Efficient immobilisation protocols are the result of perfect matching of factors depending on the enzyme, the process and the support for immobilisation. Physical-chemical phenomena, such as partition, solvation and diffusion, strongly affect the efficiency of the biocatalyst in each specific reaction system. Therefore, tailored solutions must be developed for each specific process of interest. Indeed, direct investigation of what occurs at the molecular level in a reaction catalysed by an immobilised enzyme is a quite formidable task and observed differences in the performance of immobilised biocatalysts must be interpreted very carefully. In any study dealing with enzyme immobilisation the prerequisite is the rigorous planning and reporting of experiments, being aware of the complexity of these multi-phase systems.

There is an enormous potential for synthesizing novel bio-based functionalized polyesters under environmentally benign conditions by exploiting the catalytic efficiency and selectivity of enzymes. Despite the wide number of studies addressing in vitro enzymatic polycondensation, insufficient progress has been documented in the last two decades towards the preparative and industrial application of this methodology. The present study analyses bottlenecks hampering the practical applicability of enzymatic polycondensation that have been most often neglected in the past, with a specific focus on solvent-free processes. Data here presented elucidate how classical approaches for enzyme immobilization combined\ud with batch reactor configuration translate into insufficient mass transfer as well as limited recyclability of the biocatalyst. In order to overcome such bottlenecks, the present study proposes thin-film processes employing robust covalently immobilized lipases. The strategy was validated experimentally by carrying out the solvent-free polycondensation of esters of adipic and itaconic acids. The results open new perspectives for enlarging the applicability of biocatalysts in other viscous and solvent-free syntheses

Itaconic acid is ac hemically versatile unsaturated diacid that can be produced by fermentation and potentially it can replace petrol-based monomers such as maleic and fumarica cids in the production of curable polyesters or new biocompatible functionalized materials.U nfortunately,d ue to the presence of the unsaturated C=Cb ond, polycondensation of itaconica cid is hampered by cross reactivity and isomerization. Therefore,e nzymatic polycondensations wouldr espondt ot he need of mild and selective synthetic routes for the production of novelb io-based polymers.T he present work analyses the feasibility of enzymatic polycondensation of diethyli taconate and, for the first time,p rovidesc omprehensives olutions embracing botht he formulation of the biocata-lyst, the reaction conditions and the choice of the comonomers.C omputational docking was used to disclose the structural factorsresponsible for the low reactivity of dimethyl itaconate and to identify possible solutions.S urprisingly,e xperimentala nd computational analyses revealed that 1,4-butanediol is an unsuitable co-monomer for the polycondensation of dimethyli taconate whereast he cyclica nd rigid 1,4-cyclohexanedimethanol promotes the elongation of the oligomers.

A set of a hundred aromatic substituents were multivariately characterized by nine descriptor variables taken from the literature. From the 9*100 data set were calculated four principal properties for the aromatic substituents as the four first dimensions in a principal components analysis, PCA. The first three principal properties were used to develop a strategy for selecting substituents from eight subgroups according to a factorial design.