrogen and argon converts 5 to 6N and 6A, respectively, in similar to 48-62% yields. The ceramization yields of 5 are higher than that (similar to 36%) of its linear counterpart poly[1,1'-ferrocenylene(dimethyl)silylene] (1), revealing that the hyperbranched polymer is superior to the linear one as a ceramic precursor. The ceramic products 6 are characterized by SEM, XPS, EDX, XRD, and SQUID. It is found that the ceramics are electrically conductive and possess a mesoporous architecture constructed of tortuously interconnected nanoclusters. The iron contents of 6 estimated by EDX are 36-43%, much higher than that (11%) of the ceramic 2 prepared from the linear precursor 1. The nanocrystals in 6N are mainly alpha-Fe2O3 whereas those in 6A are mainly Fe3Si. When magnetized by an external field at room temperature, 6A exhibits a high-saturation magnetization (M-s similar to 49 emu/g) and near-zero remanence and coercivity; that is, 6A is an excellent soft ferromagnetic material with an extremely low hysteresis loss.

A group of mesomorphic polyacetylenes with different lengths of alkyl spacer −{HCC[(CH2)m−OCO−Biph−OC7H15]}n− [1(m), m = 2, 3, 4, 9] and orientations of ester bridge −{HCC[(CH2)3−CO2−Biph−OC7H15]}n...

In this study polyhydroxybutyrate (PHB), produced by a methanol-utilizing bacteria, was used to prepare microspheres in the 120-200 μm size range for embolization. A solvent evaporation technique was utilized to obtain microspheres in which methylene chloride, distilled water and polyvinyl alcohol were used as the solvent, precipitation medium and emulsifier, respectively. Dogs were the test animals. Renal angiograms obtained before and after embolization and also the histopathological observations showed the feasibility of using these microspheres as an alternative embolization/chemoembolization agent.

In this study, we attempted to prepare microspheres from a microbial biodegradable polyester, i.e. polyhydroxybutyrate (PHB) as a potential chemoembolization agent. The drug loaded PHB microspheres were prepared by a solvent evaporation technique, in which methylene chloride, distilled water, and polyvinyl alcohol were utilized as the solvent, dispersion medium, and emulsifier, respectively. Microspheres were obtained within a size range of 5-100 microns by changing the initial polymer/solvent ratio, emulsifier concentration, stirring rate, and initial drug concentration. It was possible to obtain PHB with very narrow size distributions by applying gravity field-flow fractionation technique. Very high drug loadings of up to 407.6 mg rifampicin/g PHB were achieved. Drug release rates were very rapid. Almost 90% of the drug loaded was released in about 24 h. Both the size and drug content of PHB microspheres were found to be effective in controlling the drug release from these microspheres.

A series of alternating block polyurethanes (abbreviated as PULA-alt-PEG) and random block polyurethanes (abbreviated as PULA-ran-PEG) based on poly(L-lactic acid) (PLA) and poly(ethylene glycol) (PEG) were synthesized. The differences of PULA-alt/ran-PEG chemical structure, molecular weight, distribution, thermal properties, mechanical properties and static contact angle were systematically investigated. The PULA-alt/ran-PEG polyurethanes exhibited low T(g) (-47.3 ∼ -34.4°C), wide mechanical properties (stress σ(t): 4.6-32.6 MPa, modulus E: 11.4-323.9 MPa and strain ε: 468-1530%) and low water contact angle (35.4-51.4°). Scanning electron microscope (SEM) observation showed that PULA-alt-PEG film displays rougher and more patterned surface morphology than PULA-ran-PEG does, due to more regular structures of PULA-alt-PEG. Hydrolytic degradation shows that degradation rate of random block polyurethane series PULA-ran-PEG is higher than the alternating counterpart PULA-alt-PEG. PLA segment degradation is faster than urethane linkage and PEG segment almost does not degrade in the buffer solution. Platelet adhesion study showed that all the polyurethanes possess excellent hemocompatibility. The cell culture assay revealed that PULA-alt/ran-PEG polyurethanes were cell inert and unfavorable for the attachment of rat glial cell due to the hydrophilic characters of the materials.

Polyurethanes with regular and controlled block arrangement, i.e., alternating block polyurethanes (abbreviated as PUCL-alt-PEG) based on poly(ε-caprolactone) (PCL-diol) and poly(ethylene glycol) (PEG) was prepared via selectively coupling reaction between PCL-diol and diisocyanate end-capped PEG. Chemical structure, molecular weight, distribution, and thermal properties were systematically characterized by FTIR, (1)H NMR, GPC, DSC, and TGA. Hydrophilicity was studied by static contact angle of H2O and CH2I2. Film surface was observed by scanning electron microscope (SEM) and atomic force microscopy, and mechanical properties were assessed by universal test machine. Results show that alternating block polyurethanes give higher crystal degree, higher mechanical properties, and more hydrophilic and rougher (deep ravine) surface than their random counterpart, due to regular and controlled structure. Platelet adhesion illustrated that PUCL-alt-PEG has better hemocompatibility and the hemacompatibility was affected significantly by PEG content. Excellent hemocompatibility was obtained with high PEG content. CCK-8 assay and SEM observation revealed much better cell compatibility of fibroblast L929 and rat glial cells on the alternating block polyurethanes than that on random counterpart. Alternating block polyurethane PUC20-a-E4 with optimized composition, mechanical, surface properties, hemacompatibility, and highest cell growth and proliferation was achieved for potential use in nerve regeneration.

Polyurethane/urea copolymers based on poly(ethylene glycol) (PURPEG) were exposed to weakly ionized, highly reactive low-pressure oxygen plasma to improve their sorption kinetics. The plasma was sustained with an inductively coupled radiofrequency generator operating at various power levels in either E-mode (up to the forward power of 300 W) or H-mode (above 500 W). The treatments that used H-mode caused nearly instant thermal degradation of the polymer samples. The density of the charged particles in E-mode was on the order of 1016 m−3, which prevented material destruction upon plasma treatment, but the density of neutral O-atoms in the ground state was on the order of 1021 m−3. The evolution of plasma characteristics during sample treatment in E-mode was determined by optical emission spectroscopy; surface modifications were determined by water adsorption kinetics and X-ray photoelectron spectroscopy; and etching intensity was determined by residual gas analysis. The results showed moderate surface functionalization with hydroxyl and carboxyl/ester groups, weak etching at a rate of several nm/s, rather slow activation down to a water contact angle of 30° and an ability to rapidly absorb water.

A series of block poly(ester-urethane)s (abbreviated as PU3/4HB) based on biodegradable poly(3-hydroxybutyrate- co -4-hydroxybutyrate) (P3/4HB) segments were synthesized by a facile way of melting polymerization using 1,6-hexamethylene diisocyanate (HDI) as the coupling agent and stannous octanoate (Sn(Oct) 2 ) as catalyst, with different 4HB contents and segment lengths. The chemical structure, molecular weight and distribution were systematically characterized by 1 H nuclear magnetic resonance spectrum (NMR), Fourier transform infrared spectroscopy (FTIR) and gel permeation chromatography (GPC). The thermal property was studied by differential scanning calorimetry (DSC) and thermogravimetric analysis (TGA). The hydrophilicity was investigated by static contact angle of deionized water and CH 2 I 2 . DSC curves revealed that the PU3/4HB polyurethanes have their T g from −25.6 °C to −4.3 °C, and crystallinity from 2.5% to 25.3%, being almost amorphous to semi-crystalline. The obtained PU3/4HBs are hydrophobic (water contact angle 77.4°–95.9°), and their surface free energy (SFE) were studied. The morphology of platelets adhered on the polyurethane film observed by scanning electron microscope (SEM) showed that platelets were activated on the PU3/4HB films which would lead to blood coagulation. The lactate dehydrogenase (LDH) assay revealed that the PU3/4HBs displayed higher platelet adhesion property than raw materials and biodegradable polymer polylactic acid (PLA) and would be potential hemostatic materials. Crystallinity degree, hydrophobicity, surface free energy and urethane linkage content play important roles in affecting the LDH activity and hence the platelet adhesion. CCK-8 assay showed that the PU3/4HB is non-toxic and well for cell growth and proliferation of mouse fibroblast L929. It showed that the hydrophobicity is an important factor for cell growth while 3HB content of the PU3/4HB is important for the cell proliferation. Through changing the composition and the chain-length of P3/4HB-diol prepolymers, the biocompatibility of the poly(ester-urethane)s can be tailored.

Boron nitride (BN), talc, hydroxyapatite (HA), and zinc stearate (ZnSt) were investigated as nucleation agents (NA) for nonfossil-based poly(3-hydroxybutyrate-co- 4-hydroxybutyrate) (P3/4HB) plastics. Nonisothermal crys- tallization behaviors of the P3/4HB/NA blends were exam- ined by DSC. It revealed that BN is the most efficient nucleation agent to promote the crystallization rate, however, but not the crystallization degree. The lasting crystallization of P3/4HB was also removed. The nucleation effect was strengthened with increase of BN content up to 1% and then slackened deeply when further BN was added. Isothermal crystallization analysis revealed that the addition of nuclea- tion agent BN does not alter the crystal growth mode of P3/ 4HB, with maintaining the Avrami parameter n value around 2.40. Talc did enhance the crystallization of P3/4HB with however milder crystal growth rate. HA and ZnSt did not promote, but depressed the crystallization of P3/4HB plas- tics. V C 2009 Wiley Periodicals, Inc. J Appl Polym Sci 116: 1116-1123, 2010

Poly(ester-urethane)s (PUs) were synthesized using hexamethylene diisocyanate (HDI) or toluene diisocyanate (TDI) to join short chains (Mn = 2000) of poly(R-3-hydroxybutyrate) (PHB) diols and poly(e-caprolactone) (PCL) diols with different feed ratios under different reaction conditions. The multiblock copolymers were characterized by nuclear magnetic resonance spectrometer (NMR), gel permeation chromatography (GPC), differential scanning calorimetry (DSC), thermogravimetric analyses (TGA), X-ray diffraction (XRD), and scanning electron microscope (SEM). XRD spectra and second DSC heat thermograms of the multiblock copolymers revealed that the crystallization of both PHB and PCL segments was mutually restricted, and, especially, the PCL segment limited the cold crystallization of the PHB segment. The SEM of platelet adhesion experiments showed that the hemocompatibility was affected to some extent by the chain flexibility of the polymers. Hydrolysis studies demonstrated that the hydrolytic degradation of PUs was generated from the scission of their ester bonds or/and urethane bonds. Simultaneously, the rate of ester bond scission was determined to some extent by the crystallization degree, which was further affected by the configuration of polymer chains. These highly elastic multiblock copolymers combining hemocompatibility and biodegradability may be developed into blood contact implant materials for biomedical applications. © 2008 Wiley Periodicals, Inc. J Biomed Mater Res, 2009

Using tetraethyl‐3‐amino‐propane‐1,1‐bisphosphonate (BP) as the functional molecule, we functionalized Fe3O4 magnetic nanoparticles via dopamine (DA) linkage to create a system with an Fe3O4‐DA‐BP nanostructure, which possesses high specificity for removing uranyl ions from water or blood. This work demonstrates that magnetic nanoparticles, combined with specific receptor‐ligand interactions, promise a sensitive and rapid platform for the detection, recovery, and decorporation of radioactive metal toxins from biological environment.