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• Polyester-polypeptide diblock copolymers are synthesized avoiding organo-metals. • Both copolymer molecular weight and composition are well-controlled in the synthesis. • In the solid state the copolymers have the two blocks separated and orderly arranged. • The copolymers become self-assembled in water as spheres of 200–400 nm diameter. • They are precursors for charged copolymers suited for stimuli-responsive biomaterials. Diblock copolymers (PPDLx- b -pPAAy) were prepared from ω-pentadecalactone and l -glutamic acid or l -lysine amino acids by ring opening polymerization initiated by amino groups. Telechelic amino-ended poly(ω-pentadecalactone) with a length of 15–20 repeating units was firstly synthesized by enzymatic polymerization by means of CALB and then used as macroinitiator for the polymerization of the N -carboxyanhydrides of the two α-amino acids conveniently protected as benzyl and ε N -carbobenzoxy derivatives, respectively. The molecular weight of the polypeptide block was accurately controlled by adjusting the amino acid/macroinitiator ratio used in the feed. Copolymers with M n ranging between ∼5000 and ∼40,000 g·mol−1 and varying ester/peptide ratio were obtained and characterized in detail by GPC and NMR spectroscopy. The thermal properties of these copolymers were evaluated by TGA and DSC, and their structure in the solid-state including their response to heating, were examined by FTIR and XRD at variable temperature. It was shown that the polypentadecalactone segment was crystallized for all compositions and that the polypeptide counterpart adopted a two-dimensional hexagonal packing of α-helices at temperatures above melting of the polyester block. SAXS revealed the presence of a biphasic nanostructure with a repeating distance of 27 nm for the case of glutamic-based copolymers. It was demonstrated that both glutamic and lysine-based PPDL x - b -pPAA y copolymers could self-assemble in well-shaped nanospheres with a diameter in the ∼200–400 nm range and a negative zeta-potential. [ABSTRACT FROM AUTHOR]

In this paper, the preparation of PBS- ran -PCL copolyesters by enzymatic ring opening polymerization is presented for the first time. The copolyesters were produced in a wide composition range and free of metallic contaminants, so they may be regarded as potential biomaterials. The copolymers have been characterized by proton and carbon nuclear magnetic resonance ( 1 H and 13 C NMR), gel permeation chromatography (GPC), thermogravimetric analysis (TGA), differential scanning calorimetry (DSC), polarized light optical microscopy (PLOM) and wide angle X-ray scattering (WAXS). The PBS- ran -PCL copolyesters were able to crystallize in the entire composition range and displayed a pseudo-eutectic region. Most copolymers away from the pseudo-eutectic region exhibited a single crystalline phase (PBS-rich or PCL-rich crystalline phase), while within the pseudo-eutectic region the copolymers were double crystalline. Observations by PLOM, during isothermal crystallization showed that both nucleation density and spherulitic growth rate of the copolyesters are determined by the component that constitutes the majority phase. WAXS studies revealed that d spacings of selected crystallographic planes depend on composition. Therefore, both DSC and WAXS results suggest that the copolymers are probably isodimorphic, as the PBS-rich crystalline phase may contain small inclusions of PCL co -units, while the PCL-rich crystalline domains may also contain a minor quantity of PBS co -units inside. [ABSTRACT FROM AUTHOR]

A series of ionic complexes with a comb-like architecture and a nearly stoichiometric composition were prepared from bacterial poly(γ, dl -glutamic acid) (PGGA) and alkyltrimethyl phosphonium bromides ( n ATMP·Br) bearing long linear alkyl chains with even numbers of carbon atoms ( n ) ranging from 12 to 22. The n ATMP·PGGA complexes were non-water soluble but readily soluble in organic solvents, and they displayed a high thermal stability. Combined DSC and XRD studies revealed that these complexes adopted an amphiphilic layered structure with the polypeptide chain and the alkyl chain separated in two differentiated phases with a nanoperiodicity that increased steadily with the length of the alkyl chain. The paraffinic phase was found to be partially crystallized in an extent that decreased with n , so that complexes with n = 12 and 14 did not show any sign of crystallinity whereas those with n from 16 to 22 showed crystalline melting in the ∼30–70 °C range. The structural transitions taking place by temperature effects were characterized by simultaneous SAXS/WAXS using synchrotron radiation at real time. In all cases, a shortening of the layer periodicity occurred upon heating with recovering of the initial structure after cooling. n ATMP·PGGA with n ≤ 16 showed strong antimicrobial activity against both E. coli and S. aureus, a property that could be related to the weak dissociation of the complexes happening upon incubation in water. The structure and properties of these complexes where comparatively discussed taking as reference their analog complexes made from PGGA and alkyltrimethylammonium bromides already studied by us. [ABSTRACT FROM AUTHOR]

The preparation of cyclic ethylene and butylene 2,5-furandicarboxylate oligoesters and their conversion to furan-based polyesters poly(ethylene furanoate) (PEF) and poly(butylene furanoate) (PBF) by ring-opening polymerization (ROP) are described. The cyclic oligoesters were obtained in high yields by both high dilution condensation and thermal cyclodepolymerization methods, and they consisted of mixtures of small size species. Cyclic dimer, trimer and tetramer oligoesters were isolated by semipreparative chromatography and found to be crystalline compounds melting within the 140–200 °C range. ROP catalyzed by Sn(Oct) 2 of both mixtures and individual species afforded PEF and PBF with weight-average molecular weights between 50,000 and 60,000 g mol −1 . Polymerization rate was found to be higher for butylene than for ethylene cyclic oligofuranoates, and also to increase slightly as cycle size decreased. The thermal properties of PEF and PBF prepared by ROP were in full agreement with those reported for these polyesters obtained by melt polycondensation. [ABSTRACT FROM AUTHOR]

The synthesis, characterization and comparative evaluation of properties of two series of cationic PBS copolyesters bearing respectively ammonium and tributylphosphonium side groups, are reported. The copolyesters with contents in ionic units up to 50 mole-% as well as the fully ionic homopolyesters were prepared by polycondensation in the melt catalyzed by CALB or TBT. Their M n ranged between 20,000 and 5000 g mol −1 depending of composition and the type of ionic group that is involved. All the copolyesters were non-water soluble and showed good thermal stability. They were semicrystalline with melting temperatures and enthalpies decreasing with the ionic contents. The interactions interplayed by the ionic groups restricted largely the molecular mobility and caused a significant increase in the melt viscosity and glass transition temperature of PBS and a decrease in crystallization rate. Both ammonium and phosphonium containing PBS copolyesters were able to be coupled with sulfonated PBS to generate ionic polymer blends with modified crystallizability. The presence of both ammoniums and phosphoniums provided PBS with remarkable antimicrobial activity against gram-positive and gram-negative bacteria. [ABSTRACT FROM AUTHOR]

Abstract: Two cyclic acetal compounds, 2,3-O-methylene L-threitol and dimethyl 2,3-O-methylene L-threarate, both coming from naturally-occurring tartaric acid, were used as comonomers to replace ethylene glycol and dimethyl terephthalate respectively, in the preparation of PET-based copolyesters by polycondensation in the melt. Synthesis results, structure and thermal properties of the two afforded copolyester series were evaluated and compared regarding composition and type of comonomer used in each case. All the copolyesters had a random microstructure and molecular weights in the 25,000–35,000 g·mol−1 range. Their thermal properties varied logically with composition along each series but they significantly changed according to which acetal comonomer was used. PET copolyesters made from acetalized L-threitol displayed thermal stability and T g comparable to PET, whereas these two properties were depressed in the copolyesters containing threarate units. Both types of copolyesters were able to crystallize for contents in tartaric acid derived units up to around 30% by adopting the crystal structure of PET. Crystallization rates and melting temperatures decreased with copolymerization in the two series but this effect was more noticeable in copolyesters made from threitol. [Copyright &y& Elsevier]

Abstract: Poly(hexamethylene terephthalate) was cyclo-depolymerized in solution by heating to yield a fraction of cyclic oligomers of hexamethylene terephthalate (c(HT)2–5) with a content around to 95% in dimer to pentamer. Ring-opening polymerization in the melt of c(HT)2–5, either neat or in mixtures with ε-caprolactone (CL) covering a range of HT/CL ratios from 9/1 to 1/9 was carried out to produce polyesters with molecular weights above 30,000 in high yields. The copolyesters had a comonomer composition according to the feed and the microstructure evolved from random to blocky as the content in CL increases. The thermal and mechanical properties of the copolyesters were evaluated for a variety of compositions. Results obtained in this work were compared to those previously obtained by us in the ring-opening copolymerization of CL with a cyclic oligomeric fraction enriched in hexamer and heptamer (c(HT)6–7). Although the polyesters resulting from the use of these two fractions were similar, significant differences were found in polymerization rate evidencing a lower reactivity of c(HT) n with decreasing values of n. [Copyright &y& Elsevier]

A series of poly(mono n-alkyl itaconate)s, poly(methyl n-alkyl itaconate)s and poly(di n-alkyl itaconate)s with n=12, 14, 16, 18 and 22 have been prepared by radical polymerization. NMR studies point out that poly(methyl n-alkyl itaconate)s and poly(di n-alkyl itaconate)s are mainly syndiotactic polymers whereas poly(mono n-alkyl itaconate)s are obtained as almost atactic polymers. The characterization performed by DSC, solid state 13C CP/MAS NMR and X-ray diffraction, indicates that the side chains of poly(mono n-alkyl itaconate)s and poly(methyl n-alkyl itaconate)s derivatives with more than 12 carbon atoms are able to crystallize in hexagonal lattices. In the case of poly(di n-alkyl itaconate)s, when the side chains contain 12 or more carbon atoms, they are able to crystallize also in hexagonal lattices. [Copyright &y& Elsevier]

• Novel triblock aromatic aliphatic copolyesters were successfully prepared by ROP. • TBD organocatalyst does not promote transesterification due to the low temperatures used. • The inner aromatic-aliphatic segments of the ABA copolymers are able to crystallize in a broad composition range. • Thermal and structural properties are independent on PLA content up to a high concentration. Two series of partially biobased ABA triblock copolyesters were successfully prepared by ring-opening polymerization (ROP) of L -lactide initiated by two telechelic polyester polyols using an organic catalyst. B blocks were made of telechelic poly(hexamethylene terephthalate) (PHT) and poly(hexamethylene 2,5-furandicarboxylate) (PHF), respectively, with average molar masses of around 3500 g mol−1 and A blocks were made of poly(lactic acid)s (PLA) of different block lengths. For each series, four copolymers with different PHT/PLA and PHF/PLA compositions were prepared by varying the feed molar ratios. The triblock structure of the obtained copolymers was ascertained by 13C NMR, which confirms that the organic catalyst employed does not promote transesterification reactions at the low temperatures used for the reaction. All copolyesters were thermally stable under inert atmosphere up to around 300 °C. For all synthesized copolyesters, the PLA blocks were unable to crystallize, mainly due to racemization reactions taking place during L -lactide ROP. Both, PHT and PHF blocks were able to crystallize and their thermal and structural properties (T m , T c , X c and lamellar thickness) were independent on PLA content until its concentration was very high and topological restrictions difficulted crystallization. According to SAXS, most copolymers were found to be miscible in the melt. Both PLA- b -PHT- b -PLA or PLA- b -PHF- b -PLA triblock copolymers showed a single T g indicating that the components are miscible in the amorphous state. [ABSTRACT FROM AUTHOR]

• Ionic macrolactone-amino acid diblock copolymers were prepared from neutral precursors. • The two copolymer blocks were able to adopt ordered structures separately. • The copolymers became self-assembled in water in 100–200 nm diameter particles. • Glu-containing copolymers were efficient for loading and pH-mediated releasing of DOX. • Lys-containing copolymers entrapped and condensed DNA by forming ionic polyplexes. Two sets of ionically charged polypentadecalactone-polypeptide diblock copolymers (PPDL x - b -PAA y , with x = 15 or 20 and y ranging from 30 to 200), one containing α-L-glutamic acid (LGA) and the other containing α-L-lysine (LL), were obtained from their respective precursors with the side groups of LGA and LL protected as γ O -benzyl and ε N -carbobenzoxy, respectively. The copolymers were semicrystalline with the polyester block crystallized in the usual pseudo-rhombic lattice and the polypeptide in the α-helix or β-sheet conformation depending on the amino acid and the length of the block. Copolymers with PAA blocks with y ≥ 80 were water-soluble and they adopted the α-helix conformation in the aqueous medium when they are in the non-ionized state. Both LGA and LL containing copolymers self-assembled in nanoparticles with a size between 150 and 180 nm in diameter. PPDL- b -PLGA nanoparticles were able to load DOX with an efficiency of ~70% whereas PPDL- b -PLL displayed a noticeable capacity for condensing DNA. In both cases hosting was based on the ionic complexation taking place between the ionized copolymer and the guest compound. Accordingly DOX release rate was found to be noticeably depending on pH. [ABSTRACT FROM AUTHOR]

The capacity of redox D-mannitol-based polyurethanes to modulate the glutathione response under physiological conditions, as well as their effectiveness for sustained and site-specific drug release in the gastrointestinal tract (GIT), have been demonstrated in previous studies. Based on those promising results, our attention has now been drawn towards hydrolytic degradation processes at 37 °C and different pH values, from acidic to basic conditions, as in the GIT. For that, two sets of branched and linear D-mannitol-based polyurethanes containing disulfide bonds have been synthesized, which has been possible depending on the starting D-mannitol-derived monomer. Thus 3,4- O -isopropylidene-D-mannitol, having two secondary hydroxyl groups in addition to the two primary hydroxyl groups, afforded polyurethanes with a certain degree of branching. In contrast, 2,4:3,5-di- O -isopropylidene-D-mannitol and 2,3:4,5-di- O -isopropylidene-D-mannitol, lacking secondary hydroxyl groups, led to linear polyurethanes. Removal of the O -isopropylidene protecting groups resulted in more-hydrophilic materials. As in glutathione-mediated degradation, the branched polyurethanes presented enhanced degradation under physiological conditions, proportional to the content of D-mannitol, whereas linear polyurethanes were degraded slowly, and pH 8 and 10 were required. [ABSTRACT FROM AUTHOR]

• Two approaches were investigated for modulation of poly(butylene succinate) enzymatic biodegradation • Possibilities and limitations of both approaches were discussed • Polysaccharidic multilayers on poly(butylene succinate) films effectively modulate their enzymatic degradation • Enzyme encapsulation within alginate beads allows to retain enzyme activity • Enzymatic self-degradation of extruded poly(butylene succinate) was monitored Biodegradation of polyesters driven by enzymes is considered as one of the most effective way of degradation of these materials, as a way to control plastics accumulation in the environment. In this study, we present two different strategies to tune the enzymatic degradation of PBS films triggered by a lipase from Pseudomonas cepacia. Firstly, the kinetics of enzymatic degradation of PBS films was regulated by applying multilayer coats of polysaccharide alginate and chitosan (Alg/Chi) films. Secondly, self-degradable PBS films were prepared by embedding lipase-filled alginate particles. For comparison purposes, a detailed enzymatic degradation study of neat PBS films exposed to a lipase from P. cepacia in solution was made to determine the main experimental parameters influencing their degradation in solution. The results showed that an increase in enzyme concentration increased the degradation extent and rate of neat PBS films. At a fixed enzyme concentration, stirring of the solution containing the enzyme and the PBS also increased the biodegradation rate. In the case of the PBS films coated with a different number of Alg/Chi layers by spray-assisted LbL and subjected to enzymatic degradation experiments in solution, the extent of degradation was found to be dependent on the number of protective coating layers. Therefore, the Alg/Chi biobased coating constitutes an effective barrier to the diffusion of the lipase, thus proving its effectiveness in modulating the enzymatic activity as a function of coating thickness. In the case of self-degradable PBS containing lipase-embedded alginate beads (employed to protect the enzyme during high-temperature processing), only limited biodegradation was observed as the amount of encapsulated enzyme employed was too small. Nonetheless, these results are promising, as the enzymatic activity –indicative of the degradation capacity of the enzyme– determined for all these samples was about 2 orders of magnitude lower than that of previous assays. [Display omitted] [ABSTRACT FROM AUTHOR]

The use of renewable monomers and green polymerization processes for preparing new synthetic polymers is a hot topic today. In this work we have obtained high molecular weight copolyesters derived from ω-pentadecalactone (PDL), dimethyl succinate (DMS) and 1,4-cyclohexanedimethanol (1,4-CHDM) by a combination of ring opening polymerization (ROP) and two step melt polycondensation processes. The reaction has been carried in bulk under mild conditions (80–120 °C) and catalyzed by immobilized Candida artarctica lipase B (N435 biocatalyst). These reactions were followed by 1H NMR and it was observed that although PDL reacted faster, at the end copolyesters displayed a random microstructure due to transesterification reactions taking place during polymerization. These copolyesters were thermally stable up to around 350 °C and semicrystalline for all compositions with melting temperatures decreasing with the increased content of the counterpart comonomer up to a pseudo-eutectic point located at 40 mol-% of PDL composition. The crystalline structure and transitions taken place by heating have been studied by WAXS and SAXS synchrotron X- ray diffraction. Copolyesters with elastomeric properties could be obtained at intermediate compositions. [Display omitted] • High molecular weight polyesters have been obtained in bulk by enzymatic ROP/polycondensation using N-435 biocatalyst. • Random aliphatic copolyesters from ω-pentadecalactone, dimethyl succinate and 1,4-cyclohexanedimethanol have been achieved. • All copolyesters were thermally stable up to around 350 °C. • All copolyesters compositions were semicrystalline with a pseudoeutetic point at 40 mol-% of PDL composition. • Elastomeric properties were observed for intermediate copolyester compositions. [ABSTRACT FROM AUTHOR]

Abstract: Cyclic butylene terephthalate (CBT) was polymerized in the presence of a low molecular weight bifunctional epoxy resin. The resultant chain extended polymerized CBT (pCBT) showed an increased ductility compared to that of conventionally polymerized pCBT for all analyzed epoxy concentrations (1–4wt.%). The best results were obtained with 2wt.% of epoxy resin. Other mechanical properties remained relatively unaffected by the epoxy resin. 1H NMR analysis suggested an esterification reaction of the carboxyl end groups of pCBT and the glycidyl functional groups of the diepoxide. With increasing epoxy content, the chain extended pCBT showed an increasing molecular weight and a decreasing glass transition. Crystallization and melting temperatures as well as crystallinity also decreased with increasing epoxy concentration. [Copyright &y& Elsevier]

Abstract: Ionic coupling of both polygalacturonic and alginic acids with alkyltrimethyl ammonium surfactants containing 18, 20 and 22 carbon atoms in the alkyl side chain was conducted in water solution to prepare non-soluble comb-like complexes. These amphiphilic complexes are arranged in a biphasic layered structure with the paraffinic phase made of alkyl side chains alternating with the hydrophilic phase made of polyuronic chains. The complexes displayed the thermal behaviour typical of comb-like systems carrying long polymethylene groups, which melt at temperatures between 40 and 80°C without significant disruption of the layered arrangement. Melting temperature, crystallinity and thermal stability were slightly higher for the polygalacturonic complexes and all they increased almost steadily with the length of the alkyl chain within each series. The melting-crystallization process was followed by combined WAXS/SAXS and 13C CP-MAS NMR, which revealed that the transition involves an expansion-contraction of the structure that may attain up to 20% of the original dimension. The transition takes place without large conformational changes and is not fully reversible. [Copyright &y& Elsevier]

Abstract: Nanocomposites of poly(hexamethylene terephthalate) (PHT) and montmorillonite organo-modified with alkylammonium cations bearing two primary hydroxyl functions, i.e., Cloisite® 30B (CL30B) were synthesized. Organoclay incorporation was performed either by dispersion in the PHT matrix via melt blending or by in situ ring-opening polymerization of hexamethylene terephthalate cyclic oligomers c(HT). An additional procedure combining the two methods, preparation of a highly enriched inorganic “PHT–CL30B” nanohybrid masterbatch by in situ ring-opening polymerization and blending of the masterbatch with additional PHT was explored. The obtained nanocomposites contain 3% (w/w) of inorganics and displayed a mixture of intercalated morphology and exfoliated nanolayers as evidenced by X-ray diffraction and transmission electron microscopy. The nanocomposite obtained by the masterbatch technique exhibited a higher degree of exfoliation and displayed slightly higher glass transition temperatures, better mechanical properties and higher flame resistance. The improved results achieved with the “masterbatch route” are a consequence of the reactions occurring between the nanocomposite constituents allowing for the grafting of PHT chains onto the organoclay surface. [Copyright &y& Elsevier]

Abstract: The thermal decomposition of poly(γ-glutamic acid), poly(α-methyl γ-glutamate) and ionic complexes of the polyacid with alkyltrimethyl ammonium salts was studied by TGA, GPC, and FTIR and NMR spectroscopies. It was found that both poly(γ-glutamic acid) and poly(α-methyl γ-glutamate) depolymerised above 200°C by unzipping mechanism with generation of pyroglutamic acid and methyl pyroglutamate, respectively. On the other hand, the ionic complexes degraded through a two-stage process, the first stage being cyclodepolymerisation of the poly(γ-glutamate) main chain along with decomposition of the ionic complex promoted by the adsorbed water. Decomposition of the previously generated alkyltrimethyl ammonium compound followed by unspecific cracking of the resulting nitrogenated compounds accounted for the second degradation step, at higher temperatures. Mechanisms explaining the decomposition of the three studied systems were proposed according to collected data. [Copyright &y& Elsevier]

Abstract: Homopolymerization of α-olefins (1-C n H2n , n =6, 8, 10, 12, 16 and 18) and their copolymerization with styrene were carried out in toluene at 60°C using diphenylzinc–ethenylbisindenylzirconium dichloride–methylaluminoxane as initiator system. Atactic polystyrene and almost isotactic poly(α-olefin)s were obtained. Copolymerization of S/α-olefin with this initiator system gave isotactic olefin-enriched copolymers. According to DSC analysis, the homopolymers P(1-C12H24), P(1-C16H32), and P(1-C18H36) as well their styrene copolymers are crystalline. [Copyright &y& Elsevier]

A series of poly(ethylene terephthalate-co-ethylene 5-sodiosulfoisophthalate) copolyesters containing from 1 up to 50 mol% of sulfonated units was prepared by melt polycondensation from ethylene glycol and mixtures of dimethyl terephthalate and dimethyl 5-sodiosulfoisophthalate. The resulting copolymers had a random microstructure and contained oligo(ethylene glycol) units in amounts increasing with the content in sulfonated isophthalate units. Copolyesters with more than 20 mol% of 5-sodiosulfoisophthalic units were amorphous and easily soluble in water. The hydrodegradability of the copolyesters was very high as compared to poly(ethylene terephthalate), and increased with the content in sulfonated units. It was demonstrated that the susceptibility to acidic hydrolysis of these copolymers is mainly due to the presence of the sodium sulfonate groups, the influence of the oligo(ethylene glycol) units in this regard being noticeable but limited. [Copyright &y& Elsevier]

The two cyclic acetals, 2,3-di- O -methylene- l -threitol and dimethyl 2,3-di- O -methylene- l -threarate, were used for the synthesis of two series of PBS copolyesters differing in which unit, butylene or succinate, was replaced, in addition of the corresponding parent homopolyesters. Polycondensation reactions were carried out in the melt affording polymers with satisfactory molecular weights. Copolyesters were prepared with contents in tartaric acid-based units over the whole range of compositions and they all had a random chemical microstructure. The physical properties of the novel copolyesters varied widely depending not only on their composition but also on the type of unit that was replaced. They showed higher glass transition ( T g ), lower melting temperatures ( T m ), and lower crystallinity compared to the parent PBS homopolyester. Regarding mechanical properties, the presence of the stiff cyclic acetal units in the PBS chain caused an increase in the elongation at break and also a reduction in both elastic modulus and tensile strength of the polyester. Upon copolymerization the PBS notably increased its hydrolytic degradability and more slightly its susceptibility to be degraded by lipases. [ABSTRACT FROM AUTHOR]

Abstract: Stoichiometric ionic complexes of bacterial poly(γ-glutamic acid) with the cationic N-octadecyl and N-docosyl-N,N,N-trimethylammonium surfactants were mixed with alkylammonium modified bentonite (Cloisite 30B) to generate hybrid compounds covering a wide range of clay/polymer compositions. The structure of these compounds was examined by XRD and cryoTEM, which indicated extensive penetration of the biopolymer into the nanoclay galleries with widening or even destruction of the layered arrangement of the complex and the clay. Simultaneous SAXS/WAXS analysis in real time showed that hybrids with moderate inorganic contents displayed melting/crystallization upon heating/cooling within the 40–70°C interval with concomitant expansion/contraction of the intersheet spacing. 13C CP-MAS NMR revealed that an anti-to-gauche conformational interconversion of the alkyl chains was involved in the melting/crystallization process. The results provided by energy-based dynamical simulations proved the feasibility of the polyacid and the nanoclay to be homogenized in the hybrid due to the compatibilizing effect of the surfactant. [Copyright &y& Elsevier]

Abstract: Poly(styrene-co-p-tert-butyldimethylsilyloxystyrene) copolymers, P(S/p-TBDMSOS), with contents in the substituted comonomer within the 0–50% range were prepared using combined Ph2Zn–CpTiCl3–MAO initiator systems and some of them were used as precursors of poly(styrene-co-p-hydroxystyrene), P(S/p-HOS), copolymers. p-tert-Butyldimethylsilyloxystyrene was synthesized from p-hydroxybenzaldehyde by protecting the hydroxyl group with tert-butyldimethylchlorosilane and converting the aldehyde group into vinyl through the Wittig reaction. The P(S/p-TBDMSOS) copolymers with contents in substituted units equal or higher than 25% were atactic and those with content higher than 5% were amorphous. P(S/p-HOS) copolymers containing up to 20% of hydroxylated units were obtained by full hydrolysis in acidic medium of the corresponding P(S/p-TBDMSOS). The hydroxylated copolystyrenes displayed crystallinity for the whole range of studied compositions and their crystalline structure was essentially similar to that of s-PS homopolymers. The influence of the substituent on the modified-MAO catalyzed copolymerization and on the thermal properties of the resulting copolymers was comparatively examined. [Copyright &y& Elsevier]