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The aim of this paper is to investigate the interactions between industrial-grade polycarboxylate ether (PCE) polymers and ordinary Portland cement to assess whether it is possible to draw structure/performance relations for impure, yet fully characterized, poly-mers. To this end, thirteen PCE polymers were synthesised in industrial fashion, deeply ana-lyzed and tested in cement paste. Chemical stability and adsorption behaviour have been evaluated through gel permeation chromatography technique, leading to insights regarding the plasticization timing and the adsorption control. All the results were interpreted and criti-cally discussed by invoking the characteristics of initial dispersers and workability retainers; furthermore a comprehensive description has been attempted through the Gay and Raphaël conformation plot, based on the establishment of which molecular feature affects each step of the PCE’s working mechanism. The results confirm many of the findings despite the imper-fect nature of the chosen polymers and show that common impurities, such as unreacted side chains, do not noticeably interact with the binder. In particular it is clear that the limiting stage of the entire action lies on adsorption rate and occurrence, which seems to be ruled by the absolute value of charge per chain and by the conformation regime.

The production of PEEA microspheres with potential as carriers for protein oral delivery is described. PEEAs with different hydrophilicity were synthesized and characterized. Experiments showed that an increase in copolymer hydrophilicity gave particles less prone to cell interaction. BSA release profiles from PEEA microspheres demonstrated that an increase in polymer hydrophilicity was useful in limiting protein burst and modulating drug delivery rate by increasing PEEA degradability. These results show that fine-tuning of the hydrophilic/hydrophobic properties of PCL is essential for the formulation protein-loaded microspheres with specific properties.

Poly(epsilon-caprolactone) (PCL) macromers (M(n) = 1.7-3.8 kDa) which contain one Z-protected -NH2 group per chain were synthesized by ring-opening polymerization of epsilon-caprolactone in the presence of Sn(oct)2 using as initiator a diamine prepared by condensation of N-Boc-1,6-hexanediamine and N(alpha)-Boc-N(epsilon)-Z-L-Lysine. The coupling of these macromers with -COCl end-capped poly(oxyethylene) (PEO), M(n) = 1.0 kDa, afforded amphiphilic multiblock poly(ether ester)s (PEEs) which have, along the chain, regularly spaced pendant protected amino groups. Deprotection, accomplished without chain degradation, yielded -NH2 groups available for further reactions. The molecular structure of macromers and PEEs was investigated by 1H NMR and SEC. DSC and WAXS analyses showed that macromers and copolymers were semicrystalline and their T(m) increased with increase in the molecular weight of PCL segments. The inherent viscosity values (0.25-0.30 dL x g(-1)), together with SEC analysis results, indicated moderate polymerization degrees.

Microspheres of amphiphilic multi-block poly(ester-ether)s (PEE)s and poly(ester-ether-amide)s (PEEA)s based on poly(epsilon-caprolactone) (PCL) were investigated as delivery systems for proteins. The interest was mainly focused on the effect of their molecular structure and composition on the overall properties of the microspheres, encapsulating bovine serum albumin (BSA) as a model protein. PEEs and PEEAs were prepared using a alpha,omega-dihydroxy-terminated PCL macromer (Mn= 2.0 kDa) as a hydrophobic component. Hydrophilic oxyethylene sequences were generated using poly(ethylene oxide)s (PEO)s of different molecular mass (Mn= 300-600 Da) in the case of PEEs, or 4,7,10-trioxa-1,13-tridecanediamine (Trioxy) and PEO150 (Mn= 150 Da) in the case of PEEAs. The copolymers showed a decrease of Tm and crystallinity values as compared with PCL. Within each class of copolymers, the bulk hydrophilicity increased with increasing the number of oxyethylene groups in the chain repeat unit. PEEAs were more hydrophilic than PEEs with a similar number of oxyethylene groups. Discrete spherical particles were prepared by both PEEs and PEEAs and their BSA encapsulation efficiency related to copolymer properties. Interestingly, the insertion of short hydrophilic segments is enough to significantly affect protein distribution inside microspheres and its release profiles, as compared to PCL microspheres. Different degradation rates and mechanisms were observed for copolymer microspheres, mainly depending on the distribution of oxyethylene units along the chain. The results highlight that a fine control over the structural parameters of amphiphilic PCL-based multi-block copolymers is a key factor for their application in the field of protein delivery.

Star-shaped hydroxy-terminated poly(e-caprolactone)s (ssPCL), with arms of different lengths, were obtained by ring-opening polymerization (ROP) of e-caprolactone initiated by pentaerythritol, and were condensed with α-methyl-ω-(3-carboxypropionyloxy)-poly(ethylene oxide)s (M n = 550-5000) to afford four-armed PCL-PEO star diblock copolymers (ssPCl-PEO). The polymers were characterized by 1 H and 13 C NMR spectroscopy and sizeexclusion chromatography (SEC). The melting behavior of ssPCLs was studied by differential scanning calorimetry DSC). X-ray diffraction and DSC techniques were used to investigate the crystalline phases of ssPCL-PEOs.

A series of poly(e-caprolactone) (PCL)-based multiblock poly(ether-ester)s (PEE)s and poly(ether-ester-amide)s (PEEA)s were obtained from α,ω-dihydroxy-PCL (Mα=2-4 kDa) and -COCl di-terminated poly(ethylene oxide) (PEO) macromers (MAC) of different length (Mn = 150, 300, 600, 1 000 Da). 4,7,10-Trioxa-1,13-tridecanediamine was used in the synthesis of PEEAs. Bulk polycondensation processes were accomplished by one step (PEE) and two step (PEEA) procedures. PEEAs with PCL/ MAC/Trioxy molar ratios 1:2:1 and 1:3:2 were investigated. The multiblock copolymer architecture was proved by 1 H NMR and size exclusion chromatography (SEC) techniques. Unimodal molecular weight (MW) distributions and M n values int the range of 13.3-21.0 kDa (PEE) and 8.1 12.8 kDa (PEEA) were found. Crystalline PCL-type phases were identified for both PEEAs and PEEs by X-ray diffraction. The thermal transiotions were investigated by differential scanning calorimetry (DSC), The T m values (49.9-53.4°C) reflect those of the PCL component while the T g of PEEAs (-45 to 52 °C) are higher than those of the PEEs (-58 to -61°C) or the macromers. The equilibrium water uptakes range from 1.0 to 18.4 wt.-% (PEE) and from 4.4 to 8.8 wt.-% (PEEA) depending on both the composition and length of the ethylene oxide sequences. A dependence of surface homogeneity on copolymer composition was found for PEEs by dynamic contact angle measurements.