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Since extraction of the naturally occurring mussel-foot proteins is expensive and time-consuming, routes towards synthetic analogues are continuously being explored. Often, these methods involve se ...

By combining ATRP, dendrimer chemistry and ‘click’ reactions, a library of novel linear dendritic block copolymers (hybrids) was successfully synthesized. The isolated polymers displayed hydrophilic alkyne groups and Tg's ranging from 14 °C to 67 °C. A Tg threshold of 39 °C was found necessary for straightforward porous membrane fabrication via the breath figure method. Exploiting the copper(I)-catalyzed azide–alkyne cycloaddition (CuAAC) reaction, a robust and benign protocol was identified enabling surface functionalization under aqueous conditions. Such manipulations included the introduction of fluorescent rhodamine for thorough assessment by confocal fluorescence microscopy as well as polyethylene glycol chains or perfluorinated groups for tuning the membrane wettability. Finally, with the initial indication of being nontoxic to human dermal fibroblasts (hDF) and osteoblast-like MG63, the porous membranes can potentially find use in the field of controlled cell culture such as patterning of cell growth.

Itaconic acid is a platform compound for bio-based renewable materials. This study employs itaconic anhydride (IAn) as a novel monomer for lipase-catalyzed ring-opening addition condensation polyme ...

Radical copolymerization based on acrylonitrile (AN) and 2,2,2-Trifluoroethyl acrylate (ATRIF) initited by AIBN was investigated in acetonitrile solution. The resulting pol- y(AN-co-ATRIF) copolymers were characterized by 1 H, 13 C, and 19 F NMR and IR spectroscopy, and size exclusion chromatogra- phy (SEC). Their compositions were assessed by 1 H NMR. The kinetics of radical copolymerization of AN with ATRIF was investigated from sereval experiments achieved at 70 � C from initial (AN)0/(ATRIF)0 molar ratios ranging between 20/80 and 80/20 and was enabled to determine the reactivity ratios of both comonomers. From the monomer—polymer copolymer- ization curve, the Fineman-Ross and Kelen-T€ laws enabled to assess the reactivity ratios (rAN5 r1 5 1.25 6 0.04 and rATRIF 5 r2 5 0.93 6 0.05 at 70 � C) while the revised pat- terns scheme led to r12 5 rAN 5 1.03, and r21 5 rATRIF 5 0.78 at 70 � C. In all cases, rAN x rATRIF product was close to unity, which indicates that poly(AN-co-ATRIF) copolymers exhibit a random structure. This was also confirmed by the Igarashi's and Pyun's laws which revealed the presence of AN-ATRIF, AN-AN, and ATRIF-ATRIF dyads. The Q and e values for ATRIF were also assessed (Q2 5 0.62 and e2 5 0.93). The glass transi- tion temperature values, Tg, of these copolymers increased from 17 to 61 � C as the molar percentage of ATRIF decreased from 77 to 16% in the copolymer. Thermogravimetry analysis of poly(AN-co-ATRIF) copolymers showed a good thermal sta- bility compared to that of poly(ATRIF) homopolymer due to incorporation of AN comonomer. V C 2013 Wiley Periodicals, Inc. J. Polym. Sci., Part A: Polym. Chem. 2013, 51, 3856-3866

Functionalization of thermally expandable microspheres (TEMs) with a conjugated polymer is explored. These functionalized thermally expandable microspheres were prepared by grafting 3-n-dodecylthiophene via oxidative polymerization from a thiophene modified TEM. The thiophene modified TEM to 3-n-dodecylthiophene ratio was varied during grafting and the resulting poly(3-n-dodecylthiophene) grafted TEM were characterized by FT-IR spectroscopy, Thermal Gravimetric Analysis, Scanning Electron Microscopy, Thermo-Mechanical Analysis and X-ray diffraction. The particles were approximately 30 μm in diameter and upon heating, the functionalized microspheres expanded up to 50 times. This expansion property was related to the poly(3-n-dodecylthiophene) content, where the increase in poly(3-n-dodecylthiophene) on microsphere decreased the thermal expansion. The X-ray diffraction shows a sharpening of the poly(3-n-dodecylthiophene) (1 0 0) diffraction peak upon expansion. Grafting conjugated polymers to thermally expandable microspheres provides robust functional photo- and electro-active TEMs.

Emerging dendritic-linear-dendritic (DLD) hybrids that possess synergetic properties of linear and highly functional branched dendritic polymers are becoming important macromolecular scaffolds in f ...

Four sets comprising a total of 16 sequential interpenetrating network (SeqIPN) hydrogels were efficiently fabricated via UV initiated thiol-ene coupling chemistry and from 2 kDa or 8 kDa primary p ...

Poly(ethylene glycol) (PEG)-diallyls, ranging from 2 to 8 kDa, were successfully reacted with a trifunctional thiol crosslinker via thiol–ene coupling reaction to construct four different primary P ...

Considering the large number of applications for hydrogels, a better understanding of the relation between molecular structure and mechanical properties for well-defined hydrogel is essential. A ne ...

Aiming to develop new dielectric polymers containing CN and F groups with strong dipole moments, a novel copolymer of acrylonitrile (AN) and 2,2,2-trifluoroethyl acrylate (ATRIF) was synthesized in acetonitrile by free radical process as well as the respective homopolymer (poly(ATRIF)). The copolymer’s composition and microstructure were analyzed by FTIR, 1 H and 13 C NMR spectroscopy and SEC. The molar incorporation of AN determined in the copolymer by NMR was 58 mol%. Thermogravimetric analysis of poly(AN- co -ATRIF) copolymer showed good thermal stability comparatively to the fluorinated homopolymer. Both copolymer, poly(AN- co -ATRIF), and homopolymer, poly(ATRIF), were dielectrically characterized over a frequency range from 10 −1 to 10 6 Hz, and in a temperature range from 223 to 393 K. The dominating relaxation process detected in both materials is the α-relaxation, associated with the dynamic glass transition. A VFTH temperature dependence of the relaxation times ( τ ) was found for both materials, as characteristic of cooperative processes, from which the respective glass transition temperatures ( T g ( τ = 100 s)) were estimated, which differ ∼40 K, the one of the copolymer being higher (307 K) in accordance to the calorimetric analysis. This effect was attributed to a higher stiffness of the backbone in the copolymer originated by the inclusion of the acrylonitrile groups. Both relaxation functions have the same breath of relaxation times allowing constructing a single master curve, indicating similar non-exponential character. A less fragile behavior was found for the copolymer. This was rationalized in a more straightforward way by the free volume approach instead from a correlation between fragility and intermolecular coupling. It was found that in the copolymer the free volume increases at a lower rate with the temperature increase. It was inferred from the VFTH temperature dependence of the dc conductivity and low values of the decoupling index that ion motion is significantly influenced by the dynamics of the α-process.

In the last decades, the fabrication of ordered nano- and microporous structures has attracted increasing interest due to their specific properties and multiple possible applications in electronics, as templates or in the biological field. The development of such materials has been favored by the introduction of the simple breath-figure templating method in the 1990’s. In order to fully exploit the potential of these porous materials, the use of advanced functional molecules as precursors is essential. One suitable class of molecules is the well-defined linear-dendritic hybrids (LD hybrids) family. The structural variations, multiple end-groups and possible amphiphilicity of these molecules are significant advantages that could lead to highly sophisticated functional materials with potential usage in biology. Therefore, this project was directed towards the synthesis of advanced LD hybrids and the evaluation of their ability to form ordered functional porous films.A degradation and toxicity study was initially conducted on polyester-based 2,2-bis(methylol)propionic acid (bis-MPA) dendrimers under physiological conditions to support the potential usage of these molecules for biological purposes. The materials were found to undergo a relatively fast depolymerization process at pH 7.5. Moreover, the initial dendrimer and its decomposition products were proven to be non-toxic for immune competent cells, allowing for the utilization of these molecules for biological applications.A linear-dendritic-linear hybrid library was successfully synthesized from biocompatible poly(ethylene glycol) (PEG), poly(e-caprolactone) (PCL) and bis-MPA building blocks using a combination of ring-opening polymerization (ROP)and copper(I)-catalyzed azide-alkyne cycloaddition (CuAAC). The materials, consisting of one long PEG block connected to the focal point of the dendron and several PCL arms attached at its periphery, were used to construct ordered porous films using the breath figure method. The polymeric architecture strongly affected the ordering of the films with a more regular morphology obtained from a more flexible polymer. Changing the semi-crystalline PCL to amorphous polylactide (PLA) also permitted the formation of porous arrays. Interestingly, films obtained from inverted structures possessing one long PCL block and several short PEG chains, also presented a regular morphology. Moreover they could be activated to exhibit multiple surface hydroxyl groups.To increase the number of orthogonal synthetic methodologies available for the preparation of advanced macromolecules, high molecular weight dendritic macrothiols were synthesized. These molecules were efficiently coupled to a number of core molecules via thiol-ene coupling, generating a comprehensive library of dendritic materials. This approach represents an attractive alternative to the commonly used, but potentially toxic, CuAAC.Exploiting the obtained results, a final LD hybrid was synthesized from atom transfer radical polymerization (ATRP) of 2-hydroxyethyl methacrylate (HEMA) derivatives and thiol-ene coupling (TEC) with macrothiols. This macromolecule was successfully utilized to form functional ordered porous arrays and the availability of peripheral alkyne functional groups was demonstrated by efficient coupling with fluorescent Rhodamine-B. The HEMA-backbone allowed for the introduction of cross-linkable azide groups that were used to significantly improve the thermal stability of the films from 50 °C to 200 °C. These materials have the potential to be used in applications such as catalysis, in medicine and as sensors.

Rigid nanoscale polymer rods were prepared by grafting preformed amine-terminated poly(styrene) and poly(tert-butyl acrylate) onto oxidized cellulose microcrystals. Low polydispersity polymers, grown using atom transfer radical polymerization, were characterized and purified prior to cellulose attachment. Oxidation of the cellulose microcrystal led to the formation of carboxylic acids on the surface of the microcrystals. Covalent attachment of the polymers onto the cellulose microcrystals was achieved via a carbodiimide-mediated amidation reaction. The length and diameter of the polymer-cellulose composites increased upon surface modification. Typically, polymer-cellulose composites are synthesized by a grafting-from method because it can be difficult to obtain sufficient graft density using a grafting-to preparation. However, the composites reported here comprised 60-64% grafted polymer by mass. This degree of grafting-to allowed the composite to form stable suspensions in organic solvents.

Linear dendritic hybrid materials enable a range of architectural variations which offers novel possibilities in the tailoring of polymeric materials. In this study dendrons based on the 2,2-bis(methylol)propionic acid (bis-MPA) building block, bearing click chemistry moieties in the core and peripheral hydroxyl functionalities, have been used as macroinitiators for ring opening polymerization of e-caprolactone. A library of star branched polymers with poly(e-caprolactone) chains was initially constructed using dendrons up to 4th generation. In a second step, the popular CuAAC or thiol–ene click reaction was efficiently used to attach poly(ethylene glycol) chains of different lengths to the core. Potential applications of the resulted amphiphilic linear dendritic hybrids were investigated. Both self-assembled micelles loaded with doxorubicin anticancer drug and ordered honeycomb membranes with enhanced surface area were successfully fabricated and characterized.

In this contribution, the influence of abstractable hydrogen on the kinetics of photopolymerized vinyl ether/maleate monomer formulations is reported. The effects of chain transfer on the polymeriz ...

By taking advantage of the orthogonal nature of thiol−ene coupling and anhydride based esterification reactions, a facile and chemoselective strategy to dendritic macromolecules has been developed. The ability to interchange growth steps based on thiol−ene and anhydride chemistry allows the synthesis of fifth-generation dendrimers in only five steps and under benign reaction conditions. In addition, the presented coupling chemistries eliminate the traditional need for protection/deprotection steps and afford dendrimers in high yield and purity. The modularity of this strategy coupled with the latent reactivity of the alkene/hydroxyl chain ends was demonstrated by using different cores (alkene and hydroxyl functional), various AB2 and CD2 monomers and a range of chain end groups. As a result, three dendritic libraries were prepared which exhibited tunability of both the chemical functionality and physical properties including the fabrication of PEG hydrogels.

In cellulose nanocomposites, the surface of the nanocellulosic phase is critical with respect to nanocellulose dispersion, network formation and nanocomposite properties. Microfibrillated cellulose ...

Novel thermo-responsive cellulose (filter paper) surfaces of N-isopropylacrylamide (NIPAAm) and pH-responsive cellulose surfaces of 4-vinylpyridine (4VP) have been achieved via surface-initiated ATRP. Dual-responsive (pH and temperature) cellulose surfaces were also obtained through the synthesis of block-copolymer brushes of PNIPAAm and P4VP. With changes in pH and temperature, these "intelligent" surfaces showed a reversible response to both individual triggers, as indicated by the changes in wettability from highly hydrophilic to highly hydrophobic observed by water contact angle measurements. Adjusting the composition of the grafted block-copolymer brushes allowed for further tuning of the wettability of these "intelligent" cellulose surfaces.

Presently, the majority of reports deal with combining chemical reactions, in a stepwise fashion, to obtain well-defined polymers. In the future, chemists need to address new challenges such as increase in the range of available efficient reactions, developing libraries of compatible one-pot reactions, and the application of obtained materials in key industries. Indeed, the rising importance of the click concept has now devised robust synthetic approaches in various fields of research. The unique selectivity of the click reaction is today a new found toolbox for scientists to investigate one-pot multi-step systems. Several accelerated protocols have elegantly been reported to obtain a library of advanced polymers.

The preparation and characterization of a series of first to fourth generation dendronized poly-(norbornene)s are presented. The monomers were synthesized in a divergent fashion from 5-norbornene-2 ...

Four generations of dendronized polymers with a methacrylate backbone and hydroxy-functionalized aliphatic polyester dendrons based on 2,2-bis(methylol)propionic acid were studied in solutions by ...

Organic-inorganic hybrid materials consisting of nanosized silica particles with surface grafted PS or PS-b-PMMA were synthesized using ATRP. These hybrid materials were used in the fabrication of ...

Dendronized polymers with a methacrylate backbone bearing pendant aliphatic polyester dendrons based on 2,2-bis(methylol)propionic acid have been investigated by rheological measurements, different ...

A series of polymers tethered with bis-MPA dendrons was synthesized by a combination of divergent growth and atom transfer radical polymerization (ATRP). Macromonomers of first and second generatio ...

Summary: Branched aliphatic polycarbonates were synthesized by ring opening polymerization of 5,5-dimethyl-1,3-dioxane-2-one (NPC) initiated from polyfunctional alcohols and a commercial hyperbranched polyester (BOLTORN®). Polymerizations in the presence of fumaric acid under bulk conditions allowed high conversion (80%) without gelation. The synthesis of polymers with long chain branches was confirmed by size exclusion chromatography and universal calibration. The Mark–Houwink exponent decreased, indicating an increased density, while increasing the number of arms. The star polymers with up to four arms showed thermal properties Tg (20–30 °C) and Tm (100–110 °C) similar to linear PNPC. Boltorn™ hyperbranched polymer with radial polycarbonate grafts.

Three sets of aliphatic polyester dendrimers based on 2,2-bis(methylol)propionic acid (bis-MPA) were synthesized. Two of the sets had benzylidene terminal groups and either a trimethylolpropane or ...

The viscoelasticity of two thermally crosslinked polymer coatings was examined in terms of relaxation of the applied stress after a sudden strain. Two different transient methods were utilized: flat-ended cylindrical indentation testing of polymer film on a rigid substrate and tensile testing of a corresponding free-standing polymer film. The correlation between tensile and indentation tests was studied. The mechanical response of a viscoelastic layer deposited on a rigid substrate was investigated as a function of indentation depth. there was good agreement between the results of the tensile and indentation tests for thick film layers at moderate indentation depths. The findings indicate that the substrate influences the coating performance by reducing the viscous contribution to the stress response hand amplifying the magnitude of the equilibrium modulus for large indentation depths. The indentation method utilized here was shown to be a potentially suitable tool for the determination of Poisson's ratio of polymer films.

A divergent approach to synthesize dendritic aliphatic polyester structures based on 2,2-bis(hydroxymethyl) propionic acid (bis-MPA) is described. The key building block is the anhydride of isoprop ...

A series of branched polyesters consisting of poly(epsilon-caprolactone) (PCL) (degree of polymerisation: 5-200) initiated from hydroxy-functional cores and end-capped with methylmethacrylate have ...

Liquid crystalline dendrimers with peripheral mesogen-containing units have been prepared. Multistep synthesis with several selective reactions was used in the preparation of the mesogen-containing ...

A series of hyperbranched aliphatic polyethers with different degree of branching (DB) and molecular weights have been studied with respect to their rheological and thermal properties. The DB was shown to affect the ability of the polymers to crystallize and thereby also the rheological properties of the polymers. A low DB resulted in semi-crystalline polymers with melting points between 100 and 130°C. The polymers with a higher DB were essentially amorphous and behaved as non-entangled Newtonian liquids in the molten state.

The dielectric relaxation was determined in a time-domain spectrometer between 100 and 295 K and from 0.1 to 1000 Hz for series of dendritic liquid crystalline polymers with scaffolds based on 2,2- ...

The cationic ring-opening polymerization of 3-ethyl-3-(hydroxymethyl)oxetane to form hyperbranched polyethers has been studied. The polymerizations have been performed in bulk using sulfonium salt initiators. To produce polymers of different degrees of branching, the reaction conditions (reaction temperature and initiator) have been varied. Polymerizations have also been performed in the presence of a trifunctional core molecule, trimethylolpropane. The conversion of monomer turned out to be the main factor determining the degree of branching in the resulting polymer. Polymers with degrees of branching ranging from 0.15 to 0.41 were synthesized. When 3-ethyl-3-(hydroxymethyl)oxetane was polymerized by slow addition of monomer to a core molecule, a lower degree of branching was obtained compared to the one-step synthesis with full conversion of monomer. The polydispersity was generally slightly lower when a core molecule was used than in the one-step homopolymerization of 3-ethyl-3-(hydroxymethyl)oxetane.

The preparation and characterization of a series of novel ferroelectric liquid crystalline dendrimers are presented. End-capping of 1-, 2-, and 3-generation dendrimers based on 2,2-bis(hydroxymethyl)propionic acid with mesogens gave surface-functionalized liquid crystalline compounds with 6, 12, and 24 mesogen-containing units, respectively. 4 -((R)-1-Methylheptyloxy)phenyl 4-(4 '-[10(hydroxycarbonyl)decyloxyl phenyl)benzoate was synthesized and used as a mesogen-containing unit. The purity and structure of each compound were determined by H-1 NMR spectroscopy, size exclusion chromatography, and elemental analysis. Differential scanning calorimetry and optical microscopy were used to investigate the mesomorphic properties of the mesogen-functionalized dendrimers. The materials displayed a variety of mesophases, including the smectic C* phase. All the liquid crystalline dendrimers showed ferroelectricity, and tilt angle and spontaneous polarization measurements were performed. The obtained results show that the ferroelectric properties of the materials are independent of the generation number of the dendritic scaffold.

The aim of this study was to improve the toughness of EB-cured acrylate thermost resins by using hyperbranched aliphatic polyesters as additives to obtain a liquid-liquid phase-separated resin. The ...

Moisture transport properties were assessed by sorption and desorption measurements on hydroxyl-functional hyperbranched polyesters based on 2,2-bis(methylol) propionic acid (bis-MPA) as AB(2)-mono ...

A research area that has obtained increasing interest during the last decade concerns improvement of macromolecular properties by changes in the macromolecular architecture. One group of these materials is dendritic polymers, which are highly branched structures exhibiting very different properties compared with linear polymers. One potential application for these polymers is as radiation curable thermoset resins. This article describes a study where the use of an aliphatic hyperbranched polyester as a base for new radiation curable thermoset resins. The hyperbranched polyesters have been characterized with respect to cure rate and final mechanical properties compared with conventional resins. It is shown that hyperbranched polyesters can be used as versatile scaffolds for various radiation curable resin structures.

Electron-beam curing of thermoset resins used in fiber-reinforced composites has been investigated. Two resins, a bisphenol-A acrylate and methacrylate, were used as model systems. The temperature was monitored during cure to know the thermal history of the composite during cure. The thermo-mechanical properties were measured on the cured samples. It could be seen that all these values were influenced by the nature (glass or carbon) and amount (0-50 wt.-%) of fiber. A linear correlation was found between the maximum temperature during cure and the glass transition temperature. It was shown that it is possible to compensate for a lack of heat during cure in systems with too low exotherms. Some influence on the network homogeneity was also noticed when the thermal energy available during cure was too low.

This work aimed to compare three different techniques to cure thick composite matrices to see the effect of the process on the network and the thermomechanical properties of the polymer matrix. Two ...

Highly oriented pyroelectric liquid-crystalline polymers were prepared by photopolymerization under the influence of a static electric field from binary mixtures of two acrylate monomers exhibiting chiral smectic C mesomorphism. Both monomers contained nitro groups to yield second order nonlinear optical properties (second harmonic generation) and one of the monomers had two functional groups to yield a crosslinked polymer. The room temperature second order nonlinear susceptibility of the polymers showed during the first two hours a 10 % decrease after which it remained constant during the next 48 days. At elevated temperatures there was a significant difference in the nonlinear optical properties over time between crosslinked and uncrosslinked polymers. The uncrosslinked polymer showed a pronounced loss of second order nonlinear optical activity with time at ≥38°C. The crosslinked polymer showed a much smaller and basically a temperature independent decrease rate in the second order nonlinear optical properties at all the ageing temperatures (23-130°C). Both the loss in mesogen order parameter, very evident for the uncrosslinked polymer, and conformational changes occurring within the mesogens (β mechanism), may account for the observations made.

Electron-beam (EB) curing of two epoxy resins, one acrylated and one methacrylated, has been investigated. The change in thermomechanical properties, such as T-g, and the change of residual unsaturation have been studied as a function of dose. These results, in combination with in situ measurements of the temperature during cure, have shown the importance of sample geometry for the final properties of the thermoset. The thermal history of the sample during cure greatly affects the properties of the cured resin. (C) 1999 Elsevier Science Ltd. All rights reserved.

Thermally initiated cationic ring-opening polymerization of 3-ethyl-3-(hydroxymethyl)oxetane was carried out using benzyltetramethylenesulfonium hexafluoroantimonate as initiator. The resulting hydroxy-functional polyether was thoroughly analyzed by 1H and 13C NMR spectroscopy and found to have a hyperbranched architecture with a degree of branching of 0.4. The polyether was successfully employed as a multifunctional initiator for e-caprolactone. Molecular weight measurements on the polyether showed a narrow molecular weight distribution analyzed by SEC and MALDI-TOF (1.3 and 1.4, respectively).

Low-loss optical waveguides have been fabricated from fluorinated copolymers designed to incorporate photochemical amplification based on acid catalysis. Core and cladding layers were made, for single-mode (SM) channel waveguides, from the poly(pentafluorostyrene-co-glycidyl methacrylate) copolymer series and, for multimode (MM) ridge waveguides, from poly(tert-butyl methacrylate-co-glycidyl methacrylate) as the cladding and poly(pentafluorostyrene-co-glycidyl methacrylate) as core layer. The reactivity ratios for PFS and GMA monomers have been measured to be r(PFS) = 0.38 ± 0.01 and r(GMA) = 0.89 ± 0.01 in free radical polymerization. Variation of the copolymer composition allowed precise control over the refractive index measured at 589, 633, 1320, and 1550 nm. These amorphous copolymers were photo-cross-linked by contact printing and developed by wet etching to produce high quality ridge waveguides with very smooth top surfaces. Low loss single-mode (SM) waveguides exhibit averaged losses over eight ch...

Living ring opening polymerization of e-caprolactone initiated from the numerous chain-end hydroxymethyl groups of the analogous dendrimeric and hyperbranched polyesters derived from 2,2-bis(hydroxymethyl) propionic acid is described. By controlling the size of the dendritic macromolecule and the molar ratio of e-caprolactone, a variety of highly branched radial block copolymers are obtained. Comparison of the results obtained for the dendrimeric and hyperbranched initiators demonstrates that the reactivity of the chain-end hydroxymethyl groups in the dendrimer are significantly greater than in the isomeric hyperbranched case. © 1998 John Wiley & Sons, Inc. J Polym Sci A: Polym Chem 36: 2793–2798, 1998

A hyperbranched hydroxyfunctional polyester based on 2,2-bis(hydroxymethyl)propionic acid as AB(2)-monomer and a tetrafunctional polyol as core was end-capped with five different alkylacyl chloride ...

The synthesis and cationic polymerization of the new monomer 4-(2,2-dicyanovinyl)-4'-(11-vinyloxyundecyloxy)biphenyl (6) is described. The dicyanovinyl group tolerated thermally initiated and photoinitiated cationic bulk polymerization using onium salts as well as the BF 3 .(EtO) 2 -initiated solution polymerization in CH 2 Cl 2 at -15 °C. Monomer 6 was crystalline, whereas poly(6) with increasing temperature exhibited coexisting S A d and S c phases, an S A d phase with extensive thermal stability and an isotropic phase. Poly(6) exhibited a glass transition at 20 °C.

A novel method of preparing thermally stable thin films with intrinsic second-order nonlinear optical activity is described. Design and synthesis yielded new ferroelectric bifunctional liquid crystalline acrylate monomer mixtures with a fast electro-optical response in the chiral smectic C (SmC*) phase. The ferroelectric liquid crystalline monomer mixtures were poled and subsequently cross-linked by in-situ photopolymerization in the surface-stabilized ferroelectric liquid crystal state. After cross-linking the polarization is no longer reversible, hence the material is pyroelectric and not ferroelectric. The cross-linked pyroelectric materials displayed a thermally stable nonlinear optical response.

The synthesis of the following monofunctional and bifunctional liquid crystalline p-vinylphenoxy-based monomers is described : 4-methoxyphenyl 4-[11-(4-vinylphenoxy)-undecyloxy)]benzoate (1), 4-cyanophenyl 4-[11-(4-vinylphenoxy)undecyloxy]benzoate (2) and 3-(4-vinylphenoxy)propyl 4-(4-[11-(4-vinylphenoxy)undecyloxy]benzoyloxy)benzoate (3). Both free radical and cationic polymerization of the monofunctional monomers 1 and 2 yielded side-chain liquid crystalline polymers exhibiting smectic A mesomorphism. The polymers exhibited high molar masses (M n = 40000 - 100000 g/mol) and relatively narrow molar mass distributions (M w /M n between 1.5 and 3). Ordered thin films were prepared by in-situ photopolymerization of monomers 1, 2 and 3 oriented in their nematic mesophases. Thin films of a thermally stabilized ordered side-chain liquid crystalline polymer were prepared by copolymerization of the monofunctional monomer 1 and the bifunctional monomer 3, the latter present in low concentration. The films regained orientation when cooled down from temperatures above the isotropization point (137°C) as evidenced by polarized FT-Raman measurements.

The synthesis of some new liquid-crystalline polymers with sulfonyl-containing mesogenic groups is described. 4-[(S)-(-)-2-Methylbutylsulfonyl]-4'-(11 -vinyloxy)undecyloxy]biphenyl (10-11), 4-[(S)-(-)-2-methylbutylsulfonyl]-4'-[8-(vinyloxy)octyloxy]biphenyl (10-8), 4-[(S)(-)-2- methylbutylsulfonyl]biphenyl 4-[11-(vinyloxy)undecyloxy]benzoate (12-11), 4-[(S)-(-)-2-methylbutylsulfonyl]biphenyl 4-(8-(vinyloxy)octyloxy]benzoate (12-8), 4-[(S)-(-)-2-methylbutyloxy]-4'-[11-(vinyloxy)undecylsulfonyl]biphenyl (18-11) and 2-[11-(vinyl-oxy)undecyloxy]-6-{4-[(S)-(-)-2-methylbutylsulfonyl]phenyl}naphthalene (23-11) were all synthesized, and polymerized with the initiating system CF 3 SO 3 H/S(CH 3 ) 2 in CH 2 Cl 2 at 0 o C. Monomers 10-11, 10-8, 18-11 and 23-11 are crystalline, while both 12-11 and 12-8 show an enantiotropic smectic A phase. All polymers exhibit the same thermotropic behaviour as their corresponding monomers, except poly(23-11) which exhibits an enantiotropic smectic A (s A ) and a monotropic chiral smectic C phase (s C * )

Hyperbranched, aliphatic polyesters of theoretically calculated molar masses 1200-44 300 were synthesized in the molten state from 2,2-bis(hydroxymethyl)propionic acid (repeating unit of AB(x) type ...